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Cox .020TD spring starter :)

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Cox .020TD spring starter :)

Post  Surfer_kris on Fri Sep 01, 2017 5:46 pm

I'm struggling to start the .020TD engine without a springstarter and I had no spare spring for it...
I do have a few PeeWee springstarters lying around, so I though I would try to adapt one. The springs are a little too narrow for the TD and it is also very hard to have it catch the prop, especially on other props than the stock ones. Once the engine was running the spring would also vibrate terribly and this can potentially wear down the prop. So I spent some time with the lathe and made an "Auto-engage" spring starter for it Smile

I have used this technique on fully cowled engines in the past and it works really well, but this is the first time I tried it on a .020TD. So I just thought I would share a few images and a little video here, I hope you'll enjoy it and that you might get inspired to make something similar. Smile





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Re: Cox .020TD spring starter :)

Post  Cribbs74 on Fri Sep 01, 2017 6:28 pm

Good job! That's one of the better mods I have seen lately.

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Re: Cox .020TD spring starter :)

Post  roddie on Sat Sep 02, 2017 1:09 pm

Very nice work Kris! What did you use to cut the angled-slot for the wire to engage?
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Re: Cox .020TD spring starter :)

Post  fredvon4 on Sat Sep 02, 2017 2:02 pm

Neat adapter

I think I would try to reduce the spring turns some to get zero drag of the spring steel on the aluminum adapter and at least stop any wear, loss of rpm, and the chatter noise...
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Re: Cox .020TD spring starter :)

Post  Surfer_kris on Sat Sep 02, 2017 2:12 pm

I starter with a dremel cutting wheel at an angle, then finished it off with a round diamond bit in the dremel.

I have a similar one for the fully cowled Norvel .074 in my CG super super chipmunk. Works like a charm, and creates a big surprise at the field for those who are sceptical towards small engines. Smile




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Re: Cox .020TD spring starter :)

Post  Surfer_kris on Sat Sep 02, 2017 2:13 pm

fredvon4 wrote:Neat adapter

I think I would try to reduce the spring turns some to get zero drag of the spring steel on the aluminum adapter and at least stop any wear, loss of rpm, and the chatter noise...

It sounds like a much harder pressure on the spring in the video than it is in reality. After a few test runs today, the spring pressure is just enough to engage. The one I made for the Norvel has worked many years, there is no wear on the aluminium to speak of (it is also well lubed by oil from the engine front-end) and no additional noise either:

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Re: Cox .020TD spring starter :)

Post  fredvon4 on Sat Sep 02, 2017 3:09 pm

My thoughts were based on the second photo of the cox adapter where it looks like a lot of pressure and contact to the adapter... the Norvel one looks perfect

any way well done...now carve out 1000 copies for Cox and Norvels and have Bernie make you and offer for the lot you can not refuse....grin
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Re: Cox .020TD spring starter :)

Post  getback on Sun Sep 03, 2017 12:09 pm

Nice Adapt. Kris , If i had a lathe i would want one or two for myself , Finding a collar to work with would bee somewhat hard to do . I like the Super Super CG Chipmunk !! Babe Bee .049 This Site Rocks!
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Re: Cox .020TD spring starter :)

Post  Tee Bee on Sun Sep 24, 2017 1:23 am

That is fantastic work! The TD .020 starter springs are very hard to find these days and I only have a couple of them left. I've searched a lot on the web recently for some more. If these were available on the market, I'd definitely be in line for a few of them.
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Re: Cox .020TD spring starter :)

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