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Unbending problems
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* June 16, 2019, 12:35:59 PM
Further to my post from a week or so ago, I'm persevering with trying to model some sheet metal shapes featuring max six bends, which may not be parallel.

Usually I'm starting with a solid, sliced to what I wanted, before Created Surface From Solid and removing unwanted faces. Then filleted, and shelled (outwards).

Unbends sort of, sometimes, as long as the fillets have been done after Created Surface From Solid but often it takes a couple of stages, and a part (usually the first 'base') often disappears on the second un-bending. For precision I'd really prefer to do the fillets first, but doing it afterwards is near enough for my purpose [welding], although not really correct.

So all thicknesses are constant, no fillets converging, and I still have problems. Any suggestions, tips, or workarounds or alternative procedures/workflows? I've spent a week messing around with things that really should take a few hours!!   :-[

Also sometimes when I do manage to un-bend, certain segments of the edge are mirror-imaged, usually short curves, resulting in a zig-zag type edge.

Can post a file if these problems aren't familiar, or I haven't explained well?

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


* June 16, 2019, 04:00:57 PM
#1
Yes, Ian, please post a .tcw. And it would be helpful to know how you sliced a solid. One way to demonstrate would be to include the original solid along with a copy of that object after slicing.

Henry H

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* June 21, 2019, 02:09:28 AM
#2
Excuse the delay Henry, I've had other things doing, and needed a break from trying to unbend sheets, for the sake of my sanity!

Attached is a file (Unbend failures.tcw) which I hope demonstrates some of the problems I've been having. The solid was modelled/shaped by various means to what I needed: Slice by workplane, slice by line, facet edit, and quick pull. I'm trying to produce (and unbend) the three sheets, ready for cutting and CNC bending. What I'm never sure of, excluding the part tree, is whether TC entities retain a 'memory' of how they've been formed, or if they're 'clean' if they look to be so, and all nodes are connected etc?

The most complex one (Sheet 1) seems to unbend fine, and the simplest (Sheet 3) doesn't. It baffles me!

I also attach a second  file (Mirror unbend problem.tcw) where the shorter piece was produced by mirror-copying the longer one, and then modifying. But unfortunately when unbend the shorter one, some parts seem to get mirrored. Easier to try yourself than explain.

I thought I was on the right track at one stage when I realised that files hadn't been saving at 'Full Precision', but I don't think that was necessarily the problem, well not all of it at least.

I'd happily upgrade to 2019 if Unbend etc worked reliably, but I suspect it's unchanged?
« Last Edit: June 21, 2019, 02:11:59 AM by IanC »

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


* July 03, 2019, 02:37:55 AM
#3
I've just noticed that TC ProPlat 2019 features 'Unbend Tool improvements   ✓'.

Are they really improved? Things that wouldn't unbend in 2018 now will? If so I'll upgrade! I have a suspicion that a lot of unbending problems were caused by Shell and 3D fillet not producing truly parallel planes, but I may be wrong.

If anyone has 2019 and is able to try the files in my previous post and report back, I'd really appreciate it.

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


July 03, 2019, 03:41:57 AM
#4
I used 2019 and was able to unbend two of the three sheets, but I had to hunt around for the correct facet to use as the basis for the operation.  Oddly, one of those had to be unbent a second time and ended up losing most of the already flat sheet.

The unbent sheets were moved for clarity.


Jeff

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TC Pro Platinum 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1


July 03, 2019, 03:48:52 AM
#5
Your shorter object seems to have elicited a buggy response.  This should be reported to development.

In the shorter term, however, I would recommend that you re-create the object using different tools.  Alternatively, you could trace over the unbent part (avoiding the glitches) and bend it according to the markings and text that I, unfortunately, deleted because I didn't select them when I moved the unbent part for a better view.


Jeff

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TC Pro Platinum 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1


* July 03, 2019, 04:05:11 AM
#6
Thanks Jeff,

Seems like 2019 is producing the exact same problems as 2018. The only thing that possibly could have been improved I guess is the creation of the objects, prior to unbending.

