Author Topic: Re: Stripped threads repair help needed (Solved)  (Read 367 times)

Johndoh

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Re: Stripped threads repair help needed (Solved)
« on: April 19, 2019, 06:17:52 PM »
Hi guys, I bought a petrol cement mixer in a box. Apparently it wouldn't start and got taken apart. It was only a suck valve tappet and it's back together now but... The end of the crankshaftshaft where you attach the pull mechanism is stripped. I am looking for a cheap and lasting way to fix this if anyone has any suggestions?
Thanks
« Last Edit: April 22, 2019, 06:44:35 PM by Johndoh »
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BruceM

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Re: Stripped threads repair help needed
« Reply #1 on: April 19, 2019, 08:43:47 PM »
Helicoil?

Johndoh

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Re: Stripped threads repair help needed
« Reply #2 on: April 19, 2019, 09:07:55 PM »
It's external thread
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sirpedrosa

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Re: Stripped threads repair help needed
« Reply #3 on: April 20, 2019, 01:12:51 AM »
Hi JD

Cement mixer in a box? My goddness!

Is that "utensil" guaranteed by the manufacturer?

If it haven't, improvise! Like dieselspanner says: "weld and grind!"

Cheers
VP
Bernard 18A - 1968 (mama's water pump - year of my birth)
Petter PAZ1 - Jun 1967, 3HP, sn 416xxxx

ajaffa1

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Re: Stripped threads repair help needed
« Reply #4 on: April 20, 2019, 03:14:02 AM »
Hi Johndoh, If you can identify what thread it is you could buy a nut die of the same size. Build up the damaged threads with a stick welder, grind or file the shaft back to approximately the original diameter then run the nut die down it.

Bob

BruceM

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Re: Stripped threads repair help needed
« Reply #5 on: April 20, 2019, 05:49:28 AM »
Or if the threads are still semi functional, degrease nut and threads with alcohol, dry, smear with jbweld and put it together.  If you must take it apart again, you'll have to heat it to about 350F or better.

dieselspanner

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Re: Stripped threads repair help needed
« Reply #6 on: April 20, 2019, 09:26:31 AM »
I'm with Bruce for a quick fix,

If for example it's a 10mm thread, run an fettle it up with a file and run 8mm die / die nut down it far enough to get a full nut on then pack the rest out with washers.

If you want to get it out, weld a nut to the stud the whilst it's still warm, hammer it like a nail, without bending it, and as it cools 'rock' it both ways whilst applying you favourite penetrating fluid..

Should it snap, drill the stud out oversize, tap the hole and make a hermaphrodite stud - 12mm one end and 8mm the other, if you haven't got the new hole quite central make the stud offset and fit it with a good dollop of Loctite

Finally as my avatar says, run the nut down as far as you can and then weld it to the stud and leave 'til next time.........

I know the answers are 'cringe worthy' in the eyes of a lot of guys but if you're working with limited time / kit / money ect. then bush engineering is better, by far, than waiting for Fedex

Cheers
Stef
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

Johndoh

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Re: Stripped threads repair help needed
« Reply #7 on: April 20, 2019, 04:28:20 PM »
The end of the flywheel is threaded to take a nut, it's a briggs engine so likely imperial I dont have an imperial thread gauge. The nut has to be tight enough to hold the starting cup for the pull start so pretty tight. I suppose I could spot weld the cup on. I have epoxy putty i could put some of that on the shaft cover with cling wrap oil it and put on the nut? I saw tape advertised called fibrefix I was toying with the idea of it too. I was also thinking I could thread it in metric thread thats approximately the same size and put on a nylock nut. I know the correct thing is to probably take the shaft get it turned and rethreaded but the whole mixer was 20 and it might be scrap. Thanks for the suggestions keep them coming!
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Johndoh

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Re: Stripped threads repair help needed
« Reply #8 on: April 20, 2019, 04:30:29 PM »
Hi JD

Cement mixer in a box? My goddness!

Is that "utensil" guaranteed by the manufacturer?

If it haven't, improvise! Like dieselspanner says: "weld and grind!"

Cheers
VP

Its a used machine that someone took apart I bought it for 20 so far thats all it has cost me. If I can get it running I can get 5X what I paid for it. Its a small petrol mixer
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sirpedrosa

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Re: Stripped threads repair help needed
« Reply #9 on: April 21, 2019, 03:38:20 AM »
Hi JD

Is fair! Keep busy.

BR
VP
Bernard 18A - 1968 (mama's water pump - year of my birth)
Petter PAZ1 - Jun 1967, 3HP, sn 416xxxx

Johndoh

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Re: Stripped threads repair help needed (Solved)
« Reply #10 on: April 22, 2019, 01:40:07 PM »
Found a nut ever so slightly smaller ran it up snug and leave it at that. the flywheel is aluminium so welding isnt an option. I started it a dozen times seems top be holding up ok, thanks for the suggestions
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