Push rod material

[MikeN]

The ignition contact breakers on my BR2  engine are opened and closed by a cam via a push rod.
The book of instructions says to make  the push rod from "nylon".
Any idea what type of nylon to use? (I'm in the UK).
It has to be hard wearing as it runs against the steel operating cam.
Dimensions are 2.2mm dia x 20mm
Thanks

Thinking about it it could probably also be made from phos bronze.

[stevehuckss396]

Google "natural nylon rod"

[Jasonb]

Other engines that I have made that use a nylon pushrod on the contacts use it because a metal one would allow current to flow through the push rod so although the contacts will open current will short if the rod is a conductor.

I just used Nylon 6 which you can bet in black or Natural which is a dirty white. You can see it top middle of this assembly. Insulate dcontacts are a bright white Corian. Easy to see that current could frow from the contact arm down the pushrod and into the body even when the points are open if it were metal. The ignition cam follower is bronze for better wear

[Jo]

Normally a points push rod is made of nylon because it is a good insulator.

The Ignition System on the BR2 is hidden inside a dummy Magneto. The Contact breaker body, Barrel, cam, contact arm and plunger are a mixture of aluminium and steel. The push rod is running on a steel "cam" that is electrically connected to the contact arm so making it out of nylon is not necessary. What is important is that the Insulator holding the contact screw is made of an insulator like what it says in the book Tufnol.

So I would choose a good alloy to make the contact Breaker Barrel out of and something that will not wear the alloy to make the push rod out of.

Jo

[MikeN]

So I would choose a good alloy to make the contact Breaker Barrel out of and something that will not wear the alloy to make the push rod out of.

Jo

I have now completed the dummy magneto/ contact breaker assemblies. I have made the Push rods from bronze . They run in steel tubular liners in the alloy contact breaker barrel.
Thanks

[Jo]

Sounds ideal 

Don't over lubricate them when you assemble it, last thing you need is it dribbling out and getting on the insulator.

Jo