Linear feature pattern of an remove extrude not working

john_hackington

Hi,

Could anyone tell why is the linear feature pattern of an remove extrude not working in this document below:
https://cad.onshape.com/documents/a3234bd322777d65527d308c/w/545a23928aaa416e21b65aa0/e/7bebc81bc0089ccaaa9f9460

emagdalenaC2i

First, the linear feature is red because there is an error. To avoid that error you should add the Split feature in the linear patter feature too.

But that doesn't work fine
You should create the linear patter with the face pattern option

emagdalenaC2i

If you want to understand better patterns in Onshape, take a look to this document:
https://cad.onshape.com/documents/f7d8d9cbaf33f6dd7016dcde/w/b0ce5520e42fe4f90bfe63b4/e/0f6c35c06c36f5f00d388b17


Sketch and variables are features too, so you can use it inside a pattern ;-)
The features are recalculate in each instance of the array, and the position of the split feature is the same. See Part Studio 3 and 4

john_hackington

@emagdalenaC2C Thanks so much for setting up all these examples to clarify things for me! I really appreciate your kind effort

I believe I have a better understanding now. Firstly, the Onshape linear pattern does not work on the Split feature but can work on Sketch faces. Also, when the linear pattern is applied to an Extrude feature, the sketch face that it extrudes from is implicitly patterned along with it as well. That's why the linear pattern works on an Extrude that originates from a sketch face but not a split.

emagdalenaC2i

You take a look to the std document
The extrude feature https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/aff9bec3150a48098a8184ac use the transform when a extrude feature is created. https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/6d5267035f3b4a908db705cd
Instead the split feature doesn't use the transform, so the instances of the array stay in the same location

john_hackington

emagdalenaC2C said:

You take a look to the std document
The extrude feature https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/aff9bec3150a48098a8184ac use the transform when a extrude feature is created. https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/6d5267035f3b4a908db705cd
Instead the split feature doesn't use the transform, so the instances of the array stay in the same location

@emagdalenaC2C Thanks for the deep dive on the source code!

I've taken a look again and found the actual answer to the original problem. It appears that the reason why the linear feature pattern originating from the Split face was not working, was because the "Apply per instance" was ticked. I didn't notice this before, and looking at the screenshot in your previous answer, this "Apply per instance" checkbox seemed to only have been added into the Onshape interface this past week.

Take a look at the document below, you can see that when "Apply per instance" is not ticked, the linear remove pattern from the split face worked fine. But when "Apply per instance" is ticked, there is the error:
https://cad.onshape.com/documents/b2549b3e2c95ecbba05f0ffe/w/218f26f927e6fa0faf67136b/e/a7a2e5c08439fa8daca1897c






This however, is still different from the behaviour of the linear feature pattern when the remove extrude originates from a Sketch face. For example, take a look at the document below:
https://cad.onshape.com/documents/6d5c8eb24b4579650f487bad/w/26035eee245764613ec908e8/e/8d3c83ff092944b99049efdf





In this case, you can see that the linear feature pattern resolves fine whether the "Apply per instance" is ticked or not.

My original question of why the linear pattern was not working could be understood by Onshape not yet letting us specify "Apply per instance" for the case of an extrude from a Split face, as we can see that the option was not available from your earlier screenshot.

The discrepancy between patterning an extrude from a Split face and patterning an extrude from a Sketch face might then be explained by the source code behind the Linear pattern for an extrude.

When we're working on the design, I think an extrude should be just an extrude, whether it originates from a Split or from a Sketch, so I'm not sure about the rationale for this discrepancy, but if possible it would be good to get this resolved sometime in the future

emagdalenaC2i

First, the linear feature is red because there is an error. To avoid that error you should add the Split feature in the linear patter feature too.

But that doesn't work fine
You should create the linear patter with the face pattern option

john_hackington

emagdalenaC2C said:

First, the linear feature is red because there is an error. To avoid that error you should add the Split feature in the linear patter feature too.

But that doesn't work fine
You should create the linear patter with the face pattern option

@emagdalenaC2C Thanks for the help!

Yes, the Face pattern option works indeed. However, out of curiosity and wanting to understand better, do you know why the Feature pattern does not work, even with the Split included?

emagdalenaC2i

I think that it works fine. But, it create all the instances of the pattern in the same location ;-)
Actually you can test it... As easy as create a delete face feature and delete the hole before of the lineal pattern
https://cad.onshape.com/documents/1d7d8c0547ecc312c8da8427/v/306b9d782a79290f562e9433/e/6856c19e9de13b2e53624649

Also take a look to the Copy 1 of Part Studio 1 ;-)

john_hackington

@emagdalenaC2C Thanks for the follow up!

