Thread Inspection with Gom Software

[[ca...]]

Hello everyone,

We think about using  GOM software for thread inspection purposes. Which functionality does the GOM 2021 or 2022  have specifically to inspect thread geometry?

Is there any documentation that I could use as reference?

Many thanks,

Canset

[[Na...]]

Hi cansetm,

we don't have a modul or a configuration like Blade Inspect for threads. I am also not aware of a documentation, I'm afraid.
From my experience a cylinder based section (https://techguide.gom.com/en/gom-software-2022/article/cmd_section_create_multiple_cylinder_based_section.html) was a useful tool for this kind of inspection. 
What exactly do you want to measure?

Nanno

[[Au...]]

We have recently been looking into the same type of inspection with our ATOS scanners. Where our largest downfall is having to inspect small threads and only being able to see so deep into a hole. On our CMMs we use true position locators we are currently in the process of implementing these into our scanner. That may be a good solution depending on what type of threads you would be inspecting.

[[Ja...]]

I did some work with a client on various thread metrics.  There is no direct tool but we were able to build the metrics that were interesting to them.   However this was external thread in plastic.   If in metal down a hole...i personally wouldnt go near this with cmm nor 3dsl.  A good solution isto use a thread guage for checking the hole then probing/scanning the gauge end ( may need to be customised for this) to get the hole position.

[[Au...]]

That solution is similar to what we are currently testing. We use these on our CMM's/PCMM's. Attached is a picture of the tool. The only drawback we currently have is the shininess of the locator itself so we are working with the manufacture to provide them with a "dull" finish.

[[Ro...]]

Hello, how could I measure the thread's perpendicularity to a base?

 

[[Mi...]]

The software tries to construct at least three cylinder sections but may fail if the available actual data is insufficient.

I assume you tried to construct a cylinder on a mesh in this example?

You could try "edit creation (F4)" on the cylinder and have a look at the preview visualization. The selected parts of the mesh should be visible in red. If the selected red area is smaller than you expect, try to use the expert parameters in the selection cylinder dialog to increase your selection. E.g., it could be a good idea to set the angle to 90 degrees to ensure that the selection extends inside the ridges of the thread. 

[[Ja...]]

I would suggest ultimately the answer is once again adapters and measure the cylinder and perpendicularity of the inferred axis.  I do not see you can get reliable result from trying to measure this directly and fitting cylinders to thread data

[[Ch...]]

Correct, direct evaluation of thread data (at least for the GD&T section) is not (yet) supported. Due to the fact that you cannot evaluate GD&T on non fitting elements the only way (at the moment) should be

 

1) Using adapters to get a relieable cylinder axis.

2) Create at least 6 points on this axis in the area where do you want to evaluate your perpendicularity

3) Create a fitting line from these points

4) Evaluate your perpendicularity from this fitting line

 

Yes we are aware that a solution out of the box would be nice. 

 

Christoph Schult