High Quality Chainsaw Bars Husqvarna Toys

Crank flywheel side thread save.

srcarr52

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Someone sent me a 395 crank with no threads left on the flywheel side. I worked a little magic with the tig welder and lathe to make the threads reappear.

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Wilhelm

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Looks good.
Are You going to heat treat the threaded end or leave as is?
 

RI Chevy

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Wow! Awesome job there Sir!
 

srcarr52

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Looks good.
Are You going to heat treat the threaded end or leave as is?

Just leave them as is and be easy on them. It's ER70S-2 filler so it's not really heat treatable. I think the original threads may be rolled in after heat treat which are very strong.
 

Armbru84

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Just leave them as is and be easy on them. It's ER70S-2 filler so it's not really heat treatable. I think the original threads may be rolled in after heat treat which are very strong.

All my experience with thread rolling is in the green state...I don’t think you can thread roll steel that’s been heat treated.
 

srcarr52

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All my experience with thread rolling is in the green state...I don’t think you can thread roll steel that’s been heat treated.

Very common to do on bolts and studs with low stress ratios. The residual compressive stresses at the thread root are extremely beneficial for fatigue life because it delays crack initiation. Heat treatment after rolling removes the stresses and the benefit.
 

Armbru84

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Very common to do on bolts and studs with low stress ratios. The residual compressive stresses at the thread root are extremely beneficial for fatigue life because it delays crack initiation. Heat treatment after rolling removes the stresses and the benefit.
Gotcha. Guess I was more thinking of spline rolling. Didn’t really consider those other applications.
 

stihl_head1982

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Very common to do on bolts and studs with low stress ratios. The residual compressive stresses at the thread root are extremely beneficial for fatigue life because it delays crack initiation. Heat treatment after rolling removes the stresses and the benefit.

Your education is showing again sir. Nice looking save too by the way!
 

srcarr52

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srcarr52

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I buggered some crank threads on the FW side over the winter.
I found a company that makes split dies.
They work awesome!

I should have taken a before picture... there was no threads to save.

In a pinch I've made split dies but cutting a nut in half, putting a score in the 1/2's and using a adjustable wrench to back it off.
 
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