NOTES FOR SKETCHUP 'LASER' OPTION - MISSENDEN OCTOBER 2013 These notes were written for the course members on the weekend 'Laser' course at Missenden Abbey in October 2013. We had available an HPC Laser 3020 Laser with a maximum workpiece size of A4 and a 35w laser which will cut through card, plywood, mdf and plastics (eg. perspex) up to 5mm thick. Sketchup is a 3D Computer Aided Design program which can be downloaded free off the Internet. After a number of hours usages it reverts to 'Sketchup Make' which continues to be free to use. After reverting to 'Sketchup Make' A 'plugin' is required to export files as DXF files for the laser and this 'DXF and STL' export plugin is also freely available off the Internet. Instructions on how to download SKetchup and the plugin are explained elsewhere on this website. NOTE they were correct as of October 2013. Using Sketchup in 2D mode As the laser only cuts flat sheets, we need to use Sketchup in 'Top Down' 2D mode and the first part of the instructions below set up an A4 sized template to do this, as well as setting up the drawing in mm, and parallel view etc. Good Luck! Bob Gledhill 2013
Working with Sketchup (1) (Written for PC, MACs may use different keystrokes) A4 Template If figure loaded by default then select it and Delete it. Camera >Standard Views >Top Camera >Parallel Projection View >Toolbars. Ensure that ONLY the 'Getting Started' and 'Standard' boxes are checked. View >Face Style. Ensure only X-Ray and Monochrome boxes are checked. Window >Model Info >units. In top boxes of length units change to 'Decimal' and 'mm'. Select the Rectangle tool and draw a rectangle of any size Note dimensions bottom right and type 2900,2000 and then Enter (Box should re-size to new dimensions which should be in mm) File >Save As Template. Then enter 'A4 Sheet' in top box and select middle box. Check that 'Set as Default' is checked and then click on >Save Exit Sketchup. Re-load Sketchup and this Template should be loaded by default giving you a top-down view of an A4 sheet (which is the maximum size the laser will handle) NOTE: You should always see 'Top' displayed top left. Viewing Tip - showing object full screen To view your drawing at the largest size which will fit on screen use 'Shift+Z'. Try it. Instructor To invoke the Instructor screen go to 'Window' menu >Instructor option. Close in usual way. Note - advanced features require on-line Internet access so don't click them if off-line. Drawing to Size Sketchup was intended for architectural drawing (large objects). We are likely to deal with objects at the mm size. Sketchup works best if everything is drawn 10 times scale. Draw a rectangle. Note size shown bottom right (should be in mm) DO NOT MOVE MOUSE OR CLICK ANYTHING AFTER DRAWING THE RECTANGLE, but immediately enter two figures (say 300, 500) and ENTER. This will become 30mm X 50mm when we laser cut it. Your box should now have changed shape to match the new figures. Repeat the above several times for squares, circles and several-sided objects. Saving your work Your work should be saved every 5 to 10 minutes using the Sketchup 'Save As' box. This saves work to a Sketchup file which preserves all the information. To save for the Laser first remove the large A4 lines using the delete tool (brick). Now save as a DXF file go to Tools > Export as DXF or STL If 'No Object Selected' then YES export entire model Choose Centimetres as Export Unit...(this reduces size by factor of 10) and LINES as DXF export option Ensure your filename ends with.dxf and save it NOTE! Files exported as DXF CANNOT be re-loaded back into Sketchup.
