I have a couple of arbor presses that I had to make daisy wheels and snail plates for. The smaller arbor press is a Greenerd 3 1/2 which may be closer to your size, I believe. The top plate is 1” thick. The daisy wheel is 2” thick, but 1” should work fine.
The larger arbor press is a Greenerd 5S. I used 1.5” steel plate for both the daisy wheel and snail plate. Both are 12” in diameter. The 1.5” is about right for this arbor press as the gearing is compounded which generates quite a bit more force. The idea is to get the ram to center up over the hole circle. I find the snail plates more useful than the daisy wheels, but mostly I leave them together and rotate the snail plate.
On mine I rough cut the plate with a torch and then turned the diameters on a lathe. Next, I used a bandsaw to cut out the daisy wheel.
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