Model Engine Maker
Supporting => Engine Ancillaries => Topic started by: Vixen on January 02, 2017, 09:19:40 PM
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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
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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
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Hemmingway sell them or you can cut up TIG electrodes and silver solder them on.
http://www.hemingwaykits.com/acatalog/Ignition.html
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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 (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 (https://www.findernet.com/en/content/relay-contact-materials-does-it-matter)
http://www.aeroelectric.com/Reference_Docs/Tyco/Tyco-Relay_Contact_Life.pdf (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 (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 (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:
(http://thumbs.ebaystatic.com/images/g/qS0AAOSwcUBYGqbz/s-l225.jpg)
http://www.ebay.com/itm/2-5mm-Thread-10-8mm-Length-Tungsten-Steel-Ball-Contact-Points-2pcs-/351882496033 (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).