2014/2015/2016. The Stuart Half Beam Engine

Transcription

1 2014/2015/2016 The Stuart Half Beam Engine Ian s Home Projects 11/20/2014

2 The Stuart Turner Half Beam Casting Kit 1 The Stuart Half Beam Engine Table of Contents The Stuart Turner Half Beam Casting Kit... 3 Machining the Baseplate... 5 Bearings... 6 Various spindles, shafts, spacers, bosses and pins... 7 The Piston and Piston Rod... 9 The Cross Heads, Links and Levers Main Bearings The Pedestal The Crank The Glands The Steam Chest The Steam Chest Cover Bottom Cylinder Cover Top Cylinder Cover The A-Frames The Cylinder The Eccentric Sheave and the Eccentric Strap The Eccentric Rod and Eccentric Clevis The Flywheel The Beam The Connecting Rod and Big End Sleeve Bearing The Pulley The Assembly & Finishing... 46

3 2 The Stuart Half Beam Engine This page is left unintentionally blank.

4 The Stuart Turner Half Beam Casting Kit 3 The Stuart Turner Half Beam Casting Kit The Stuart Half Beam Engine is built from a kit given to me by Brenda for Christmas. The drawings are detailed in imperial sizes so being a child of the SI system I created a 3D CAD model in imperial units and then converted them to metric dimensions and recreated the drawings with metric dimensions for manufacture. I added limits and fits and some geometric tolerances where I thought it applicable. The final drawings are included in an appendix at the back of this document. Figure 1 - Stuart Half Beam 3D CAD Model The kit comes in a sturdy box with most of the parts vacuum packed; only the main castings are loose within the box. It is worth checking that all the parts are there. I was missing the casting for the pulley wheel, although Stuart Turner happily sent the missing item on to me when I requested it. The material supplied within the kit for the spindles was mostly carbon steel to imperial sizes. To maintain metric limits and fits (as the reamers and drills I own are nearly all metric) I purchased some metric stainless steel round bar and used this for the spindles and shafts. The stainless steel also polishes to a more pleasing lustre than the supplied carbon steel. I decided that it would be a good idea to record the process of building the engine in some kind of log. I had meant to do this when building the Stuart 10V Vertical steam engine completed last year. However, I kept forgetting to take the photos. I will try not to forget this time!

5 4 The Stuart Half Beam Engine Hopefully this will be something that is fun to look back on Figure 2 - Stuart Half Beam; The box it all came in Figure 3 - Stuart Half Beam; The contents of the box. Note I forgot and had already started to machine the base plate when I took this photo

6 Machining the Baseplate 5 Machining the Baseplate The Baseplate is one of the largest castings to be processed within the kit but certainly not the most complex. The edges of the casting were filed flat, true and square with respect to each other. I did contemplate machining the rear of the casting to ensure it was level when machining the raised pads. However, my machine does not have the lateral travel to machine the base completely. Therefore I opted to level the part on the machine table and using shims. This ensured that the minimal material had to be removed and that the machined pads would remain at a similar height and not become unsightly. Figure 4 - Preparing the Baseplate by filing Figure 5 - Machining the cast raised pads The raised pads were machined with a 14mm diameter cutter in two setups. The first, machining the cylinder, valve gear and crank bearing interfaces; the second, machining the beam support interface. Between each setup the part was re-levelled and clocked to ensure the flatness across the pads was less than 100 m. After machining the pads I marked out and centre punched the holes to be drilled and used the borer to drill the various holes. Those that required tapping were tapped carefully by hand to ensure the thread was square to the part. Finally, the underside of the Baseplate was filed flat to ensure that it sits evenly onto the surface plate without rocking. This will then sit down level on the base when that is made. Figure 6 Marking out the holes prior to drilling

7 6 The Stuart Half Beam Engine Bearings The bearings that constrain the Beam Support and the Valve Spindle assembly are manufactured from bronze alloy material that is supplied as an extrusion. The extrusion was mounted in the 4-jaw chuck and the ¼ diameter circular feature was clocked in to run true. Figure 7 Small Bearings being centre drilled Figure 8 Drilling and reaming each Bearing The 3mm hole was centre drilled, drilled and reamed out to the 3.0mm H7 tolerance and to a depth that exceeds the width of the final part. The Bearing was then parted from the extrusion. The part was de-burred and a reamer, run through the hole to clean up any deformation caused by the parting process. Figure 9 Small Bearings being Parted off Figure 10 Drilling holes in the base of each Bearing The holes in the base of each bearing were marked out with the height gauge on the surface plate. The markings were used as a visual guide to ensure that when the table was indexed, the centre drill was in the correct location. The bearings were held in a small toolmaker s vice and were then clamped to the table of the borer. The holes were then centre drilled and then drilled through at 2.8mm diameter. The parts were then each de-burred for trial assembly. All the bras components will be cleaned up using successively finer grades of wet and dry before using Brasso to provide a polished finish on final assembly.

8 Various spindles, shafts, spacers, bosses and pins 7 Various spindles, shafts, spacers, bosses and pins There are numerous shafts, spacers and spindles required for the Valve Gear, Beam and Crank Shaft. The material supplied in the kit is mostly carbon steel so I decided to purchase some stainless steel alternatives. Each of these parts was machined to drawing, taking special care to ensure minimise run out and to maintain the fit where required. A number of the Valve Spindles need to fit to levers. An easy running fit H8-f8 was used to for these parts. The Valve Spindles were turned to diameter ready for their and their corresponding holes to be reamed. All parts were held in a three jaw chuck with thin shim stock used to prevent the chuck jaws from marring the surface of the parts. The scroll of the 3 jaw chuck is kept clean and I have found that I can get a nominal dimensional repeatability of around 10-15um from this chuck. This allows me to turn the features on one end of the spindles, turn them around and machine them to length and put the features on the other end. Where the parts required a thread, such as the Valve Rod ; a die was used mounted in the tail stock die holder. The Crank Shaft and Crank Pin were machined with a close running fit H7-g6 to minimise the potential play in these parts. A precision run fit is used as the Crank is made from cast iron and the amount of strain needs to be minimised when it is fitted to the shaft. The Crank Shaft itself is a relatively simple component that only requires the feature to fit the Crank to be turned and the part can be faced to length. Figure 11 Turning the taper on the Beam Linkages The Crank Pin was machined in one setting. The two precision diameters, 6mm f8 and 5mm g6 were machined to size and faced to length. The M5 threaded portion, which is approximately 6mm long, was formed using a die mounted in the tailstock holder to ensure the thread was square and true. The final operation was to part off the pin from the bar stock. The Beam Linkage requires tapers to be turned on them, to give that bellied look. This was done by tilting the compound slide. The parts diameter reduces from 8mm to 5mm over a distance of 30mm.The angle was set by tilting the compound slide in increments and measuring the run out using a dial test indicator. We could quickly and accurately set the angle by ensuring a gradient of 0.5mm for every 10mm of compound slide motion. Once the taper was machined the parts were smoothed and polished with wet and dry before removing from the machine and final polishing with Brasso.

