Checking for missing items

[[To...]]

I am trying to write a program that will use a self-centering point to determine if a heli-coil insert in present in a hole. I will also be measuring the depth of the insert, though it will be some derived number. My problem is that if the insert is missing, I will reach the "search after nominal limit" and the machine will stop. Without PCM, does anyone have any ideas for how to let the machine continue even though the point was not satisfied? I did think about having the probe continue until it hit the fixture below it but I won't always have that option available.

TIA

[[Ch...]]

I think it could be done with PCM,

without PCM; how about a condition? Put a tolerance on the depth, let it measure the depth, if the insert isn't there, dimension will be out of tolerance, condition will proceed as needed.

Only thing I can think of at the moment.

[[Je...]]

What about checking the minor diameter instead of using a self centering point?

Another option could be using the "Bore Missing" feature. Attempt to measure the ID using the same stylus, if it contacts the helicoil then allow it to skip the feature. Reporting the size would be an indication that a helicoil is not present.

This doesn't fix your depth measurement problem however. Could also maybe measure with a stylus that is at an angle to the axis of the threaded hole. If the probe goes too deep it will shank out and give you a depth O/S.

[[To...]]

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If the insert is not there, it won't hit anything to establish a depth.

[[To...]]

Ok. I will open up the possibility of using PCM.

[[He...]]

If you are trying to increase the travel distance after nominal point you can find it under measurement plan editor features -> probing -> search distance after nominal position.

[[To...]]

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Henrik, but if the insert is not installed, it will not technically hit anything, no matter how much you search.

[[He...]]

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How big is this hole/insert? How is the hole oriented? What does the stylus system look like?

[[Am...]]

The only thing I can think of without PCM would be to create another characteristic that checks something different that can be identified. I'm not really sure what the part or insert looks like but is there something else that is different about it without the insert? Like say a diameter, you could make it check that and then have a condition that either checks for that self-centering hole or skips it based on the result you get from the previous characteristic. Just throwing thoughts out there but hopefully it gives you an idea.

[[Jo...]]

could you put a generic 4 point circle in with bore missing function, and branch from there ? If it finds bottom then.. if it doesn't it skips.. either conditional statement or note to operator. Like Jeff's suggestion, it would get you around the problem of just stopping if out of range. At least the program could continue either way.

[[To...]]

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For example, I am working on a hole with a 4-40 UNC-2B Heli-Coil. The tap drill is .120" diameter thru. The minor diameter of the installed insert is around .089" diameter.

If I use a 3mm (.1181") probe and take a point and if the insert is installed, the probe will be stopped by the insert and will produce a depth reading. I will have to come up with a relationship between the probe depth and the insert depth but result element can handle that.

If the insert is missing, the probe will travel thru the hole until it reaches the search distance limit but it will error out and stop the program.

[[He...]]

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If the stylus is parallel to the hole the machine will probably stop at the cone at the end of the stylus. You just have to change the search distance after nominal probing.

If the hole is bigger than the cone on the stylus you can attach a cube and put a sideways extension that will contact with the part.

Or am I missing something?

[[To...]]

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John, I think you might be onto something. Though I have had issues with the missing bore either stopping or continuing but I currently don't remember what the issue was. I just need to skip the point features located at the circles that were measured, i.e. Diameter with a result, means the insert is missing. Diameter without a result means circle was skipped because bore missing (insert in place). Check depth with point only at these circle locations.

[[To...]]

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I see, said the blind man. I did not think about using the cone at upper end of the stylus.

[[An...]]

See attached.

Contribution_27_02_2020_1.pdf

[[To...]]

Ok guys. Next order of business. I am checking the diameter of the tapped holes and if the insert is installed, I get a "good" result and if the insert is missing, I get an over-sized diameter. Everything is good so far.

Next, using a larger diameter probe, I check the depth using a self-centering point. If the insert is present, I get a depth (D1). Using a height gage, I was able to measure the depth to the top of the insert and calculate the difference between depth of the self-centering point (D1) to the top of the insert(D2) and use a Result Element to report the specified depth. Still good.
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However, I currently am unable to differentiate between a depth of an insert is just out of spec or a depth from a missing insert, as they both fail, without looking at the values.

Bottom line, I want to report the depth of inserts and I want to report if an insert is missing but don't want to have to look at values, just red or green. If anyone has any suggestions to point me in the right direction, I would greatly appreciate some assisitance.

[[An...]]

See attached.

Contribution_04_03_2020_1.pdf

[[Ma...]]

I imagine your depth is pretty far out of spec when the insert is missing if you're allowing it to bottom out on the cone of the stylus, you could adjust your tolerance and set a warning limit percentage so that when you're out of spec you get yellow and when the insert is missing you get red. Though it might be difficult if you aren't going much deeper beyond the insert depth to reach the cone.

For example if you're going way past the insert depth tolerance (more than 2x) to reach the cone, you could double the tolerance and set the warning limit to 50%. You'd get yellow for out of spec in either direction, and assuming you go beyond 2x the depth tolerance before hitting the cone, you'll get red on a missing insert.

It doesn't make the report binary but it's darn close...

[[Je...]]

How about using two different results for the same measurement. 1 for helicoil missing, the other for helicoil depth. Say your helicoil depth range is .010 - .035". Set the "Missing" depth at an arbitrary number larger than the .035, such as .100" maximum. If it shows out of tolerance, ignore the helicoil depth report.

"Insert Present" - Green/Red = pass/fail (as a .100" depth maximum)
"Insert Depth If Present" - Green/Red = pass/fail (.010 -.035)

This scenario seems like a great sales argument for PCM...