Step 1: Cleaning Up Original Surface
If you have a cheap anvil that's made of cast iron or a soft material that you've already put to use and the face is pitted from the hammer striking it try to get it as flat as possible.
Step 2: Prepping the Plate
Now that you have your tool steel plate or whatever type of plate your going to use, you have to do a couple of things before you weld it on.
Step 3: Cutting Out the Hardy Hole
First thing you do is you drill holes where your going to cut the hardy hole slot out so that you don't have to cut as much. Then you cut the hole out.
Step 4: Drilling Holes in the Plate
This is optional but I did this to make the plate not have a hollow spot under the plate. So drill holes in random spots on the plate.
Step 5: Welding the Plate On
Now clamp the plate on and make sure it's where you want it. Then weld all the way around the plate twice for extra strength. Then fill in the holes with the welder a little above flush. Then grind the top smooth.
Step 6: Flatting the Top
Now get a sanding wheel on a grinder and sand the top lightly till it's flat and smooth. As you can see I drilled a hole all the way through and made the pritel hole.
Step 7: Rounding the Horn
Now get a grinding wheel and take of as much as you want so that you think it's round enough. Then get a sanding wheel on a grinder and smooth the horn.