Can't open your TCW (guess it's 2019 version?), but I can see what's happened. I've got around this problem for now, as you suggested, but it's very frustrating when I keep having un-bend fails, after putting in a lot of time.

How do I 'Report to Development'?

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


July 03, 2019, 04:08:18 AM
#7
How do I 'Report to Development'?

I can do it (I'm a Beta Tester, so I'm supposed to report this sort of thing).

Which version of TurboCAD are you using?


Jeff

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TC Pro Platinum 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1


* July 03, 2019, 04:24:03 AM
#8
Great, thanks!

2018 ProPlat 64-bit, build 49.0 (though object were created with the previous build - 43.5 I think from memory?).

I think you can reproduce the 'buggy response' by producing some sheet object with some complex polylines (or arc segments?), and then mirror-copying it prior to un-bending. Maybe it's important that it's in some arbitrary plane? Not sure. But it's happened to me every time I've mirror-copied.

I wonder if in 2019 you're able to produce the sheet entities from the solid, as I've done? Which was to 'Created Surface From Solid' and then removing unwanted faces. Then filleted, and shelled (outwards). It should work!!

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


July 03, 2019, 05:44:24 AM
#9
Here you go.


Jeff

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TC Pro Platinum 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1


* July 03, 2019, 06:06:26 AM
#10
2019 appears to be exactly the same as 2018  >:( I just wonder if the creation of the 3mm sheets is where the problem starts, rather than the un-bending?

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


July 04, 2019, 01:25:06 AM
#11
I've played around with your file from a couple different approaches.  The attached image came from using Extract Entity / Extract Face with a 100 mm offset and a thickness of -10 mm.  The light grey sections are the curved facets.  3D Adding selected objects based on what you want to unbend may work and it may not.

I think you would be better off re-designing this so that each facet doesn't have so many triangles and, perhaps, slicing it in ways that support Shell Solid in a way that allows unbending.

Alternatively, you could start with sheets of the desired thickness and start adding flanges at the desired bends.


Jeff

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TC Pro Platinum 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1


* July 04, 2019, 02:28:33 AM
#12
Thanks. Tried the small one that refused to un-bend previously, using Extract Entity / Extract Face with a 3mm offset and a thickness of -3mm, to give the 'sheet' I want. Added the three solids, and much to my surprise it did un-bend! I'm surprised, as I would have though behind the scenes Extract Face would have worked in a similar way to Shell. Maybe counter-intuitively it's doing it in separate parts that makes it work....

I'm slightly puzzled - AFAIK my solid doesn't have any triangles (mesh I assume you mean)? It started as a cube which I've sliced perhaps half a dozen times, and then fine tuned, and filleted. In fact thinking that it could have been corrupted, I did re-create it using facets of my original creation as the slicing planes.

I'm trying to mimic an imprecise 3D scan with  non-planar faces (which was on another layer) as precisely as I can, so first modelling as a solid lump, which represents the inner face of my sheet metal is definitely the easiest way I've found, as it's easy to adjust faces. If un-bend worked every time as I believe it should, it would be an extremely efficient workflow.

Did you flag this as a bug?

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


* July 04, 2019, 02:46:22 AM
#13
There's something very strange going on with the un-bend tool!

I just tried to produce an image of what I'd done, by copying entities to produce three copies. One of the three would not unbend (the right-hand one). Just tried it again, using the same starting face, and it did.

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


July 05, 2019, 01:18:39 AM
#14
How do I 'Report to Development'?

As it turns out, it is not necessary if you have 2019.  I forgot about the Correct deformation shape option (only available under the RMB when the Unbend Sheet command is invoked).

It takes a substantial part of a minute, but gets the job done.


Jeff

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TC Pro Platinum 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1


* July 05, 2019, 01:29:25 AM
#15
Well that's one problem sorted!

But does this option help with the other problem, that some objects still won't unbend when they should? And a third, which I've had and you also encountered, where an object does unbend, but part of it disappears?

I'll happily upgrade if so!

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


July 05, 2019, 03:35:47 AM
#16
I tried, but was only able to unbend two sheets.  I have attached in 2018 format.

What was very interesting is that, when I did the work in 2019 and saved it, the file size was over 4 MB.  When I then saved as 2018 format, the file size was reduced 78%.