9 8 The Stuart Half Beam Engine The Beam Pivot Supports are machined from brass stock round bar. The female has the boss faced and turned to diameter and length. It is then centre-drilled to allow the part to be supported with a live centre whilst the radius is machined with a form tool. The process applies a considerable amount of force and the adequate support prevents the tool from chattering. Finally an M5 thread was drilled and tapped into the boss. The part was then taken out of the chuck and the part sawn off. The part was then held in the 3 jaw chuck by the boss. Thin sheet was used to protect the part from being marred in the jaws and the part was faced to length and a chamfer applied to the edge. Figure 12 Machining the Beam Pivot Supports Figure 13 Threading with the die in the tailstock The male Beam Pivot Support was machined using a similar process. However, the end was first faced and then lightly centre-drilled; deep enough to allow adequate support but not too deep to use up the remaining material. The radius was formed and the diameter for the M5 male thread was turned and faced to length. I then reversed the part in the 3 jaw chuck gripping the 5mm diameter portion and faced the part to length and chamfered the edge. The part was then reversed once again in the 3 jaw chuck and the M5 thread formed with a die in the tailstock die holder. Care was taken to ensure the orientation of the part in the chuck was maintained and thin sheet was used to prevent the jaws of the chuck marring the parts. Figure 14 Finished Beam Pivot Supports assembled to the Beam Linkages

10 The Piston and Piston Rod 9 The Piston and Piston Rod The Piston Rod was machined in the 3 jaw chuck. The surface finish of the Piston Rod requires a bit of extra care and attention as any damage to the surface will affect the seal at the stuffing box gland. I used thin sheet, shim stock to protect the rod whilst forming the threads at both ends and facing the rod to length. The O ring supplied as part of the kit for the Piston is an inch series BS 1806 type 210. This has an outside diameter that matches the 1 bore of the cylinder. Changing to a metric 25mm bore means that a change is required to the O ring and the groove machined on the piston. The closest metric equivalent is the BS 4518 type The groove was resized to match the O ring but I decided that due to the width of the piston I would slightly reduce the groove width. The remainder of the dimensions are as specified in the standard. The Piston was machined in the 3 jaw chuck. The clearance hole was centre drilled and drilled through. The counter bore feature was machined using a slot drill mounted in the tail stock. The outside diameter was left 0.25mm over size whilst the O ring groove was machined to the correct depth compensating for the larger outside diameter. The piston was then parted off. I did this slightly longer so that I could reverse the Piston in the 3 jaw chuck and face the part to length. The reason for leaving the outside diameter over-sized was to machine this when it is assembled to the Piston Rod. This will ensure the concentricity tolerance between the rod and the piston is maintained. The assembled piston and rod was mounted in the 3 jaw chuck by the Piston Rod. Again thin sheet was used to protect the surface finish of the rod. The outside diameter was then brought to size. Figure 15 Finished Piston Rod Assembly with O ring fitted With the Piston Rod assembly removed from the lathe and de-burred. The assembly was the thoroughly cleaned and degreased using brake cleaner from Carplan which was purchased for around 2 from local motor factors. The O ring was then fitted and the Piston Rod polished using Brasso.

11 10 The Stuart Half Beam Engine The Cross Heads, Links and Levers The Valve Shaft Cross Head is made from 6.35mm square bar. The square bar was clocked in to the 4 jaw chuck to better than 10um. Then the cylindrical feature was turned to diameter and length, the hole for the valve shaft drilled and tapped and the component parted off to length. Figure 16 Machining the Valve Cross Head Figure 17 Drilling the Valve Cross Head The hole for the Valve Spindle was marked out and drilled to 3.8mm before reaming to 4mm H8. The part was then de-burred and cleaned up. The remainder of the 6.35mm square section bar is for the manufacture of the 2 off Valve Levers and the 1 off Eccentric Lever. Both parts are very similar, though the Valve Levers have a clevis machined into one end to allow for the Valve Linkage. Figure 18 Valve Levers, Spindle and Rod Assembly Each of the levers was faced on one side and then reversed in the chuck and faced to length. The 3mm holes were marked out, drilled to 2.8mm diameter and reamed to 3mm H8. The two Valve Levers were then mounted on the milling machine and the slot drill used to machine the clevis. The rectangular bar stock for the Beam Cross Heads was clocked into the 4 jaw chuck to better than 10um. The diameter of the boss feature was machined and faced to length. The thread then drilled and tapped using the tailstock to guide the tap to ensure the thread was square and true. The Beam Cross heads were then parted off and faced to length. I re-clocked the bar stock into the 4

12 The Cross Heads, Links and Levers 11 jaw chuck for every one of the crossheads to ensure that the boss feature on each of them would be central to the bar stock. The parts were then mounted on the mill and a slot drill used to drill down and machine the material away to make the square form of the clevis. The remaining material was removed by using the side cutting action of the cutter. Incremental cuts were then taken to ensure the depth and gap between the clevis was correct and even about the central axis defined by the boss. Once this was completed the distance across the outside of the clevis was brought in by milling each of the half of the clevis to size. The 3mm hole was marked out, drilled to 2.8mm diameter and reamed to 3mm H8. The radius at the end of the clevis was then carefully filed on each of the cross heads. Figure 19 Machining the Beam Cross Head boss Figure 20 Milling the Beam Cross Head clevis to size The Piston Cross head was manufactured in a similar way. The main difference is the orientation of the part with respect to the milling cutter when the radius form of the clevis is machined. An 8mm slot drill was used to bore a series of holes these were then milled out to form the clevis. Figure 21 Machining the Piston Cross Head Figure 22 Milling the Piston Cross Head clevis to size

13 12 The Stuart Half Beam Engine Again a series of incremental cuts were taken to ensure the depth and gap between the clevis was correct and even about the central axis defined by the boss. The crosshead was milled to size on each of the four sides in turn. The 3mm hole was marked out, drilled to 2.8mm diameter and reamed to 3mm H8. The radii at the ends of the clevis were then carefully filed on each of the cross heads. Figure 23 Machining the Piston Cross Head The Link Arms for the valve gear were manufactured from the supplied carbon steel flat bar. In an attempt to make the profiles identical the two pieces were mounted back to back with double-sided tape. The holes were then drilled using the borer and the outline marked on and the profile filed using a combination of round and half round files. The surfaces were then cleaned up using a series of needle files. Figure 24 Filing the Link Arms Figure 25 Finishing Link Arms with wet and dry The parts were then split with a razor blade and the two main faces filed to bring the thickness to size. The edges were draw filed with the needle files and the faces of each link was ground using wet and dry paper on the surface plate. This process was continued until all the file marks had been removed. The parts were then ready for trial assembly and then polishing.

