[bob2251]

I want to build a small radial engine , but the smallest plugs I have seen listed is 1/4 " And I will need smaller than that. What do you use as an insulator

[dynosor]

Don't know how to make a ceramic insulator, but how about these plugs?

http://sparkplugs.morrisonandmarvin.com/

[stevehuckss396]

I want to build a small radial engine , but the smallest plugs I have seen listed is 1/4 " And I will need smaller than that. What do you use as an insulator

I made a spark plug that had a 6-56 thread. The insulator was made from Corian counter top material. The electrode was .020 nichrome wire super glued thru the corian. I dont have it any more because i dropped it and it broke.

It worked!

[vlmarshall]

I've seen machinable ceramic... I think McMaster Carr sells it...
Here's a link.
http://www.mcmaster.com/#machinable-ceramics/=1zopf8

[stevehuckss396]

I've seen machinable ceramic... I think McMaster Carr sells it...
Here's a link.
http://www.mcmaster.com/#machinable-ceramics/=1zopf8

Looks like it would be good stuff. At 7 bucks an inch for 1/8 inch rod, i think i would stick with the corian. I got a 20 pound box on ebay for 8 bucks including shipping.

[vlmarshall]

I got a 20 pound box on ebay for 8 bucks including shipping.

Wow, I'll have to remember that one.

[LongRat]

If you can get it, you could try Macor. It is a machinable mica based ceramic and I can tell you from experience, machines very well with carbide tooling. It has the electrical resistance you'd need but also very good thermal insulation and low thermal expansion.

[stevehuckss396]

If you can get it, you could try Macor. It is a machinable mica based ceramic and I can tell you from experience, machines very well with carbide tooling. It has the electrical resistance you'd need but also very good thermal insulation and low thermal expansion.

Again 7 bucks an inch for 1/8 inch. Corian is cheap and will live in a model engine for years.

[T.L.A.R. eng]

bob2251, can you tell us anymore about the radial engine you are building?

[One of Many]

I made about 10-15 a few years back. The trials were made of pink corian and stainless electrodes, which I gave away as trinkets to friends. The keepers were white with tungsten electrodes. Spark was decent!

Pink is nice on some things, but not my engine. LOL!

DC

[CarveOne]

I made about 10-15 a few years back. The trials were made of pink corian and stainless electrodes, which I gave away as trinkets to friends. The keepers were white with tungsten electrodes. Spark was decent!

Pink is nice on some things, but not my engine. LOL!

DC

How do you attach the ground electrode? Arc weld it with a power supply of some sort using a fixture to hold the parts in place?

CarveOne

[One of Many]

How do you attach the ground electrode? Arc weld it with a power supply of some sort using a fixture to hold the parts in place?

CarveOne

The insolator well is drilled to a depth that leaves a flat inner face cap on the ground electrode end. I then screwed the threaded steel body from the underside of a 1/4" plate of aluminum held in my vise. The cap, errrr soon-to-be ground electrode setting proud above the plate was then CNC'd by a U shaped path, profiling the tang in one pass. Unscrew that one, swap it for another and hit the go button again.

The upper wall of the steel body is thin enough to swedge over(with a custom tool) after locktiting the corian insolator into the body for a good leakproof seal. The spark electrode is sized for length to set the spark gap, then locktited or superglued into place.

DC

[CarveOne]

Many thanks for the drawing and description. It's more than I expected and will tinker with these when I get a chance. I have looked for ignition coil winding info in the recent past but didn't find anything that I thought was useful.

CarveOne

[One of Many]

The profiles don't really need to be so detailed. I used these as a self tutorial for programming a CNC lathe......while still being productive? LOL!

Check into the index on the Strictly IC website. There was a lengthy multi-part article on coil winding and possibly a build project of the winder IIRC.

By the way for those that had not heard, Robert Washburn, the owner and editor of Strictly IC passed on about a month or so back.

DC

[CarveOne]

The profiles don't really need to be so detailed. I used these as a self tutorial for programming a CNC lathe......while still being productive? LOL!

Check into the index on the Strictly IC website. There was a lengthy multi-part article on coil winding and possibly a build project of the winder IIRC.

By the way for those that had not heard, Robert Washburn, the owner and editor of Strictly IC passed on about a month or so back.

DC

One of these days I will CNC a small lathe. Not sure I want to do it to my 12x36 lathe. That one needs to remain manual.

I'll check out the site.

CarveOne

[JimV]

You might want to check out this website

http://sparkplugs.morrisonandmarvin.com/