View Full Version : Metal in a microwave?

The Artful Bodger
03-04-2017, 03:09 PM
I have made a gavel** from recycled HDPE, both head and handle are HDPE and now I need to work out how to attached the two.

Maybe if I spun the handle in the head I could friction weld but I am unsure so I am thinking of wrapping wire around the thin end of the handle and putting the assembled gavel in the microwave to heat the wire and weld the HDPE.

How say you?

**gavel "a small hammer with which an auctioneer, a judge, or the chair of a meeting hits a surface to call for attention or order."

Mike Amick
03-04-2017, 03:18 PM
As long as the wire around the handle is "within" the head and hot exposed, it shouldn't do
any harm ( to the microwave )

As far as how the HDPE will react, I have no idea but am curious.

I would try short bursts to test it ... like 15sec shots

03-04-2017, 03:28 PM
A while back I tried to heat up some thing that was in a plastic jar. I don't recall what it was. But although I loosened the top I failed to inspect for metal. The traces of foil left by the original seal heated up and sparked and melted and burned the plastic.

I'm not saying you could not use wire in this way as a heat source. But the risk of failure without a lot of previous trial and error is very high.

Plastic is typically a very poor heat source. What I'd do is heat both the socket and end of the handle with a low flame from a propane torch and when both are quite sticky I'd push and twist them together. Or even better would be to fit them and then cross drill and pin them together with a nice dark hardwood dowel or brass pin that is a nice firm hammer in place push fit.

03-04-2017, 03:32 PM
I'd use an induction hot plate for that. Dirt cheap now.

03-04-2017, 04:05 PM
Put a (red) hot knife between the two pieces. Press the pieces together and remove the knife. Clean up on the lathe.

03-04-2017, 07:51 PM
I would REALLY like to see if that works...never thought of using a microwave in that way.

03-04-2017, 08:41 PM
You might find that just winding a helical coil of wire won't do much- but if you short the ends together it could vaporize. Part of the equation is the gauge of the wire, and part is the length. It's an experiment worth trying anyway. For short duration testing you aren't going to hurt the microwave- but do allow time for the magnetron to cool between tests.

The coil can be tested before placing it onto the handle. Just wind it such that it would slip onto the handle properly, then set it up on something to keep it off the floor of the microwave. If it heats too quickly it may not work for you, as the plastic doesn't absorb heat very quickly and might burn before enough plastic is melted to form a weld. On the other hand, the burn might turn out to be the 'filler' that bonds the pieces together. I think I'd prefer a slower heating so I could 'wring' the parts together, knowing that it would end up as one piece.

George Seal
03-04-2017, 08:41 PM
I heat my Vinnia sausages in the can in the micro wave

put unopened can in a cup of water heat for 2 minutes

03-04-2017, 09:11 PM
I heat my Vinnia sausages in the can in the micro wave

put unopened can in a cup of water heat for 2 minutes

In your case the water is both acting as a partial shield as well as conducting the heat away fast enough to keep anything "dramatic" from occurring.

The Artful Bodger
03-04-2017, 09:39 PM
I found the answer, I just smeared the smallest amount of conductive paint in the join and gave it about 5 seconds!

Mike Amick
03-04-2017, 10:17 PM
And ????!!!!!

The Artful Bodger
03-04-2017, 10:57 PM

...just a little gavel made from recycled milk and shampoo bottles etc.

03-05-2017, 01:25 AM
What kind of conductive paint did you use? Did you make your own like this: http://www.instructables.com/id/Conductive-Paint/

The Artful Bodger
03-05-2017, 01:56 AM
I used conductive paint from RS Components, it is black and presumably carbon based.

Lew Hartswick
03-05-2017, 08:26 AM
:-) I'd call that stuff (all of it) "Resistive paint" not conductive. The "Conductive paint" I've seen used is silver particles filled and would have had a few Ohms between the two probes in the "experiment" above. :-)

03-05-2017, 11:53 AM
See I'm gonna have to play with this whole idea....re:off the wall microwave uses Let it "cook" in my head awhile. :>)) Surprised the conductive paint did so well. :>))
Used to service them, so I'm familiar with failure modes. A piece of wire in the cavity (cooking area) usually won't be a problem except it might melt/burn anything touching it. (steel wool = great fireworks!) U can however damage the magnetron tube with any reflective metal item in the cavity..like foil or a container. Energy can be bounced back to the tube and overload things in general. Once saw a magnetron tube with a 30cal hole melted thru the glass from that! Even an empty cavity can be bad if the mfg did not allow for that! There is a "mode stirrer" in the top of the cavity that rotates and is intended to keep the energy from being focused in one spot. Some also rotate the dish inside for the same reason. Drop some mini lightbulbs in a cup of water, nuke it, and u can see the beam passing over them.

There are very dangerous voltages involved internally, and a capacitor capable of holding that voltage sometimes for weeks after the device was last connected . If u play with the innards make SURE u know what u r doing! Once got sent by the company to work for "a few weeks" at another branch about an hour away that needed a replacement tech.. Found out later the reason a replacement tech was needed was the customer found the last one dead, draped over a Litton unit he was sent to repair. Of course the *&%#* company didn't mention that at the time ****

03-05-2017, 02:40 PM
Some crazy things to do (or not) with a microwave:



Safe to use aluminum foil and trays in microwave:

General info: