Author Topic: Tubular nuts...  (Read 3256 times)

Offline Kjelle

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Tubular nuts...
« on: November 22, 2015, 11:57:29 AM »
Well, I might bet nuts, but when you can't buy what you need, you'll have to make it!
One annoying problem I have had för at least a couple of years, is the lack of tubular nuts in M3 dimention. M4 and larger, no problem, but M3... Nope. They are needed to fasten the light switch on my Italian bikes, due to CEV being a bit, shall we say, eccentric. Follow the link, and you'll see how they do it
http://www.pillondorino.com/index.php?_r=2511&id=81&cat=15
The lower picture is the complete holder, and the switch is screwed to it with the nuts from below, and the screws from above;
So I made some nuts.
It's one of the first things I have made from metal (ok, so I have made som bushings, but nothing more), and I had to hold a certain length...

Happy Bunny!

Kjelle


Offline Lew_Merrick_PE

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Re: Tubular nuts...
« Reply #1 on: November 22, 2015, 12:32:43 PM »
Kjelle,

1) I assume that the attachment force restraining the switch does not have to be too great.
2) I assume that the screw to nut attachment needs to be (fairly) weatherproof.

If those two assumptions are correct, then machining a tubular nut should not be that great of a challenge.  In essence, you are taking a piece somewhat larger than a screw's stock, machining the hole-clearing diameter on it, and then drilling & tapping the M3 thread to the greatest depth reasonably possible.  You may have to reduce the length of the mating screw's body.

So long as you have 1.5X the major diameter of the thread (4.5mm in this case) in engagement, normal (even reaching towards high) loads should not be an issue.  [Impact or high cycle fatigue loading are the main concern here.]  Leaving 1-1.5X the major diameter of thread (3-4.5 mm in this case) between your pilot drill tip and the load face of the nut's head should leave you with plenty of strength even if your are entering the "high load" region.  A bottoming tap will leave you the longest "mating screw engagement (even though that is unlikely to be required).

Does that help?

Offline Kjelle

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Re: Tubular nuts...
« Reply #2 on: November 22, 2015, 04:01:56 PM »
Thanks, Lew. I didn't think my humble attempt at makeing this would attract your attention!

The biggest reason for makeing those nuts, is the price of the parts. The parts in the link (both pictures) are approx €27! And I got to practice cutting off brass... Did go quite well.

Kjelle

Offline Lew_Merrick_PE

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Re: Tubular nuts...
« Reply #3 on: November 22, 2015, 10:03:06 PM »
The biggest reason for makeing those nuts, is the price of the parts. The parts in the link (both pictures) are approx €27! And I got to practice cutting off brass... Did go quite well.

I am glad to hear it went well for you.  My tendency is to make them from 12L17 (Ledloy) steel and oxide finish them.  12L17 cuts like a dream, is easy to tap, and finished up beautifully.

Offline Noitoen

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Re: Tubular nuts...
« Reply #4 on: November 23, 2015, 05:25:23 AM »
You could get a piece of tube, thread both sides and locktite a screw on one side.

Offline Manxmodder

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Re: Tubular nuts...
« Reply #5 on: November 23, 2015, 05:46:30 AM »
Nice job Kjelle. I don't know if you are aware of a product known as Wellnuts,or if they are any use for your particular application.

I use these quite often and because they are rubber they also seal out any water ingress very well.....OZ.

Well Nuts link: http://www.ebay.co.uk/itm/like/151127175188?adgroupid=16885268106&hlpht=true&hlpv=2&rlsatarget=kwd-124273563186&adtype=pla&ff3=1&lpid=122&poi=&ul_noapp=true&limghlpsr=true&device=c&chn=ps&campaignid=270621186&crdt=0&ff12=67&ff11=ICEP3.0.0-L&ff14=122&viphx=1&ops=true&ff13=80
Helixes aren't always downward spirals,sometimes they're screwed up

Offline awemawson

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Andrew Mawson
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Offline Kjelle

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Re: Tubular nuts...
« Reply #7 on: November 23, 2015, 04:31:11 PM »
Thanks, guys! Wasn't aware of "wellnuts", but this might come in handy one day! And Noitoen, I could have done as you suggested, It's also an excersise in lathe-work for me, I haven't done anyting like this since I left school (35 years ago!).

Kjelle