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Unbend Sheet Bug
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* December 10, 2019, 01:19:48 PM
Hello,

It seems as though a successful unbend is dependent on the flange height which I would consider a bug.  I’m new to the forum and hoping some of the users have more familiarity with the Unbend Tool than I do.

I'm using TurboCAD Pro Platinum 2019 on Windows10.

In the attached model, the height of the short flange is currently at .075”.  If I attempt to unbend this sheet using the back face as its base, the short flange will not unbend successfully, while the longer will.  If I increase the height of this flange to anything beyond .09” it will unbend successfully, and at .08 I get an message “Unable to unbend.”

I’ve experimented with the bend radius and Neutral Depth settings but learning nothing.

If there are defined rules for bend/unbend are they documented anywhere?  The User Guide barely covers this, and I’m not seeing much in terms of searches.

Thanks in advance for your help!
« Last Edit: December 10, 2019, 01:51:27 PM by TCNewbie »

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* December 10, 2019, 02:51:16 PM
#1
It unbends fine when you do the following from with the Selection info pallet:
1. Unbend the 90 degree bend 1st by setting to 0 degrees.
2. Then unbend the 168 degree bend by increments ie: unbend to 90 degrees then 0 degrees.


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Daz
TCW V21, 2015-2019 PP, Animation Lab V5.2 & Redsdk enabled, LightWorks rendering mostly.


* December 10, 2019, 03:15:37 PM
#2
The problem is that the short flange has no flat region; Unbend seems to require that all bends connect flat faces. "Unbend sheet" works OK if I use Quick Pull to create a flat extension on the short flange.

Henry H

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* December 10, 2019, 05:56:20 PM
#3
The problem is that the short flange has no flat region; Unbend seems to require that all bends connect flat faces. "Unbend sheet" works OK if I use Quick Pull to create a flat extension on the short flange.

Henry H

I appreciate the response Henry.

But anything beyond the .05" bend radius does have flat regions right?  There must be a flat distance requirement which I'll have to play with.

And I like the Quick Pull approach to obtain the unbend, except that will have to remove that from the unbent piece so laser cut dimensions are restored.

Thanks!

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* December 10, 2019, 06:00:36 PM
#4
It unbends fine when you do the following from with the Selection info pallet:
1. Unbend the 90 degree bend 1st by setting to 0 degrees.
2. Then unbend the 168 degree bend by increments ie: unbend to 90 degrees then 0 degrees.

I appreciate your taking the time to review this too Darryl.

I think Henry has determined one of the requirements of the unbend which I'll continue to study, but I your workaround could be optimum.

Thanks!

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* December 10, 2019, 06:26:32 PM
#5
The problem is that the short flange has no flat region; Unbend seems to require that all bends connect flat faces. "Unbend sheet" works OK if I use Quick Pull to create a flat extension on the short flange.

Henry H

I appreciate the response Henry.

But anything beyond the .05" bend radius does have flat regions right?  There must be a flat distance requirement which I'll have to play with.

And I like the Quick Pull approach to obtain the unbend, except that will have to remove that from the unbent piece so laser cut dimensions are restored.

Thanks!

In your drawing, Quick-pulling to .010" allows me to Unbend but QP to .009" does not. I don't know what the general rule is -- if there is one.

Henry H

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* December 10, 2019, 11:30:37 PM
#6
It might be predicated on being able to be physically produced - the bend could be stamped flat, but unbending it in a brake needs something to grip that isn't in the bend material.  10 thou is half a millimetre, a clamp would probably not be practically able to grip even that and I can't imagine a manufacturing scenario that would put an unsupported bend on the edge of a sheet anyway.  I will be fascinated to be enlightened if a case for it exists.   

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December 11, 2019, 06:37:36 AM
#7
I'm just wondering what the heck TCNewbie is building that has a "short flange is currently at .075”  " ???, that short flange's length seeming to be about half the object's length (I can't open version-2019 drawing files).  Forget about a "brake", I think it would take a putty-knife and tweezers to bend the thing. ;D

Anyway... I replicated the thing the best I could in version-21 based on the images I see and the input I read.
>The initial object (Box) being .75"x4"x.01".
>Created 2.25" long flange, .075" Height.
>Bent the object 168° right at the top of that flange.
>When I Unbent* via the "back face", it worked for me.  The caveat:  Neutral Depth had to be greater than a particular value.  .01" does not work; .009" does.  I haven't given much thought as to where the math dictates this working.

Anyway... For what that's worth...
____________
*(the Unbend operation altered my "Source Copy" from a Part to an ACIS Solid, I didn't like that.)

