Option 1: False Frame Bent

Size: px

Start display at page:

Download "Option 1: False Frame Bent"

Heather Hunt
6 years ago
Views:

1 Black Bear Construction Co. Standard and Narrow Gauge railroads are often used in industrial or short line operations. These areas often require drainage that can be provided by trestles. Black Bear Trestle Jigs can be used to build trestles of any height and in a variety of designs. If taller trestles require multiple stories, they can be modeled in any of the methods described below. Option 1: False Frame Bent A true frame trestle bent is shown at the bottom of the page. True frame bents are hard to build and very weak because of all the butt glue joints. The FALSE FRAME BENT at the right is much easier to build, is very strong, and most folks (modelers or not) will be just as impressed. The difference is that the sills, which prototypically break the legs into separate pieces, are simulated by side braces. In this way you get the distinctive shape of a timber trestle bent, without the drawbacks of the true frame bent. Build the bents any height by extending the legs out the end of the jig. Option 2: Notched Frame Bent The NOTCHED FRAME BENT is an excellent compromise between the ease and strength of the false frame bent and the authenticity of the true frame bent. One of the best articles on trestle building ("Tackle a Timber Trestle", John S. Corbet, Model Railroader, Dec ', p 54; republished in Kalmbach's Model Railroad Bridges and Trestles) describes the notching of the sills and the legs to create a bent that looks prototypical from one side. These instructions describe an easy, reliable, and teachable process for notching the parts. They look great. Build the bents any height by extending the legs out the end of the jig. Option : True Frame Bent For the ultimate modeling experience, nothing beats prototype modeling. Option of the instructions describes how to use the Black Bear Trestle Jig to build TRUE FRAME BENTS. The jig is also used to cut the parts to length. You can easily adjust the height of the sills so your bent can have several different sill spacings. Building bents taller that 40' may require the modeler to build a fixture to register the lower posts. TRESTLE JIG All Designs - 4 Leg Trestles c Black Bear Construction Co , 2015

2 TIPS HOW TO BUILD A TRESTLE - ALL OPTIONS Use white glue or carpenter's glue. Stain all the parts before you begin. Size trestle guide to have same height as stringer. Shim it to line up with top of roadbed. Mark guide every 12 to 18 feet to locate trestle bents W W Sub-roadbed Build a trestle guide that lies exactly where the trestle will be installed. The guide should be narrower than the trestle cap. Refer to width, "W". The guide will be used to line up the tops of the trestle bents and hold them in place while the plaster, or Hydrocal*, sets up. (NOTE: Midwest Products' Trestle Buddy** performs this function in HO scale.) Mark the guide at 12 to 18 foot increments to show where the trestle bents will be installed Roadbed Trestle bent locations Vertical height of each bent Center line of trestle Trestle Bent Number Locate the retaining walls to create evenly spaced bents. Height of Bent Brace the trestle guide in place. Cut and assemble your track to make sure the alignment is correct. Number your bent locations. Locations 0 and 9 in the figure are the retaining walls. 4 Make a table to record the heights of each bent. Record the vertical heights of each bent. 5 Rubber bands Use the Black Bear Trestle Jig to build each bent that you need. Follow the instructions that are attached to build one of the three options. Make sure all the diagonal braces are oriented the same. Check the bents on the layout in case any of the bracing has to be skewed at an angle because of the terrain. *Hydrocal is a trademark of U. S. Gypsum Roadbed Cut holes in scenery Cut or drill holes in the terrain for the legs of the bents. Suspend the bents from the trestle guide with rubber bands. c Black Bear Construction Co

3 HOW TO BUILD A TRESTLE - ALL OPTIONS (cont'd) 7 Anchor the posts to the scenery with white glue, hot melt glue, plaster, Hydrocal, or other adhesive material. Make sure they are vertical. Diagonal side bracing 8 9 Final scenery Remove the after the adhesive material has dried. Finish the scenery at the base of the trestle bents. Stringer timber Install the girts and diagonal side bracing between the bents. 1 Girt Build the stringers as shown. Cut strips of card stock and color the edges with a black felt tipped marker to create a gap between the timbers. Laminate the timbers and card stock as shown. 11 Card stock Cut pieces of stringer to span between the bents. Sand the stringers flat on top and re-stain them before installing the track. Install flex track, sectional track, or hand lay the ties and track. c Black Bear Construction Co

