Anyone know what this material is?

[waddycall]

Anyone know what the arc covers/chutes on this 75 year old contactor are made from. They seem like some form of ceramic. Just curious if they could be ACM. Coils burnt out. I’ll be replacing it (probably)

 

[Pete.]

Could well be ACM. Just dismantle it carefully and don't break them. Do it outside in abreeze if it really bothers you.

The pull-in coil doesn;t look cooked. Might be a simple break.

 

[waddycall]

Thanks Pete. The wrap on the coil is burnt up and insulation on a leader burnt out. The control circuit fuse popped and shut the machine off. I could smell burning but we have a neighbour who’s a pyromaniac so assumed it was him

 

[waddycall]

I’m wondering if the coils rewindable but I’ve got enough scope creep on projects at the moment

 

[waddycall]

Looks like I can run this on a vfd in the meantime

 

[Pete.]

Thanks Pete. The wrap on the coil is burnt up and insulation on a leader burnt out. The control circuit fuse popped and shut the machine off. I could smell burning but we have a neighbour who’s a pyromaniac so assumed it was him

Yeah it sounds dead. Winding it should be a trivial matter. Just get some same-diameter magnet wire off Brocott on ebay and a pot of their red laquer goop. measure the diameter of the winding on the bobbin and re-wind it to about the same diameter, or a little more. Solder you leads, secure them well to the winding, paint on your varnish and let it cure and you're done. Being just a pull-in coil it'll have a good tolerance for number of turns.

 

[Seadog]

If you do decide to rewind, I've a few spools of wire of varying gauges. Message me and I'll see if I have the correct gauge.

 

[waddycall]

Thanks chaps. It would be good to save it. The machines pretty much original from 1951 and I’d like to keep it that way. I’ll see if I can get the electrical assembly out tomorrow. It needs to come out as one thing by the looks of it and I’ll go from there. Maybe rewinding the coil could be easier than wiring up a VFD

 

[waddycall]

I’ve got the electrical sub assembly out and stripped the contactor down. The bobbin looks really cooked. I think it’s had it’s day. Removing the old contactor and fitting new would probably mean a pretty comprehensive rewire. I’m thinking I could strip back the old contactor hardware to just the base and mount a new contactor on a bit of din rail mounted on some stand offs. I can then add extension wires onto the old terminals to connect to the new contactor. Could also add an overload on it.

 

[waddycall]

But also just found you can buy bobbins!

 

[waddycall]

Or I could sketch it up at work in lunch time and 3d print it I guess.

 

[waddycall]

Ive got a load of nylon bar. So pondering making a bobbin on the lathe.
No idea what temperature ratings these things need. Any ideas? It’s a 240v coil by the way.
Might have a bit of ptfe too

 

[oldbikedavey]

Ive got a load of nylon bar. So pondering making a bobbin on the lathe.
No idea what temperature ratings these things need. Any ideas? It’s a 240v coil by the way.
Might have a bit of ptfe too

Red fibre might be worth a look at for a bobbin material.
Tufnol might work, depending on the temperature requirement.
150C , maybe ?

 

[Seadog]

Vulcanised fibre, as it's known.

 

[oldbikedavey]

If you do decide to rewind, I've a few spools of wire of varying gauges. Message me and I'll see if I have the correct gauge.

As have I .....

 

[waddycall]

Currently unwinding the coil with the lathe. Going very slowly so I don’t miss any details

 

[waddycall]

Definitely not reusing the original!

 

[waddycall]

So the wire measures up as 0.165mm. I can see Brocott have it as Pete suggested.
I’ve checked out the red vulcanised fibre and it seems it’s not that great for temps above 100-120. Wondering if PTFE might be a goer as that’s good to over 200c.
All input appreciated! I’m in uncharted territory for me.

 

[oldbikedavey]

So the wire measures up as 0.165mm. I can see Brocott have it as Pete suggested.
I’ve checked out the red vulcanised fibre and it seems it’s not that great for temps above 100-120. Wondering if PTFE might be a goer as that’s good to over 200c.
All input appreciated! I’m in uncharted territory for me.

Delrin ? Peek ?
Plaster of Paris has to be way up on the temperature resistance scale, but as for its electrical characteristics, ... dunno.....
There's porcelain, of course....

 

[Seadog]

Is 0.165 including the lacquer?
It sounds like 38swg which I think that I have.