Gauge to check Perp. on an I.D.

[[Je...]]

Hello. I am not sure if the following post will be germane to the forum, so moderator feel free to remove or edit as necessary.

Does anyone have an idea on how to functionally check (or create a hard gauge for) perpendicularity of the ID of a cylinder to the face of the same cylinder?

• This part will eventually be checked on our CMM, but for specific reasons, we need to come up with a functional check (near the CNC machine) while the part is in-process. The part can be unfixtured in order to measure it.

• Below I've added the drawing for the part.

We do have the option of creating a functional gauge, but cost for the gauge should not exceed $1,000 U.S..

Thanks for any ideas / suggestions!

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Jeff Frodermann
Windings, Inc.
Windom, Minnesota

[[Da...]]

The drawing is not valid. You must specify if you want the axis of the ID or OD perpendicular to plane A.

If you used a Maximum Material Modifier on the call-out, the construction of a functional gauge would be easier. Without it, you would need a gauge with an adjustable diameter feature (inside or outside, depending on your revised call-out).

If you had such a gauge, you’d „simply“ insert it, adjust the diameter feature so that it would clamp the part with a ground surface (being perfectly perpendicular to your adjustable diameter feature) making maximum contact to the part's plane A, and then just look for light making it through the contacting area. If you see no light coming through, the part's okay (but six more weeks of winter). If you see light, the part doesn’t pass.

Sounds complicated if you need the perpendicularity of the ID and, well, it is. If you need the perpendicularity of the OD, there is the special challenge to be able to see the light gap when the OD of the gauge blocks access to the contacting area.

Personally, I’d talk to the engineers to add an MMB to the call-out or keep on measuring on the CMM.

[[Je...]]

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Thanks for the great feedback, Daniel. You are correct about the drawing not being valid. I updated it to specify the ID as the feature to be inspected. I do not know yet if MMB will be allowed, but basically, are you suggesting it would look like this with MMB:

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And this without MMB:


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I will have some discussion with the customer about this. And yes, I am going to push for a CMM check instead of a functional gauge. However, if they won't budge, perhaps they would allow a runout check instead. Would the following concept (definitely a work in progress) fit for a runout check on the end section of the ID?


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Thanks again, and more feedback is definitely welcomed!


Jeff Frodermann
Windings, Inc.
New Ulm, Minnesota

[[Da...]]

If the engineers chose to add an MMB to the ID, they would usually also give the ID a tolerance determining the allowed MMB, defining how by how much the perpendicularity or any other form error may have more wiggle room.

It’s very unlikely to have the MMB defined by a general tolerance, cause the allowed form deviation might get huge then.

And I think your alternative setup would work, but still you would need an adjustable stud or something like a chuck for the ID.

[[To...]]

MMB would only apply if Primary Datum feature was a feature of size. For example, if you reversed the perpendicularity features and made B the Primary Datum.

Like Daniel stated, we need to know what the tolerance of the ID is to apply MMC.

[[Da...]]

Both datums A and B are features of size, at least if in the drawing, the datum letter "A" was drawn on the same height as the distance 6, indicating the datum to be the center plane between both planes, making A a feature of size.

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Still, you're right, Tom, in this particular drawing, A would only be a single plane, making it not a feature of size. I was only assuming the drawing needed a little improvement.

[[An...]]

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[[Ow...]]

Questions of size, form and maybe cost aside, an expanding mandrel or actually a bar-arbor fixture would be my preference.
It has been a few moons since I've worked with them but, the guys at Precision Devices Inc in Michigan do great work.
See attached or go to their weblink below.
https://www.predev.com/

[[SH...]]

We use gauge like this, price will be above mentioned by you.

IMG20210315172648.jpgIMG20210315172641.jpg

[[Je...]]

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Thanks, Owen, for the info and the brochure! I'll check out Precision Devices.


Jeff Frodermann
Windings, Inc.
New Ulm, Minnesota

[[Ma...]]

The old school method of checking something like this would be to use an Indi-Square on a surface plate by recording the results of 4 equally spaced trams in the bore to separate the tilt of the axis and the taper of the bore.
A new Indi-Square will set you back more than $1000 but has many uses beyond one part.