STL export - tapped hole threads not showing up in 3d print slicer

mark_casey

Title says it all.  I've made a simple tap handle with a threaded 3/8-16 hole to directly screw onto a tap.
The intent is to 3d print the part with the threads integral to the part.  It exports fine but the threads are not showing up in the slicer and thus will not print.

If fact, the threads do not show up in the Onshape part display although they are defined as being there using the Hole command.

I'm sure I'm doing something wrong, but just can't figure it out.  

My tap handle is available publicly at 
https://cad.onshape.com/documents/9c35aff9403733481b7cec82/w/9f21851b66cf7e794f5394f4/e/d67efd1deb907b02b5d0b924
if anyone cares to look.

thanks in advance for any advice.
Mark

lougallo

@mark_casey Our hole feature does not add threads.  Just the tap drill diameter.  If you want to print threads you will need to add the threads yourself or look for a featurescript that can cut them for you.

Jake_Rosenfeld

Hi Mark,

The issue you find with your file size is actually why we don’t add threads.  From a tessellation point of view, threads are very expensive to create as they require a very large number of triangles to represent. The average user does not need these threads, as the metadata for the thread carries over to our drawings, and the user can annotate the drawing to actually drill this hole at the manufacturing stage, and at no point has to slow the document down by adding these very small, but expensive, cosmetic features.

That being said it is a valid use case to need these threads for 3d printing, and if you would like to see this feature in the product you can raise an improvement request to the right -->

owen_sparks

The rise in file size is normal, and is a reason most folks chose not to model the threads themselves unless really needed.  There will probably be more triangles in that little thread than the rest of the model put together.

I do a bunch of 3D printing using OS files.  How big a thread do you need?  If they're not large then I'd either print the pilot hole and tap it (if using a suitable material) of have captive nuts included part way through the print.  I got fed up doing this manually so wrote a Nut Pocket featurescript to do it for me.   Or melt in threaded inserts.

Cheers,

Owen S.

lougallo

@mark_casey Our hole feature does not add threads.  Just the tap drill diameter.  If you want to print threads you will need to add the threads yourself or look for a featurescript that can cut them for you.

mark_casey

Any plans to add this feature?  It seems like a fairly basic need.  The process to add threads is vey kludgy and when I follow steps in the video tutorial that I found after posting this question, my system does not react the same way.  I have been unsuccessful in using the helix and extrude surface tools to create a threaded hole.  I found a beta featurescript and am not sure how it works, which it does, but adding one 1 inch 3/18-16 tapped hole to a part increased the size of the stl file by 5.4MB (or more than quadrupling the file size).

Apart from this (minor) frustration, I find Onshape extremely useful and powerful.  I'm new to CAD and if I think about what I'm trying to accomplish in advance, it really is fairly intuitive.

thanks for taking my question.

Mark

Jake_Rosenfeld

Hi Mark,

The issue you find with your file size is actually why we don’t add threads.  From a tessellation point of view, threads are very expensive to create as they require a very large number of triangles to represent. The average user does not need these threads, as the metadata for the thread carries over to our drawings, and the user can annotate the drawing to actually drill this hole at the manufacturing stage, and at no point has to slow the document down by adding these very small, but expensive, cosmetic features.

That being said it is a valid use case to need these threads for 3d printing, and if you would like to see this feature in the product you can raise an improvement request to the right -->

owen_sparks

The rise in file size is normal, and is a reason most folks chose not to model the threads themselves unless really needed.  There will probably be more triangles in that little thread than the rest of the model put together.

I do a bunch of 3D printing using OS files.  How big a thread do you need?  If they're not large then I'd either print the pilot hole and tap it (if using a suitable material) of have captive nuts included part way through the print.  I got fed up doing this manually so wrote a Nut Pocket featurescript to do it for me.   Or melt in threaded inserts.

Cheers,

Owen S.

owen_sparks

Doh, Jake got there before me, sorry.

mark_casey

Thank you both.

It seems that there must be a more efficient way (not that I know how) to create threads.
As a test, I created a 2 inch cube and then a 2 inch cube with a 3/8-16 threaded hole 1 inch in length.  The resultant .stl files were 684 bytes and 4.13MB respectively.

I did the same thing in TinkerCad and the resultant .stl files were 684 bytes and 182 kB respectively.

Seems there is an opportunity to make a more efficient threaded item.

I'll make the request.

thanks again.

ilya_baran

The file size is purely a function of how finely Onshape tessellates the thread.  You may also consider using the thread creator custom feature: https://forum.onshape.com/discussion/4867/new-featurescript-thread-creator

mark_casey

Thanks!  I'll try that.

mark_casey

ilya_baran said:

The file size is purely a function of how finely Onshape tessellates the thread.  You may also consider using the thread creator custom feature: https://forum.onshape.com/discussion/4867/new-featurescript-thread-creator

Turns out this is the feature script i was using.  it makes beautiful threaded parts but results in extremely large .stl files. 

best,
Mark

owen_sparks

Is the time of terabyte hard drives and gigabyte USB sticks there any downside to large files?

Owen S.

mark_casey

Storage is pretty much a non-issue, but the 3d slicers choke on them a bit.

tom_leenheer

Mark,
Great work, the thread creator works perfectly