Drilling for thread grafts? Prevent wood burn?

[19Mateo83]

Would a brad point bit be better than an auger? Maybe that's because it might be easier with the brad to keep the diameter of the hole small enough for the whip (smallest auger I have seen is 1/4")? But an auger would help keep debris clear.

A Brad point bit is designed to drill clean holes with minimal tear out in wood, especially smaller holes. I would take the trade off of a few extra seconds to back the bit out and clear shavings over the possibility of unnecessary extra damage to the tree in and around the entrance and exit holes. I have never drilled a hole through a tree for a thread graft myself, but I have drilled many thousands of holes in many species in lumber form. For small holes Brad points are ideal, especially in hard wood. For larger holes spade bits and auger bits with very sharp cutters work well. Forstner bits are also good at cutting very clean holes but they are not made in very small sizes and are best utilized in a drill press.

 

[Scrogdor]

Final result. This is about as far as I wanted to go without risk of snapping the whip. Got some good length and positioned a bud pretty close to the exit hole. (This is a new branch from the previous one that I damaged)

 

[River's Edge]

Final result. This is about as far as I wanted to go without risk of snapping the whip. Got some good length and positioned a bud pretty close to the exit hole. (This is a new branch from the previous one that I damaged)

Nicely done, when appropriate wire slightly up in my view.

 

[Scrogdor]

The graft on this died on the opposite end all the sudden. It had sprouted a few buds and seemed like it was doing well, then started to shrivel up and dried out.

Question now is, where do I go from here? I have some very thin whips I could use, but there would be quite a bit of room. I just sealed up the holes for now with some clay/paste.

 

[Adamski77]

The graft on this died on the opposite end all the sudden. It had sprouted a few buds and seemed like it was doing well, then started to shrivel up and dried out.

Question now is, where do I go from here? I have some very thin whips I could use, but there would be quite a bit of room. I just sealed up the holes for now with some clay/paste.

I'm no expert in grafting but what's important is to push the graft towards the top of the hole and fix that firmly... just putting cut paste at exit will not do the trick. So question is if you did it on the one that just died... and if not maybe something to consider with next move.

 

[Scrogdor]

Update: So this graft failed a couple of months after it was done. I'm guessing the donor branch was damaged on the inside, where I couldn't see when I pushed it through or something. But the exit side was dead completely, so I removed it. The holes have both closed.

Is it better to try and drill through that same hole and try again, or pick a new exit and entrance? I have two long leader branches, is it okay to use the smaller/thinner one to re-thread it, or is it better to wait for a new thin branch that isn't being used to thicken the next section of trunk?