14 Main Bearings 13 Main Bearings The Main Bearings are machined from a bronze alloy that is supplied as an extrusion which has the correct approximate shape and size. I had wanted to split the bearings to allow for wear over time. However, after checking the size of the supplied material it quickly became apparent that the there was insufficient material to allow for this. Therefore, the Main Bearings were manufactured without the split as detailed in the Stuart drawings. The material was mounted in the 4-jaw chuck and clocked in, to minimise the run-out on the curved feature at the top of the bearing extrusion to better than 50um. This ensures that the position of the centre of rotation is within an acceptable tolerance to the location of the bore required for the main shaft. The next task was to face the material and form the cylindrical boss. Figure 26 Facing the Main Bearing stock Figure 27 - Machining the cylindrical boss The hole for the Crank Shaft was then centre-drilled and bored out undersize to nominally 10mm. To ensure the bore is perpendicular to the faces of the Main Bearing the bore is not finished until the other faces of the part are machined. Figure 28 Main Bearing faced to length Figure 29 Bore drilled and reamed 12mm H7 With the 10mm bore defining the bearing axis I removed the part from the chuck and sawed it into two equal parts. I re-chucked the first bearing clocking in the bore and tapping the machined face back onto parallels to ensure the part was reasonably square. The part was then faced to length and

15 14 The Stuart Half Beam Engine the boss feature machined. The 10mm was drilled out to 11.5mm diameter and then reamed to a diameter of 12mm H7. The second Main Bearing was machined in a similar way by clocking in the 10mm diameter bore and machining the main faces and cylindrical boss before drilling and reaming the bearing diameter to size. The two bearings were then assembled to the Crank Shaft this co-locates the two Main Bearings relative to one another to ensure that they will be machined relative to one another. The assembly was then clamped to the machine table of the borer and clocked in to ensure that the minimum of material was removed to clean up the interface surface. The surface was milled removing only 150um of material to bring the surface to form and size. The clearance holes for mounting the bearings to the baseplate and support pedestal were then centre drilled and drilled 5.0mm through to suit the 2BA fasteners. Figure 30 The Main Bearings Assembled to the Crank Shaft. The parts were then cleaned up with a file and emery paper. On assembly I intend to polish these parts with Brasso Note: Not only did I find that the material stock was not sized to allow the Main Bearings to be split but they were not quite tall enough to obtain the 22mm (Stuart Drawing specifies 7/8 ) dimension from the axis of the crank bore to the base of the part. Even with cleaning up a very small amount around 150um I could only get this dimension to nominally 21mm. I did this for both bearings and checked the effect on the CAD model. In fact the change meant that the piston stroke was much more central to the cylinder than it had been with the bearings at 22mm. An Improvement all around!

16 The Pedestal 15 The Pedestal The Pedestal is like many of the components supplied as a casting. It tapers from the base to the surface that interfaces to the Main Bearing. The part was set down on parallels with a packing piece used to set the part level. The base surface was then orientated to keep the pedestal nominally orthogonal and then machined to provide a datum surface. Once complete the table was indexed and the top surface machined and the part brought to the correct height. Figure 31 The mandrel used to machine the Flywheel With the mating surfaces machined and parallel the part was removed from the mill and the holes for the base and the bearing were marked out and centre punched. The part was then clamped to the vertical slide mounted on the cross slide of the lathe. The clearance hole in the base were then machined, the part was then reversed and aligned to allow the holes for fixing the Main Bearing to be drilled. These holes were then tapped by hand on the bench. The part was then finished by removing the flash and casting marks with a file.

17 16 The Stuart Half Beam Engine The Crank The casting required filing all over to remove the flashing left from the casting process. The Crank was mounted in the 4-jaw chuck and the larger of the two bosses clocked in to run true. Machining the castings does require some thought and planning to ensure that the components are finished to the correct nominal sizes and that you do not run out of material. I took time to calculate how much would have to be removed from the various surfaces in each of the machining operations to maintain the components nominal dimensions. I marked the drawing up to indicate the depth of cut of each of the surfaces being machined. Figure 32 The Crank in the 4-jaw chuck Figure 33 Crank bore drilled and reamed The main boss that interfaces to the Crank Shaft was faced and enough material removed to ensure the part would be at nominal size when the crank web (on the other side of the part) was machined to size. The smaller boss that interfaces to the Crank Pin was faced and machined to ensure the offset dimension between the two surfaces was nominally correct. The boss was then centre-drilled, pilot drilled to 5.5mm diameter, drilled out to 9.5mm diameter and then finally reamed to a diameter of 10mm H7. The fit with the shaft was checked and the edges of the bore broken to allow a snug fit of the Crank Shaft to the Crank. Figure 34 Drilling and Pinning the Crank

18 The Crank 17 The Crank and Crank Shaft are assembled and mounted into the vertical slide where the assembly is drilled for pinning. A 2mm diameter hole machined though the boss feature of the Crank and the Crank Shaft. This hole is then reamed by hand to suit the tapered dowel. With the dowel in place the Crank and Crank Shaft assembly can be mounted in the 3-jaw chuck. Thin sheet was used to prevent the jaws of the chuck marring the parts and the Crank web machined to bring it to the correct dimension. Figure 35 Facing the Crank to size The Crank was then removed from the Crank Shaft by removing the tapered pin and mounted to the borer using the small tool makers vice. The dimension of the hole centres are given as 17.5mm (11/16 ). However, this means the hole would not be central to the boss feature. In this case, the actual dimension takes only a secondary importance over the aesthetic; it was modified to 17.8mm and the hole located at the nominal centre of the boss. The hole was then centre drilled, drilled to 4.8mm diameter and reamed to size of 5mm H7. Figure 36 Drilling the Crank

19 18 The Stuart Half Beam Engine The Glands The material supplied in the kit for the glands is a brass elliptical shaped extrusion. This generally simplifies the machining operations to reasonably simple turning operation. The material is held in the 4-jaw chuck and centred to run true using a dial test indicator to equalise the minima and maxima readings. The machining operations for each of the glands are basically identical. The gland boss is faced and turned to length. (See figure below) The bore is then centre drilled, drilled and then reamed for the piston and valve glands. The steam port gland is then drilled and tapped. The gland can then be parted off the bar at length. Two off of the steam port glands were made, one for the steam chest and a second for the exhaust port. Figure 37 - Machining the Piston Gland Figure 38 Drilling the flanges Each gland requires two additional holes to be machined into their flanges. These holes are marked out and drilled with their corresponding parts to ensure the parts to ensure alignment. A centre drill is used to provide an accurate pilot to ensure both holes are in position. The holes are then drilled through at 2.8mm for clearance for a 7BA thread. The parts are then de-burred and polished using a fine abrasive. These parts will be polished with Brasso prior to assembly.

