Unfold cylindrical Surface

Tredory

Hi,
I'm new to Onshape and try to work me in.
Now i have Designed a part for a new projekt.

The Part: https://cad.onshape.com/documents/14a9efceed7c7be4ca3ebfcf/w/dfab4f756c09c59f6a2a6850/e/01d19c9c0085f6738a64102f
(hope this Link works)

Is it possible to get an unfolded view of the outer cylindrical Surface ? it does not matter where the surface is "cut" to unfold.
The idea is to print out this unfolded view in 1:1 scale and glue it onto the raw material and then use this mask to cut it out.

Actually the Part is for 3d printing, but for no reason i want to know how to do the unfolding

Greetings
Tredory

owen_sparks

@konstantin_shiriazdanovis the man you need to ask about this.

Owen S.

konstantin_shiriazdanov

i have actually a two FS that can unwrap cone, cylinder or arbitary extracted surfaces, Sketch Wrapper FS has a better perfomance but works only with cone and cylinder faces, Fold FS handles arbitary extracted surfaces but has rather poor perfomance. I had to split your shape by 0.05 mm cut, because both FS seem to not unwrap closed faces.
https://cad.onshape.com/documents/3c0722b6da310e3810a57cd2/w/8d928bb8f9eaa2e0e412729e/e/4ddc302232ca9af35986a1b6

Tredory

konstantin_shiriazdanov 

Thank you. Thats great !

romeograham

@konstantin_shiriazdanov
I am having trouble with your General Cone Unfold - it's worked well for me up until V35.

Here's the feature using V36:

And here's the feature using V34:

I made the same selections for both versions.

The surface that is being unwrapped is a revolved surface, with a trimmed-out portion so that it's not continuous.

Is there something I should do differently so the new Version will work? (BTW, the sketch unwrapper FS didn't seem to work on this geometry either).

Thanks!
Romeo

konstantin_shiriazdanov

@romeograham hi, can you share the link?

romeograham

@konstantin_shiriazdanov
It took me a few minutes to remove the private bits from the file.
Here's a public document: https://cad.onshape.com/documents/8688b9c2f0fdaadd6e3f3330/w/4e2efd77ce16c1b7e38b2908/e/d1bc41f242708a9140310994

When I update the General Cone Unfold FS, the sketch created is incorrect.



Thanks!

konstantin_shiriazdanov

@romeograham

This seem to be the bug of edge length parameter evaluation inside evDistance(). When i noticed they introduced this new capability I remooved my original iterative function which calculated this parameter and used evDistance for it. And in your case it returns negative parameter values, while according to documentation it should return values within 0 to 1 range, so I beleve it's featurescript bug. I reccomend to use v34 for now.

romeograham

Excellent - thanks for the explanation. It makes sense, because it looks like the sketch is being created "upsidedown"...which would follow from those negative values you mentioned.

Thanks,
Romeo

renier_strauss969

Hi @konstantin_shiriazdanov

I am having trouble understanding how to create an unfold for a sheet metal cone.  Using the General cone unfold does not seam to produce the correct result.  Is there perhaps further explanation of how to use it correctly and the limitations of the script?

I have been testing it on the following example part:
https://cad.onshape.com/documents/a9ae792128b0edfad550670c/w/e047a7bf0dc050ab91ab5bc0/e/41960ca9a39337306454c482

Thanks,
Renier 

renier_strauss969

Hi @konstantin_shiriazdanov

I am having trouble understanding how to create an unfold for a sheet metal cone.  Using the General cone unfold does not seam to produce the correct result.  Is there perhaps further explanation of how to use it correctly and the limitations of the script?

I have been testing it on the following example part:
https://cad.onshape.com/documents/a9ae792128b0edfad550670c/w/e047a7bf0dc050ab91ab5bc0/e/41960ca9a39337306454c482

Thanks,
Renier 

konstantin_shiriazdanov

@reiner_strauss969

I have two reccomendations here:

1. For true cones to use Sketch wrapper feature with unwrap option.

2. Downscale copy of large objects to a certain degree, apply the feature and upscale the result. This is because I didn't implement any profound heuristics for discretizations step, it is always simply around 0.5 mm. So when the feature tries to process some long contours it faces some internal limitations of spline points number or sketch verteces number or something else.

here is your solution:

https://cad.onshape.com/documents/1957c816839e7e9d662159af/w/03b1b6b09ff3a310254a46dc/e/5405a99aa10cd746d490e31f

renier_strauss969

Thank you very much @konstantin_shiriazdanov, I appreciate the help!

urs_egger099

Hey there, 
Tried to follow your advice with the two feature scripts. Sketch Wrapper and Fold didn't quite work as I expected. 
Can anybody help me to unfold the intersection line to the top datum plane or mate connector?

https://cad.onshape.com/documents/b9d23f7702cc34d9e52c85b6/w/085b6d0bd117d8a34b9e4bd1/e/176fd507387fb4291eceef4f?renderMode=0&uiState=63bc84f105567d5fe6f4f0d2

steve_shubin

urs_egger099 said:

… Can anybody help me to unfold the intersection line to the top datum plane or mate connector?

Can’t unfold the curved line
But can do this

https://cad.onshape.com/documents/bd3ee59ecd36879dc4d61eb5/w/31c75f172767a9934d13d609/e/45ae11778ed30e6311003c6b

Did a thicken of .0001 in both directions of the curved surface

Then a Boolean subtract to cut the cylinder

Then an unwrap

urs_egger099

Thank you Steve. 
That's kind of what I was looking for. Is there a way to unwrap it and keep the coordinates under control. I would like to attach it / unfold it so the mate connector will be fixing point for the unwrapped curve. 

steve_shubin

@urs_egger099

When you use the unwrap, it does not create a part or a surface — at least not one that is LISTED

So from the wire that it creates within the sketch or modeling window, I used FILL to create a surface

I next modified the location of your Mate Connector to where it was at the center of the line

Then I put a Mate Connector at the center of this new surface created using fill

Then used Transform (by mate connectors) to move this surface created with fill over on top of the original mate connector

In the link to the document in my post above, look at the part studio called Aligned

steve_shubin

@urs_egger099

edited the document

Something looked funny so I took a look at things from a right view and saw what I did.

I had to rotate the second mate connector around the Z-axis 180°

The GIF and document are now both in order

urs_egger099

oh wow...that's a creative approach. But it does what we need. I'm still wondering why cylindrical unwrap is not part of the onshape native wrap command. 
Thank you very much for your help steve!

steve_shubin

My pleasure