4 OPTION 1 - BUILDING THE FALSE FRAME BENT 2 Top Cap Mark ends with a dot to keep track of precision cut ends. Rough cut LEGS from 12" x 12" stock and place them in the jig. Use a razor saw or sand paper (or miter saw, or disk/belt sander) to cut the ends of the legs parallel with the bottom of the jig. Allow the ends of the legs to extend beyond the bottom of the jig while cutting. Cut a piece of 12" x 12" stock for the TOP CAP and place it in the jig. 4 Flip the FULL LENGTH LEGS around and glue them to the top cap. Wait to glue the short legs in place. Keep the dots up and the legs in the same slots to make sure the ends of the legs match up with the top cap. 5 Sand flat spot Glue the top side HORIZONTAL and DIAGONAL SIDE BRACES in place. Remove the bent from the jig and turn it over. Trim the shorter legs to fit against the vertical legs. Glue the SHORT LEGS against the braces. Glue the HORIZONTAL and DIAGONAL SIDE BRACES in place on the back side. c Black Bear Construction Co

5 1 OPTION 2 - BUILDING THE NOTCHED FRAME BENT Extend over end of jig if required 2 Top Cap Mark ends with a dot to keep track of precision cut ends. Rough cut LEGS from 12" x 12" stock and place them in the jig. Use a razor saw or sand paper (or miter saw, or disk/belt sander) to cut the ends of the legs parallel with the bottom of the jig. Allow the ends of the legs to extend beyond the bottom of the jig while cutting. 4 5 Cut a piece of 12" x 12" stock for the TOP CAP and place it in the jig. Mud sill Flip the four (4) FULL LENGTH LEGS around and glue them to the top cap. Wait to glue the short legs in place. Keep the dots up and the legs in the same slots to make sure the ends of the legs match up with the top cap. Glue a piece of SCRAP WOOD across the bottom ends of the legs. This piece and the portion of the leg it is glued to will be cut off later. 7 Scrap piece of wood Temporarily glue pieces of 12" x 12" SILL stock to the legs. Place them where they will be fitted later. Do not let the glue squeeze out of the joints. If you will have a mud sill, glue it on now. 8 Use a sharp hobby knife to SLIT THE LEGS along both sides of each sill. 9 Break the UPPERMOST SILL away from the legs. 1 Re-cut the cut marks made in Step. 11 Remove the bent from the jig and carve the surface of the wood away from between the cut marks on the legs. 12 Re-cut the sides of the notches to make them deeper. Carve the bottoms of the notches out so they are all about 1/2" deep. Place the bent back in the jig. Use a razor saw to cut the sides of the notches half way through the legs. Place an additional cut in the center of the notch. Remove the bent from the jig and carve out the material in the bottom of the notch. Go at least halfway through the leg material. c Black Bear Construction Co

6 OPTION 2 - BUILDING THE NOTCHED FRAME BENT (cont'd) Use a square file to clean up the notches Repeat Steps thru 1 to notch all of the four main legs. With the bent out of the jig, place the uppermost sill in the top set of notches. 18 Make sure it is flat Turn the bent over and score the sill with a hobby knife where the legs cross it. Next set 19 2 of legs Using the notching process described in Steps 8 thru 1, cut notches into the sill. Use the razor saw and the jig for this cutting also. Glue the uppermost sill into the notches in the leg. Press the assembly between two flat surfaces to ensure alignment. 21 With the bent out of the jig, glue the next set of legs to the bottom of the sill and the brace across the bottom. 22 Take a piece of 12" x 12" sill stock and cut a long notch out of the side of it. Look ahead to the next step so you know how deep and long to make the notch. 2 Turn the bent over to put the leg notches up. Use the notched sill stock from the previous step to mark the notch locations in the new legs. 24 Using the procedure described previously, notch the legs and the sill with the bent outside the jig. Use the existing notches to align the razor saw. Glue this second sill in place. Continue installing legs and sills as described until the bent is built to its full height. Cut off the legs along the bottom of the mud sill. Build all the trestle bents you need and install them on your layout. Notice that the bottoms can have a mud sill or legs that go into the ground. Orient them so the viewer sees only the side that looks like a true frame bent. c Black Bear Construction Co