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* December 11, 2019, 07:07:33 AM
#8
I'm just wondering what the heck TCNewbie is building that has a "short flange is currently at .075”  " ???, that short flange's length seeming to be about half the object's length (I can't open version-2019 drawing files).  Forget about a "brake", I think it would take a putty-knife and tweezers to bend the thing. ;D

Anyway... I replicated the thing the best I could in version-21 based on the images I see and the input I read.
>The initial object (Box) being .75"x4"x.01".
>Created 2.25" long flange, .075" Height.
>Bent the object 168° right at the top of that flange.
>When I Unbent* via the "back face", it worked for me.  The caveat:  Neutral Depth had to be greater than a particular value.  .01" does not work; .009" does.  I haven't given much thought as to where the math dictates this working.

Anyway... For what that's worth...
____________
*(the Unbend operation altered my "Source Copy" from a Part to an ACIS Solid, I didn't like that.)

Alvin,

This is a flat, hardened, stainless spring.  Granted I omitted a lot of additional detail to convey the issue.  The edge flanges are merely a means to provide ribs, or to force the spring pivot at the top of the .1" radial bend.  Without them, the piece will "pillow" along the entire lengths instead of maintaining straight edges.

I like to provide the manufacturers an unbent drawing so they can easily quote material usage, and they can also use it as the profile for laser cutting prior to any bends.

I appreciate your feedback!

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December 11, 2019, 07:25:24 AM
#9
...
Alvin,

This is a flat, hardened, stainless spring.  Granted I omitted a lot of additional detail to convey the issue.  The edge flanges are merely a means to provide ribs, or to force the spring pivot at the top of the .1" radial bend.  Without them, the piece will "pillow" along the entire lengths instead of maintaining straight edges.

I like to provide the manufacturers an unbent drawing so they can easily quote material usage, and they can also use it as the profile for laser cutting prior to any bends.

I appreciate your feedback!

Gotcha.  As Torfinn would say "You could always write a PPM script." :-)

If you were in the habit/business of creating these things.

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


December 11, 2019, 08:57:07 AM
#10
The Neutral Depth value of the Flange, (Bend?), and UnBend seems to be the thing to get right.
I can get the UnBend to work successfully repeatedly with the Neutral Depths set to certain values.  I used .005 for my .01 thick object-- for all three, the Flange, the Bend in the middle, and the UnBend; I figured at .01", the center has gotta be pretty well close enough*. It works like a champ.

________
*although, the resultant object's volume does not equate to that of the original box object-- .032 in the result, compared to .030 in the original; maybe the stretch in the original bends created more volume; or maybe the neutral depth being in the center was not the correct way to go about it.
« Last Edit: December 11, 2019, 10:15:50 AM by Alvin Gregorio »

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* December 11, 2019, 11:06:41 AM
#11
The Neutral Depth value of the Flange, (Bend?), and UnBend seems to be the thing to get right.
I can get the UnBend to work successfully repeatedly with the Neutral Depths set to certain values.  I used .005 for my .01 thick object-- for all three, the Flange, the Bend in the middle, and the UnBend; I figured at .01", the center has gotta be pretty well close enough*. It works like a champ.

________
*although, the resultant object's volume does not equate to that of the original box object-- .032 in the result, compared to .030 in the original; maybe the stretch in the original bends created more volume; or maybe the neutral depth being in the center was not the correct way to go about it.

I'm currently looking into write ups on recommended neutral depths, but my initial attempts experimented with ranges of half the material thickness (.0075") through 0.  I was never able to unbend successfully unless my flange height significantly exceeded the bend radius of .05".  Henry brought up a good point indicating flat surfaces are probably required which makes sense, but unfortunately without knowing how high, I'm forced to add a generous amount, then remove it later after the bend.  Darryl also offered an excellent suggestion of forcing the bend radius back to 0 which will also work.  While both of these suggestions will work, they're workarounds with additional steps.  Ideally the User Guide would have better content, but I'm OK with workarounds.

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* December 11, 2019, 02:29:52 PM
#12
The Neutral Depth value of the Flange, (Bend?), and UnBend seems to be the thing to get right.
I can get the UnBend to work successfully repeatedly with the Neutral Depths set to certain values.  I used .005 for my .01 thick object-- for all three, the Flange, the Bend in the middle, and the UnBend; I figured at .01", the center has gotta be pretty well close enough*. It works like a champ.

________
*although, the resultant object's volume does not equate to that of the original box object-- .032 in the result, compared to .030 in the original; maybe the stretch in the original bends created more volume; or maybe the neutral depth being in the center was not the correct way to go about it.