Jeff

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TC Pro Platinum 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
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* July 05, 2019, 04:53:52 AM
#17
And did those two un-bend first time OK (with the RMB option)? If so, there's a definite improvement. And does using the RMB option improve un-bending generally, or only the mirroring problem I was having?

The middle-sized piece either 'Can't Unbend' or breaks when I do it in 2018, depending on which facet I select as fixed.

Regards filesize, are you sure you don't have Compression on/off set differently? Accessible as an option with the 'Save As' dialog.

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


July 05, 2019, 10:37:40 AM
#18
I got different results than what I got earlier (see the pictures), but the command takes so long to run with that option selected that I ran out of time.  I would suggest that you download the trial version of 2019 and see what it does for you.


Jeff

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TC Pro Platinum 2019, 2018, 2017, 2016 & 2015 (all with LightWorks & RedSDK) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1


* July 08, 2019, 01:11:25 AM
#19
Thanks Jeff.

The UK vendor is asking questions of IMSI, I'm hoping they might give me the upgrade, as it fixes something that's broken. But I won't hold my breath  ;D

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !


* July 08, 2019, 05:10:55 AM
#20
Further to my post from a week or so ago, I'm persevering with trying to model some sheet metal shapes featuring max six bends, which may not be parallel.

Usually I'm starting with a solid, sliced to what I wanted, before Created Surface From Solid and removing unwanted faces. Then filleted, and shelled (outwards).

Unbends sort of, sometimes, as long as the fillets have been done after Created Surface From Solid but often it takes a couple of stages, and a part (usually the first 'base') often disappears on the second un-bending. For precision I'd really prefer to do the fillets first, but doing it afterwards is near enough for my purpose [welding], although not really correct.

So all thicknesses are constant, no fillets converging, and I still have problems. Any suggestions, tips, or workarounds or alternative procedures/workflows? I've spent a week messing around with things that really should take a few hours!!   :-[

Also sometimes when I do manage to un-bend, certain segments of the edge are mirror-imaged, usually short curves, resulting in a zig-zag type edge.

Can post a file if these problems aren't familiar, or I haven't explained well?

Hi Ian,
What happened to the part tree?
Do you have a version of the drawing with the Part tree....

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Windows 7 64 bit HP > 2019-2018-2017, TurboCad Platinum 21,20,19 and 18.Using LightWorks, Anilab lab 5.  HP all in one  23" Touch smart screen with Nvidia Geforce 210, open gl 3.3. Intel Core i5 ,2.27GHz,4 GB ram.


* July 18, 2019, 12:56:01 PM
#21
Dean, sorry I don't have such a file......


But attached is a file where I demonstrate two different methods of producing what should be a consistent 5mm thick sheet.

My aim is to end up with flat metal sheets, ready for laser cutting, based on a solid model of which some surfaces represent the inner face of the sheet. Everything works great until the unbend fails.

Attached is a drawing illustrating the problem, in stages, after producing the '5mm metal sheet' by two different methods. Both based upon a solid which represents the inner face of the sheet, as I believe that is the easiest way to play around with the overall desired shape. The edges of the sheet need to be square, thus forming a V-joint suitable for welding.

In both cases, the resultant sheet TC produces must be of constant thickness, and in both cases, I'm getting "Can't Unbend Sheet" error.

This occurs in 2018 Plat and 2019 Plat. And so far has cost me a significant amount of time!

Sometimes I'll get a partial un-bend, where part of what should be the flat sheet has disappeared, typically at the fixed end. But I cannot predict why/when this occurs, it seems pretty random.

Incidentally the base solid was produced by extruding a polyline prior to slicing and 3D filleting. So the face I'm trying to use here should be flatten-able.

I'm sure this is a bug, and have produced this file and sent it to IMSI, to a contact of the UK vendor Paul Tracey. Not too optimistic, but I can only try.
« Last Edit: July 18, 2019, 12:57:59 PM by IanC »

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Currently installed v17.2 Pro (with VBA) and 2018 Pro Platinum on Windows 10.   Started with TC v2 !