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Spline Chart?

i_r_machinist

Titanium
Joined
Apr 12, 2007
Location
Dublin Texas
I have an internal involute spline that is eating my lunch. It has a major id of 2.222 and a minor of 1.907. It has 10 splines. I can't for the life of me figure out what pin to use to start measureing this thing with. Theres a calculater in Gibbs but I have to know the pressure angle to use it.
Is there a chart out there that shows the different sizes?
thanks
i_r_machinist
 
If it's an involute spline, it doesn't really matter what pin you "have to use". You can just measure between wires over maybe 3 different wire sizes (as long as they cleanly sit on the profile). Once you have that, it can be reverse engineered from there. Try and use a set of wires that almost contacts the major diameter, a set that almost sits near the minor diameter, and one near the middle.
 
Post the measurements if you decide to approach it that way and I'll do the calcs for you (unless one of the many smart people here beat me to it!). ;)
 
Between .375" pins is 1.387"
Between .356" pins is 1.470"
Between .341" pins is 1.539".
I scanned the male spline with our Faro cmm today and generated a model of the spline, but I still can't figure out diametral and circular pitch.
Thanks for your help
i_r_machinist
 
Spline data

irm,

at a glance 5/10~30°~ flat root side fit came to mind, the numbers all though close do not fit:

Mj 2.274"
Mi 1.819"

I ran some numbers for basic CSW, 5/10-30°-FRSF modified to your actuals. the blue lines compared to your black, with your pins, you definatly have a special. The 30° PA looks large, maybe 27.50°?

VisualCADD403-10TINTSPLN01322010952.jpg


Cheers,
 
That was my first guess too... I've tried a few other combinations so far, but have not hit on it yet.

Still working on it....

I'm back. :)

lesawharris,

What do you think of 5 module 25° ? CTT of .2781" / CSW of .3403". MBW is on the money with .356" wires and +.0014" with .341" wires (though it's possible that the .341" wires might have just been touching the major diameter during measurement since (.341*2)+1.539 = 2.221" )

I'm slightly skeptical that largest wire size (.375") is actually on the profile since the middle wire size is already contacting within .0082" of the minor diameter in this configuration. IF there is a radius where the profile intersects the minor diameter (yes... I'm speculating!) that might explain the discrepancy.


i_r_machinist,

I've uploaded a DXF of the spline here (might need to right-click and "Save As") ... and also attached a screen grab below.

I'm not yet convinced that this is correct, though it's the closest I've managed so far. How does the DXF compare to your CMM data?

5mod-25.jpg
 
Precision,
Your dxf is an perfect fit for my scan of the shaft. You wouldn't happen to be in the gear making business would you?
(5 module 25° ? CTT of .2781" / CSW of .3403". ) Is this how I would designate the spline on a drawing?
I can't thank you enough. This has been a real thorn in my side.
Thanks again to all who replied!
i_r_machinist
 
l_r,

I'm in the wire edm business, and I tend to gravitate toward cutting gears and splines that are "difficult" or impossible to make via conventional gear cutting methods (or impractical to tool up for because of low volume).

The "circular tooth thickness" or "circular space width" (the latter being more common on an internal) is what determines the "fit" of the spline. Increase space width, and the internal becomes "looser" on the male spline. "5 module" simply means the number of millimeters of pitch diameter per tooth.

I'll have to do a bit of digging to see if there is a defined specification for that particular spline -- I can find out shortly (today I'm sure).
 
I have a solid works model of the splined gear now. I'm working on getting a drawing. Your dxf file had just a hair of a gap with my scan.I figure that would allow for the slip fit needed. I'll need this gear and one other. No spline on it. Just a bore and keyway with a 30 tooth gear. If the price is right I may get two sets. That way if this guy starts winning (tractor puller), I'll have a set to sell to his competition!
Thank again for all the help.
i_r_machinist
 
I'd be happy to look over the parts and provide a quote and/or advice, if required.

Shoot me a private msg here if I can help.



thx
 
Pm post # 7 reply



PM,

Concurr, small pin at your numbers interferes 2.222" Major Dia, by 0.0009",
0.375" pin must rest on corners of Minor Dia, as offset from profile does not intersect c/line,
have not drawn 0.375" dia pin.

VisualCADD403-10T5MM25PA01332010616.jpg



VisualCADD403-10T5MM25PA01332010613.jpg


Cheers,
 
In my case, I just played with different DP/PA combinations (which changes the base circle) until the tooth form matched your measurements over different wire sizes.

:)
 
Vogle equations

I hate to flaunt my ignorance, but how are you calculating pressure angle with that drawing?
Thanks
i_r_notengineer
DR WERNER VOGEL equations from "INVOLUTOMETRY & TRIGONOMETRY" Michigan Tool Company, put into A Quatro Pro Spreadsheet & juggled to put tooth space at the top as in Gear grinding work. Calcs points on the involute at actual tooth dimensions, can spline thru 9 points for very accurate, 2 circular arcs thru 5 points within a tenth or so 3 point arc good over 30 teeth gives "S" shaped involute chart within a few tenths, low N.O.T.'s error increases, Ground thousands of gears this method with simple circular arc dresser.

SAMPLE 10T.
QuattroPro-CDocumentsandSettingsOwn.jpg



Cheers,
 
Les, that looks like a tremendous amount of work to get entered correctly and make it work.

Would you be by any chance at all interested in sharing that spreadsheet? :drool5:
 
Les,
You wouldn't happen to work out at the missle base? That sure looks like rocket science to me. I wouldn't mind haveing a copy of that either....
Thanks
i_r_
 








 
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