Center axis as a datum not repeat

3 hits 2 levels on a cylinder with a TP of .002 is not enough. I recommend 8 hits 3 levels on all cylinders. with the number that you are using you are not picking up the actual form error.

Little confused the drawing posted has datum B as the 1.125 diameter and estimate 2 inch long, the code is showing datum B as 1.375 diameter length 0.36 with depth and end offset that reduce the cylinder length to 0.222.

Ignoring that it appears the wrong cylinder is being used as datum B the length of the cylinder and the number of hits used will not create a stable axis.

Can't as I have said many times management does not allow anything but minimal points. I'd tou can take thw trimos take a point too and bottom to create the circle then rake a point top an dbottom on the other circle and they are within .002 your part is good. Chips have to be cutting parts are machined to the model so they are correct. Cmm takes to long and cost us money.

Yes I had thay backwards. I had fixed that already.

"a center of an cylinder is just that a center of a cylinder. Points do not matter if pcd is not smart enough to make a cylinder with 6 points it is useless.zeiss and polyworks can do it eveytime with minimal number of points. Asme defines a cylinder as 6 points. Pcd can't not dictate or tell me how many points I need. A pin fits in that hole so form is good and size is good. Pcd can not tell or use other info to change the fact a asme defined cylinder is 6 points. Anything else is just creating error in the measurement."


"We used a boring bar so it is impossible to not be in position to b. They are cut at the same time with the same tool.why can the cmm and hexagon not figure out to.measure parts correctly"


Not my words but my manager words. He found using the height gage the center of b and then found the center of the other hole was .0003 off center so the part is good and shipped.

PCDMIS does fine with correct information just remember garbage in garbage out, if you are still using short cylinder lengths that is what you will get and has nothing to do with the software but your incorrect measurement strategy.

6 points for datum B can never be enough to assess the cylindricity requirement or be confident that the bore is the correct size.

Maybe post your corrected code then we might be able to work out the problem.

I agree. Exactly what I tell them. But you and i are wrong.

No need they shipped the parts out. They got them Good with a height gage pins an d calipers.

I was given about 30 minutes to write this program. rhey wanted measured and had a program run time limit of not more then 10 minutes. The part has to have a set up thay a machinist can run this part as they pull it off the machine. If a machine is down longer then we have to find a faster way to measure. In this case they did some pin checks a few caliper checks and a couple height and called it good.

I truely hope none of the guys on here are our customer. I hope these parts fail. And get kicked back. Sometimes management needs that kick in the pants to plan and understand better. Cost of quality

browningdmis

Here's some ammunition to counter your manager's assertion that 6 points are sufficient for a cylinder...

ASME Y14.5 - 2018, section 4, Fundamental Rules.

4.1 (o) UOS, all tolerances and datum features apply for full depth, length and width of the feature.

and

4.1 (s) All elements of a surface shall be within the applicable specified tolerance zone boundaries.

He should also read section 5.8 and 5.8.1 which talk about limits of size and the envelope principle (variations of form).


How would you ensure that your parts meet those requirements if you are only sampling 6 points?

On the print, why is there no datum on the True Position? I don't think I've ever seen that. Is that allowed per ASME? Just curious...

Off subject but management sure seems to disagree with you a lot. Sure hope you are considering a job search soon. Haha. They don't seem like a pleasant bunch to work with. If I had that kind of negative feedback constantly, I'd be out of there. Especially if they are just trying to do the bare minimum part checks instead of what should be done. They are picking a height gauge over you. But if you stay, I hope you can eventually win them over.