20 The Steam Chest 19 The Steam Chest The Steam Chest requires filing to clean up the flashing in particular in the central bore for the slide valve. The drawings from Stuart do not indicate that machining of the external surfaces is required. However, the split mould line was very clear and there was an offset between the two halves of the casting. So I decided to machine each face that I could, the face with the valve stuffing box port not being practical because of the shape of the gland interface. Each surface was machined removing only the minimal amount of material to ensure the surfaces cleaned up. This did bring the surfaces only fractionally under size but I am happier with the overall appearance. Figure 39 Machining the Steam Chest boss feature Figure 40 Machining the external faces Once again I surveyed the part and marked up the drawing to show the depth of cuts required to bring the part to size. The casting was then mounted in the 4-jaw chuck and the cylindrical boss was clocked in to run true. The part was awkward to hold in the chuck so packing pieces were used to ensure the grip was firm without over tightening. As this may result is a cracked casting, something we want to try to avoid! The boss was turned to a diameter of 7.5mm, at which point the adjacent surface was cleaned up. I faced the boss to a length of 9.5mm and machined a radius feature. See Figure 39. The part was then repositioned in the 4-jaw chuck to machine the two sides of the casting whilst trying to maintain the 35mm width dimension. Care was taken to ensure that the machined surfaces were square to each other. This is important not only for aesthetic reasons but also because these surfaces will be used to hold the steam chest whilst the port faces are machined. The faces cleaned up with a width dimension of 34.7mm which is acceptable at 0.3mm below size and a length dimension of the rectangular portion of 38.9mm which is only 0.1mm below size. With the sides of the Steam Chest, now machined, the part was re-orientated in the 4 jaw chuck and the port face clocked in to ensure it was square to the machine. The face was machined to size with the gland port boss used as a reference. The part was then reversed in the chuck tapped down onto parallels and the opposite face brought to size nominally 11.5mm. The two port faces were parallel to around 50um. See Figure 41 The next operation was the machining of the interface for the Valve Rod and the Valve Gland the part was again re-orientated into the 4-jaw chuck and the valve port boss was clocked in. The boss

21 20 The Stuart Half Beam Engine was then faced, and centre drilled. The 3mm and 6.5mm hole features were then drilled into the boss. See figure below. Figure 41 Machining the Steam Chest port face Figure 42 Machining the Valve Gland Interface It was at this stage where I hit a bit of a problem. The design requires a 2.5mm diameter hole to be drilled to depth of 51mm from the face of the Valve Boss. Its purpose is to guide the Valve Rod as it moves back and forth. Unfortunately when I drilled this hole, the drill wandered on the cast surface and the hole was out of position. I machined a piece of mild steel to 2.5mm diameter and filled the hole. It was bonded in with Loctite 638 and left it overnight. Then, the following morning, filed the face flat. Using a pistol drill I carefully re-drilled the hole. This was tricky as the drill bit desperately wanted to wander again. I would suggest that this operation is done with great care and with plenty of visibility of where the drill contacts the cast material. However, after a small amount of fitting work with the gland in place I was able to ensure the valve rod ran nice and smoothly in the Steam Chest. Figure 43 Marking out the Steam Chest port face Figure 44 Machining the Valve Gland Interface The remaining holes were then machined into this component. The first a set of 6 through holes 3mm diameter was marked out on the surface plate and then drilled using the borer. The second a set of 2 blind 7BA tapped holes to secure the Valve Gland were drilled through at 2.0mm and then tapped on the bench and the Valve Gland drilled out for 7BA clearance.

22 The Steam Chest Cover 21 The Steam Chest Cover The material for the cover of the steam chest is supplied as a cast blank. The surface finish was quite rough and the part looked like it was open cast. I held the part in the 4 jaw chuck. The part is thin at around 5mm thick and so work holding has to be done with care. I tapped the part down onto a parallel and sequentially tightened each of the jaws taking great care not to over tighten the chuck. The intermittent cut required the spindle speed to be set to no more than 150 RPM. The part was then faced until the entire surface cleaned up. The part was then reversed in the 4 jaw chuck and again tapped down onto a parallel. The part was then faced to a length of 3mm. The work holding was tricky and I struggled, but managed to achieve a parallelism of better than 0.2mm for this part. The outer dimensions were then brought to size by filing. I did consider machining these edges. However the part is so close to the final dimensions of the Steam Chest there is very little work to do. Figure 45 Drilling the 7BA clearance holes Figure 46 Marking out steam port gland holes There are 3 sets of holes that require machining into the Steam Chest Cover. The first are the clearance holes for the 7BA studs that mount the Steam Chest and the Steam Chest Cover to the Cylinder. These were drilled through from the Steam Chest to ensure they were well matched. The remaining 3 holes; the two 7BA threaded and the 5mm diameter steam port, were marked out, centre punched and drilled using the borer. The 5mm diameter hole was pilot drilled at 3mm before finishing at 5mm. The 7BA holes were drilled through at 2mm diameter and then tapped on the bench. The holes in the steam port gland were marked out and drilled to 2.5mm to provide clearance for the 7BA fasteners. Figure 47 Drilling the 7BA clearance holes

23 22 The Stuart Half Beam Engine Bottom Cylinder Cover The Bottom Cylinder Cover is machined from a relatively thin square section casting with a similar thickness to the Steam Chest Cover. This was again mounted in the 4-jaw chuck, the part tapped down on to parallels. Care being taken not to over tighten the chuck. The cast boss feature was clocked in so that the part was reasonably well centred. The boss feature and the Main Cylinder mating surface were faced and brought to size. The diameter of the boss was then machined, bringing it to ф25mm f8. The intermittent cut meant that the RPM and feed rates had to be kept low. Figure 48 Machining the location boss Figure 49 Machining the part to size The part was then reversed, and the part mounted in the chuck via the boss feature. Thin shim stock was used to protect the machined surface of the boss from damage from the jaws of the chuck. The surface was then faced and the plate machined to the final thickness. The spindle speed and the feed rate were kept at low until the surface was cleaned up.

