Tool steel can be a tricky one to weld, but it can be done. I used S7 tool steel which is a very good choice when it comes to shock loads which is exactly what an anvil sees. Alternatives can be H13, A2, or even one of the "O" series of tool steels if its all you can find. Alternatives to welding the plate to the top block can be flat head socket screws, blind or through dowels, roll/spring pins or plug welding. These were in the back of my mind for backup plans should the perimeter welds fail or cause issue. The good thing is that they can be added after the fact if welding doesnt turn out for you.

I first machined the Hardy and piercing hole into the S7 to match the top form. Before welding I ensured that all features were in perfect alignment using the Hardy hole and 1" square CRS pin. Check and double check these fits now!

To weld any tool steel it must first be preheated. I waited until my wife was gone and using her kitchen oven, placed the tools steel on the rack and set it to 485 degrees, (485 because my target welding temp was 450 and it is cold in Indiana and I had to get the TS from the house to the shop, thus I knew it would cool off). I allowed it to be in the oven for 90 mins, (while I welded everything else up first) before welding it to the top form.

Do not allow the welded parts to cool too quickly. I used a LP brush burning torch to control the cool off post welding. Allow for 3-4 hours for the weldment to return to room temperature. The slower the better to prevent cracking of the joint.