topic Re: Get thread centre point in the API in Fusion API and Scripts Forum

Get thread centre point in the API

DWhiteley — Wed, 15 Apr 2020 14:09:09 GMT

I have managed to get to the 'threadfeature' for a threaded hole.

My question, is how do I find the centre point of the threaded hole from 'threadfeature'?

Many thanks in advance.

Dave Whiteley

Re: Get thread centre point in the API

BrianEkins — Wed, 15 Apr 2020 15:21:38 GMT

You're right that the thread feature itself doesn't provide any information about its location in space. However, it looks like there are a couple of relatively easy solutions.

The first is to get the original cylinders that were used as input to create the thread. However, those cylinders aren't available after the thread has been created because they may have been consumed. However, you can roll the timeline back to just before the thread feature was created and then query for the cylinders using the inputCylindricalFace property of the ThreadFeature. Then you'll need to move the timeline back to where it was.

The second is to look for a cylinder that was created as a result of adding the thread feature. I checked and it looks like even when you model the threads that all thread types will create a cylinder as part of the geometry to model the thread. I like this approach better because it's strictly a query operation and doesn't involve making changes to the model. To do this you will use the faces property of the ThreadFeature and then use the geometry property of each face and look for the face whose geometry is a Cylinder type of object. Then you can use properties on the cylinder to find the position and axis, which will be the same for the thread.

Re: Get thread centre point in the API

DWhiteley — Thu, 16 Apr 2020 09:56:58 GMT

That's superb, thanks Brian.

Re: Get thread centre point in the API

DWhiteley — Fri, 24 Apr 2020 16:38:50 GMT

Hi Brian,

I think I'm nearly there.

I can't seem to get the correct centre point. I was hoping to obtain a point at the top centre of a drilled and tapped hole. Method 2 seems to give a centre point of the cylinder in some strange position.

Is there any way I can get this info?

Re: Get thread centre point in the API

BrianEkins — Fri, 24 Apr 2020 17:24:48 GMT

It's not always obvious what the "top" of the hole is. Although admittedly it is in 99.99% of the cases, here's one where it's not. Is the top where the axis emerges or at the highest point where any part of the cylinder exists?

The latter case is easier to handle and will also provide the "correct" answer in the other 99.99% of the cases. The approach is to get the bounding box of the cylindrical face and get the Z value of the max point (assuming the Z-axis defines up in your case) and use that as the Z value of your point. The X and Y values will come from the cylinder point.

Re: Get thread centre point in the API

DWhiteley — Sat, 25 Apr 2020 08:41:19 GMT

Yes I suppose I could get the COG of the part and use that to determine which end of the cylinder is top?

Many thanks for your assistance again.

Re: Get thread centre point in the API

BrianEkins — Mon, 27 Apr 2020 01:17:49 GMT

I don't see how the center of gravity will help. If the orientation of the part is known and consistent you can code your program for that. If the part can be in any orientation, then there is a lot more work to be done and probably some input needed from the user to define what direction is "up".

Re: Get thread centre point in the API

Anonymous — Sat, 13 Jun 2020 17:23:35 GMT

Hi Brian,

The second option works for me until I have a threaded hole in a pattern.

If I try and iterate through the threaded hole features in the component, I only get the original feature.

How can I access the positions of the threaded holes if they are in a pattern?

I'm really lost on this one!

Dave