Pourable Resin for Making Electrical Parts?

[The New Steve H]

Anyone know of a good product to use for molding electrical parts?

I got a good deal on an Ebay variac, but the Bakelite terminal board is cracked. I was thinking I'd glue it together, make a mold from it, and make a new board by pouring in some kind of plastic resin. I have West System epoxy, but I don't know how it would hold up to the temperatures in a running variac.

[Prairie Dawg]

Epoxy would work just fine-variacs don't get that hot inside. I probably would take some chopped up glass fiber and mix it with your resin before you pour it.

[The New Steve H]

I appreciate the info. I have never run a Variac, so you can imagine how much I know about how hot they get.

I have some black resin pigment, so I could probably make a board so pretty it would almost look original.

In case anyone is Googling this stuff, Superior Electric still exists, and they still make Powerstat variacs. I have an email in to them asking about parts, but it's the weekend. If it's reasonably cheap, I'll just order the part. This thing costs over $300 new, and I got a gorgeous NOS job for $75 including shipping.

[Phil_S]

Steve, I can't imagine Variacs have any sort of vintage value to them, which means you don't have to concern yourself with cosmetic issues. If it were mine, I'd epoxy the board, and depending on the break, maybe stabilize it at the edge with something non conductive, and make jumpers to reconnect the broken traces. This doesn't need to look pretty. It just needs to work.

[selloutrr]

why not wire it point to point?

[Paragon]

If you have turret board material, that would work.

[ISOTone]

careful what you use. some epoxies are/can be electrically conductive. i used to make living building HVAC hybrid bridge, SCR and Tyristor ckt. assemblies - we molded the sub-assemblies in plastic cases with epoxy. we used products made by epotek (epoxy technology). it's pricy and kind of a bitch to cure. some can be had that will cure at room temperature, but those types can literally take days. basically what you want is an thermal type with thermal conductivity properties (dissipates heat), and one that is thixotropic, (holds shape when you form it) that has a high viscosity (thicker - like a paste) so it's easier to form. below is a link to a list of products that should work for you. there are other brands - epotek is whom i'm most familiar with.

http://www.epotek.com/subapplications.asp?ID=9&SID=11

cut & machine piece of 125mil FR4 ( find it a plastic supply house) and use eyelets or turrets. if it were me, that's probably the path i'd take.

--ISO

[Prairie Dawg]

I appreciate the info. I have never run a Variac, so you can imagine how much I know about how hot they get.

I have some black resin pigment, so I could probably make a board so pretty it would almost look original.

In case anyone is Googling this stuff, Superior Electric still exists, and they still make Powerstat variacs. I have an email in to them asking about parts, but it's the weekend. If it's reasonably cheap, I'll just order the part. This thing costs over $300 new, and I got a gorgeous NOS job for $75 including shipping.

That's nice to know. I have two Superior Adjust-a-Volts, one of which was made when they were in St. Paul, Minnesota. A friend of mine bought a house complete with junk collection that had belonged to a reclusive guy who had operated the biggest Super 8 film lab in Iowa. The Superior looked like it had been dredged up from the bottom of the Raccoon River. I got it home, cleaned out the dust, gave it a coat of paint, installed a couple of binding posts for monitoring purposes and it has been my go-to variac for years. They're a dual range job that will get you above 150v on the output.

[The New Steve H]

I know the looks shouldn't matter, but this thing looks like it was made yesterday, apart from the damaged board. Still waiting for a reply from Superior Electric.

[Structo]

Steve what kind of board is it?

Could you make a new one out of Garolite? Like we use for turret or eyelet boards?

1/8" thick and the F4 type is fire resistant.

[The New Steve H]

It's a thick molded terminal board with curves and so on. It's part of the structure of the machine; I would think that a thin piece of circuit board would fail to support the housing correctly.

I may just send the thing back. Superior Electric says the board costs $50, and they still haven't gotten back to me to tell me whether the boards they currently sell will fit this model. It's apparently ancient, although you could put it on a store shelf today and convince people it was new.

If the board fits and the seller will cough up a substantial part of the cost, I'll keep it. Otherwise I think it's time to send it back.

[The New Steve H]

I'm planning to send it back. Superior Electric says the board costs $84 retail, so with shipping, a new one will cost close to that. Maybe I'll go Chinese, since they now rule the world anyway.

[selloutrr]

If you are going to buy another Variac.

I use an Eico 1178 that I've modified by tapping off the Voltage and Amperage meters to run large 8" Western Electric VU meters.

The amperage meter is a huge help in troubleshooting and starting up new builds / repairs.

[Lonely Raven]

It looks like a secreted resin...

Yeah, but secreted from what?

[The New Steve H]

I may regret this, but I decided to try and fix it, even though Bakelite is considered very hard to repair.

I got some kind of superglue kit made for plastics. I assume the primer pen that came with it does nothing whatsoever to Bakelite, but what the hell. I followed the instructions and put the corners back on the board, and they look very good. It held up when I screwed the machine back together. Surprising, but satisfactory.

Most of you probably know how it is when you repair plastic. Line it up and glue it, and it looks great. Apply a tiny amount of stress, and it flies apart. But this is holding.

The socket is still crap, but I have to replace it anyway.

I have a sad weakness for pretty tools, especially when they're old quality tools from the US or Europe. This thing is something like 60 years old, and it literally looks like they made it last week, and I just had to try to repair it.

What it will look like after I butcher it to add a three-prong socket...hard to say.