1924 chief fork legs

[T. Cotten]

"If it got bent cold, bend it back cold" It didn't get bent cold. When it was impacted there was an absorbing of energy. Force or energy if you will creates heat even if it's in the abstract. Frames and forks were brazed which also stress relieved the weldment. They were never tempered as that is a whole different process. The reason the early forks and frames were so tough was in their design of bracing, lamination, etc.So heat is usual applied to relieve the energy that was absorbed upon inpact.

Too abstract for me, Rich.

frameoven.jpg

frameovens.jpg

....Cotten

PS: If dealing with brass braze repairs,

XLCR Brazing dept 2.jpg

Its better to chill it!

PPS: Back to shot blasting versus shot peening: I was taught they were the same.

[RichO]

Any undo stress incurred during brazing is released by heat in the oven.

[T. Cotten]

Any undo stress incurred during brazing is released by heat in the oven.

But you said they were never tempered, Rich!

Assembled flamed (or later welded),

FRAMBRAZ.JPG

The stress came from straightening.

So then came the ovens, or so I understand...

(Shot peening is a pretty modern thing, I think.)

....Cotten

[RichO]

Tempering is when an agent like oil or a chemical treatment is introduced. None of your photos show that. I don't see a straightening process in any of you photos. I do see them going into the oven to be stress relieved though after they are brazed. I'm done. You see apples where I've always dealt with oranges.

[T. Cotten]

Tempering is when an agent like oil or a chemical treatment is introduced. None of your photos show that. I don't see a straightening process in any of you photos. I do see them going into the oven to be stress relieved though after they are brazed. I'm done. You see apples where I've always dealt with oranges.

Its not always a liquid quench, Rich...

Tempering occurs with any moderated reduction in temperature, whether its a controlled oven, or even welding blankets or sand.

Too fast and its brittle, too slow and its a noodle.

They knew what they were doing, and if you apply heat, you don't.

....Cotten

[RichO]

You call it tempering I call it stress relieving apples and oranges but if you apply heat to straighten a weldment that has nothing to with either tempering or stress relief. I always use a blanket to cool down the cylinders that I do fin repair on buthat isn't tempering by a long shot it makes sure there isn't a fracture zone and all the molecules (I call cells) allign properly. Gas weld or brazing with a torch preheats and gets them moving when you introduce your filler material. When leather workers built shields and carriage skins and leather springs. The cells were worked with heat to either make it pliable or harden it. If the cells are tighter together it's harden if their farther apart it's softer. Like kitchen stainless to avoid contamination. Take am welding glove and heat it with a torch and see how tight the cells get. You always get the last work so have at it Tom. Mic drop!

[gharper]

All very interesting, but I'll stick with the end result of my work, which in my opinion is well proven with lots of real miles. Big X frame straightening.jpg

[T. Cotten]

G day everyone, I have a question about the 1925ish fork legs/ droppers, both of mine have a slight bent in them and would like to know if anyone has straighten these before, not sure of what metal they are made , hence do it cold or heat them up, thanks for any response, Rob

They straighten very easily cold. Jerry

The first answer you received, Rob,..

Was the best.

....Cotten

[Tom Wilcock]

When steel is bent cold does not the outside of the bend stretch? When it is bent back to it's original shape cold, the inside of the bend would stretch easier than the outside would shrink, resulting in a longer piece. If heat was used only on the outside (stretched) portion to bend it back to its original shape, it would tend to shrink the stretched section back to where it was originally. (that's my theory and I am sticking to it)
Tom

[T. Cotten]

When steel is bent cold does not the outside of the bend stretch? When it is bent back to it's original shape cold, the inside of the bend would stretch easier than the outside would shrink, resulting in a longer piece. If heat was used only on the outside (stretched) portion to bend it back to its original shape, it would tend to shrink the stretched section back to where it was originally. (that's my theory and I am sticking to it)
Tom

Armchair engineering is one of my favorite exercises, Tom!

Necessary, but its so often at odds with practicality.

My contention is that these are tempered springs.
Imagine straightening a kinked screen door spring.
You can tweak it with pliers pretty close, but what happens if you grab the Bernzomatic?

You no longer have a spring. You've got tie wire for chicken fence.

...Cotten