After going through your materials and illustrations, I just have a couple of questions that I'm not clear of and hope you could explain more on:

1.
Why are the instances of the pattern in my original document in the same location, even though I set the Direction and Distance in my Linear Pattern feature?

How can I make it such that the instances are not in the same location?

2.
Why is the "Linear pattern 1" in Copy 1 of Part Studio 1 successful, even though it only has a single "Extrude 2" in the "Features to pattern" entity, compared to the "Linear pattern 1" in the original Part Studio, which gave an error with a single "Extrude 2" in the "Features to pattern" entity?

What is the mechanism behind the error?

Really much appreciate your help on my questions and welcome anyone who's familiar with the matter to join in the discussion too!

emagdalenaC2i

If you want to understand better patterns in Onshape, take a look to this document:
https://cad.onshape.com/documents/f7d8d9cbaf33f6dd7016dcde/w/b0ce5520e42fe4f90bfe63b4/e/0f6c35c06c36f5f00d388b17


Sketch and variables are features too, so you can use it inside a pattern ;-)
The features are recalculate in each instance of the array, and the position of the split feature is the same. See Part Studio 3 and 4

john_hackington

@emagdalenaC2C Thanks so much for setting up all these examples to clarify things for me! I really appreciate your kind effort

I believe I have a better understanding now. Firstly, the Onshape linear pattern does not work on the Split feature but can work on Sketch faces. Also, when the linear pattern is applied to an Extrude feature, the sketch face that it extrudes from is implicitly patterned along with it as well. That's why the linear pattern works on an Extrude that originates from a sketch face but not a split.

emagdalenaC2i

You take a look to the std document
The extrude feature https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/aff9bec3150a48098a8184ac use the transform when a extrude feature is created. https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/6d5267035f3b4a908db705cd
Instead the split feature doesn't use the transform, so the instances of the array stay in the same location

john_hackington

emagdalenaC2C said:

You take a look to the std document
The extrude feature https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/aff9bec3150a48098a8184ac use the transform when a extrude feature is created. https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/6d5267035f3b4a908db705cd
Instead the split feature doesn't use the transform, so the instances of the array stay in the same location

@emagdalenaC2C Thanks for the deep dive on the source code!

I've taken a look again and found the actual answer to the original problem. It appears that the reason why the linear feature pattern originating from the Split face was not working, was because the "Apply per instance" was ticked. I didn't notice this before, and looking at the screenshot in your previous answer, this "Apply per instance" checkbox seemed to only have been added into the Onshape interface this past week.

Take a look at the document below, you can see that when "Apply per instance" is not ticked, the linear remove pattern from the split face worked fine. But when "Apply per instance" is ticked, there is the error:
https://cad.onshape.com/documents/b2549b3e2c95ecbba05f0ffe/w/218f26f927e6fa0faf67136b/e/a7a2e5c08439fa8daca1897c






This however, is still different from the behaviour of the linear feature pattern when the remove extrude originates from a Sketch face. For example, take a look at the document below:
https://cad.onshape.com/documents/6d5c8eb24b4579650f487bad/w/26035eee245764613ec908e8/e/8d3c83ff092944b99049efdf





In this case, you can see that the linear feature pattern resolves fine whether the "Apply per instance" is ticked or not.

My original question of why the linear pattern was not working could be understood by Onshape not yet letting us specify "Apply per instance" for the case of an extrude from a Split face, as we can see that the option was not available from your earlier screenshot.

The discrepancy between patterning an extrude from a Split face and patterning an extrude from a Sketch face might then be explained by the source code behind the Linear pattern for an extrude.

When we're working on the design, I think an extrude should be just an extrude, whether it originates from a Split or from a Sketch, so I'm not sure about the rationale for this discrepancy, but if possible it would be good to get this resolved sometime in the future

emagdalenaC2i

Thanks @john_hackington

Seems this is a new improvement
If you check the Apply per instance option all the instance are recalculate

And if it is unchecked it just copy the geometry

Here is the link to this document https://cad.onshape.com/documents/82b4f8320598247dfa2b9fea/w/e5613c929a82bb3271d7602e/e/385335c3237f50589d0218b0