Exporting objects with Threads

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mnuser
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Exporting objects with Threads

Post by mnuser » Fri Jan 24, 2014 9:04 pm

We exported a file that has two posts on the object so it can be mounted to a the wall of a package. The two rods had threads in the program Inventor 14 Auto Desk. Once I export it and place it into the 3D printing software the threads do not show up. I exported it as an .stl file and in mm so it loaded correctly in the 3D software.

Any ideas why? Am I missing something?

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DrewPetitclerc
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Re: Exporting objects with Threads

Post by DrewPetitclerc » Sat Jan 25, 2014 1:24 am

Most all CAD packages when you create a tapped hole it is not really threaded, it is a representation with a text call-out telling you it needs to be a tapped hole, the sheer number of surfaces to describe a threaded hole multiple times in a solid would quickly choke the system.
Drew Petitclerc
Petitclerc Designs
Owner/Senior Principal Designer, prototype, tooling and test equipment design and 3D printing
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amd-tec
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Re: Exporting objects with Threads

Post by amd-tec » Sat Jan 25, 2014 8:03 am

mnuser wrote:We exported a file that has two posts on the object so it can be mounted to a the wall of a package. The two rods had threads in the program Inventor 14 Auto Desk. Once I export it and place it into the 3D printing software the threads do not show up. I exported it as an .stl file and in mm so it loaded correctly in the 3D software.

Any ideas why? Am I missing something?
Here's some guides for making threads from cosmetics.

http://www.cadsetterout.com/resources/t ... or-plugin/
"3D design with intelligent printing"
http://www.amd-tec.com

Helicopter
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Re: Exporting objects with Threads

Post by Helicopter » Sat Jan 25, 2014 6:02 pm

The other option is (since sadly not all CAD software offers such a nice addon - have yet to find one for solidworks, and it has always bothered me that such a professional software doesn't offer a standard option to convert cosmetic threads to real ones) to actually find the screw dimensions in for example the machinists handbook or similar publications, and do a swept cut with a triangle along a helix around the positive or negative cylinder to create a real thread.

doraemon
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Joined: Wed Sep 19, 2012 3:37 am

Re: Exporting objects with Threads

Post by doraemon » Sun Jan 26, 2014 3:26 am

Similarly, maybe download a 3D file of a bolt (or nut) from a reseller like McMaster-Carr and then merge the features into your model? No looking up of dimensions needed in that case.

cj7hawk
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Re: Exporting objects with Threads

Post by cj7hawk » Mon Jan 27, 2014 12:36 am

I get pretty good threads from my Mini, and it prints without problems down to 32tpi and I once even succeeded at 40tpi. Most threads are pretty close to perfect, though sometimes I have to allow for shrinkage.

The biggest problem I had printing threads prior to writing my own software was that they often looked right when loaded into the UP software, but the software had trouble printing them because they were too complex, sometimes crashing the application. I would end up with it not able to tell the inside from the outside of faces.

If your CAD system supports LSP files, you're welcome to use/adapt my routine. It creates solid threads in CorelCAD and I think it might work in some versions of AutoCAD but I'm having trouble getting it to run in Version 14 of AutoCAD.

PM me an email address if you want me to send it ( or you can download it from the CorelCAD forums )

Image
The upper most part, the inside is threaded 1.2" 32TPI - The thread program is metric, but ISO standard for metric and imperial is the same.

The UP will handle threads quite well if made to ISO standards. I found earlier versions created that weren't quite right didn't print correctly and had trouble with machined parts interacting with them, but lately they all work well.

Regards
David

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