Glueing / repairing plastic ?

Emp_Fab

One of the lugs on the door latch on my microwave has snapped off.  I can't find a replacement anywhere that matches.  I've tried using epoxy resin glue to stick it back on (using generous amounts and roughening up the surfaces etc) but it fell off after one use - possibly due to the steam.

Any suggestions on how I can reattach the lug securely ?  (I was thinking maybe create some metal splints from tin cans to hold either side).  If I can't fix the plastic lug back on, the whole oven has to go in the bin.

Here's a similar door latch with both lugs attached....

ICBM

From experience repairing broken kids' toys, I would suggest using metal pins in holes drilled very slightly undersize, and heated into the plastic. Cut-down nails work well, especially if they have serrated sides - and if they don't, add some with wire cutters. You can use epoxy on the joint surfaces as well - did you use the slow-set stuff or the quick-set? (Quick set is crap!)

But before you do, is it definitely on the outside of the microwave cage? If not, the last thing you want to do is introduce any metal into it.

guitarfishbay

I hope Emp reads that second paragraph.

Emp_Fab

It's definitely outside the cage.  As for metal in a micro - it's alright....  you might get a bit of lightning but it's not the end of the world.

I used the slow-cure stuff, but it seemed to go soft after the first use.... which makes me wonder if it was the steam from the spuds or whether there's any microwave leakage.  Due to the construction of the latch, there's almost nothing I can seat a metal pin into - certainly nothing thicker than 2mm.

If I could perform some kind of plastic weld, that would work as I could fill up the cavities in the cross section which is a bit like an RSJ.

  i.e.   |---|  

I tried that with the epoxy, but it just separated on the stress line (i.e. where the initial break was).  The latch has to withstand a fair bit of pressure longitudinally - left to right on the lugs in the photo above - as it rides over the sprung interlocks in the oven.  If I could take the stress off the leading edge (left in the pic) with a thin strip of metal that would work - but - I suspect the epoxy would again not be strong enough.

ICBM

Doesn't sound hopeful.

It is a bugger when this sort of thing happens. A couple of years ago I had to replace our dishwasher when the door seal went and was no longer available as a spare - it was just too old for the manufacturer to keep them, probably a year earlier and I'd have got one. I bet they knew that . Carefully-designed built-in obsolescence is a fine art...

The good news is that the replacement dishwasher is more effective and more efficient, so I suppose all was not lost.

Paul_C

is a replacement part available ?

Emp_Fab

Emp_Fab said:

One of the lugs on the door latch on my microwave has snapped off.  I can't find a replacement anywhere that matches.

No.  Can't get one anywhere.

BUT !!!  IT DOESN'T MATTER ANYMORE !! :-)

After reading up a bit about the different kinds of plastics etc, how glue is a waste of time for a strong bond and that plastic welding is the only way to go, I poked about in my 'room of shame' (messy work / junk room) melting various plastic things with a soldering iron (Mrs Fab is not best pleased with the smell) until I found an object that looked like the same stuff and smelled the same when melted (a SFF Hard Drive blanking panel).  I then attacked my door latch with a soldering iron and melted dollops of the blanking panel into the recesses in the latch, digging the iron bit in so that the filler plastic melted into the original.  Ten minutes of tidying up with a file and it's stronger than new !!!  My microwave lives on !!  HUZZAH !!!

thisisguitar

Late to this, but plastic welding for the win. Fixed a spring-loaded mechanism on my old Kenwood CD player with this trick, it lasted for a good few years after :-) I usually take some material from somewhere else on the actual part I'm repairing, that way the plastic is the same.

Hope it holds out for you.

imalone

Emp_Fab said:

Emp_Fab said:

One of the lugs on the door latch on my microwave has snapped off.  I can't find a replacement anywhere that matches.

No.  Can't get one anywhere.

BUT !!!  IT DOESN'T MATTER ANYMORE !! :-)

After reading up a bit about the different kinds of plastics etc, how glue is a waste of time for a strong bond and that plastic welding is the only way to go, I poked about in my 'room of shame' (messy work / junk room) melting various plastic things with a soldering iron (Mrs Fab is not best pleased with the smell) until I found an object that looked like the same stuff and smelled the same when melted (a SFF Hard Drive blanking panel).  I then attacked my door latch with a soldering iron and melted dollops of the blanking panel into the recesses in the latch, digging the iron bit in so that the filler plastic melted into the original.  Ten minutes of tidying up with a file and it's stronger than new !!!  My microwave lives on !!  HUZZAH !!!

Nice stuff.

thermionic

Great idea, but I suspect a soldering iron would be too hot to do this with any finesse? Maybe a temperature controlled iron on its lowest setting would be good. Makes a mess of your bit, I suspect.

littlegreenman

Emp_Fab said:

Emp_Fab said:

One of the lugs on the door latch on my microwave has snapped off.  I can't find a replacement anywhere that matches.

No.  Can't get one anywhere.

BUT !!!  IT DOESN'T MATTER ANYMORE !! :-)

After reading up a bit about the different kinds of plastics etc, how glue is a waste of time for a strong bond and that plastic welding is the only way to go, I poked about in my 'room of shame' (messy work / junk room) melting various plastic things with a soldering iron (Mrs Fab is not best pleased with the smell) until I found an object that looked like the same stuff and smelled the same when melted (a SFF Hard Drive blanking panel).  I then attacked my door latch with a soldering iron and melted dollops of the blanking panel into the recesses in the latch, digging the iron bit in so that the filler plastic melted into the original.  Ten minutes of tidying up with a file and it's stronger than new !!!  My microwave lives on !!  HUZZAH !!!

I may resurrect the broken yoke on my snapped headphones yet!*



* If the fumes don't kill me in the process

chillidoggy

I'm late to this too, but I'd have gone with plastic welding. I've given up trying to glue most plastics, they really don't like it. Well done, Emp!

Paul_C

Sorry for not reading the OP completely

I should have thought to suggest the soldering iron as I've used mine to repair a broken handle on some wire cutters, but I'd forgotten that I'd done it until I saw your post !