barrel bending

[petew]

Mooncoon, the concern I have with thermal straightening is possible cracking even with a slow controled cool down.
Pete.

 

[mooncoon]

Mooncoon, the concern I have with thermal straightening is possible cracking even with a slow controled cool down.
Pete.

I think that would be extremely unlikely. The only risk that I can see is if the barrel were heated red hot and then water poured over it. A 4140 barrel would then potentially become brittle or at least very hard in that location. I am not quite sure how the method works; there are two choices

1. heat the inside of the curve which would expand it and stretch that side but a slow cool would probably allow it to contract back to square one.

2. heat a segment of the barrel all the way round then pour water over the outside of the curve which should shrink the outside of the curve and pull it towards straight. I suppose reheating to around 700 F or so might leave the barrel straight but anneal the hardened segment to spring temper and unlikely to crack or shatter

cheers mooncoon

 

[petew]

I think that would be extremely unlikely. The only risk that I can see is if the barrel were heated red hot and then water poured over it. A 4140 barrel would then potentially become brittle or at least very hard in that location. I am not quite sure how the method works; there are two choices

1. heat the inside of the curve which would expand it and stretch that side but a slow cool would probably allow it to contract back to square one.

2. heat a segment of the barrel all the way round then pour water over the outside of the curve which should shrink the outside of the curve and pull it towards straight. I suppose reheating to around 700 F or so might leave the barrel straight but anneal the hardened segment to spring temper and unlikely to crack or shatter

cheers mooncoon

1.When you do thermal straightening the side you heat will shrink when it cools. If you heat the inside of the curve it will become a larger curve and the problem will be worse.

2 Quenching is not a good practice. Mild steel is afected little, however many other steels become tempered/brittle and subject to cracking. Also quenching one side will not make it pull more on that side. It will make it initialy pull faster, but when everyhing is cold again both sides will be the same. Another problem with heating is the bore diameter will shrink also.

 

[sovereignright]

My goodness that looks painful, I suppose it's gotta look worse before it gets better