On Topic: Splines

No, not the CAD kind. I'm talking about splined shafts. Splines are something I've somehow never learned. That's not normally a
problem, except that I have something with an ID spine in it, and I need to buy or make a shaft to mount it on.
It's an involute spline, with 8 teeth that look like they're too far apart. Like, the thing should have 12 or 16 teeth, but doesn't. The major diameter is roughly .782", the minor is about .602, and I don't have a clue about where to look for the specs, details, or how/where to buy something that will help me.
Any spline experts in the group, or links that might help?
TIA! KG
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Kirk Gordon wrote:

From your dimensions you appear to have a 30deg pressure angle, flat root side fit, 12/24 pitch spline.
I can email you the pages from my spline table book if you wish. The tables give you all the dimensions required to cut the spline. If you require the least runout of the part, you might have to go to a flat root major diameter fit spline instead. There is also a page for the over pins measurements.
gk
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Usenet at it's best! :)
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vinny wrote:

Absolutely!
KG
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gk wrote:

That would be awesome. Just take the 2 out of my address, and it's good. Thanks so much!
KG
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Anyone still using Machinery's Handbook? In my antique 21'st edition there's a big section on splines. P991-1015
-- \|||/ (o o) ______.oOO-(_)-OOo.____________________ ~ Gil ~ the self proclaimed IT13 king
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cncmillgil wrote:

I have the 24th, and there's lots of spline info; but none that seemed to describe this particular spline. Maybe I just don't know how to read it. Looks like I'm in for an education.
KG
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Damn, I wish I had something that new. Mine is first printing of 17th edition. Got it as a high school graduation gift in 1964.     
--
Remove "nospam" to get to me.

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Here is a quick tutorial on splines -
http://www.utm.edu/departments/engin/lemaster/Machine%20Design/Lecture % 2020.pdf
Since your spline is an involute form it can be rolled or hobbed. The design of the shaft will also dictate whether or not hobbing can be used. If they don't allow the radius of the cutter at the end of the spline it would probably have to be rolled.
All hard to say without seeing the drawing.
Other options include form milling and shaving. Star Cutter and others sell form milling cutters for involute splines and other tooth forms.
Star Cutter - http://tinyurl.com/ybgn4lg
Star also makes hobs but probably not in a small enough diameter to be used in one of your cheezy Citizen Swiss machines. There is a German company that makes small ones suitable for use in a lathe attachment, but my memory is failing me at the moment. If you are thinking about hobbing on one of your Swiss machines, I can get their name on Monday. But you'll need a hobbing attachment and the control option for hobbing/polygon cutting.
Schwanog makes shaving tools that you can use in a lathe, but with an 8 pitch you'll likely have to take a lot of passes. But it is a cheap method for producing precise splines without having to spend a fortune on tooling, attachments, control options and/or machines.
Schwanog - http://tinyurl.com/yavyte6
I believe Schwanog will also make form milling cutters.
If this is a high volume part, rolling is hard to beat. There are plenty of shops in Michigan that have spline rolling machines sitting mostly idle. Not too long ago I had a customer that bought a refurbished spline roller for not a lot of money. IIRC, they bought it from these guys - http://www.roto-flo.com/machines.html
Anyway, I have hobbed splines on a lathe before. If you are interested in going that route let me know and I can give you some more detail.
--

Dan

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D Murphy wrote:

Thanks very much for the info. Like I said in an earlier post, it looks like I'm in for some education. This isn't a production part, though, or even a work project. It's something I'm playing with on my own. If the spline is a standard, then I'm hoping I can just buy some rolled or extruded shaft, and turn down the ends for bearings and mounting. The spline will be the biggest diameter. If that doesn't work, then hobbing will probably be easiest.
And, just FYI, the shop I work at uses Star Swiss machines. They're wimpy, not cheesy. Having grown up in a world where 12" chucks were normal, and 30" chucks were common (on 60HP spindles with 3 or 4 gears), I tend always to think Swiss machines should be making watch parts and transmission components for MatchBox cars.
Different strokes, I guess. Thanks again for your help!
KG
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20Design/Lecture%
others
be
Monday.
8
fortune
plenty
spline
interested
Spline shafting (bar stock) - http://www.grobinc.com/
It sounds like a standard Metric spline to me. But here at home I don't have any reference material to look it up.
Involute splines are a PITA for a one off. The tooling cost is a killer. Straight sided splines are easier to make with standard tooling but weaker than an involute form.

They're

gears),

I couldn't remember which brand you had so I figured I had a 50/50 shot at getting it right.
You need to get one of these -
http://www.remsales.com/home/swiss_automatics/tmu1_series.html
--

Dan

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D Murphy wrote:

Sweet! 38 mm is almost big enough to make some real stuff. I wonder if the spec genuine, though. I wasn't kidding about our Star machines being wimpy. The 32's will handle 32mm bar stock; but the machines themselves are too light for much over over 20mm in stainless or Ti. They should be sold as 20's. And the 20 size machines should be 16's. Only the 10mm models do everything they're supposed to, as long as your eyes are good enough to know when invisibly tiny drills aren't there any more.
KG
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eng2.com:

The main spindle is 15 horse and the driven bushing bearing stance and diameter is in the ball park of a good A2-8 lathe spindle. Plenty of milling grunt too.
--

Dan

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