Chapter 7, Part 2, Section 1
Constructing the Drop-Outs
Written by Rickey M. Horwitz
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The dropouts for the Thunderbolt are both constructed out of .250 thick, 6061-T6 Aluminum stock. Unlike conventional drop-out designs which interface both seat and chain stays, the Thunderbolt drop-outs interface only the chainstays. Not only does this design offer excellent strength, it also gives the trike a touch of artistic styling.
5" x 5" x .250", 6061-T6 Aluminum
Computer and Printer
Metal Band Saw
Misc. Metal Files and emery cloth
10 MM x 1.0 Metric Tap
8 x 32 UNC SAE Tap
Metal Drum/Belt Sander
The fastest and easiest approach to building the drop-outs is by taking the actual drawing, glue it on the aluminum stock and simply use it as a template. I have included some dimensions so that the builder can scale the drawing to the proper size when printing. Upon printing the drawing use a ruler and verify that the dimensioning is within spec, resize as required.
Below is a drawing of the Dropouts in a Microsoft Windows Metafile (*.WMF) Format. Click on the filename below to download:
Prior to cutting the Drop-Outs, drill out all required holes. These include both rack/fender mounts using a #29 drill, the Derailluer Hanger using a 23/64" thread and both Axle Channels (as shown below). Once these hole have been made, the Drop-Outs are ready to be cut using a metal band saw. As shown, the 3/8" holes provide a perfect radius for the axle channels. With a little patience 85% of all the shaping can be accomplished using the band saw. For final finishing use a file or belt/disc sander.
Upon final finish, tap the rack/fender mounts using a 8-32 tap. Tap the derailluer hanger using a 10mm x 1.0 metric Tap. the Drop-Outs should now be ready for Stay assembly.