Cutting Internal Splines?

[Krusty Karl]

I've been trying to find some information on internal spline cutting.

First, a little background info. I'm a mechanical engineering student working on a project with the University of South Carolina - the Society of Automotive Engineers Baja student design competition. The short of it, students design and build a prototype offroad go kart. I'm working on the drive system of our vehicle; I have a really nice continuously variable transmission that I want to use, it has a 1" ID keyed center..hub. This needs to be mated to a splined gearbox input shaft (spine specs below). This is clearly a problem; we've talked about making some sort of sleeve, but I would sleep much better if I could machine a new center "hub" for the CVT pulley with the correct splines. Machining the outside will not be a problem in our fab shop. Cutting the splines on the other..that's the problem. The machinist that works with us said he could cut external splines very slowly and meticulously, but internal splines are not a capability of our shop, hence my post here.

Is there any means to do this without spending an arm and a leg (we aren't funded by the engineering college, we just get a donation here and there from friends and families with ties to local industry). If not, could you suggest anyone (either a shop or an individual) who would be able to cut the necessary internal splines at some reasonable cost?

We have a press in our shop, if we could get the correct broach, that would work.

Thanks


Driven Clutch Spline Data
Involute Spline
(Per Std ANSI B92.1 Tolerance Class 7)
(Fillet Root Side Fit – Non Chamfered Tooth Profile)

Number of Teeth 19
Pitch 24/48
Pressure Angle 45 deg
Major Dia. 0.850 +.009 -.000
Minor Dia. 0.7667 +.0015 -.000
Pitch Dia. 0.7917 (Ref)
Form Dia. 0.8349

Circ. Tooth Thickness
Max Actual 0.0789
Min Effective 0.0738

Distance Between 0.080 Pins
Max 0.6713
Min 0.6693

[CNC_BOB]

at first it seems that a wire edm process is required. I could not find in your specs how thick the detail is so whether a small carbide endmill could generate the spline remains to be seen, what is the smallest inside radii to be formed? would like to help further questions

[Krusty Karl]

Originally Posted by CNC_BOB at first it seems that a wire edm process is required. I could not find in your specs how thick the detail is so whether a small carbide endmill could generate the spline remains to be seen, what is the smallest inside radii to be formed? would like to help further questions

I'm sorry for leaving out some important details.
The splines are to be cut (centered) into a 1.500" OD piece of stainless steel.
I don't have an exact number on the depth at the moment (will have tommorow), but its approximatly 4". For now just imagine cutting the splines into a 1.5" OD X 4" cylinder. There are a couple of features on the OD of the cylinder but nothing out of the ordinary (a snap ring groove and a small keyway).

We do have a 3-axis bridgeport cnc mill; If I could somehow draw out the involute in Pro/E or Solidworks...would it be possible to generate the code and mill out the splines that way with a really tiny endmill?

[mc-motorsports]

I would also vote wire EDM. Have you tried any local shops? I think if you explain it's a school project for your engineering class and if your lucky and the shop owner is a motor head, your in!

[TomB]

Do a google search on 'Rotary Broaching"

[Kiwi]

Could you get the centre from a clutch plate which suits the spline and fit this into your hub.
Hint: Take absolute minimum off splined sleeve when machining to suit hub as this may shrink when welding to the hub

[Krusty Karl]

Originally Posted by Kiwi Could you get the centre from a clutch plate which suits the spline and fit this into your hub. Hint: Take absolute minimum off splined sleeve when machining to suit hub as this may shrink when welding to the hub

That could be an option, if i could find one such center. Tommorow I will contact the nearest wire EDM shops and consider what they advise.

[ALLtra Mach]

Originally Posted by Krusty Karl I'm sorry for leaving out some important details. The splines are to be cut (centered) into a 1.500" OD piece of stainless steel. I don't have an exact number on the depth at the moment (will have tommorow), but its approximatly 4". For now just imagine cutting the splines into a 1.5" OD X 4" cylinder. There are a couple of features on the OD of the cylinder but nothing out of the ordinary (a snap ring groove and a small keyway). We do have a 3-axis bridgeport cnc mill; If I could somehow draw out the involute in Pro/E or Solidworks...would it be possible to generate the code and mill out the splines that way with a really tiny endmill?

You are never going to be able to enmill splines 4" deep!
Whats the material of the hub?

If your machinist can make external splines, he could make multi flute broaches and press them thru. Not a good production method, but for a prototype shop with limited capabilities it is an option.

[RICHARD ZASTROW]

Possibility: www.grobinc.com/coldrolled/bushings.htm

Dick Z

[RICHARD ZASTROW]

You might also contact the clutch manufacturer. They often have replacement parts to adapt the clutches to different shafts. Some are keyed straight shaft, some are tapered shafts with locking nuts, some are splined etc.

Beside that, for a little free advertising they may have your needed components at a reduced price or possibly donated. Wishfull thinking? LOL

Dick Z

[HuFlungDung]

For a one of, we'd just make up a single point tool (hand grind) and cut the spline on the shaper or the slotter.