Good ceramic tube supplier for making sparkplugs?

[HopperParticipant @hopper]

[HopperParticipant @hopper]

Can any of our IC engine builders suggest a supplier of good quality ceramic tubing suitable for making sparkplugs?

Looking for 1.6mm ID x 3mm OD. I know there is some on eBay but they say dimensions can vary greatly from the nominal, so wondering about a supply suitable for model engineers.

[jason udallParticipant @jasonudall57142]

If you can find nothing else …try electrical fuse bodies…readily available

[JasonBModerator @jasonb]

Fish spine beads are what one of our former members used for small plugs down to 4mm thread. HAve a search through the forum on spark plugs as I think he posted a link to a suplier

May not be on teh forum now but some details on MEM

Edited By JasonB on 08/11/2014 08:04:27

[JAParticipant @ja]

Posted by JasonB on 08/11/2014 07:29:57:

Fish spine, is what one of our former members used for small plugs down to 4mm thread. HAve a search through the forum on spark plugs as I think he posted a link to a suplier

I used RS.

JA

[Ian S CParticipant @iansc]

There was an article in ME about using Fish Spine beads, the plug had a metal body, the insulator through the body was a little glass tube from inside an incandecent light bulb with the electrode through that, and the ceramic bead on top. There was a previous article using machineable ceramic.

Ian S C

[Richard MarksParticipant @richardmarks80868]

I repaired a miniature plug years ago using the body of a wirewound resistor and using diamond saws and burrs to shape it, you could try to find some on ebay or ex WD if it helps,

[HopperParticipant @hopper]

Thanks guys. That has given me a few starting points.

[BubbleParticipant @bubble]

Hello Hopper

In BR Research we used to carry out high-temperature fatigue testing (among a few other activities), using extensometers that worked up to about 1000 deg C. We used to make fittings for these using a natural machineable material called pyrophyllyte. This was machined using ordinary HSS tools, by then fired in the test furnace and became a hard ceramic. There is also a machineable ceramic called Macor. Google has results for these. It is available down to quite small blanks eg 1/4 inch square by 3 inch long. A piece this size is about 8$ in the USA. It is available from RS or Farnell in UK but expensive. Used in university labs also.

Jim

[John Stevenson 1Participant @johnstevenson1]

What about Corian, the solid surfacing stuff for worktops ?

It's electrically non conductive and will withstand hight temperatures but don't know whether as high as plugs stand.

[JasonBModerator @jasonb]

Tends to go a bit soft as the temperature goes up, thats how you bend it around worktop edges etc. Would be OK for the top half of the plug but not the business end. I quite often use it for the insulators on the ignition contacts on Hit & miss engines not to mentionsd Kitchens & bathrooms in my work.

J

[Clive HartlandParticipant @clivehartland94829]

I did try a post this morning saying that Mica may be good for what you want, I have found spark plugs on old tractors with Mica insulation.

Would it be possible to use PTFE as an insulator? What about Fire cement, this could be put in wet and then fired.

Clive

[Ian S CParticipant @iansc]

Both PTFE, and Araldite have been used for mini sparkplugs.

Ian S C

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