24 Bottom Cylinder Cover 23 The rotary table was set up on the cross slide. The centration of the rotary table was achieved by clocking in the chuck by mounting a DTI to the lathe spindle and measuring the run-out. The lateral adjustment was achieved using the cross slide. The vertical was more subtle as this required shimming. Using shim stock I was able to get the rotational centre to within 50um. The Bottom Cylinder Cover was mounted in the rotary table chuck via the cylindrical boss feature. The part was brought to vertical using an engineer s square from the bed of the cross slide. The first set of holes was equally spaced on a PCD. These were marked out with a scribe mounted in the lathe chuck; the position of each one being indexed around with the rotary table. The positions were then checked and the holes then centre drilled, drilled to size before they were countersunk. The second set of holes were on a square pitch, but were also centred on the axis of the part. So, I decided to calculate the relevant angle 45 degrees in this case and PCD for the holes. The holes were then marked out, again using the scribe in the lathe chuck. These positions were then checked using the linear pitch dimensions as the reference. Each of the holes was centre drilled, then drilled to size. Figure 50 The Rotary Table used to index the holes during drilling operations

25 24 The Stuart Half Beam Engine Top Cylinder Cover The Top Cylinder Cover is machined from a shaped casting. As with the other cast components care and planning is required to ensure that the finished sizes can be achieved. Initially the part was set up in a 3-jaw chuck via the chucking piece that forms part of the casting. The gland port face and the bolting face were machined, leaving a 25mm diameter by 2mm thick cylindrical feature of cast material. The holes for the gland, the 5mm and 8mm diameter holes were then drilled into the face. Figure 51 Drilling the Gland Boss The part was then reversed in the 3-jaw chuck and mounted on the 25mm diameter boss. Thin shim stock was used to protect the machined surface of the boss from being bruised and the chuck only lightly tightened. The intermittent cuts caused the part to flex at the corners making controlling the thickness more difficult. Light cuts of around 30 m to 50 m were then taken to bring the square section to the correct thickness. The cylinder location boss was then turned to the correct diameter, ф25mm f8 and then faced to length. To ensure the part can be accurately located onto the rotary table for drilling the cylinder interface the chucking piece was machined to ensure it was concentric with the location boss. Figure 52 Machining the Location Boss

26 Top Cylinder Cover 25 The rotary table was set up on the cross slide and the axis of the table clocked into the axis of rotation of the chuck. The required adjustments were made as discussed previously. The part was mounted in the rotary table chuck via the chucking piece. The part was brought to vertical using an engineer s square from the bed of the cross slide. Figure 53 Rotary Table mounted to the Lathe The first set of holes, that interface to the cylinder, were equally spaced on a PCD. These were marked out with a scribe mounted in the lathe chuck; the position of each one being indexed around with the rotary table. The positions were then checked and the holes then centre drilled and then drilled to size. The second set of holes were on a rectangular pitch, but were again centred on the axis of the part. So, I decided to calculate the relevant angles and PCD for the holes. The holes were then marked out, again using the scribe in the lathe chuck. These positions were then checked using the rectangular pitch dimensions as the reference. Each of the holes was centre drilled, then drilled to size. Figure 54 Drilling the 7BA clearance holes Figure 55 Marking out steam port gland holes

27 26 The Stuart Half Beam Engine The part was then mounted in the 3-jaw chuck and the chucking piece removed and the face of the location boss cleaned up. The final operation was to drill and tap the two threaded holes for the gland. This was done by spotting through the holes drilled into the gland and then drilling the two holes in the boss using the borer. The two holes were then tapped to 7BA and the gland trial fitted. An alternative method of machining the part, possibly more accurate came to mind during the machining of this part. If I was to do this again I would probably follow this procedure: Mount the part in a 4-jaw chuck via the square portion with the chucking piece facing outwards. Clock in the cast boss feature so that the part is reasonably well centred. Machine the Main Cylinder mating surface and turn and face to length the location boss. At this time machine the chucking piece to ensure that when the part is reversed and mounted in the 3-jaw chuck the features machined will be nominally concentric to the location boss. Reverse part mount in the 3-jaw chuck. Machine the gland port face and drill the holes as required. Machine the boss feature and the bolting face. Machine the holes on the PCD s using the rotary table. Re-mount the part in the 3-jaw chuck via the gland port boss and face off the chucking piece, bringing the cylinder location to size.

28 The A-Frames 27 The A-Frames The A-Frames are supplied in the kit as two identical castings that require filing to remove the flashing and casting marks. Extra care was taken when filing the outer edges of the parts so that they could be polished. A range of files were used from a fine second cut to a needle file that could access the rather hard to reach areas. Figure 56 Filing the A-Frame removing the casting marks Periodic checks of the surface were made using a surface plate and engineers blue. The high points Identified were then filed in an attempt to keep the surfaces reasonably flat. The next stage was to polish the edges with progressively finer grades of wet and dry on the surface plate.. Figure 57 Removing the filing marks

29 28 The Stuart Half Beam Engine This removed any machining marks and brought the parts to a reasonable finish. Oil was used with the wet and dry to assist with the polishing process. The A-Frames were then mounted in toolmakers vices and clamped to the milling table. The parts were then machined along the face that mates with the Top Cylinder Cover. This brought the overall height of the components to 77mm from base to apex. Figure 58 Machining the base of the A-Frame The part were then removed from the vice and clamped directly to the milling table. The raised edges were then machined to bring the part to the correct thickness. This required approximately 0.5mm to be removed from each side, bringing the width of the part to 6mm. It is important to note that these parts will be clearly visible in the final assembly and so care was taken to ensure that as far as possible a reasonably uniform distance remained between the machined lips and the lower cast area to maintain the aesthetic. Figure 59 Machining the A-Frames raised features

30 The A-Frames 29 The faces of the parts were then polished with progressively finer grades of wet and dry on the surface plate. Figure 60 Comparison of the A-Frame before and after The holes were then marked out on a surface plate with the height gauge. With the parts aligned and clamped to the table of the borer, the spindle was positioned to drill the hole in the apex of the A-Frame. The hole was centre drilled and then drilled to size. The table was then indexed to the position of the second hole which was centre drilled and then drilled to size. Figure 61 Drilling the clearance holes in the A-Frame The last pair of holes in the base of the A-Frames were drilled using the vertical slide on the cross slide of the lathe. The holes were marked out on the surface plate with the height gauge and the parts then clamped to the vertical slide. To ensure that the holes were drilled reasonably square, the other A-Frame was used as a setting piece. The position of the holes was then checked using a scribe mounted in the chuck as shown in the figure below. The holes were then centre drilled and then drilled to a 2.5mm diameter; the cross slide being used to index between each position. The holes were then tapped 5BA on the bench.

