3D DXF loads like an STL file in Rhino

[thinkntink]

Hello,

I just started using Gearotics and must say that I am very impressed with it's capabilities.  I am, however, having a bit of trouble with its Output Manager.

I am building a project that will consist of a couple of spur gears driven by a pair of straight bevel gears (90? mesh). When I try to save the geometry of any one gear as a 3D DXF file, it is saved as a set of polygonal meshes much like an STL. I can open the file by importing it to Rhino, but cannot convert it to a solid for use in Alibre or SolidWorks. I suspect that I am doing something wrong and would like to be able to model in GM and use the output as objects in a 3D CAD package. Is there a way to save the design as an IGES or STP file for importing into other packages?

On a related note, we will be sending the designs out to a prototyping shop for a short fab run. What information do I send them? Is the fabrication information for each gear saved in a text file somewhere. I looked in the parameter file but it does not appear to contain sufficient information to produce the prototypes.

Any advice on these subjects would be most appreciated.

Best regards,
Ron Reed

[ArtF]

Hi Ron:

  A 3d DXF file is basically the same as an STL. Each is a triangulation file of the model of that gear.
They both represent  a solid, but then the term "solid" varies from package to package. IGES and STP
are really output types that represent CAD objects in that they describe the operations necessary to
build an object. GM cannot do that type of output as it doesnt use normal CAD methods to build
its objects. Its a bit hard to explain the differences. I am looking into the possabilities of making other
output types but as yet havent found an approach that works.
  You may want to try some of the free programs on the web that will allow you to load an STL, and save
an OBJ or STP output. Since my usage is typically for stl's Im not much of an expert on which convertors to use
for such a thing, or which output formats work best for describing a solid to other CAD programs.

  For prototyping the information you need depends on the manufacture method, it its a gear shop, the DXF
and the module and number of teeth is all thats needed for normal involutes. the 3d types, such as helicals or
bevels really work the same,  with module and tooth count being all a shop needs to produce a gear of pretty
much any type. Spokes and such are the only reason a dxf can be required.


Art

[thinkntink]

Hi Art,

Thanks for the quick explanation. Since last night I have been digging into file conversions and trying a number of different options. To wit:

• Rhino4 will load the STL file but will not export it to any Alibre CAD supported formats (STP, IGS). The reason given is that the file flavor selected will not support polygon meshes.
• There is a very good STL to STP converter called InStep (v2.1, https://www.solveering.com/instep.html) that loads the file and does a pretty thorough analysis of it. It also sports some file repair functions. Unfortunately, it could not fix all of the issues that it detected with a sample bevel gear that I used to test it. An 18 tooth, Mod 1.5 gear imported with 21 "pierced facets" and 100 unattached edges. The repair tools knocked it down to 7 unattached edges but could not improve on that. Nonetheless, I was able to write a STP file that will open in Rhino but not in Alibre (latest flavor).
• Opening the STL in BLENDER proved pretty straightforward, but I could not figure out a way to clear up the issues detected by InStep
• I am going to try a run through Adobe Illustrator (CS6) to see if I can get it to behave.

That is about as far as I have gotten so far. I may have to use Rhino to model the gear train but there does not seem to be an easy way to incorporate the model in Alibre (where the rest of the system is being designed)

[ArtF]

Hi Ron:

    If your dealing with STL's , make sure you save a GM project file, then load it in GT ( which is in the dev release) and export the STL from there.
GT's STL's should have no issues, while GM's can have several, specially in bevel's..

Art

[thinkntink]

Hi Art,

I tried exporting the STL from GT a while back. It loaded without a problem but it was MUCH bigger (26MB vs 10MB) than the equivalent GM file. There were also some structural differences that might have added the increased size.

[ArtF]

Hi:

  Yeah, they are larger for sure. Their much higher resolution that the older stl's. Ive been reading on the topic and I see
its a pretty hot topic in google. STL's are the best way to do modeling , yet solids programs hate them..unless its a very expensive solids program. The problem is one of feature recognision. But, the good news is it only really affects a bevel, all the other models can be done with dxf and a simple extrude. Also, the research seems to show it may be possible for me to put out the bevels as a step file or similar since I do have the feature data in the program as GT makes the bevel. So thats on my list of developments to do when the rest of the program has been migrated. I still have lots to do till then so it wont be real quick.. :)

Thx
Art

[Mooselake]

You can try resizing the stl files in meshlab and see if that helps, although you'll need to be careful and not remove too much detail.  Keep the original file and play around with the options.  I've used it successfully with GT output, although the world is conspiring to keep me away from GM and my CNC/3DP toys^^^^tools.

There's several tutorials available, like this one, to get you started.

Kirk

[thinkntink]

Thanks for the replies.

It is probably a good thing that messing with bevels takes so long in Alibre / Geomagic. GM is just too bloody addictive and I really do need to do something productive once in a while.