Filename TIP Start your filename with increments of the alphabet. ahouse, bhouse, chouse, dhouse etc. You will always be able to find the latest version really easily (and delete old ones). Line Tool (looks like a pencil) Try drawing some rectangles and adding triangles (like pitched roofs) to them using the ruler and line tools. Immediately typing a dimension into the dimension box + 'Enter' will draw a line of exact length Placing and measuring objects Draw a rectangle 2000 x 1000. We are going to round the corners. Find the Tape Measure icon. This is REALLY USEFUL and worth mastering. From each side 'pull' a guide line inside (dotted line) and enter 200 into the dimension box (bottom left). Remember 10x size so this will become 20mm. Find the 'Arc' tool and click on the intersection between a guide and the edge of the box, now click on the opposite intersection (you should have two red crosses) and move the cursor to where you think the curve should be. You should get a message near the cursor 'Tangent to Edge' - click again. You should now have a smooth curve on the corner. Do the other three corners. Choose the 'Select' Tool (Arrow) and select each of corner lines outside the curve in turn and delete to leave the curved corners. A blue dot marks the midpoint of a line. To measure without leaving a guide line use Ctrl key to remove the + near cursor. Practice using the Tape Measure tool - it is invaluable! Use it to make guides to position and to draw to an exact size. Cursor will snap to guide points. Line Tool (looks like a pencil) Try drawing some rectangles and adding triangles (like pitched roofs) to them using the ruler and line tools. Deleting Guide Lines Select individual Guide and delete to delete it, or 'Edit' >Delete Guides to delete all guides Moving object around screen Select the hand shape and hold down left mouse button to move object around screen. (remember 'Ctrl + Z ' to display object full screen). PRACTICE 1 - DRAWING WINDOWS AND CUTTING THEM OUT Use the drawing tools learnt above to draw a couple of different styles of windows (NB. 10x times size), save your file, then export as DXF (remember to delete A4 outline) to your memory stick. Then take to laser to be cut! (c) Bob Gledhill 2013
Working with Sketchup (2) (Written for PC, MACs may use different keystrokes) Moving and Repeating Objects Moving... Draw a rectangle 1000,100 Select it using 'Select' - turns blue and shaded in dots Select the 'Move' tool and move the object. Enter 300 in the dimension box to move it an exact amount Copying... Select the 'Move' tool and tap the Ctrl key to get a small + by the cursor. Move will now COPY the object Move the rectangle to the right and enter 150 into the dimension box (this sets exactly the amount of move). IMMEDIATELY enter *5 and 'Enter' into the dimension box. You should see 5 more copies Alternatively to space evenly between exact dimensions... Delete the above (select all rectangles and 'Delete') Draw the rectangle as before but this time move it 2000 Now enter /5 and 'Enter' into the dimension box. You should see 5 copies evenly spaced between your original rectangles. This is fantastic for exact spacing for fences, awning edge, signal box window frames etc. Drawing smooth circles and sizing them By default Sketchup draws circles with 24 sides. Number of sides To increase the number of sides select the circle tool and immediately enter the number of 'sides' into the dimension box, try 8 then 48 to see the difference. Size of circle After drawing the circle immediately enter the radius into the dimension box Offset tool (F) This tool allows you draw a line parallel to another, even if curved or a rectangle. Draw a long line. Draw an arch above the line using the 'Arc' tool. Select the Offset tool and click on the arch. Pull down with the left mouse button to form a line under the arch In the dimension box enter 50 You now have an arch 5mm deep (remember x10)! Try the same for a rectangle
Rotate an object Draw a rectangle and select it Select the rotate tool and click on the object at the point of rotation A protractor will appear at that point Move the cursor to the right (outside the protractor) and click Now as you move the cursor the object will rotate about the chosen point Enter the exact number of degrees of rotation required into the dimension box and tap Enter PRACTICE 2 DRAW A SHORT LENGTH OF FENCE AND CUT IT OUT Using the tools learnt above, draw a short length of fence and cut it out. Remember 10x, Move with + to copy, save then export as DXF (centimetres and line) (c) Bob Gledhill 2013 NOTES ON THE ACTUAL LASER USED FOR THE COURSE The laser is sold by HPC lasers (http:/www.hpclaser.co.uk) and is an LS-3020 model currently available and costing 1,125 + VAT. The laser comes complete with everything you will need, extractor fan, water pump, compressor (except, perhaps exhaust ducting). This model comes with 'Newlydraw' program which accepts only a limited number of file types but in my experience has not proved too much of a handicap. (Newlydraw somes with a dongle and is Windows XP only). Although having a container of water (large plastic container) and circulating the water with the provided water pump is adequate for short bursts of 'home' use, I found that using the laser all day in the house the water temperature rose and the laser became less effective. I bought a Chiller Unit from HPC costing 395 (+VAT) which keeps the water cool all day long at any laser power setting. I would strongly recommend venting to the outside either through a window or dedicated hole in the wall. HPC do two more expensive lasers which have better software supporting 'layers' from CAD programs such as Autocad and Coreldraw, work with Windows 7 but are 2,150 (+VAT) for a similar sized machine or 2,450 (+VAT) for a machine with an A3 bed size. LASER BUREAU SERVICES I have limited experience of laser bureau services, but most will accept DXF files and you should discuss your needs with them before sending them your files.