31 30 The Stuart Half Beam Engine Figure 62 Holes being marked out ready for drilling and tapping in the base of the A-Frames. The parts were then ready for a final polish with wet and dry to remove any remaining marks and then finished with Brasso. However, before that a trial assembly of the A-Frames together with the Top Cylinder Cover, Beam Pivot, and Piston assembly was carried out to ensure the parts fitted well. Figure 63 A-Frames, Top Cylinder Cover, Beam Pivot trial assembly

32 The Cylinder 31 The Cylinder The casting supplied for the cylinder was excellent and only required a small amount of preparation. There was some flashing around the ports in the bore and mould marks along the centre line of the part, both of these were removed using a file. Time was taken to dimensionally assess the casting and plan the operations and each face to be machined was marked with the amount of stock removal with an indelible marker. Figure 64 Cylinder mounted in the 4-Jaw Chuck Figure 65 Marking out steam port gland holes The first step was to machine the interface for the Steam Chest. The cylinder was mounted into the 4-jaw chuck using the recess for the jaws to work as a location for the round section of the cylinder. The face to be machined was orientated using an engineer s square off the saddle to minimise the metal to be removed from this face. Shim stock was used to prevent the chuck jaws from marring the cast surface. As the cuts initially were intermittent only small cuts were taken at a low speeds. The spindle speed was increased for the last cuts and the feeds reduced. The cylinder was then set up on a Keats angle plate that was mounted to the lathes faceplate. The cast bore was centred using a combination of the centre on the tail stock and a DTI. The bore was located to within 0.5mm of total run out. Figure 66 Cylinder boring

33 32 The Stuart Half Beam Engine The cylinder end was faced removing nominally 1mm of material. It was then bored through to 25mm diameter H7 tolerance as specified for the O Ring (BS 4518 type ) in the same setting to ensure the bore and the top end face are perpendicular. This is important as it will ensure the piston can run true in the cylinder without binding. The cylinder was then reversed in the Keat s angle plate using the port face again as the reference and the reverse, bottom end was faced. Nominally 1mm was removed to bring the length of the cylinder to within tolerance. The parallelism of the two faces was checked using the surface plate and the height gauge and found to be within 100 m. The cylinder was then mounted on to some 25mm diameter ground silver steel. The cylinder bore was a snug fit and a small amount of tape held the part fast. The six holes in each of the end faces were then indexed and drilled. The figure below shows the arrangement. Care was taken to ensure the drill did not break through and the holes were each drilled to a depth of 3.5mm. Figure 67 Drilling the holes in the Cylinder end faces Figure 68 Port face holes drilling The port face holes were then marked out on the surface plate using the height gauge. The holes were marked relative to the top end face. So this face was placed on the surface plate. The top end face is the one faced at the same time as the Cylinder was bored. As stated previously this was done to ensure it is perpendicular and that the piston will run true.

34 The Cylinder 33 The Cylinder was then set up on the vertical slide. Packing was used to ensure the port face was square to the chuck. Then each of the holes was centre drilled and then drilled to depth. Each of the sets of holes, both those in the end faces and those on the port face were then tapped on the bench. Due to the shallow depth of the holes it was necessary to grind the end of the tap flat to allow the tap to thread to the full depth of the hole. Once these operations were complete the whole Cylinder Sub Assembly could be trial assembled. This allowed both the Cylinder and Baseplate assemblies to be brought together for trial assembly. This can be seen in the figures below. Figure 69 Cylinder Sub-Assembly Figure 70 Cylinder and Baseplate Assembled

35 34 The Stuart Half Beam Engine The Eccentric Sheave and the Eccentric Strap The Eccentric Sheave is machined from a piece of cast iron round bar that is supplied in the kit. The cast iron is used as it will run smoothly on the gun metal material supplied for the eccentric strap. The bar was mounted in the 4-jaw chuck and clocked in to run concentrically. The part was turned to the OD which is a general tolerance along a length longer than that of the part. The two concentric features that form the bearing surfaces were then machined to the f8 tolerance. The length of first feature includes the length of the both the bearing surface and the boss to be machined eccentrically. The second bearing surface forms the location rib. The length and location of the second bearing surface has to ensure the thickness of the location rib is within tolerance and that the bearing surface is long enough to get the whole part from the bar. See Figure 71 below. Figure 71 Turning the Eccentric Sheave Bearing Surfaces Figure 72 - Machining Eccentric Sheave boss The part was then decentred in the 4-jaw chuck. A dial test indicator was used to ensure that the boss would be machined with the correct offset. It should be remembered that the offset is half of the full scale deflection indicated. This allows us to position the part with a reasonable degree of precision with a 10um DTI. The boss was then machined to diameter and length. The bore was centre drilled and then drilled out to 11.5mm before finally reaming the hole to achieve the ф12 H7 tolerance required. The part was then be parted off from the stock and mounted in a 3-jaw chuck by the boss feature. Shim material was used to protect the finished surfaces from being marred by chuck jaws. The part was then faced to length and the small boss feature machined. The part was removed from the lathe and mounted in the mill to drill and tap the 5BA securing screw. Figure 73 The Eccentric Sheave machined to size

36 The Eccentric Sheave and the Eccentric Strap 35 The Eccentric Strap is machined from a bronze extrusion. The stock, as supplied was measured and the machining allowances were marked on the part and the drawing. The first step is to bore the two 2.5mm clearance holes that will be used to join the two halves of the strap together. These are located on the approximate centre line of the part to allow an even amount of stock removal from the front and rear faces. The strap can then be removed from the vertical slide and sawn along the line marking that is part of the extrusion. The joining faces were checked and the two mating faces were machined so that the lugs were nominally 6mm thick. Figure 74 The Eccentric Strap Reassembled Figure 75 Facing the rear of the Eccentric Strap The part was then bolted together using the 5BA screws that come with the kit. The centre of the parts was then marked out and the part set up in the 4-Jaw chuck. The rear face of the component was set facing away from the chuck and this surface was machined to size. The rear surface now becomes the datum and the part is then drilled and bored out to size. The diameter 27mm H7 bore was checked against the eccentric to ensure it would run smoothly. The retaining groove that keeps the Eccentric Sheave in place was then machined. Figure 76 The Eccentric Strap Bored Figure 77 Milling the rebate the Eccentric Strap The part was then revered in the chuck and re-centred and the front face machined to size. The part was then moved to the milling machine. The part was clamped to the machine table and the rebate for the area that connects to the Eccentric Rod was produced. The two holes were then added to suit the holes drilled into the Eccentric Rod. This operation was left until the assembly to ensure that the parts were correctly integrated.