7 OPTION - BUILDING A TRUE FRAME BENT 1 2 H1-1st Story H2-2nd Story H - rd Story Determine the lengths of the posts (legs) you will need. Rough cut (at least 1/4" too long) as many posts as you will need to complete your first bent. If you are sure of what you are doing you can cut all the posts you will need for the entire trestle, but it is suggested you see what you are getting into first. Rough 4 5 end Place each set of legs in the jig. Sand or saw off the ends parallel to the bottom of the jig. Mark the posts on the end so you know which position they go in. Also, put them in labeled containers so you know what story they correspond to. 7 1st Story Posts Adjust the Leg Cutting Guide so that the distance from the guide to the end of the jig is about equal to the height of the story to cut. 8 Put each set of posts in the jig with the previously sanded end against the cutting guide. Sand or saw the ends of the posts flush with the bottom edge of the jig. 9 Spacer rd Story Posts 2nd Story Posts Top Cap Cut all the posts for one full bent. Keep the story section posts separate. 1 1st Story Posts Cut a piece of 12" x 12" stock for the TOP CAP and place it in the jig. " x 12" Stock Tape OPTIONAL STEP: Insert spacers in the TOP CAP slot if you want to model a shorter top cap. Diagonal Brace Glue the 1st STORY POSTS to the bottom of the top cap. Tape a piece of " x 12" STOCK (provided with the jig) across the bottoms of the 1st story posts. This piece is temporary. It will be discarded later. Glue the 1st story " x 8" diagonal brace across the 1st story posts to hold them together. Place the end of the diagonal brace over the " x 12" spacer just like it will overlap the actual sill later. c Black Bear Construction Co , 200, 2015

8 OPTION - BUILDING A TRUE FRAME BENT (cont'd) Set aside posts 2 and Insert into the jig, the 2nd STORY POSTS that extend the legs just started. In this case, posts 1,, 4, and. Set the other posts (posts 2 and 5) aside to install later Tape a piece of " x 12" STOCK across the bottoms of the 2nd story posts. This piece is temporary. It will be discarded later. Glue the 2nd story DIAGONAL BRACE across the 2nd story posts. Extend the brace over the " x 12" stock just like it will overlap the sill later. 18 1st Sill Repeat Steps to build the rd STORY section You can now remove all the sections from the jig. Save the piece of stock for the next bent. Cut the 1st SILL to length. Glue it to the 1st story section. 21 Glue the 2nd STORY SECTION to the first sill. 22 Cut the 2nd SILL to length and glue it to the bottoms of the the 2nd story posts. 2 Mud sill Likewise, glue the rd story posts and bottom sill (mud sill) in place. 24 Turn the bent assembly over and glue the missing posts in place from the back side. Lay the bent on top of the jig to make sure the legs are parallel. Glue the DIAGONAL BRACES in place. Notice that the braces overlap the ends of the sills. Build all the trestle bents you need and install them on your layout. Notice that the bottoms can have a mud sill or legs that go into the ground. c Black Bear Construction Co , 2015

A WORD ABOUT BRACING PART A - BUILDING A STRAIGHT, PILE BENT, OPEN DECK TRESTLE. Built in Place, Straight

A WORD ABOUT BRACING PART A - BUILDING A STRAIGHT, PILE BENT, OPEN DECK TRESTLE. Built in Place, Straight BUILDING LARGE SCALE TRESTLES You have many options when building a large scale trestle. The choices you make may be based on the prototype you are modeling; the era or industry you are modeling; or, simply