Oh! The Pressure, the pressure. P=F/A

[boyntonstu]

Since pressure equals force divided by area, let's talk welding.

I am old enough to remember when women's spike heels put holes into the floor of airplanes and they had to strengthen the floors.

A sharp knife cuts while a dull one won't is because the thiiner blade creates more pressure.

Pounding hot steel with a 2"x2" flatter and with a force of 100 pounds produces 25lb/square in.

Hit again with a 1/2" x 1/2" flatter and we have 400 pounds/sq in.

I believe that nibbling at it with a rather narrow ~1/4 " blade flatter may be the way to go with us weaklings.


BoyntonStu

 

[Laredo7mm]

Hmmmm, I am only speaking for myself here but I don't use a flatter. And let me tell you I am not very efficient with a hammer either. I leave my dings and divets, but i am getting better. I end up grinding them out and getting everything flat that way. Plus, a little grinding makes the damascus looks better.

But if you are trying to forge the blade to shape with as little grinding as possible, I would use the 2 x 2 flatter. The metal may move slower because of less force, but you will be able to join the flatted sections together better with the 2x2 than the 1/4. Does that make sense? Well, not to me. Let me try again: If you use a 1/4 flatter I think you will end up with more wave or ripples in the blade surface because there is not land to overlap on.

If you use the 2x2 and just use a 1x2 section and overlap as you work your way down the billet, you will get better results. I think

 

[Laredo7mm]

Ok, now that I havw re-read your post, are you talking about the pressure to get steel to forge weld?

If you are, then you might want to be careful. I have been having a few problems lately with forge welding. Seemed like I lost the touch for a while. What i found out was that i was hitting the billet too hard when trying to set the welds.

I never had that problem before, but since I have been getting better with the hammer and getting more control, i can hit harder and more acurately. Now I have to tell myself to hit soft when welding. More or less I let the weight of my 2 pound hammer do most of the work. I still give it some muscle, but not like I am trying to move steel.

I think the big thing is force, but like it has been said before; you can get a shim stock billet to weld by squezzing it in a shop vice. Now the guys with hydraulic presses have an advantage, but from what I understand, alot of them still set their initial welds with a hand hammer and anvil.

There is a big difference bewtween the Impact force you impart to the billet when hitting it with a hammer compared to when you squeeze it in a press. The hammer is dynamic and the press is more or less static.

If you go easy and set the welds ith a hammer and then come back later and beat the living bageezes out of it, you should be ok.