Best or good practice for Splines (ID or OD)

[[Ri...]]

I have a few Spline gages to inspect on the CMM.
I can scan them with styli or use Viscan (Still learning Viscan).

Are there any methods that are tried and true?

[[Ma...]]

Spline tolerances are usually based on go/no-go gages and tooth thickness measurement of one type or another. What and how best to measure them on the CMM depends on a lot of variables.
What characteristics are you required to measure on the spline gages with your CMM? Are they involute splines? Are they normal spur splines or helical? Approximate pitch, diameter, face width and quality class? Do you have GearPro? Do you have a rotary table, etc?

[[Ch...]]

Gear (and spline) guy here..

Splines in general : quality is often overlooked in my opinion. They are not as critical as gears and only are responsible for rolling with a mate or transferring motion. Because there is no callout for lead.profile or pitch on the drawing Many people (quality and manufacturing) just measure a wire size, maybe major/minor Ø and call it a day.

What spec are these for ANSI B92.1 ?

For splines themselves (not gages): technically tooth geometry can be accepted with proper use of Go & No-Go gages.(go gage goes fully, no-go does not go in all spaces at both ends of spline). Other features such as : dimension over pins/wires, runout, major/minor Ø's still need to be verified.

In lieu of gages : full analytical CMM Inspection should be done for Fp, Fß, Fa (Cumulative Pitch, Lead, Profile).

Keep in mind spline gages will not really inspect the lead/helix : due to : if you had a taper tooth thick at bottom and thin at top, the wire size may be in on both ends, however you could have excess lead error, and go gage will probably go on both ends.

Good spline manufacturing process is to check the first pc manufactured with gages, wire size, major/minor Ø, and full CMM. Depending on the process (such as shaping), it is recommended to accept subsequent part to gages, pins and root diameter at the machine, and inspect every 5th pc or so on the CMM. It is good practice to always inspect last pc as well. Root radii should be measured every 1st, every 5th and last pc as well.


For spline gages : now we're talking a whole 'nother story. If you don't have much experience with splines I would not recommend diving into gages. However if you have to check them - I suppose we can help here .. More info about the gages may be needed ( sizes / pitch ,ring gage or plug gage, etc.).

I have lots of experience inspecting master gears and spline gages.

Spline gage tolerances : These are found buried in the ANSI B92.1 spec. If there are no datums on the spline gage drawing most will use and face and a concentric ground ring for a spline ring gage, or perhaps the bore of a spline plug. While these may be what was used to manufacture the gage (and sometime they are not), if no datum is specified - the datum is then the spline gage PD ( which you can probably imagine is difficult to establish : HINT : gage ball in the gaps top and bottom to construct PD Cylinder)

Good luck, let us know how you make out.

[[Ri...]]

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This is the spline information I have.
(It is not an involute.)

(Metric)
ID Spline Gage
30T - 1.0Mod - 30° PA
Number of teeth = 30
Module = 1.0
Pressure angle = 30°
Pitch circle diameter = 30.0000
Base circle diameter = 25.9808
Major diameter (min) = 32.35
Form diameter (min) = 32.10
Minor diameter = 30.155 +0.025 -0.0
Circular space width = 2.0922
Pin diameter = 1.750
Dimension between (2) pins = 28.373

[[Ch...]]

Rick,

Thanks for the info. Is this a gage or just a splined part ?
The only thing we do not have is face width size (which would govern lead/helix tolerance), and datums.

Does it list a spec (ANSI B92.1 or DIN / ISO ?)

If this is just a splined part : Are go-no go spline gages available to inspect it ?

[[Ri...]]

It is a Gage (ID) for calibration
DIN / ISO

[[Ch...]]

Rick,

Ok. thank you for that info.

Does it have a sketch / drawing (with datums specified) ?

Does the drawing have tolerances ?

Do the ends appear ground? is there a ground OD conc band ?

Does it mention a class # ?

Does is specifically say "non-involute" ? , most non-involute straight sided splines are 45° pressure angles.

[[Ri...]]

Ill get back to this shortly...

[[Ch...]]

Rick,

Hi, just checking back in.

Best practice here would be to locate on flattest surface in chuck if available. Indicate the concentricity band(if available) to ~ 1 µm. {Make sure Rotary table is running very true as well, and proper RT calibration has been done prior}.

Based on the data you shared, it seems like there is ample face width. Provided there is a large enough ground OD, you can make that cylinder the primary datum - unless of course datums are otherwise specified on the drawing.