37 36 The Stuart Half Beam Engine The Eccentric Rod and Eccentric Clevis Both the Eccentric Rod and the Eccentric Clevis are produced from carbon steel flat bar stock that is supplied with the kit. The length of the rod according to the model is 116mm long. However, I have decided to finish this part once the remainder of the assembly is complete so that I can be sure to set the length correctly. However, the three holes at the valve end of the part can be marked out and then drilled at 2.6mm diameter for the pair that connect to the Eccentric Clevis and drilled and reamed for the 3.0mm diameter H7 hole, that connects to the valve gear. In addition to this, the radius was formed at the end by filing. Figure 78 The Eccentric Rod and Eccentric Clevis Figure 79 The Eccentric Rod and Eccentric Strap The Eccentric Clevis is slightly more complex, in that the position of the holes and the bend are quite critical. The first stage was to bend the part to provide a 6mm offset. This was hard to do to sub millimetre accuracy but I was happy with the 7mm offset I achieved. The 3mm diameter H7 hole was then drilled and reamed and by aligning this to the 3mm hole in the Eccentric Rod the radii could be filed to match and the holes could then be marked through and any adjustments required to the Eccentric Clevis could be made. With the connection to the Valve Lever complete, the length of the Eccentric Rod could be assessed on the full assembly. The 116mm length appeared correct and so the part was cut to length and the connection drilled to the Eccentric Sheave. The part was then ready for assembly to the Crank Shaft. <Picture of the Eccentric Assy after >

38 The Flywheel 37 The Flywheel The Flywheel casting is one of the larger castings to be machined. The flash and other casting marks were removed with a file and the part measured and the depth of cuts determined for each of the surfaces. The casting was mounted in the 4-jaw chuck with the jaws set to clamp on the internal surface of the rim of the flywheel. Figure 80 Centring the Flywheel Figure 81 Machining the Flywheel Boss The wheel was centred and the run out reduced on the central boss and the lip to around 300um on the cast surface. The first operation was to face and turn the boss to size before drilling and reaming the 12mm H7 diameter hole for the Crank Shaft. The hole was initially centre drilled then drilled through at 6mm diameter and then 11.8mm diameter before reaming. The next step, whilst the Flywheel was held in the 4-jaw chuck was to face and turn the outer rim. By machining this in one setting ensured that both the boss feature and the rim of the Flywheel remained concentric. Figure 82 Keeping the Boss and Rim concentric Figure 83 The Flywheel mounted on a mandrel After these operations were completed, I machined a mandrel from some 18mm diameter carbon steel stock. In fact it was the other end of the mandrel that I had machined for the Stuart 10V Flyweel. The mandrel was turned to a 12mm g6 diameter and terminated with an M8 thread to secure the Flywheel. The mandrel was mounted in the 3-jaw chuck and the Flywheel was secured against the shoulder with the un-machined parts facing towards the tool post. As the lathe was spun up the Flywheel could be seen to be running true. The second boss feature was then faced and turned to size and the last face of the rim was faced to bring the Flywheel rim to width. Care had to be taken with the

39 38 The Stuart Half Beam Engine spindle speed as the tool was liable to chatter. I reduced both the speed and the feed for the final cut and the finish was good. Figure 84 The mandrel used to machine the Flywheel The last operation was to drill and tape the retaining screw in the Flywheel boss the hole was drilled with a pistol drill and tapped by hand on the bench. Figure 85 The finished Flywheel

40 The Flywheel 39 The Beam Support The Beam Support is supplied as a casting and requires finishing in a similar way to the A-Frames. Initially the part was supported by a parallel and clamped to the table of the borer. The two faces were machined to allow the relief pattern to be polished at a later date and to bring the part to the correct thickness. The bottom edge was then milled to provide a reference edge and the inner surfaces of the yolk were cleaned up. Figure 86 Machining the Bean Support Figure 87 Removing the file marks The outer edges were then filed smooth to remove the features left over from the casting process. The bulk of the material was removed with a second cut file. A needle file was used to remove the marks left by the file and then the edges were treated with progressively finer grades of wet and dry. This was done on the surface plate top maintain the square edge of the part. A small amount of oil was used to improve the finish. Figure 88 The finished Beam Support Finally the two faces were polished with wet and dry and a small amount of oil to remove the machining marks and bring the surfaces to an even finish ready for polishing for polishing.

41 40 The Stuart Half Beam Engine The Beam This rather simple looking casting along with the steam chest caused me the most difficulty in machining to a satisfactory state. I started off by cleaning up the outer flanged surfaces with a file. There were a couple of small features left from the casting process that needed to be removed and the whole of the outer rim of the beam needed to be cleaned up ready for polishing. I started with a second cut file before moving to a needle file and then to wet and dry laid on the surface plate with a small amount of oil. Figure 89 Dressing the Flanged surfaces of the Beam The beam was then supported on parallels and clamped to the borer table. The bosses and rim of the flanged edge brought to the correct thickness. The four holes were then marked out on the surface plate with the Vernier height gauge. Figure 90 Milling the faces of the Beam I then drilled the 3mm and 12mm diameter holes undersize, 2.5mm and 10mm respectively. I removed the beam from the table and to my horror, the holes, whilst central on one side were off centre by a large amount on the other! After stopping and some careful consideration I thought about scrapping the Beam and buying a new casting. However, I first decided to find out what had gone wrong. It transpired that the bosses