I'm currently looking into write ups on recommended neutral depths, but my initial attempts experimented with ranges of half the material thickness (.0075") through 0.  I was never able to unbend successfully unless my flange height significantly exceeded the bend radius of .05".  Henry brought up a good point indicating flat surfaces are probably required which makes sense, but unfortunately without knowing how high, I'm forced to add a generous amount, then remove it later after the bend.  Darryl also offered an excellent suggestion of forcing the bend radius back to 0 which will also work.  While both of these suggestions will work, they're workarounds with additional steps.  Ideally the User Guide would have better content, but I'm OK with workarounds.

The need to add material beyond the bend is just a TurboCad quirk, to make it possible to flatten your 3D object in TCad. Would you have to do it in the real world?

Henry H

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December 11, 2019, 02:34:12 PM
#13
I've been working on this off-&-on for a while today.  Being unemployed and obsessive and liking to learn tends to do that.

I think I've figure out some stuff.  Can someone please save back TCNewbie's "Unbend Test.tcw" file to version-21.  I'd appreciate it.

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* December 11, 2019, 02:47:25 PM
#14
I've been working on this off-&-on for a while today.  Being unemployed and obsessive and liking to learn tends to do that.

I think I've figure out some stuff.  Can someone please save back TCNewbie's "Unbend Test.tcw" file to version-21.  I'd appreciate it.

I did that, Alvin, and guess what? See the attached screenshot, made in v21...

Henry H

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December 11, 2019, 02:51:49 PM
#15
I've been working on this off-&-on for a while today.  Being unemployed and obsessive and liking to learn tends to do that.

I think I've figure out some stuff.  Can someone please save back TCNewbie's "Unbend Test.tcw" file to version-21.  I'd appreciate it.

I did that, Alvin, and guess what? See the attached screenshot, made in v21...

Henry H


I can't tell what that image is supposed communicate to us Henry; not having the original to go off of.
But I'm guessing you are suggesting that the UnBend works successfully in version-21PP.

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* December 11, 2019, 02:52:27 PM
#16
I've been working on this off-&-on for a while today.  Being unemployed and obsessive and liking to learn tends to do that.

I think I've figure out some stuff.  Can someone please save back TCNewbie's "Unbend Test.tcw" file to version-21.  I'd appreciate it.

Here ya go Alvin.

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John R.

V17—V21, 2015—2019
Designer, Deluxe, (Professional, Expert, Basic), Platinum
RedSDK enabled
Windows 10 Pro (1903), 64-bit


December 11, 2019, 02:53:15 PM
#17
I've been working on this off-&-on for a while today.  Being unemployed and obsessive and liking to learn tends to do that.

I think I've figure out some stuff.  Can someone please save back TCNewbie's "Unbend Test.tcw" file to version-21.  I'd appreciate it.

Here ya go Alvin.

TU

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


December 11, 2019, 02:57:14 PM
#18
I've been working on this off-&-on for a while today.  Being unemployed and obsessive and liking to learn tends to do that.

I think I've figure out some stuff.  Can someone please save back TCNewbie's "Unbend Test.tcw" file to version-21.  I'd appreciate it.

I did that, Alvin, and guess what? See the attached screenshot, made in v21...

Henry H

I can't tell what that image is supposed communicate to us Henry; not having the original to go off of.
But I'm guessing you are suggesting that the UnBend works successfully in version-21PP.

Oh... there's a piece missing.  The little flange.  Hmmm...
What was the parameters of that little thing?

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* December 11, 2019, 03:03:51 PM
#19
I've been working on this off-&-on for a while today.  Being unemployed and obsessive and liking to learn tends to do that.

I think I've figure out some stuff.  Can someone please save back TCNewbie's "Unbend Test.tcw" file to version-21.  I'd appreciate it.

I did that, Alvin, and guess what? See the attached screenshot, made in v21...

Henry H

I can't tell what that image is supposed communicate to us Henry; not having the original to go off of.
But I'm guessing you are suggesting that the UnBend works successfully in version-21PP.

Oh... there's a piece missing.  The little flange.  Hmmm...
What was the parameters of that little thing?

Here's what the Part Tree has to say in v2019...

Henry H

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December 11, 2019, 03:15:41 PM
#20
..

Here's what the Part Tree has to say in v2019...

Henry H

That's interesting.  A bit.  I guess the V2019-to-V21 filter isn't 100% perfect.

In V21, not only is a parameter of the Flange operation different than V2019 (Height), it shows as an unsuccessful operation in the Part Tree.

Not much we (I) can do about the filter not being 100%.  Except maybe purchase the current version.

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* December 11, 2019, 03:19:56 PM
#21
The file went from 2019 (V26) to 2016 (V23) to Version 21.

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John R.

