thread inserts in acrylics.

[Eszett]

Hi! I have a little prob. How to get threads into acryl layers (4mm thick)? Hand tapping didn't work :-( I'd like to have the threads flush, without flange or anything jutting out. There are different thread inserts, but which one to take and how to apply them? Heat thread inserts? Press thread inserts? Acrylics easily splitters or breaks. It easily melts too. What would you propose?

[Tactile]

I'd drill  hole & use an adhesive to secure a nut of the proper thread size.

[Eszett]

You mean, to glue a nut of the same height as the layer (to have it flush), into the layer?

[Tactile]

You mean, to glue a nut of the same height as the layer (to have it flush), into the layer?

Yes. The object of the game, for me, would be to have metal threads as opposed to threaded plastic. 4mm material thickness doesn't allow for very much thread engagement. I'd want metal threads for strength & durability.

[Eszett]

Yes. The object of the game, for me, would be to have metal threads as opposed to threaded plastic. 4mm material thickness doesn't allow for very much thread engagement. I'd want metal threads for strength & durability.

I agree, metal threads are way better. I considered your proposal but...
- the nuts's height is standardized, and it doesn't match the height of my layer.
- you need a good glue, since metal doesn't adhere well to acrylics
- glue may melt the acrylics
- when I fasten the screws, the nut may break off, this is what I fear the most..

[jbondeson]

I would  get a threaded insert not a nut. You can then drill the hole partially and do a heat insertion to fully seat the insert. They aren't super cheap, but it'll certainly hold and can be done flush.

[Eszett]

Hey jbondeson! Yes, that sounds reasonable. I found these ones:
http://www.ebay.com/itm/Fixed-Vane-Brass-Inserts-Fixed-Fin-Metric-threaded-Press-in-Brass-inserts-/331854591284?
... which have as M2 thread size exactly the same length as my acrylics layer is thick (4mm).
But do they really sit tight enough? To how much degrees do I have to heat them up? My acrylics must not melt like ice around it, just a little bit yes?

[heedpantsnow]

I got my M2 inserts from McMaster. You want to drill a hole slightly smaller than the insert. Put it on the tip of your soldering iron, heat it up, press it in. Much better than glue.

[jbondeson]

Hey jbondeson! Yes, that sounds reasonable. I found these ones:
http://www.ebay.com/itm/Fixed-Vane-Brass-Inserts-Fixed-Fin-Metric-threaded-Press-in-Brass-inserts-/331854591284?
... which have as M2 thread size exactly the same length as my acrylics layer is thick (4mm).
But do they really sit tight enough? To how much degrees do I have to heat them up? My acrylics must not melt like ice around it, just a little bit yes?

You want the insert to be heated to above the melting point of acrylic (~160 C) but not too much higher. The goal is to melt the surrounding area and have it cool around the insert. If you don't get it hot enough it can fracture or pull out, and if too hot you'll  warp the surrounding area. Most hobbyists use a soldering iron to heat the insert. There are some youtube videos showing different methods to do the insertion.

And if done right, they're definitely strong enough.

Oh and you'll want to  do it on a nice flat metal bench if it's the same height as your acrylic layer so you have a built in stop.

[Eszett]

@jbondeson (and heatmypantsnow) Neeato, that sounds perfect! Already ordered these inserts.

[noobas4urus]

I got my M2 inserts from McMaster. You want to drill a hole slightly smaller than the insert. Put it on the tip of your soldering iron, heat it up, press it in. Much better than glue.

Came here to suggest this. I've seen it done several times in the custom PC case world.  Don't be afraid to try it on a scrap price of acrylic before you do the real deal.

[Eszett]

@noobas4uruus Ye. Could you please give a reference of the actual piece you bought at McMaster?
http://www.mcmaster.com/#standard-threaded-inserts/=14gv6ag
There are tons of different inserts..

[noobas4urus]

@noobas4uruus Ye. Could you please give a reference of the actual piece you bought at McMaster?
http://www.mcmaster.com/#standard-threaded-inserts/=14gv6ag
There are tons of different inserts..

Taking a quick look at it, I'd go with the Heat-Set inserts, they're specifically designed for getting melted into plastics with a soldering iron.  If you look on the left hand side of the browser window you linked there's a heat set group.

They also tell you what diameter drill bit to start with when you melt in.  Looks like they have M2 inserts 3mm and 4.8mm deep depending on what you need.  If you want 4mm dead on I'd get the 4.8mm length ones and grind them down to 4.  I don't think you'd loose much holding power.

[Data]

I'd probably use something like this.

http://www.mcmaster.com/#94100a110/=14h8mus



And since it's acrylic, rather than do a real press fit (which could result in cracks/breaks) I'd use the heat method.

[FletchINKy]

Great info here! Thanks for posting!