42 The Beam 41 cast into the face of each side of the beam were not in aligned to one another. Would a new casting be any different? I decided to try to recover the Beam. I mounted the beam on the vertical slide mounted to the cross slide of the lathe and aligned the 10mm diameter bore to the axis of the machine. I then drilled and reamed this hole to the 12mm size and checked the concentricity of the hole to the cast boss. A minor correction was made to the cast boss using a small Dremel type grinder. The vertical slide was replaced on the cross slide by the rotary table fitted with a 4, 3 jaw chuck. The chuck was clocked in so that its axis of the rotary table was aligned with the axis of the lathe spindle. The Beam was then mounted to the rotary table chuck via the mandrel produced for the Flywheel. The part was then orientated using the rotary table and the lathe cross slide and the 3mm holes were carefully and slowly milled into the part using a slot drill. This ensured that the 3mm holes were reasonably parallel to the main 12mm diameter hole. On inspection the hole that interfaces to the connecting rod was still not central to the cast boss feature on one side. So I decided to machine a larger hole, slightly offset to minimise the decentre on both sides. This worked and required only a small amount of correcting or the cast feature with the small Dremel type Grinder and needle files. To correct for the now over-size hole I machined a small brass sleeve insert which also acts as a bearing. This will hopefully be obscured by tines of the connecting rod. All in all I am happy that I managed to save the Beam from the scrap pile. Unfortunately, I neglected to take any photographs of this process as my mind was elsewhere. This whole episode reminds me that I should not be complacent and I should double check everything before making a cut! <Picture of the Beam after >

43 42 The Stuart Half Beam Engine The Connecting Rod and Big End Sleeve Bearing The material for the Connecting Rod is supplied as a flat bar of 5/8 (15.8mm) x 1/2 (12.7mm) section. The first step was to mount the stock into the 4-jaw chuck and clock in so that it ran true about the axis. Both ends were then faced and centre drilled for the subsequent turning operations. The main features, the big end, little end and bottom of the yolk were marked out and centre punched and drilled through with pilot drills. The waste material in the yolk was then chain drilled to remove the majority of the material before machining a slot which will eventually form that feature. Figure 91 The Connecting Rod drilled The Connecting Rod was then clamped to the table and supported on a pair of aluminium plates to allow the cutter to go through to the full depth without damaging the table. The rotary table allows the length of the stock to be clocked in very easily. The cutter was then touched on and brought into position. Initially an 8mm slot drill cutter was used to remove the majority of the material and the slot was finished with a 10mm diameter cutter to bring the width of the slot forming the yolk to size. The part was then removed from the table and deburred. The width and shape of the big end and the width of the tines of the yolk and the circular features around the small ends were then marked out on the surface plate Figure 92 Machining the Slot for the yolk Figure 93 Marking out the other features

44 The Connecting Rod and Big End Sleeve Bearing 43 The Connecting Rod was then clamped to the vertical slide that was mounted on the cross slide of the lathe so that the big end pilot hole could be opened out to size. A 9.8mm diameter drill was used, followed by a 10mm diameter reamer to bring the hole to size. Figure 94 Drilling the Connecting Rod Big End Figure 95 Reaming the Connecting Rod Big End The part was then mounted between centres. The top slide was adjusted using a DTI to machine a taper of 1 in 30. This will be used to machine the fish bellied effect. The tool was aligned to the portion to be machined and the diameter was reduced down to 8mm using the saddle. Figure 96 The Connecting Rod between centres Figure 97 Machining the Connecting Rod The taper was then machined into the central portion. The top slide was then repositioned to machine the taper in the other direction and complete the fish bellied effect. The surface was then polished with progressively finer grades of wet and dry paper to remove the tool marks and make a smooth uniform finish. The Connecting Rod was then clamped to the table of the borer and big end machined down to the size. The end was then sawn off and the radii filed to shape. See the figures below. Figure 98 The Connecting Rod filed to shape Figure 99 The Connecting Rod

45 44 The Stuart Half Beam Engine The Connecting Rod was then set up on the borer so that the tines could be machined down to size. Sufficient material was left to form the radii at the end of the tines. Once the tines had been machined to the correct width the job of carefully filing the radii at the end began. A combination of round files and needle files were used. The end was then removed and the part finished. Figure 100 The Connecting Rod radii being finished The Big End Sleeve is a relatively simple component but the outside and inside diameters are controlled by limits and fits. The part was machined from a piece of Phosphor Bronze. The outside diameter was turned to size and the inside diameter drilled and reamed. The Big End Sleeve was then parted from the stock at length. It was then deburred and trial fitted to the assembly. Figure 101 The Big End Sleeve drilled and reamed

46 The Pulley 45 The Pulley The pulley casting was actually missing from the kit of parts when I received it. However, Stuart were very helpful and once we told them it was omitted from the kit, they happily posted one through. The part was carefully surveyed and the depth of cuts required to machine the part to the final dimensions were calculated. It was then mounted in the 4-jaw chuck by the larger of the diameters and centred using a DTI to minimise the run-out in the boss portion. The boss and the near side face of the pulley were faced and then brought to final size. The boss was then centre drilled, and the bore for the main crank shaft, drilled to ф11.5mm before it was then reamed to ф12mm H7. Figure 102 Drilling the Pulley Bore Figure 103 Turing and facing the Pulley The part was then reversed and mounted in a 3-Jaw chuck. Thin shim material was used to protect the finished surfaces from being marred by chuck jaws. The part was then faced to length and the outside diameter of the part brought to size. A series of 3 groove features were then machined in to the outer surface. Chamfers were then added to break each of the sharp edges. Lastly the 5BA hole was drilled and tapped into the boss. Figure 104 Finished Pulley

47 46 The Stuart Half Beam Engine The Assembly & Finishing The parts were trial assembled in their sub-assemblies as time went on. These were then integrated into the main assembly to ensure they would fit. At each stage some fitting work was required to ensure the parts operated together and run true. With the completion of the bulk of the parts the final trial assembly and integration could begin. The components on the Crank Shaft such as the Pulley, Eccentric and Flywheel needed fitting to the shaft. The positions were set and I found that there were small gaps. So, I machined a number of spacers from Delrin to ensure the Crank Shaft did not wander as it was driven. Figure 105 The Valve Gear Assembled. Figure 106 The Beam and Crank Shaft Assembled. In addition to this the smaller bearing components and the valve gear required adjusting so that the timing was correct. A small amount of fettling was required to ensure that the valve operation was satisfactory and was relatively free of friction. The assembly was then run using an electric drill.

48 The Assembly & Finishing 47 Figure 107 The Trial Assembly Completed The next step was to finish the oak base and begin the finishing processes for each of the parts. Both the Baseplate and the Pedestal were fixed down using custom screws made from hex-bar to fasten the engine to the oak support base assembly. The engine was then stripped down and each of the parts cleaned, painted and polished as required ensuring a pleasing finish.