V17—V21, 2015—2019
Designer, Deluxe, (Professional, Expert, Basic), Platinum
RedSDK enabled
Windows 10 Pro (1903), 64-bit


December 11, 2019, 04:17:50 PM
#22
Did Rob Flange the Flange?

In the version-21 drawing file, the Extrude is 1.163, and the first flange is 1.669.

Then it appears-- from the images I've been seeing in this thread-- that the first Flange has the little, second, Flange.

Perhaps flanging the flange is an issue when trying to UnBend.

In version-21, I went the other way, and successfully UnBent:
>Via/In the provided file, via Selection Info Part Tree, I copied the initial Extrude.
>I pasted that into Modelspace.
>I made the Y size of the Extrude's associated Polyline 1.669.
>I then did the first Flange, all the values being the same as the original file, except the Height being 1.163.
>I did the second Flange-- on the initial Extrude Part, now having a 1.163 Flange, same values as the original file.
>Successfully UnBent from the "Back".  That result is the Blue Part, in the attached file.

I would think that it would also be good practice to make the Neutral Depths the same, when working with the same sheet metal object.
I can see how having them varied, as in the original file, can cause issues.  The Flanges' Neutral Depths are different, in the original file (filtered for V21) provided to me.
Plus, isn't that how it'd be done in the real-World anyway.
Just makes more sense and makes it all easier to work with if all the Bends and Flanges have the same Neutral Depth.
« Last Edit: December 11, 2019, 04:26:00 PM by Alvin Gregorio »

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* December 11, 2019, 05:27:41 PM
#23
"Plus, isn't that how it'd be done in the real-World anyway.
Just makes more sense and makes it all easier to work with if all the Bends and Flanges have the same Neutral Depth."

In the real world, Neutral Depth might be different if the bend radii are different.

Henry H

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* December 11, 2019, 05:42:38 PM
#24
"In version-21, I went the other way, and successfully UnBent:"

Now, that's really interesting. I opened your drawing in v2019 and the short flange had not unbent--nor was I able to Unbend it. But in v21 it works just fine.

...But your part isn't identical to Bob's. Look at the World Plan view.

Henry H

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* December 11, 2019, 07:05:56 PM
#25
Re Johns last reply, I did ask in the beta forum sometime back for the file save filter from 2019 to save back to V21. Seems to me that this a must have, whereas the upcoming V2020 application could save as far back as V23 and that would be acceptable.

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Daz
TCW V21, 2015-2019 PP, Animation Lab V5.2 & Redsdk enabled, LightWorks rendering mostly.


December 13, 2019, 09:15:12 AM
#26
Something else to try with "unfolding" that spring Part so as to have something that can be cnc laser cut:

>Do UnFold_Face on all the faces/curves, and move and rotate them all together and put them on the same plane, and trace a polyline around the perimeter of that group.

But I liked this better:
>In Part Tree, Suppress the second, small, Flange operation.  UnBend Sheet.  Back in Part Tree, UnSuprress that Flange operation previously Suppressed.
  Works well for me in V21PP, with the small Flange values as they originally arrived to me (below) or even a smaller Flange Height value.

Or even this:
>Use Transform/Move/Keep_Original_Object on the flanged/bent Part.  In my version that results in an ACIS Solid object (no Part Tree associated).  Do an UnBend Sheet on that.
In my V21PP that works consistently-- even with a tiny-er Flange Height.  With the added benefit that the original flanged spring object is maintained, and not unbent just for the purpose of deciphering a sheet cut.

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Alvin Gregorio
Intermittent TurboCAD user since yr. 2000 (ver6.5).  No formal CAD Training.
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* December 13, 2019, 10:52:59 AM
#27
Something else to try with "unfolding" that spring Part so as to have something that can be cnc laser cut:

>Do UnFold_Face on all the faces/curves, and move and rotate them all together and put them on the same plane, and trace a polyline around the perimeter of that group.

But I liked this better:
>In Part Tree, Suppress the second, small, Flange operation.  UnBend Sheet.  Back in Part Tree, UnSuprress that Flange operation previously Suppressed.
  Works well for me in V21PP, with the small Flange values as they originally arrived to me (below) or even a smaller Flange Height value.

Or even this:
>Use Transform/Move/Keep_Original_Object on the flanged/bent Part.  In my version that results in an ACIS Solid object (no Part Tree associated).  Do an UnBend Sheet on that.
In my V21PP that works consistently-- even with a tiny-er Flange Height.  With the added benefit that the original flanged spring object is maintained, and not unbent just for the purpose of deciphering a sheet cut.

Thanks for your investigative efforts Alvin!  I'll take a look at your suggestions later this weekend.

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