Tool for melting plastic stub fixing?

Question

I'm looking for a tool to "melt" those plastic stub/peg fixings that poke through PCB holes to give mechanical strength to large items, or hold non-electrical things like light guides in place.

For a quick bodge I just use the standard soldering bit in a Weller heat gun, but that always looks messy and probably isn't very secure, see the two black blobs on this:

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I was hoping there would be a suitable bit for the Weller, with a concave tip like this, but can't see anyting suitable:

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I suppose I could mod a normal bit to be hollow, but how are these things normally done (ultrasonics?)

I may have several hundred to do...

legg · Accepted Answer

On Mon, 19 Jan 2026 12:31:03 -0000 (UTC), Ianwrote:Even the cheapet gear seems to manage self-tapping screws for this kind of mechanical security, these days.RL

Roger Mills · Answer

It's outside my experience - but apparently it's called Thermal Staking, and does indeed use ultrasonics in a factory situation.

There do seem to be a few DIY options - see

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nothing specifically for your Weller

john larkin · Answer

On Mon, 19 Jan 2026 12:31:03 -0000 (UTC), Ianwrote:It would be easy to glue them, like with a UV-cure adhesive.John LarkinHighland Tech Glen Canyon Design CenterLunatic Fringe Electronics

The Natural Philosopher · Answer

Dab of hotSnot™

john larkin · Answer

On Mon, 19 Jan 2026 17:14:43 +0000, The Natural Philosopher   snipped-for-privacy@Try that and let us know how it works.I had in mind Bondic or an eqivalent. Use a UV flashlight, not thedinky blue LED that comes with it. Dab and flash in maybe 8 seconds.John LarkinHighland Tech Glen Canyon Design CenterLunatic Fringe Electronics

Ian <$ · Answer

Ta. Glue of some kind is a good suggestion. Will do some experiments.

Ian <$ · Answer

Thanks for the search term, I had no idea what it was called :)

john larkin · Answer

On Mon, 19 Jan 2026 12:31:03 -0000 (UTC), Ianwrote:Press fit into oval holes.John LarkinHighland Tech Glen Canyon Design CenterLunatic Fringe Electronics

Don · Answer

pertains to a DIY tip for a Weller. It looks easy enough. One professional product's pricier than a piece of copper wire from your junk drawer:

TTman · Answer

Buy 'starlock washers' from Ebay etc. Push on, don't come off- so long as you use the right diameter- not hard if going over a plastic 'stud'.

Ian <$ · Answer

Yep, it's just thick copper wire/rod with a thinner bit as the "tip".That's the sort of thing I was expecting to find, so it can be donethat way.Ouch (and that's just the stand!)

Tool for melting plastic stub fixing?

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