Need Help!- Need to put a spline in cast bronze

[Fadal Error]

I was given a cast bronze part that is a replacement for the original (NLA) piece made from aluminum. The original part has a tapered 22-tooth spline. I need to put that spline in the bronze part. The diameter is roughly 10mm. Any ideas on how to attack this one?

[plasmator]

Can you find a broach for that profile?

[Fadal Error]

Good question. It is a window crank for an old Fiat and they didn't have a standard from one car to the next. I don't even know where to find a broach like this. When I start looking, I usually come to the conclusion that it will need to be a custom-made broach. I am hoping somebody knows where to look.

[keebler303]

If you could find a spare shaft that it fits on you might be able to use the shaft as a broach. All depends on what the material is but it might be worth a look. If you have access to a shaper, you could grind a bit with the profile of one spline and index it around for all the splines. Other than that, EDM is probably your next option short of getting a broach custom ground.

Matt

[RICHARD ZASTROW]

This is a tapered spline? EDM would do it after you made a tapered spline electrode. A shaper with a tilted rotary table also.

Do you have access to a bridgeport with a shaper attachment? Could tilt the head rather than the rotary table.

Possibly, form by beating a taper splined shaft end into a properly sized tapered (reamed) bore. (Might require heating the part)

Dick Z

[packrat]

If the spline in the aluminum part is still good, you could cut the handle from it and make an arbor to fit the ID of the splines in the lathe. Then mount the cut part on the arbor and turn the OD. Bore the bronze part to fit the aluminum "spline/sleeve" as a light press fit. Then press in using green "extra strength" loctite.

The diameters you use would be approximately the dia. shown in your photo where it looks like the splined section is higher than the main body of the handle.

cary

[neutronics]

Originally Posted by packrat If the spline in the aluminum part is still good, you could cut the handle from it and make an arbor to fit the ID of the splines in the lathe. Then mount the cut part on the arbor and turn the OD. Bore the bronze part to fit the aluminum "spline/sleeve" as a light press fit. Then press in using green "extra strength" loctite.

Interesting.

How about milling a square hole in the new handle and milling off the old spline so it fits into the square hole? If the square hole isn't milled through (leaving a locating step) I think that would be more secure against the rigors of manual rotary motion. ;-) Hard to tell from the pics of there's enough meat to do that though. Maybe a round tapered fit would be better.

[Fadal Error]

The old handle is still functional. I am making a matching one for the other side.

[plasmator]

If what you need is just a functional part, you could make a silicone casting of the original spline, then bore out the new handle and use the silicone plug to cast in the spline portion with urethane plastic or a low-temp metal alloy.