If he's running a router, he'll be stuck at a very high speed, probably 12k+. I have a 4hp spindle and the lowest that will go is 6k.suntravel wrote: ↑Fri Oct 27, 2023 12:59 pm No Risk No Fun
2000rpm 10mm/min 1.5mm peck drill should be ok to start. Depends on the quality of the drill bit and on good flushing
No MDF, directly mount a fixture plate 20mm flat milled AW5083 or cast iron
If you use a vise, directly mount on granite
Uwe
Another consideration for a brittle material like granite is that it's tough and scratch resistant but it can shatter with uneven loads or sharp blows. And once it's cracked, it's cracked forever. No fixing it.
One possibility is to flood it with epoxy about 1/4" thick. Epoxy would provide a decent, albeit shallow, spoil board and be repairable easily, and it would be perfectly flat and level.
One advantage of an MDF spoilboard is that it can work with a vacuum hold down system. I love using a full table hold down system for sheets of material, be they ultra thin plastic or metal, or warped sheet goods like an old piece of plywood.