for the machinists out there....well jim and ret
can you mill a square tapered hole to fit onto a 3piece bottom bracket?
can you mill a square tapered hole to fit onto a 3piece bottom bracket?
milling question
- Thread starter junkyard
- Start date
It's called a broach. You drill a hole first, and then use an arbor press to push a broach into the hole. The broach shaves the metal out of the corners. This is also how straight key slots are cut.
It could also be done with a wire EDM, but it would be expensive.
The milling machine will always leave a radius in the corners.
Jim
I'm not sure what you mean "to fit into a 3 piece bottom bracket?" Milling wouldn't be an option. There are ways to cut square holes, broaches, E.D.M.'s, lazers, water jet, also not sure why you need a tapered square hole? Explain.
John
I think he's talking about the pedal crank shaft.
I've got the 3 piece set-up on my Spoilers. The shaft is square and tapered at the ends 2-3 degrees.
The hole in the crank has a corresponding square, tapered hole so that the crank is forced onto the taper for a positive fit. There is a bolt that draws the crank onto the shaft.
Jim
I've got the 3 piece set-up on my Spoilers. The shaft is square and tapered at the ends 2-3 degrees.
The hole in the crank has a corresponding square, tapered hole so that the crank is forced onto the taper for a positive fit. There is a bolt that draws the crank onto the shaft.
Jim
you said the magic word....expensive
ok even tho i love the clean look of the bottom bracket jackshaft im probly gunna try to use a steel hub like i did on my electric drive conversion
thx for the info
yes what jim said....to fit onto the bottom bracket like the crank would....sorry for any confusion
edit:the idea was to make a piece for one side to mount 2 freewheels back to back and a piece for the other to mount the larger sprocket to the engine......both pieces would bolt onto a standard bottom bracket
but the idea revolved around making the square tapering hole like a crank arm has
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O.K. I am with you guys now. I thought at first he wanted to cut a tapered square hole through the bottom bracket, just tapered at one end. I couldn't figure out what you could use it for.
Got it now.
John
