There has to be a better way to inspect timed threads than what we are using. We have a set of masters that when screwed together a matching flat was machined on each. The masters were then used to make working gages using the same method. The driver was standardized at 7 in-lbs and then at 30 in-lbs. The thread plug has a hex in it. The size is small of course 1/4-32. There are only 1.5 threads of engagement on the parts (more on the gages).

We can't seem to get better than ± 2° out of the working gages (40% of production tolerance determined via GR&R). To make maters worse now, the higher pressure is wearing the masters out. Masters that were in print at the start of the GR&R are now 2 degrees out of tolerance plus the hex is rounding out. :bonk:

I'm afraid to go with carbide with the higher pressure since I think it will just break the threads or head or strip the parts.

Now the question, is there a commercial method out there for this? I can't imagine that we are the only company with this issue (watch makers come to mind).:cool:

Most of the seraches I have done only give me discussion thead tools or standard inspection methods.

Are you still in need of a solution for your problem?

Thanks,

Tom Thread

Yes... I'm looking at annual costs of $100K in gages

Satellite:
What type of material are you threading and are these male or female threads?

Thanks

Tom Thread

Titanium, both male & female - for mating parts.

Satellite:
Might it be possible to inspect the parts with a master profile that all manufactured parts would be compared to. A capacitive probe used to check the internal and external threads could develop a master and check all parts to that master. Such a probe has the ability to measure at 1 micron. These probes can measure minor and major diameter and thread pitch and diameter. What characteristics of the threads are critical? Do you check 100%

My understanding of capacitive/eddycurrent may be incomplete. My understanding is that as long as the item met the pattern it would pass the part. The problem is that the thread orientation could be in any position radially and still pass the item.

This was what I have used in the past to inspect large cold headed bolts. It was one of the selling points of the system was that orientation was not an issue to the system. Maybe it was only this system.

This issue I have is the thread run out must end at a particluar point at a specific ft-lb of torque. I can certainly run a correlation to determine where that point is for the torque requirement - as long as I can locate the orientation of the thread.

Satellite:
You are correct a pattern is the means to check all parts. Are your parts in some type of repetitive position? Are there operators with torque wrenches checking your parts now?

Yes, we are using the matched set of gages with torque wrenches to test these parts. I only have 1.5 threads to work with.

Satellite:
It is possible to produce a profile with capacitance that can look at a specifc area to determine what the lead is in that area. I would recomend you consider our process which uses capacitance. Look at auto-in.com and let me know what you think. All in all it would be very possible to provide a method to match you threads to be within a certain degree so that engagement of male and femal won't bind.