Taylor Race tripod spline questions

[Tilman]

Hello guys,

I am stuck with the Taylor Race tripod spline data ...

I emailed Scotty some weeks ago and he gave me the following data:
<pre class="ip-ubbcode-code-pre">
MIN 24.64MM
MAX 24.677MM
PIN SIZE 2.032
ACCUAL MIN 1.938
MAX 1.977
MAX EFFECTIVE 2.011
</pre>
I guess the unit used is millimeters for all sizes.

I did not know what to do with this data, I expected something like "DP 24 / 48, 20 teeth" or similar ... Scotty told me to use the QuickSpline-software that can be found at http://quickgear.bizland.com/id9.html.

This did not help me because this software does not draw splines and moreover, the description of the values is not very detailed ...

Then I did some research and found some interesting pages in the machinery's handbook (28. ed). From this I guessed that accual max, accual min and min effective all referred to the circular tooth thickness or the circular space width.
Furthermore, there was a formula to compute the pitch from a given pin size (which is exactely 0.08 inches). The formula is d_i = 1.92/P (for 45° pressure angle) where d_i is the pin size of the measuring pin and P is the pitch. This gave me a pitch of 24 ( to 48) because the formula for pressure angles of 30° and 37,5° returned a pitch of 21.6 which is obviously wrong.

Then I went back to the QuickSpline program and entered External Spline B92.1, 45° pressure angle, 20 teeth, fillet root side fit. This gave me a nice table with lots of sizes, i modified the appropriate sizes to the values Scotty gave me (min/max being the measurement over pins and accual min/max and max effective belonging to the circular tooth thickness).

Here is the Output of QuickSpline (http://129.217.231.229/joomla/images/dokumente/axlespline.pdf).

Now my question is: Was this the right way? Are the values correct?

Next question: How do you mill such a spline? Do you really mill the involute profile or do you mill tooth with even sides hoping they will fit the tripod?

I hope you guys can help me ... thanks in advance!

Tilman Schröder
GETracing Dortmund
University of Technology Dortmund
Germany

[Tilman]

Hello guys,

I am stuck with the Taylor Race tripod spline data ...

I emailed Scotty some weeks ago and he gave me the following data:
<pre class="ip-ubbcode-code-pre">
MIN 24.64MM
MAX 24.677MM
PIN SIZE 2.032
ACCUAL MIN 1.938
MAX 1.977
MAX EFFECTIVE 2.011
</pre>
I guess the unit used is millimeters for all sizes.

I did not know what to do with this data, I expected something like "DP 24 / 48, 20 teeth" or similar ... Scotty told me to use the QuickSpline-software that can be found at http://quickgear.bizland.com/id9.html.

This did not help me because this software does not draw splines and moreover, the description of the values is not very detailed ...

Then I did some research and found some interesting pages in the machinery's handbook (28. ed). From this I guessed that accual max, accual min and min effective all referred to the circular tooth thickness or the circular space width.
Furthermore, there was a formula to compute the pitch from a given pin size (which is exactely 0.08 inches). The formula is d_i = 1.92/P (for 45° pressure angle) where d_i is the pin size of the measuring pin and P is the pitch. This gave me a pitch of 24 ( to 48) because the formula for pressure angles of 30° and 37,5° returned a pitch of 21.6 which is obviously wrong.

Then I went back to the QuickSpline program and entered External Spline B92.1, 45° pressure angle, 20 teeth, fillet root side fit. This gave me a nice table with lots of sizes, i modified the appropriate sizes to the values Scotty gave me (min/max being the measurement over pins and accual min/max and max effective belonging to the circular tooth thickness).

Here is the Output of QuickSpline (http://129.217.231.229/joomla/images/dokumente/axlespline.pdf).

Now my question is: Was this the right way? Are the values correct?

Next question: How do you mill such a spline? Do you really mill the involute profile or do you mill tooth with even sides hoping they will fit the tripod?

I hope you guys can help me ... thanks in advance!

Tilman Schröder
GETracing Dortmund
University of Technology Dortmund
Germany

[SNasello]

In terms of milling the splines, the most time effective way to do it would be to determine the exact profile of the spline and have a tool ground to that profile. If you don't change the splines you use from year to year, then it is very cost effective to get a few of them ground at the same time.

We have been toying with milling splines in house. Our shop just picked up a 4th axis attachment for one of our Haas mills so we can chuck up our driveshaft in it and mill the splines precisely. We will be getting some circlip groove milling tools ground to our desired profile. This would be the fastest way to mill them. You might want to have the tool ground slightly undersize and run finish passes, or just take a partial depth rough cut and then a few shallow finish passes. I would also suggest milling a test piece first out of aluminum or nylon (much faster to machine) to make sure you got it right.

We have also toyed with using a really small ball end mill and surfacing them but this is not a very good use of time. In 4340 it took us about 24 hours of machining time to do one driveshaft (let it run overnight). Again, for this you need to draw the profile.

There is another program by Camnetics called Geartrax that generates male and female spline profiles in solidworks. You can get a 10 day trial for free, and the program cost 95$ US for an educational license. the program will also generate any type of gear profile, including rack and pinion, sprockets, etc. Its a worthwhile purchase as it will save you lots of time.

[rjwoods77]

Geartrax is garbage. Not even an involute spline. If you are going to market your program as having involute splines it better have involute spline and not some made up crap. Most times it is best to send them out to be done by a shop who knows what they are doing. There is a bunch going on with material, heat treatment, machining, grinding, etc.

http://esoxrepublic.com/blog/c...ry/geometry/splines/ (http://esoxrepublic.com/blog/category/geometry/splines/)

[SNasello]

This is a very good point you raise Rob. I never realized that there was this issue with the way that geartrax generated its profile.

Like I said, its worth machining a test piece first to see how it actually fits in the mating spline. With the relatively small splines that we are using (I can see how the error would be a big issue for bigger gears) I am doubtful that this error will be very large compared to the machining tolerances.

So far we have been able to machine 'good enough' splines in house that allow us to not have to outsource the job. Not that outsourcing something like this is a bad thing, but for us, it works out better this way. Most teams would not care to consider this and just get someone else to do it, especially the heat treating.

[rjwoods77]

Stefan,

Most gear shops I have been told machine splines on a blank, then heat treat and then grind to finish up. I would imagine splining a 4340 bar with RC of 46-50 would cause a bunch of fretting. I don't know what tooling you are using but it is hard to cut proper(good accuracy) splines with a pre hardened bar. Then again how much accuracy do you need for a cv. I would always go on the side of what gear shop standards are. My two cents but with today's economy that might be worth shit allhttp://fsae.com/groupee_common/emoticons/icon_smile.gif

[Tilman]

Heyho,

thank you guys for you quick replies.

Milling the splines in our university is another question, perhaps we will have access to a 5-axis-cnc-mill to do the job without a special ground tool (I don't know what it will cost).

I am asking all this stuff because we do not have the money to order some taylor-race tripods and then realize that we cannot use them because the spline is too complicated to do it ourselves ...

Did you all use Taylor-Race tripods? If yes, can you please check whether the dimensions I calculated are correct?

I would like to know this because I cannot draw involute profiles and do some cnc-programming for this spline if the spline dimensions are wrong ...

Thank you,

Tilman

[Scotty]

Tilman.

I sent you an e-mail with all the currant spline data for our 02002011 tri-pod joint.

scotty
Taylor Race Engineering
scotty@taylor-race.com