Mike-hr,
Your idea of forging 2” of 1” square stock under the flat dies is a good idea. First, most all of the mild steel we are getting today is A36, and it varies both in chemistry and thickness in one 20’ bar the way we buy it. After cutting several sample pieces and measuring them, I found them to vary from .002” undersized to .002” oversize. There is a possibility that the reason for this thickness difference is the chemistry of the steel. I have had several experiences where I found a bad piece of steel after doing a lot of hard work on the opposite end of it. So, difference in chemistry of the steel could have something to do with the difference in thickness when they are rolling it. It could also be that the rolling dies for this low grade of steel where the dimension is not guaranteed.
For a true test, we should use either 1020 or cold rolled steel. Either way it is not going to make a whole lot of difference. There are also some other issues. How does one know that they have hit at the 2” mark? For my test, on my 60 Kg Say-Mak, I put one center punch mark at exactly 2”, and then 3/16” behind it, I put another center punch mark. This helped me to see where the true mark was, and the forged piece revealed the results. I also found that with 10 blows under the 60 Kg, the stock grew 1 3/8” in the long plane. My dies are 3” wide. However, the amount of taper down to the final dimension under the flat dies was 3/8”, which means anybody performing this test must have dies that are at least 3” wide, and even wider if they are going thinner than my 10 blow test.
Now the test results for my 60 Kg were:
5 blows: .320”
10 blows: .260”
The most important factor besides the size of the hammer is the blows per minute. My 60 hits 220 beats per minute. The more beats per minute, the more iron one can forge, but controlling anything over 240 beats per minute is very difficult regardless of the size of the hammer. As soon as I get another 50 kg running, I will do a test on it.
I think the best way to really test this is for all parties interested to come to the SOFA Conference in September. We will take sample pieces to all of the vendors that sell these hammers. Let’s see for ourselves, in public, what we are really comparing.
Let me toss out another challenge. Take a piece of 2” round 6” long, leaving 2 1/8’ on each end and see how long you can draw the piece out in one heat. I would recommend that every hammer being used in this test use the standard drawing dies that came from the manufacturer. I’ll do this demo at Quadstate, and will furnish the steel for any other manufacturer who is selling new hammers today that is willing to accept the challenge.
Best Regards,
Tom Clark
