Make part round again

[[To...]]

Here's one that I don't think is going to be possible but.....

Customer has round part with a bolt pattern. When the part is in the fixture and the hole pattern is machined, the part is round. When the part is released from the fixture, it is no longer round. Customer would like Calypso to measure the OD (Datum Feature) and evaluate the data to make the part round again, and also measure the hole pattern and have Calypso compensate for the roundness error. In other words, make the part and hole pattern round again.

Thanks in advance.

[[De...]]

Is that like when the operations manager comes in and asks you to make the printout green? 🤣

In all seriousness, I can't think of a way to compensate from an unconstrained part unless to constrain it. We had round parts that needed a collar placed around them to constrain the part in a round condition for the measurement to occur.

[[La...]]

There is no way to duplicate the fixturing condition in the machine tool? I wonder if you could use Gauge correction and measure the same diameter ring gauge and apply the correction...

[[De...]]

Would it be possible to evaluate the position of each hole in the bolt hole pattern to a localized measurement of the datum (OD)? If you look at the radial deviation between the individual holes and the local datum surface, then calculate Min/Max deviation. This should account for radial change between restrained and unrestrained condition, but not any angular deviation.

[[Da...]]

Start by indicating the OD to find the highest point. Now grab the biggest hammer and.... 🤣 🤣 🤣

[[No...]]

I don't know if and how one could make an oval diameter round again, but if the average offset between round and non-round is known for each hole in the pattern, the customer could recall each hole and compensate the offset with formulas. Then make a new hole pattern with the corrected holes.

[[Ow...]]

Therein lies a common problem/disconnect between engineering,manufacturing and quality.

All too often you see a drawing where the part wasn't designed rigid enough to compensate for distortion when material is removed or the wrong type of material or process treatment was applied or the manufacturing process wasn't designed to not distort the part.

When you see a drawing specifying that a part MUST be checked in a free state - or- MUST be checked in a fixture that constrains and replicates the part mating to its intended component, then you know this has been thought thru and tested. However, in my 30+ years, only in the last 10 to 15 years (I still see them today) has manufacturing/engineering evolved to include these critical directions, including best fits, bonus tolerances, etc,etc on a drawing.

[[Me...]]

We went round and round with a similar issue. If there was a restraint condition the print it would have been easier to produce, but no. The thickness and OD was finished off the lathe relatively round, then the ID and threaded holes were machined on a mill. Everything was good in the machine until it was unclamped. All the true positions out and min/max for ID Ø out of tolerance. Hundreds of hours trying to straighten the parts, back to the CMM, straighten, CMM, over and over. They were climb milling the ID with multiple passes. I asked them to consider at least one conventional mill pass. Now everything runs in tolerance. Problem solved, not a CMM fix. I was asked too if I could do something with the CMM. I said no.