I have a woodburner with two parts (a hinge pin and the nut that holds on the door catch) that slowly slacken off and eventually fall out/off. Can anyone suggest a way of holding them on? I've tried threadlock and silicone, but (I imagine) the high temperatures (the hinge pin can get up to several hundred degrees C) destroy them.
I suspect the only way to do it is mechanical; peen the end of the pin over. Not sure about the nut. Squash it oval with Mole grips, perhaps?
If you have enough thread, two thinner nuts "locked" together?
You can still get stiffnuts (the predecessors of nyloc nuts), which should work even when hot.
Is there enough thread left for a split pin after the nut? You could drill through both nut and thread if not.
or cross drill and stick a split pin through it.
Add an extra locking nut... or a few turns of PTFE to make the threading a little stiffer.
I forgot they existed, I haven't seen one for a while!
PTFE heated to a few hundred degrees quoted by the OP would be very dangerous indeed - gives off phosgene (?) or something equally nasty.
I'd shy away from peening over just in case any nearby casting cracks with reaction to the blows.
Either squashing the nut or split pin would be my choice.
Not worth buying just for this but if you happen to have any high temp. "cylinder" paint or barbecue paint it might be worth trying
Hmmm. Sounds possible.
Nope. But wirelocking the not sounds possible.
Sadly not, but a good idea.
What about two half nuts set as a locknut pair? Brian
that's one way. I've been looking on the net for high temp threadlock, but nothing really looks appropriate beyond maybe car exhaust sealant, designed to harden under temp
ISTR that you had to heat it to over 500 - 600 for it to be a problem (was there not an issue with producing hydrofluoric acid in some circumstances?)
How about drilling a concentric hole up the end of it and sticking in a pan head self tapper with a head diameter a bit larger than the main diameter?
I wonder if you could use a few strands of glass fibre insulation as a thread lock?
The nut's likely OK - it never gets that hot, but the hinge pin is for a top-loading door (which works really well, despite my initial misgivings) and as a result gets seriously hot.
More likely than phosgene. ISTR that phosgene contains chlorine but PTFE only contains carbon, hydrogen and fluorine. Having worked with liquid hydrogen fluoride some years ago I can confirm that it is a very corrosive substance.
Malcolm
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Take your pick.
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