Horizontal CMM Experience? Looking for info...

Two questions:
Did you verify that your CMM program was outputting good numbers by checking some dimensions through other inspection means?
Are all three of you using the exact same program?

If yes and yes...and if 2 out of 3 are saying its good, and the 1 saying they are having issues hasn't been calibrated in 5 years...... then I think we have found our issue.

To Milicron Mike 's point....I hate horizontal CMMs due to the exact issues he has laid out. There is a fine science that must be learned & applied in order to measure properly and accurately.

Two questions:
Did you verify that your CMM program was outputting good numbers by checking some dimensions through other inspection means?
Are all three of you using the exact same program?

If yes and yes...and if 2 out of 3 are saying its good, and the 1 saying they are having issues hasn't been calibrated in 5 years...... then I think we have found our issue.

To Milicron Mike 's point....I hate horizontal CMMs due to the exact issues he has laid out. There is a fine science that must be learned & applied in order to measure properly and accurately.

We use a 3rd party company that makes up their own program, chooses their own points and all that jazz. The 3rd party company verified that the fixture was good to the nominal that they picked.

We don't use the same program. They sent me their nominals though. I brought them into our original program and snapped them to our CAD surfaces and they worked... So their program is good, even though it isn't the exact same points as the points we picked.

It's just awkward because it's a big customer and we have to be like: "Hey budz, it's effed on your end, not ours".... and they insist that their all good there....



So why would anyone opt to use a horizontal machine? What are the benefits of having one of those??

Oh boy. "Pizzing" contests aren't good (especially if they're people you're trying to get money from).

I would do is this:
1) Get a copy of your CMM calibration cert. Hopefully you're fully calibrated to a NIST standard. This proves your machine is calibrated & working properly.
2) Write a quick little program to measure something like a tightly toleranced thread ring THAT HAS BEEN CALIBRATED TO A NIST TRACEABLE STANDARD. I'd do it 30 times...each time re-aligning the part before DCC measurement. Collect the data. Run through CPK formula to provide further data that your CMM is repeating on this gage. Once/if satisfied....
3) Request for your fixture back. Measure it 30 times...each time re-aligning the part before DCC measurement. Collect the data. Run through CPK formula to provide further data that your CMM is repeating on your fixture.
4) Last but not least....do a 100% layout inspection of your fixture on the plate. Collect the data in an inspection report. Hopefully all checks out well.
5) Send them: your CMM cal cert, CPK data on your ring gage or whatever you choose, cpk data on your fixture, and accepted layout inspection report.
6) Ask them to prove to you respectfully yet objectively how they can reject two reputable source's data with an un-calibrated piece of junk (i suggest you choose your own working but I'll leave that up to you).

There's a lot there, hopefully i was able to help

DAN_M Man, I've actually been doing this as I've been talking to you guys. I'm doing a basic ball bar setup on one of our machines (we're calibrated every few months or sooner if an oopsie happens)... I'll send them the bar and ask them to run the same program and see their results. Getting the fixture back is kinda tough as it's in a different country. I'm hoping proving the repeatability of the machine along with the calibration records will be enough.

The company trusts their machine and their operator, hopefully not regardless of the numbers I provide. I think he's got them bamboozled pretty hard.

It is ABSOLUTELY INCOMPREHENSIBLE to reject someones work with an un-calibrated instrument. Especially a CMM. ESPECIALLY a horizontal CMM. There is so much wrong with their line of thinking its not even funny.
Sounds like your on the right track. I'd still perform a CPK on your ball bar internally, then send it out for measurement like you said to the outside sounce. Your CPK study, along with their acceptance of your ball bar, along with your cert SHOULD be enough. All you can do is plead your case with what you've got.

If they still refuse to accept your data, then I'd broach the topic of having the fixture returned & doing a CPK on that as I have said previously.

Somethings got to give...and if you can prove from 8 different angles that you're right and all they've got is an uncalibrated machine that has known hardware faults and a "guy that they trust"....then not only will you gain some respect at your company but they won't challenge you again either.

I deal with this a lot. ESPECIALLY with aerospace and medical OEMs who couldn't program/design/manufacture their way out of a paperbag

DAN_M My knowledge of CMM outside my little bubble is so limited. I'd love to learn more about Aerospace work one day. I kinda thought that was the highest skill point in this field, was I wrong?

I'll do a full study on the ball bar and see what happens. I just don't get why they're being so stubborn. Everyone else I've dealt with running CMMs has been so cool and helpful, like we're on the same team...

I think a big part of it is we're a relatively young company and I'm a young programmer/Figure-***-out-guy and they're trying to jostle for pricing or something? They're a big company though so I would hope they'd be more credible than that.

Of course when the customer questions our results the owners start questioning me and I just end up confused because I know our numbers are good.

Thanks for making me feel better

Aerospace and medical are what I deal with every day. They are considered to be "top tier" work...but once you get down to it..its all the same stuff with tighter tolerances and slightly different customer requirements.

Absolutely do a study on that bar. This is critical to proving your case. And will make you look like a G to your boss.

Rest assured my friend...the larger and more "reputable" the company is, the more they will TRY to beat you into a corner and make you admit you're wrong even when you know that you are 100% correct. This is done to protect their rep, yes beat you down in pricing (they're a huge company, thats how some of them get that way), and to avoid a corrective action on their end. If they can convince you that they're right even when they're wrong, they save time effort energy and paperwork. Be professional, but DO NOT let this happen.

I know what you mean...I am 26. Self taught until I got my first legit training 2 years ago. I learned how to program by literally sneaking in my first shop at night when I wasnt supposed to be there and using the CMM/watching youtube videos/studying pre-existing programs until 2am some nights. When you prove your case (I have supreme confidence that you will) your boss will have gained some respect for you and hopefully your customer will give you more work.

DAN_M So we're basically the same person then haha. I'm self taught, I'd love to have some training though... maybe one day.

I'm the first to admit when I'm wrong, but all the numbers are in my corner right now... So We'll see how the ball bar goes and I'll let ya know what ends up happening

Thanks for helping on my quest for G-dome!

No worries brother, keep fighting the good fight