The last step in the long story of the kickstart shaft project is to machine the flat for the lever cotter pin. We are back on the lathe with the vertical slide and will use this setup to machine the slot:
The cotter pin is about 3/8 diameter so we will use this 3/8 end mill to cut the slot.
This is the last pass of 3/8 end mill - and it's a pass I wish I hadn't made. I was very near the end and used a trial fit to find that the slot I was milling was about 1/32" too shallow. For some reason I decided that it would need another full turn of the lead screw to finish the cut - completely forgetting that the lead screw pitch is 1/16". So now that slot is too deep.
I could weld this up and re-machine it, but the cotter pin still fits and stays in place properly. I guess I will leave this until it becomes a problem - I can't get a 3/8" bolt in there, which would be possible if the slot was any deeper.
So for now, the kickstart shaft is finished.
I've watched with interest. I do similar jobs on small Albion boxes which share the same standard bicycle size kick start shaft/cotter pin arrangement. One day I hope to find a formal drawing with dimensions. I know I'm close but confirmation I can rely on would be great. Regardless of the internal end of the kick start shaft the actual attachment of the kickstart to the shaft via a cotter pin appears to be to standard bicycle dimensions across the board no matter what make of gearbox. Someone must know.
ReplyDeleteThe lever goes on a 0.75" diameter, and measuring from the flat part of the cotter slot to the opposite side of the shaft is 0.600" - so the depth cut with the end mill is 0.150" and the slot is 0.375" wide.
ReplyDeleteThe cotter pin I made is 0.375" diameter; the thread on the end is 5/16" CEI, and the axis of the threaded part is offset 1/32" from the axis of the cotter.
The cotter pin hole in the lever is 0.375", and a 5/16" rod will go through this hole when the lever is on the shaft which gives you some idea of the position of the cotter hole in relation to the flat on the shaft.
Hope that helps a bit!
Thanks for that. Every bit of info makes it a little easier. I keep thinking of tackling the Veteran Cycle Club, they seem to have a fund of info on the early cycling days and so much of our stuff has such obvious cycle parentage.
ReplyDeleteI also make my own cotter pins but use a 1/4" BSF thread as this closer to the original oddball thread size (15/64 x 26?) . I made a little fixture with an offset 3/8" hole drilled to the correct depth that I can just pop in the three jaw chuck and everything is nicely lined up ready to machine.
This makes turning a preprepared blank to size and threading it the work of moments. I keep half a dozen or so to hand and its surprising how they go. They're a marvellous little swap item.
Thanks again,