Working with Sketchup (3) (Written for PC, MACs may use different keystrokes Using Layers Introduction Most CAD programs have 'layers' which can be turned off and on. For example the 'wall layer' could have window openings and the 'window layer' could have the window frames. Each can be shown separately or together. Several window frames can be placed exactly in the correct position on the wall layer. This enables us to laser cut the inner wall complete with window frames knowing they will fit behind the outer wall exactly. Sketchup has something called Layers but it works only with objects which are GROUPS or COMPONENTS. Both can be copied, but edit the original COMPONENT and all copies will also change. Think of layers in Sketchup as different OBJECTS. So we have a 'wall' object and a 'window frame' object, each a group and each on a different Sketchup 'layer'. Objects which are GROUPS or COMPONENTS can only be edited if they are first made editable in the edit menu (select the object to edit then edit >component/group (bottom of edit menu) and then Edit (add or change the group/component) or Explode (which ungroups the object enabling regrouping with other objects etc) Using Layers in Sketchup First turn on the Layers Toolbox by selecting View >Toolbars... >Layers Next click on the 'i' in this Toolbox to give you a floating Layers Menu... Move this menu to top right Now click on the + to add another layer and call it Windowfan Add another called Windowframe (double click the name to edit it) ALWAYS LEAVE LAYER '0' SELECTED (dot in circle) WHEN DRAWING Draw a rectangular frame with a circle in it (to represent a fan opening) as below...
Now select the frame and hole (select tool, hold left mouse button and drag) then Edit >Make Group Now this object is a group drawing over it will not affect it. Objects which are GROUPS or COMPONENTS can only be edited if they are first made editable in the edit menu (select the object to edit then edit >component/group (bottom of edit menu) and then Edit (add or change the group/component) or Explode (which ungroups the object enabling individual lines etc., to be deleted, and re-grouping with other objects etc) Next select the drop down Layers in the Toolbox and click on Windowfan (a tick will appear left of title) showing this object has been assigned to the Windowfan layer. After selecting an object, clicking on this Toolbox menu assigns it to the specified 'layer'. Objects can be moved from layer to layer using this menu (but it is easy to wrongly assign two objects to the same layer!). Now draw another rectangle over the first, and a smaller rectangle inside it (left diagram below). Note these will not affect the Windowfan object. Click the tick against Windowfan on the Layers menu and the Windowfan object should disappear leaving the newly draw windowframe (right diagram below). Select the Windowframe and assign it to the Windowframe layer by clicking on the drop-down menu in the Layers Toolbox and then on Windowframe. Find the 'Visible' tick list' in the Layers menu and try clicking the various 'layers' (objects) on and off. Try starting again and drawing a wall with three or more window openings, grouping them (and the wall outline) and assigning these to a named layer. Next add the wall outline again and then window frames in (make the first a component and then copy it to the other openings). Now any alteration you make to the first component (need to choose edit component first) should be mirrored in the others. Finally turn off the openings, select all your frames, make them a group and assign them to new layer. Check you have the concepts of layers before continuing. Turn each layer on or off and select the relevant objects before saving as DXF files and only the selected lines will be saved to the DXF file for cutting. Save as Sketchup file first! If your layers are in the SAME material, then you can move some of the objects side-by-side before creating the DXF file so they can be cut in one go. Save as Sketchup file first! PRACTICE 3 Draw a two-part fence or windows and window frames using layers, save it as a DXF files and take it to the laser to be cut. (c) Bob Gledhill 2013
