Full Version: CURVE TANGENCY - CONTINUITY RESOLUTION

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Does that error message come upon initial import of the STP file or is it generated by the post processor engine generating GCODE in pipebender?

The files to compare are the stp files not dxf.

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Hi Burrman

The error comes up with the STP import before getting to Gcode stage so its definitely something in the tangent to tangent structure as the only change I make to the same underlying curve pathway in SW is to lock the tangents - which must mean there is a further degree of tangency that perhaps the PARASOLID engine enables for the PIPEBEND software to read the 3d part.

Thats just my current thinking.

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Ok. I was trying to apply my CAM softwares thinking when it is parsing arc and such. The post processor has several setting for various machines and software outputs.

Break arcs into quadrants. Combine more than 180 degrees. Etc… etc… something about signed arcs and the processing into xyz coords that the machines controller reads. There are tons of controllers. Not all created equal.

Was taking a guess at what “lock tangents” is actually doing or setting in the step file with regard to arcs. Was trying to figure out if yyspipebender is actually trying to post process the geometry and needed one of these specific settings

Maybe if we can see the 2 stp files we can figure that out…

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Thanks Burrman,
Here is my workflow - file created in MOI
Export dxf into SW
Lock Tangents in SW
Export Step
Import STP into PIPEBEND

Attachments:
1TEST ARCS.3dm
2 TEST ARCS.dxf
3 TEST ARC SW.STEP
4 TEST ARC SW.DXF

Image Attachments:
20250320_104353 (1).jpg  LOCKED TANGENTS.jpg 

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Thanks for follow up Alex. I will certainly look over you outpit and locked tan files a bit later.

With my last post and just “looking at the screenshot” in your last post, it appears that last arc is greater than 180? (Havent verified this yet)

If it is, try adding a couple trim points to make it 2 or 3 smaller arcs and try it without the locked tan process to see if yyspipebender will accept that….

I’ll respond again after i get a look at the stp file output

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Hi Alex,

I took a look at your file "3 TEST ARC SW.STEP"

Pipebend likes this file, correct?

Would you also post a STEP that Pipebend rejects?

- Peer

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""""""Would you also post a STEP that Pipebend rejects?""""""

Take the MoI 3dm file and save it as a STP...

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Thanks here are files

Attachments:
TEST ARCS MOI EXP.stp

Image Attachments:
IMPORT FAIL.jpg 

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Hi Alex,

It looks like the problem I mentioned before: the Sweep command in MoI (which the pipe script is based on) has limited accuracy. I examined the surfaces in both STEP files in MoI using Construct > Curve > Iso and then checking the properties of the generated curves. The isocurves of the solid exported from SolidWorks are very close to being circles and so are recognized as circles by MoI which shows a diameter value for them in the details area in the upper right corner. Doing the same thing on the "TEST ARCS MOI EXP.stp" shows that the curves aren't as close to being true circles, and so MoI just shows bounding box dimensions rather than a diameter value:



Have you tried exporting a STEP from SolidWorks without doing "lock tangents"? Is Pipebend still happy if "lock tangents" is skipped?

Another way to see what's going on is by opening the STEP files in a text editor and doing a text search. The SolidWorks file is made up of TOROIDAL_SURFACE entities. The MoI file just contains general freeform surfaces.

- Peer

Image Attachments:
TEST ARCS MOI EXP.png 

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Thanks Peer,

Your CAD forensics are impressive - all makes sense I was wondering were PIPEBEND was collecting the bend info.
I did think there was an underlying structure difference between Parasolid and Open Nurbs and the way the surface was created.

I tried a part from SW without Tangent lock and same curve from Moi and that imported AOK into pipebend so yes that curve pathway is tangent - but have a look at the MOI Fillets file that was a series of polylines with fillets applied and then shelled. That solid imports into PIPEBEND aok so strange it structures the surfaces in some instances in same fashion and then in other style that PIPEBEND cant read.

Really appreciate the insights.

Attachments:
MOI FILLETS.3dm
MOI FILLETS.stp

Image Attachments:
MOI FILLETS.jpg  SW NO LOCK.jpg 

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No help from this member of the peanut gallery on the problem at hand, but just to say that I'm looking forward to pics once your new sculpture begins to come to life Alex!

--Larry

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Hi Alex,

Re:
> I did think there was an underlying structure difference between
> Parasolid and Open Nurbs and the way the surface was created.

I doubt this has anything to do with Parasolid vs OpenNURBS. Both are capable of analytic representation of a torus.

Re:
> That solid imports into PIPEBEND aok so strange it structures the
> surfaces in some instances in same fashion and then in other style that
> PIPEBEND cant read.

I'm guessing that Pipebend is smart enough to look at general surfaces and check whether they are sufficiently close to being a true torus. The key word here is "sufficiently" because if MoI and Pipebend use different tolerances for "close enough" then sometimes they are going to agree, and sometimes not.

One thing you could do is look through the Pipebend settings to see if there's an import tolerance setting somewhere. If there is, you could try setting it to a larger number like 0.03 mm.

- Peer

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Thanks again for input definitely shedding some light on the internal process of file translations.
I checked in Pipebend and yes there is a option for loosening the tolerance in the import I will have a play with that and see if that gets all the MOI files flowing in.

Just getting the next project ready to start bending 90m of 20mm pipe bent and welded into one continuous pencil style drawing.

Modelled in Moi should be completed in the next couple of months.

Image Attachments:
GLOBAL TENSION.jpg 

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Neat design Alex, where will it be installed?

--Larry

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Thanks Larry - will be installed in September on Currumbin Beach - Gold Coast Australia.
Almost there working out the mechanics of bending this much tube ill post some production shots as it comes to life.
No rest for the wicked!

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