We have this part that has a feature called out 45 deg from a clocking datum midplane. The thing is it could be 45 deg to the left or 45 deg to the right.
All the views on the print have it to the left, and that is how it must function, but I could entertain the argument the parts made opposite...
If I had the time and could legally divulge prints, I'd do as Eric suggested and showcase the poor GDT I see every day on youtube for fun. It would be crazy educational...much more so then a standard GDT video in my opinion. This is a great idea ;)
I'm gonna second the motion that 3dDave stated...
I've got this square callout for size then a position for said size.....I still don't remember much from the standard on this square drive symbol.
I measure both linear sizes independently and both positions independently. Seems simple and to the point. I measure both opposing planes as a...
Ryan,
Thanks for that snippit. I see those modifiers all the time in our software and I need to do a better job learning them. They could come in handy at some point.
pmarc,
Do you like iso better for some reason?
Ryan,
Is there anywhere I can read a copy of the ISO standard for free? We may have one at work, but I'm sure you cannot Ctrl-F and search for a term as most pdfs we have seem to almost be scanned pdfs. I'm at the point where I could handle the brain damage from reading some ISO stuff.
BTW...
Hope you all are doing well, happy new year.
I'm questioning my understanding on whether this is a rule for a pattern or simultaneous rule. Seen below is a bolt hole pattern, no bottom datum as this is a quick example. There is some datum shift with the A datum, I just forgot to put the symbol...
I'm questioning if the many profile callouts I see that don't have a profile section that includes a straight portion should not have a secondary datum for clocking in the secondary FCF
A good example would be the below pic from the 2009 std....IF the second FCF had AB instead of just...
Dave,
The real senior exam is here on this forum rubbing shoulders with the likes of older grumpy crazy experienced professionals like yourself that I dearly love, reviewing customer prints, discussing concepts with mentors, etc. Why would I rely on a certification test to tell me what is...
greenimi,
I think I may be seeing the light...
If you have a 4 hole pattern and there is no datum shift modifiers, there really is no difference in measuring them individually vs as a pattern for the ultimate fit and functionality.
BUT...if there are datum shift modifiers you would be...
Wait a minute...I'm a complete idiot. If you use a poorly machined plane for the clocking you could still input 3mm for each sphere, it would just force the spheres to clock to that surface.
Sometimes, I'm stupid.
I guess where I kept getting hung up is if there is this simultaneous...
Burunduk,
You are correct if manually checking the part. But I'm writing a program that must check 100 parts per week, run by operators, without any manual input or overrides. Therefore, to check them individually, I need to tell the software how far from a datum plane each sphere sits so I can...
There is no datum shift in this example, I don't want to even think about that right now.
I initially conceptually agreed with greenimi, that the clocking datum doesn't matter when reporting out the spheres separately to make sure they are conforming simultaneously, but let me share a quick CAD...
3dDave,
I'm using both a CMM and CT scanner. CMM is more accurate point to point, but the CT is proving to be more accurate with assembly to summarize as it seems to be getting more surface area at an average correctly. You can measure hole simul on a CT. Whether you agree with the output is...
I cannot agree more with your sentiment that it isn't a feature of size. I'm arguing tomorrow in a meeting about this issue.
My original question still is up for debate...
To measure each sphere simultaneously you would need to be SURE they are the within the basic distance from each other...
Dave......I don't give a shit about the standard or FOS or non FOS I care about one thing...if I measure each sphere idependently, will they fit as a group per my datums and the fact I am measuring them seperately
My last question would be this on a technical side...
Whether you use the midpoint between both spheres to clock the XY datum or use the midplane of overall part....measuring both spheres for positional tolerance independently would or would not ensure they are in tolerance as a pattern?
3dDave,
I agree with what you said, but I'm trying to push us into a more professional approach...these goofy irregular fos callouts are taxing.....
One thing to mention is our parts get plated and come back to us to get finally inspected for assembly so its not like the cat is hung out to...
pmarc,
10-4 appreciate the confirmation.
Alex,
I had a meeting recently where a positional callout was at MMC 0.0mm and the feature was a 120 deg torus with a radius at +- 0.025mm. They only gave me 0.05mm of bonus...on a diametrical positional callout...i told them whether you identify on...