This section documents my third version for the engine frames. The first version attempted to build a frame through 3 dimensional folding and frankly, didn't work. Version two was a more "classic" frame build from brass side panels with brass spacers soldered in between. While this worked to some extent, there were enough mechanical and electrical problems that I decided to try the current approach. (All image thumbnails can be clicked to see the larger photo).
1. The frames consist of two brass side plates, so the first step is to cut out two 16 mil thick brass blanks. A blank for a four wheeler measures 1/2" x 2.5" and a blank for the six wheeler measures 1/2" x 2.75".
2. Next, cut a matching sized sacrifical blank from 1/2" plywood and mount two brass blanks to it using double sided tape. Then add a copy of the frame design on top (with more double sided tape) and mount this in a drill press.
3. Fit a #1 center drill bit in the press and use it to mark the location of the 3/64" holes that will be used to attach the frame side to plastic spacers. Then fit a #4 center drill bit and mark the location of the 5/32" holes for the axles.
4. Drill out the holes in the blank and remove the sacrifical backing.
5. Cut to shape with a jeweler's saw. Use files to finish if needed and remove pattern and doubled sided tape.
6. The frames have an inside spacing of 1/4". Evergreen 3/32" tube is used for center frame spacing, held in place with two #0-80x1/8 brass hex head screws for each tube. Evergreen 1/4" channel is cut to length and used as a spacer and support for both the front end assembly and cab. each channel is held in place with four #0-80 x 1/16" socket set screws (two for each side).