I built a pneumatic can crusher, but I wasn’t satisfied with with just crushing
it, I wanted to flatten them. So I put it it on a lever, it has ~2.4 mechanical
advantage.
[https://lemmy.world/pictrs/image/006f9b61-f86d-44da-ae09-3750bbe7b4ae.jpeg]
Feed down or volts up. But I see your welder is Harbor Freight so that may be the best you can get although I have the HF Vulcan that has infinitely adjustable speed and volts