Ceramics in the Workshop

No I don't mean a Grayson Perry teapot, but is there anyone who could write about things like making spark plug insulators etc.?

Neil

**LINK**

RS usec to sell it, quite expensive, and that's as much as I know!

Looks excellent stuff, but has anyone got experience of using it - or similar?

Neil

Used a hollow ceramic wirewound resistor core to repair a miniature spark plug, cut using diamond discs in a dremel and shaped using diamond bits,worked well.

Not me - too expensive

Rod

Recently made some spark plugs for a small I/C engine, Rudy Kouhoupts Pioneer, I used 1Amp fuses as the insulators, yanked the metal bits off the ends and stuck the whole lot together with high temp Loctite. So far the engine has had over one hours running and plug is still as new. Could also use JB Weld to stick them together. Only problem with using the fuses is the writing on the ceramic but a few seconds in the grit blaster gets it off.

I've never used it, but my father used to work in the high voltage lab of Metropolitan Vickers before WW2, and apparently they used soapstone to make insulators.

**LINK**

As its name implies this has a soft consistency like soap so it can be carved and turned, but when fired at ~1100 C it turns into a hard ceramic. So useful for making small numbers of insulators. I see from that link that it contains talc which has recently been implicated in cancers, so be cautious about the dust. Isee you can buy the stuff at Homecrafts, 9mm thick, might be possible to stick it together for larger thicknesses, or other suppliers, it's quite cheap.

**LINK**

On the face of it, the prices for Macor here seem a lot more user friendly.

The material you are thinking about is known as Steatite. It is a moldable ceramic which is then fired at high temperature.

I'm not sure if Soapstone can be fired to give a hard ceramic but Pyrophyllite certainly can - we used to use it for trays for passing thick film circuits on alumina substrates through a belt furnace. In the raw state it is very similar to soapstone.

Rod

I have no idea about their electrical insulating properties but chemical setting dental glass ionomer filling material might be a consideration.. or even the light-set stuff in small quantities. Whilst that is usually set with a fancy light tool I have set it in emergency (tool got dropped) just using a very bright lightbulb (through a fibre guide on that occasion).

Many years ago, in a previous existance, used pyrophillite to make specialised rotary type switches, (high temperature safety swtich), great stuff.

If you dig deeply enough into back issues of ME I'm sure there was an article about using PTFE insulators in small spark plugs. Wouldn't have been my first choice as I would have thought the face exposed to the combustion side would char and then conduct, but it must have worked for the author

Need to be clear, although the suggestions are interesting - I am looking for someone with experience of using ceramics in a home workshop situation to write me a short article sharing their experiences.

Neil

I have made a couple of spark plugs following a Graham Meek's design using small fish spine insulators. In the open the plugs seem to work satisfactorily but I have not used them in anger yet.

You can buy fish spine insulators by the hundred from RS for not very much. They are a standard insulator for high temperature wiring.

JA

<sigh>... Yes, I read the Wikipedia article too. Not mouldable but carvable.

There was an article in ME about using Fish Spine insulators along with the little bit of glass tube that you can find inside an incandescent light bulb. I have seen something, somewhere about using Araldite to make insulators for spark plugs.

Ian S C

The late great Dan Calkin got Champion to knock his own design up because insulators were such a pain to make, (his own father was a Dentist with a knowledge of ceramics as well)

Modern materials may make the task easier nowadays, but it has always been a challenge, even for the highly skilled

Once commercially produced ones became available in the late 1930s he always used them

It's the sort of area which 3D printing could make a lot easier

Edited By Ady1 on 03/03/2016 10:52:47