Working with Sketchup(4) (Written for PC, MACs may use different keystrokes Advanced Cutting and Engraving If you wish to mark your material with lines (eg. brickwork or bargeboard lines) then it can be quicker and more effective to CUT these lines at a low power rather than engrave them. Registration Mark If marking and then cutting your material you will need to do this in two processes, a low power cut which will mark your work and a higher power cut with sufficient power to cut through your material. These will need to be drawn accurately one above the other and then exported as two drawings (remember the need to GROUP them and allocate each to layer). In order that the two line up correctly you need to place a REGISTRATION MARK at TOP LEFT on EACH layer. A small circle 2mm diameter works well. LOAD the low power (engrave) layer into the laser and line up the circle with the two lines top left on the MASTER PAGE (zoom to 400% to do this). Then place your material in the laser and cut on LOW POWER sufficient to engrave the lines (one third cut power is usually about right). DO NOT MOVE YOUR MATERIAL IN THE LASER, OR THE LASER HEAD (laser head always returns to its start position at end of job even if you have moved this so it is not top left). DELETE the first image and LOAD the high power (cut) layer, and again line up the circle with the two lines top left on the MASTER PAGE, and turn the power up to that which will fully cut through your material. Cut out your material. Awning example - low power on left, cut power on right. NOTE registration circle on both. Engraving The laser will engrave a raster image (BMP or JPEG format). IMPORT your black and white 'dithered' raster image into the Newlydraw laser software and then click on 'Engrave'. Next click on 'Prop' (top right) and check the 'Scan' settings for speed (100 to 300 usually) and 'Gap' (.075 to.2 usually), then 'OK'. Now start the engrave. Use the POWER setting to darken or lighten the resulting engraving until you are satisfied with the results. When engraving the laser head moves backwards and forwards across the laser bed, moving down the specified 'Gap' amount each time (looks much like a colour inkjet printing a photograph). By
altering the Speed, Scan Gap and Power you can alter the engraved effect on your chosen materials. Harder materials require a slower speed and more power. Engrave then Cut (requires suitable CAD program) It is possible to engrave then cut. You need software such as CorelDraw or Inkscape which can have layers of vector (line- dxf) images and raster (bitmap) images. EACH LAYER needs a registration mark as described above. First load your bitmap, align your registration mark. Do similar with the raster (line -dxf) image, again lining up your registration mark with that on the bitmap image. Check speed, gap, cutting speed and finally the power. Now when starting the laser it will first engrave then cut out your work. Using this technique it is possible to do arched brickwork on viaduct/retaining walls etc. Preparing a photo for engraving The laser can either be 'on' or 'off', but it can go from one state to the other very rapidly. In order to engrave a photograph, the photograph must be in black and white and consist of lots of dots. Each dot represents an 'on' and each non-dot an 'off'. There is a good illustration of how to use CorelDraw to produce the correct format of image at www.rabbitlaserusa.com/manualstutorials - look under APPLICATIONS. The software - NewlyDraw - supplied with the HPC 3020 Laser supports engraving then cutting in one operation, however there are certain caveats... You need image processing software which will let you take an image to a dithered black and white image. It is useful if you can lighten and darken this b/w dithered image Your CAD software should support layers and import of raster images (JPG, BMP etc) and filling an area with this image (tiling it). You need a 'registration mark' top left on both vector (line) and raster (image) layers so you can align them in Newlydraw (laser software), as described above. The SPEED, GAP and POWER settings on the laser are critical to the appearance of the engraved image and the success of the cutting and you will need to experiment with these to achieve acceptable results on different materials. Export DXF files for the vector (line layer) and image - raster files (JPG or BMP) for the engraving layer. The FULL version of CorelDraw (which includes Corel paint) does all the above very well, but unfortunately the Home and Student version (X6) no longer supports saving of DXF files and is therefore unsuitable. More expensive lasers may come with driving software which allows direct import of CorelDraw (and other CAD software) files. You need to check carefully with the seller AND request a demo of it working before committing yourself. Further information on Lasers at www.hpclaser.co.uk (c) Bob Gledhill