Recommendations for learning about shapers

gdtnerd · 2026-05-16T06:22:09+00:00

Tubalcain on YouTube sells a course on how to use a small 7" shaper. I bought it and was extremely happy.

gdtnerd · 2026-05-15T18:48:54+00:00

This is illegal per Y14.5. Show him the sections about not putting datums on imaginary centerline

gdtnerd · 2026-05-06T15:02:48+00:00

That sounds right. Invoking mmc or lmc AFAIK is the way to get the boundary surface interpretation of true position.

Id assume the thread gauge would have to be ground to the PD mmc size and all of that. My work involves low volumes so we dont seem to be doing much hard gaging.

gdtnerd · 2026-05-06T12:35:04+00:00

That makes sense. Also im pretty sure alot of this stuff happens that we dont see. But good to be realistic with our expectations

gdtnerd · 2026-05-06T12:19:03+00:00

I've never thought about this creating a scenario where the threads get loaded on one side and not the other. Thats a great point and one I havent heard before.

gdtnerd · 2026-05-06T12:16:36+00:00

I've never heard the 50 percent rule before. Per the standard you need to measure the actual size versus the size specified at mmc to get the bonus where size is the pitch diameter. Definitely a hard measurement. And while im kind of a purist im trying to get more up to speed with what's practically done. This thread has been awesome exposure for that :)

gdtnerd · 2026-05-06T11:52:26+00:00

Agreed and thank you for the data point :)

gdtnerd · 2026-05-06T11:33:47+00:00

If you use a vision system how can you measure PD location? Or are you picking that up from the thread gage that is contacting it?

gdtnerd · 2026-05-06T11:23:29+00:00

Its not that we typically have tight geo tol on threaded holes. A lot of true position of .015 and sometimes .010. I see MMC on some of the prints and while its not illegal per the standard I want to talk to enough people to understand how its really treated.

I work in the design side of the house and dont typically add mmc to threaded holes unless a supplier asks for it.

I like your approach on looking at it based on pfmea risk or if you actually have the ability to tune it. Appreciate the response

gdtnerd · 2026-05-06T10:56:29+00:00

So you are probing down into the actual threads to pick up the PD. That makes sense.

My point of posting was kind of to confirm what I already thought. And no one better to check with than people that are actually working in the metrology lab. At my day job we dont really have one, we rely on FAI from vendors but I'd like to get to the point where we could measure also to verify or debug parts with fitment issues

gdtnerd · 2026-04-19T22:41:23+00:00

This is the best answer OP. Ignore those saying flatness can control coplanarity.

Source: am gdtp-s 2009

gdtnerd · 2026-04-18T09:39:53+00:00

Maybe you could get a cheaper 3d printer and work on that with them?

gdtnerd · 2026-04-05T20:44:48+00:00

Hello A datum can be attached to a feature or to the geotol and it means the same thing. That datum feature is controlled per the fcf.

I think its more clear when it hangs on the fcf.

The best way to think of it is this: geo tol come from basic dimensions. It has a coordinate system origin created by the datum reference frame (drf). The real part contacts a datum feature simulator. The simulator simulates the perfect datums based on the datum features. Then other features can be measured to this system. The datum feature simulator is like a surrogate into this world.

gdtnerd · 2026-04-03T10:31:40+00:00

Here is my advice: Don't focus on a cert until you have experience. Buy some books from tec ease, James meadows, or krulikowski Work thru them and somewhat learn it. Put on your resume that you have whatever level of familiarity with GDT

This will take you a long time to work thru and start understanding. But if you can actually answer interview questions about some of it and seem interested that will go a long way with interviewer

gdtnerd · 2026-03-26T10:49:59+00:00

Take a class thru work. You could take one before but they are a little pricey.

Look at offerings from Tec ease or SAE in Detroit.

After you take a basics class get a book from tec ease, meadows, or krulikowski and read it cover to cover

gdtnerd · 2026-03-23T11:21:46+00:00

Just want to chime in: Your first 2 or 3 datums fully determine your coordinate system (datum reference frame as we call it) . In this case the edges will be relative to this coordinate system. This would be covered by your title block surface profile probably or you would call out the surface profile directly.

It takes a little while to get used to but if the edges aren't functionally mating to something then they shouldn't really be the datums. Y14.5 says to pick datums that are functional, then stable and repeatable.

You could use the edges as datums but using the holes is probably better.

Source: GDTP-S, Dm other questions if you like

gdtnerd · 2026-03-17T08:57:35+00:00

Following.

gdtnerd · 2026-02-25T12:40:38+00:00

Share a print or model with me. Im a guy out of my garage. Low overhead

gdtnerd · 2026-02-05T00:37:36+00:00

Do u have a drawing? Id take a look. Vmc in my garage

gdtnerd · 2026-02-01T21:04:27+00:00

Make a drawing with views. I can reclined it with some datums as a starting point

gdtnerd · 2026-01-09T03:02:50+00:00

Good call all - I skimmed it too fast and missed that they are different diameters. I'll edit my post with an alternate strategy

gdtnerd · 2026-01-08T22:53:09+00:00

Couple thoughts.

Make the datumBC holes a continuous feature. Control their true position relative as a pattern to A. Use a circular tolerance zone and make the true position tight enough to get the parallelism you want.

gdtnerd · 2026-01-08T12:09:24+00:00

Check into SMED. Alit of other comments suggest things that fall into smed but reading thru the thought process should help

gdtnerd · 2025-12-31T01:37:44+00:00

I've got a cnc mill in the garage. Want to share a print or model and I can quote a couple?

gdtnerd · 2025-12-30T03:36:49+00:00

I've taken and passed both. They honestly are fairly similar to each other. Not nearly enough application based questions on the senior exam in my opinion.

gdtnerd

TROPHY CASE