Bending The Truck Bars
Early on in this project I discussed bending the bars with Dan Staron. One thought was to use a die of sorts. He said he had tried a die and was not happy with the results; the bars sprang back some after removal from the die. He found that bending the bars around a post worked the best. I tried it and it worked great!
The photo above shows the tools used to bend the bars The plate with the posts (1/4" dowel pins) is the bending fixture. The shorter bar in the middle is a drilling template and the larger bar at the top is the bender. The plates and screws on the left are used to secure the bars during the bending process, Drawings of these tools are at the end of the page.
The drilling template made of 1/2" square bar stock has six holes at the correct position for the six rods. The holes are tight clearance holes for 6-32 rods for the arch bar support rods (middle two holes) and 4-40 rods for the journal box rods (outer two holes on each end). The first step is to use the fixture to spot the two middle holes in the bar as shown in photo above. After the holes are spotted, the template is removed and the holes drilled through. .
The next step is to mount the bar on the bending fixture as show above. This is the 1/8" thick middle bar. The middle posts are separated such that the 6/32 screws fit snuggly against the inside of the posts. The screws go through holes in 1/8" X 1/2" stiffening plates that were also spotted using the drilling template.
Next. the slot in the bender is slipped over the bar adjacent to the post and the bar is bent just beyond the hole for the outside post. This can be done very precisely --- if the bend is too far, just use the bender to bend it back a little.
Next, the outer post is pushed into the hole, the bender moved to just outside the post and the bar is bent so that the end is parallel with the middle section.
The next step is to make the two bends at the other end.
Next the drilling template is mounted across the top of the fixture using rods through the center two holes. The clamps are then added to make sure everything is against the base plate. The holes for the journal box rods are then spotted using a hand drill through the outer holes in the drilling template. Next, the bar is removed from the fixture and the four outside holes drilled through the bar. The last step is to make sure that the side of the bar is straight --- lays flat against the base plate. If not, it can be bent slightly by securing the bar in the vise and using channel lock pliers to grasp the bar at the appropriate spot and bend as necessary.
The upper bar is bend using the same procedure as for the middle bar except it is secured against the middle two posts of the bending fixture as shown above.
The lower bar is bent using the same process as for the other two bars except in this case only the two upper posts are used to attach the bar to the fixture. The photo above shows the situation after the bar has been bent and the drilling fixture attached to spot the journal box rod holes. Note that the two slots in the drilling template allow the template to hold the bar against the two outer posts.
The finished bars are shown above. The middle bar is the stiffest; the other bars will tend to conform to it when the rods are installed and tightened. Recall that the holes were made at the minimum clearance size for the rods. If the holes don't line up exactly the holes can be enlarged to the standard clearance size with no sacrifice in appearance. The ends of the bars are trimmed after the sides are assembled.
The length of the drilling template is not critical 9 1/2" to 10" will work fine.
As noted, the bending fixture base should be at least 2" wide and 3/8" thick. I used a scrap piece of 3/8" X 2" bar about 18" long. All the holes were drilled slightly undersize and reamed to 1/4". After the pins had been inserted and removed a few times a couple fell through the holes. Duck Tape on the under side stopped the pins from falling through.
The slots were made by first drilling holes at the bottom of the slots and then sawing sides. My slots don't look as nice as the drawing. . The left slot was a little over 1/8" but a good fit over the 1/8" bars. The right slot is used for the 3/32" and 1/16" bars. I used a piece of scrap 7/8" square bar stock; 3/4" square stock would have been a better choice but I didn't have any.