3D printing objects that have a tread

[adelaidered]

Help please. We are using iventor 2012 at my school and have recently purchased a makerbot 3D printer abd having lots of fun. Howver i recently created a model that has an M40 Thread as part of the model. However when i try to 3D print it, it doesn't recognise the thread and it isn't printed. I seethre thread on the ipt but once it is saved as an stl it seems to disappear. Any ideas?

[Anonymous]

I would suggest that the makerbot is simply generating its output based on the 3D model. Inventor doesn't the threads as physical parts, it simply puts in a 'placeholder' that can be later referenced in your drawings. You'll probably find that you'll need to create your thread using a sketch profile of the thread and then sweeping it around the cylinder that you want the thread on. HTH.

[BLHDrafting]

This has been posted and answered earlier this week.

You either need to model the threads (as Inventor uses a graphic to represent them) or install this add-in to generate the threads. But even that still needs checking as 1 forum user says it may not be correct. Also this shows as compatible for 2013 and 2014, but I remember using it in 2011. Maybe search for an earlier version elsewhere.

http://apps.exchange.autodesk.com/INVNTOR/en/Detail/Index?id=autodesk.appstore.exchange.autodesk.com...

[JDMather]

Seems like some instructors aren't covering the basics

http://forums.autodesk.com/t5/Autodesk-Inventor/Screw-threads-exported-as-STL-files/td-p/4294591

or maybe the students aren't paying attention.

[graemev]

3D printing of an M40 thread with a machine having a 0.1mm resolution (highest quality) is going to be a severe challenge.  Expect it not to fit at all well or, if you chose to accommodate the tolerance and roughness problem, fit together more like a baby rattle than a nut & bolt - doable, not useable.

[JDMather]

We routinely print 3D threads on a machine with about .25mm resolution without trouble.

The trick is to print out a sample and adjust model from actual results.

From just a few trials I know how much allowance I need to get pretty smoothly fitting threads.

Just have to remember that it isn't a close tolerance machining process and make adjustments based on experience.

My students are always amazed when I tell them exactly the allowance to make and it works.

[graemev]

Yep, I hear ya.  I've actually printed out an "inverse" acme thread - dovetail, if you prefer - and managed to get the clearance in the model just right on the first shot.  There was a cearance (face to face) of 0.005" on the model and the printed parts were just barely a slide fit.

Experience is a damned fine teacher.  lol