I would recommend also using this cylinder to 'Measure/Determine RT Axis' as described in Calypso manual (Chapter 14?) - hopefully you have done this before.

Select proper internal stylus size, I'm guesstimating at 0.8mm or smaller to clear for profile - I would start with 0.5 or 0.6mm if available.

I don't have access to ISO spline specs for tolerances, but typical tolerances in inches for ANSI are :
Profile Fα : .0002", Lead/Helix Fß: .0002" / 1.0" in face width (if shorter than 1", tolerance is about .0001"),
Cumulative Pitch Fp : 0.0004 - .0005"


I also noticed there is no tolerance on the dimension between pins or C.S.W.; perhaps this is an ISO thing where the drawing specifies nominal and the spec states + and - tolerance ?

I've heard some people just measure a wire/pin size for yearly spline gage calibration : I would not recommend this as they are gages and used for product acceptance. Even if you measure at top middle and bottom, it may not tell the whole story of tooth geometry errors. Once you learn the process it gets easier and is second nature. It is well worth the time spent verifying, and this way you know you are fully compliant with the spec as well.

It is also important to do a good visual inspection of all the teeth as with all master gears and gages, etc.

Good luck,
Keep us posted.

[[Er...]]

I'm new to checking splines. Previously, all our parts are sent to a supplier who creates the spline feature, sends us the inspection data. Now, we are machining the spline here, and I have never created programs to inspect spline requirements so any suggestions is appreciated. I do not have gear pro, nor a rotary table, and I have a contura, and duramax with RDS XXT sensor. Thanks.

[[Ch...]]

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Chris,

Would you be willing to share any reference documents you have found helpful in your time measuring gears/splines? We work with some gears and splines and I always like picking the brains of gear people.

[[Ch...]]

Chad / Eric / All,

Sure. Basically start with ANSI B92.1-1996 , and Gear Pro manual if you have one.
Keep in mind splines are not gears and typically not as critical.

B92.1 spec clearly says splines can be accepted with proper Go/No-Go gages, and I would strongly recommend this for most production. Analytical CMM inspection is good practice on first/last piece and incrementally depending on lot size, etc.

For the part Eric shared, this is obviously highly modified, due to the cutouts in the spline tooth OD/ major dia.
Since the pin size for Spline B is .080" you should use 2 mm ball to self center (also be sure to use midpoint eval) in each gap to establish PD 'position' to -A-.
Form Dia is REF or BASIC. Dimension over pins can be calculated with the self-centering the 2mm in all gaps.
Pitch Dia, Pressure angle and Pitch are all BASIC Dims.

what might help here is how to line up a spline tooth or gap in Calypso - see attached.

Good luck.

Clocking the Gap of a spline and creating a datum from the pitch circle.pdf

[[Ma...]]

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Rick,
You state that "it is not an involute" yet your data contains a base circle diameter. The base circle diameter is by definition "the diameter of the circle from which the involute form is generated", so I think it is quite certain that your internal spline gage has an involute profile.

[[Er...]]

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Chris, This worked very well. Thank you for sharing your knowledge. We are trying to burrow, rent, or purchase our supplier's Go/No Go gauges, but haven't gotten any information from them. Do you recommend any other inspection to ensure they are machined correctly while we are waiting for them? Thanks again for all your help.

[[Ch...]]

Eric,

Not really, not without Gear Software You could report runout of the spline PD along with the position callout.
All of those slots in the tip of the tooth should keep you busy reporting 20X dimensions.

TIP : Check the No-Go gage on both side of the spline in case there is 'taper'.

Good luck and welcome to the world of metal teeth 🤣

[[Ma...]]

I have never seen a straight sided spline that is specified to mate with an involute spline like this before. The slots in the tip of each tooth are unusual as well. Do you know if this is meant to be a press-fit with the mate? Are the slots to allow the tips of the teeth to deform when pressed together?
Being straight sided it should be possible to measure the flanks for flatness and angles in both directions but it will require a fairly small stylus to get very close to the root.

[[Er...]]

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I wish I knew what this was used for. I think this could be press fit, because this is actually made out of plastic and I believe it might be an insert for something, if I had to guess. I thought about running a curve around the teeth, curious what the profile would look like, but i have been too busy with updating other programs at the moment.

[[Ri...]]

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Thank you educating me. 😉

[[Ri...]]

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The print is very similar to what I get.
Except mine are generally from the 1950's.