Im starting to plan a little project, however this will require internal splines inside a shaft.

Does anyone have an idea how to machine internal splines?, the only way i could think of doing it would be using a broaching machine, however i dont have one of those

[Edited on 4/3/06 by Gav]

it is possible to do it on a lathe

Thanks you, would you care to elaborate on how?

ive had a quick google and a flick through some machining books but i havent come up with much on the actual process

Yes it is possible on a lathe assuming you can lock the spindle and rotate it through a known angle (should be easy to work out from the gearing).

You need to make a tool to fit in the turret that has a nose/cutting edge, the shape of the grooves you want to cut. Take cuts by winding the saddle along, depth of cut governed by cross slide.

Rather slow and laborious, but possible, if not what a lathes intended for!

David

ah gotcha!

Cheers.

In the past when I have done this I have used a piece of the splined shaft as a broach to finish of the spline after rough planing in the lathe .You will find that unless you are making the spline in a soft material like brass or ally that it will be tapered smaller to the back as the tool always pushes off slightly, so ideally needs broaching or hand finishing with a needle file or similiar.
Paul.

quote:

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Originally posted by flak monkey
Yes it is possible on a lathe assuming you can lock the spindle and rotate it through a known angle (should be easy to work out from the gearing).

You need to make a tool to fit in the turret that has a nose/cutting edge, the shape of the grooves you want to cut. Take cuts by winding the saddle along, depth of cut governed by cross slide.

Rather slow and laborious, but possible, if not what a lathes intended for!

David

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use an indexing head to rotate the shaft through a set angle and then cut the splines using a drill for round bottomed splines or a shaper for pointed splines

Cheers guys!

We do this by getting a broach made (not cheap unfortuantely) and then the "broaching machine" is just a hydraulic press!

are your pulling pushing the broach with a press? presumably it will wont be able to pull as much as it pushs?

Where i used to work we had a 20' broaching machine and the broachs were about 8' long they were incredibly tough in tension as they were pulled through the gear, i evan dropped one once and it shattered into tiny pieces! the boss wasnt impressed!

We push em through with the press, but they are only 14" long ones!

Worked in the GM auto gearbox factory a bit in Strasbourg a couple of years ago, they have a HUGE pull-broaching machine there cutting HELICAL internal gear teeth for auto box ring gears for the epicyclics, a monster of a machine.

The Helical cutting motion is a nightmare for relief angles on the broach teeth!

Broaches were approx £40,000 a piece.

wouldn't want to drop one of them

hmmm, we broke 3 in one day while we were there, not a good day that one!

If I was needing internal splines for a project I would forget about cutting them myself. I would be looking around at existing designs / splines and trying to adapt one to my application.

First places to look would be gearboxs, half shafts and the hubs, steering shafts and steering wheels or Uj`s, propshafts etc.

There are companies that specialise in drive applications.

John