Author Topic: Contact Breaker Points  (Read 2119 times)

Offline Vixen

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Contact Breaker Points
« on: January 02, 2017, 09:19:40 PM »
I know that tungsten is the material of choice for ignition contact breaker points.

Where can buy or obtain some suitable miniature tungsten rivets or points?

Can I salvage the points from electrical relays?

What do all use?

Mike
It is the journey that matters, not the destination

Offline Don1966

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Re: Contact Breaker Points
« Reply #1 on: January 02, 2017, 09:22:11 PM »
I know that tungsten is the material of choice for ignition contact breaker points.

Where can buy or obtain some suitable miniature tungsten rivets or points?

Can I salvage the points from electrical relays?

What do all use?

Mike
That would make good contact point if you can salvage them from relays Mike.

Don

Offline Jasonb

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Re: Contact Breaker Points
« Reply #2 on: January 02, 2017, 09:40:45 PM »
Hemmingway sell them or you can cut up TIG electrodes and silver solder them on.

http://www.hemingwaykits.com/acatalog/Ignition.html

Offline PStechPaul

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Re: Contact Breaker Points
« Reply #3 on: January 02, 2017, 10:04:53 PM »
Relay contacts usually are made from a silver alloy for high conductivity:

http://www.electronic-products-design.com/geek-area/electronics/relays/relay-contact-materials

https://www.findernet.com/en/content/relay-contact-materials-does-it-matter

http://www.aeroelectric.com/Reference_Docs/Tyco/Tyco-Relay_Contact_Life.pdf

Tungsten is used for high voltage switching where there may be considerable arcing. Ignition points usually see several hundred volts as long as the capacitor (condenser) is properly sized, and tungsten may not be needed for model engines that run for short periods of time compared to an automotive engine. It is fairly easy to add a transistor to an ignition system so that the points will see only a few volts and maybe a couple hundred milliamps, so there will be no arcing or contact wear, other than surface oxidation.

Here is a company that makes tungsten rivets and other shapes for use as contacts:

http://www.tungstencontact.com/company-profile.html

You can still get tungsten ignition point assemblies for around $10:

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xtungsten+contact.TRS0&_nkw=tungsten+contact&_sacat=0

Or ball shaped contact points:

2.5mm Thread 10.8mm Length Tungsten Steel Ball Contact Points 2pcs
http://www.ebay.com/itm/2-5mm-Thread-10-8mm-Length-Tungsten-Steel-Ball-Contact-Points-2pcs-/351882496033

They are made for dial indicators, but might work for ignition points. However, they would not provide much contact area for the current required (usually 2-10 amps).