How to determine what splines to cut
I have a shaft to reproduce. Not anything special, except for the splines on one end. Question is how to determine what pressure angle and pitch the old spline is in order to reproduce it. Easily set up in a mill with a dividing head or a VMC with a 4th axis, then cut a slot every 36 degrees, but getting the correct cutter geometry requires knowing what these two details are. 1.121" od with a .921" minor dia and 10 teeth is about all I have to go on. Anybody got any ideas? Oh, they appear to be involute, as the sides are not parallel to each other. Can't really make out a radius across the face of the spline tooth, but there isn't a real good means of measuring or checking it.
are you sure this is not metric? because
my math just does not work out for a standard
american pitch. only thing i can say is try a
Pitch gage would probably suffice, if I had one. I may know where I can borrow one on the way home tonight. As for metric, ther numbers dont really translate for that either. Hope I haven't been handed some offthe wall, home grown part that they had a cutter laying around for, whether it was the right size or not. Not likely that though, as they would also have to have cut an oddball female spline for it to work in. I was hoping to come up with something to measure with conventional measuring tools. May not have any luck there, but hope is cheap.
Best to get a look at Machinery's Handbook. About 50 pages of frightening looking data there which will get you to the bottom of things if its a standard spline. Take things methodically its by no means as hard as it looks at first glance. Tip:- look at the standard 10 spline fitting sizing data and get your head round that first. Its much simpler so you can see what's going on. Involute spline data is effectively exactly the same but with more terms because the spline teeth are curved. My 22nd edition has pages with pictures that you could do a blow up copy of and use as worksheets to scribble on as you progress.
Best of luck.
It's possible there isn't a curve. Some shafts have straight splines, sometimes called Serrations, and the teeth are angled but not curved. Typically at 45° or 60° angles.
Can't really make out a radius across the face of the spline tooth, but there isn't a real good means of measuring or checking it.
I have been through this, the best way to start is to get the mating part or te old spindle onto an optical projector and find out what you are after, if the job is not too vital I have solved the problem by hobbing the teeth with a 'nearest' gear hob and slowly upping the depth of cut until the mating part fits.
do you know what type of application this was
used for, and about how old it is? this might give
some indication if it is american, or metric.
if it is old, probably not, and may be 14.5 degree
involute. is this part broken? this is when you have
difficutly with measuring, and such, because the
part may be stretched,(elongated), and the teeth
could be damaged. i have had to deal with this
problem before, when making new splined shafts.
if you are not able to match this with a pitch
gage, you may have to custom grind a tool to
cut this spline. it would have to be very precise,
and i hope you have good eyes, because this is
what is needed, with this type of operation.please
keep us informed on your progress, and
Look at the shaft from the end holding it so a "key" is straight up. Do the sides appear to be parralel? Measure the width of this key, 1 1/8-10 spline has a key width of .174 to .176 when new. If it is a parralel spline it is easy to cut with simple end mills and a dividing head. Ed.
After some measuring,and conferring with the gear and spline cutter catalog, and the 24th edition of the Machinery's Handbook, I had decided that it was the common old 10 spline. This was confirmed by an associate who has cut a lot more splines (and everything else) than I have. "Looks like a duck, walks like a duck, and quacks like a duck, it's probably a duck." Machinery Handbook dealt mostly with involute splines, and the sides of the "keys" on this are NOT parallel, so I'm assuming they're involute. In any case the numbers from the measurements add up to a ten spline, and I can get the cutter for that easy enough. Don't really want to grind a tool for this, as it's going to be a recurring , low volume job, and I need something I can count on to set up on short notice with some fairly inexperieced help. I have a hobber if I wanted to go to the trouble of setting it up and get the proper cutter for that, but in the volume we looking at (12 a year), I'd just as soon set it up in a small VMC with a 4th axis and run a year or two's worth and be done with it.
Thank's for the replies. This isn't something I've dealt with a lot in the past and the widespread experience in this forum is a welcome help. Done a lot of weird stuff, some really off the wall, but splines just haven't reared their head often, and the handbook's info was a bit daunting.
when you say it was the common old 10
spline. exactly what to you mean? is it a
10 pitch? if so, the od would have to be
larger than what you posted.
please let us know, and
SAE J499 spline series:
Table 4 is 10 splines:
As will be seen when machining these type of spline,they are not involute ,nor can they be produced with end mills. They are indeed straight sides
In this case the OP was concerned with a "male" spline ...This entails milling away the steel between ....as you see ,you most certainly must cut an angled sided slot,leaving a straight sided spline.. Divide the number of "cuts" into 360 degrees... this tells you the included angle of the cutter....Now you can either make a flycutter with this angle or buy it somewhere?
The Machinerys Handbook is quite clear on this procedure,it is not hard to understand.
I don't know what the mythical "pitch gauge" is but it is not needed anyway.
Some times a subject will come up and it's easy to tell right away that many posters
really don't have a clue, but they will tell you how anyway.
This is how it is done.
It is late and I must be cranky ...sorry
HELLO TO ALL,
i have cut the straight sided splines, only this
was a 6 spline. i used to two slitting saw type cutters,
with the proper spacers in between them. there was
a small bit of metal left between the splines, and i
cleaned this up with an end mill.
will try to post a pic of the setup.
good luck to all.
parallel, 30 degree and 45 degree for spline. Sounds like you have a mower splindle/tractor of some sort 30 degree most popular by far.
You can have a side milling cutter that is wide enough ground to the appropriate angles on both sides and the root radius so that everything is the correct form.