Threaded Inserts for Thermoplastics

As I was thumbing through my McMaster-Carr catalog, trying to while away the time waiting for my first 3d printer kit to arrive in the mail, I came across these "Threaded Inserts for Thermoplastics" halfway down page 3265:

[www.mcmaster.com]

Has anyone used them to melt in fine-threaded holes into ABS or PLA printed parts? It seems they are meant to be used with an attachment to a soldering iron, but I imagine with a carefully printed guide hole (or even a teardrop) they could be pushed in with minimal heating for a very accurate fine thread.

Any experienced users out there? Does this sound like a good idea only to a newbie like me?

James

I might be oblivious here, but how is that different than a simple nut trap? Even below m3 size, a nut would work, or?

For certain parts you can also tap the thread directly into the plastic, though it has its limitations of course.

---

--
-Nudel
Blog with RepRap Comic

Nutserts are often inserted into blind holes and the screw enters from the same side.

I expect they will work fine in printed parts. I have some, I should try it someday.

---

[www.hydraraptor.blogspot.com]

I've been able to get away with using a tap to put threads in printed parts.

Captive nuts and nutserts are good for when you want to be able remove and replace the screw, otherwise self tappers are good for one off insertion and they work fine in printed parts.

ABS is a bit soft for machine screw tapping, PLA is probably better but may be a bit brittle for self tappers and need a bigger pilot hole. Using nuts and nutserts allows designs to be less material dependent.

---

[www.hydraraptor.blogspot.com]

Thank you! I'm learning a great deal from this forum. If you were going to design a piece that used nutserts, what size would you design the hole to melt it into? I assume slightly smaller than the minimum diameter of the nutsert, but what is a good rule of thumb? Likewise, I can look up recommended pilot holes for tapping, but should I make any adjustments when printing a hole in ABS vs. PLA to be tapped?

Thanks again for sharing your knowledge,
James

Nutserts state the recommended hole size, so I would go with that as a starting point. Some are designed to be melted into thermoplastics so I don't see why it would need to be different using reprapped parts.

I am not sure how much bigger you would need for PLA. I would think when tapping for machine screws you would use the normal drill size but when you see data for self tapping screws sometimes they give different diameters for hard and soft materials.

Having said all that printing holes that come out the right size is not trivial. See [hydraraptor.blogspot.com]

Fortunately reprapping lends itself to trial and error if you can afford the plastic and machine time.

---

[www.hydraraptor.blogspot.com]

The soldering iron method sounds like it would work for harder or glass filled plastic. I think you might get into a sticky mess with ABS or PLA.

It might be better to forget the heated route and go for a self tapping insert. There are hundereds of different ones, but probably ones with very coarse external threads might get you around the hole sizing problems that we have in the reprap community. You might experiment with warming them slightly in hot water before screwing them in.

Just google images for "self tapping insert" and take your pick.

Edited 2 time(s). Last edit at 01/07/2012 06:16PM by martinprice2004.