Thank you yeah a forstner bit was the bit I was thinking of but couldnt remember the name. I agree that a step bit would be better because as one drills it would be easier to get the size correct which basically means when to stop? Do you stop when there is x amount of heartwood left to reaching the cambium? X amount being an eighth or sixteenth of an inch or am I way off? I assume there should be some meet left if you know what I mean since one would be risking hitting the cambium... Thanks again
It depends like with most things. I get right up to the green, most elms are aggressive callousers And dont really care. Just point the green towards where you want callous to go.
I dont want to Hi-jack
@markyscott thread too much so maybe he can speak to how he judged how much to leave. If you want to discuss that specific drilling technique more in-depth, it might be worthy of its own thread!
I would like to specify the grinder bit/ power chisel is MY preferred method for Hardwood removal for *most* wounds for correct callusing- however-
I have been trying to develop Zelkova brooms from seed with ground growing in multiple sizes, and a drill bit/ step bit is the fastest way to get deep holes quickly that swell inward.