Forstner bit not clearing holes

[Wood_workur]

I'm drilling some 1/2" diameter holes about 2.5" deep that will eventually become mortises. I'm using a forstner bit, and according to the wood magazine speed chart I have, in the pine I'm drilling I should have a speed of 2400 RPM. I set my drill press to 2340 (and I'm sure my drive belt was sufficiently tensioned so it wouldn't slip) as that was the closest I had, and started drilling. I back the bit completely out of the hole about every 1/8" to 1/4" to clear the chips. After about the 3rd hole, the bit was completely clogged with chips and they would not clear, so I had to stop the drill press and pull them off by hand. This continued again, so I tried stepping the speed down to 1720 RPM to see if that would have any effect, but it did nothing.

Anyways, I've drilled some 3/4" holes in pine earlier for a different set of mortises on this project, and I had absolutely no problems with the chips clearing, and I've used this same 1/2" bit in red oak before for another set of mortises on a different project, and it functioned perfectly then. I'm assuming this means that its a function of the wood, and being pine that it is very sappy and sticking to the bit.

Going forward, I have about 15 of the 250 or so holes that I need to have drilled in the pine. At this rate I'll be finished in 3 weeks, so I'm looking for suggestions to help keep the bit clear of chips.

[Dal300]

Clean the pitch off with mineral spirits then wax it with a teflon based wax?

I dunno, it could be that after so many holes the bit is starting to lose it's edge and picking up more of the pitch than it use to. Maybe keeping a rag wetted with mineral spirits close by to wipe the bit will help.

These are just musings as I really don't know.

[sweensdv]

Just a guess but is the pine you're drilling a bit on the sappy side?

[Wood_workur]

Just a guess but is the pine you're drilling a bit on the sappy side?

It is a 2x8 from the BORG. I ripped it down and it didn't seem sappy when I cut it, but I'm sure its sappier than most of the wood I work with.

I'll give the mineral spirits and wax a shot, I do have both of those sitting in my workbench.

[cabinetman]

It is a 2x8 from the BORG. I ripped it down and it didn't seem sappy when I cut it, but I'm sure its sappier than most of the wood I work with.

I'll give the mineral spirits and wax a shot, I do have both of those sitting in my workbench.

I wouldn't use any wax. The wood could have an elevated moisture content, sap, along with a not so sharp bit, along with the bit getting hot, you get a gummy situation.

You might try a different design (cutting edge) bit.

.

[LCHIEN]

a spade bit might work better if the hole quality is not paramount and you don't need a real flat bottom.

in half-inch size, auger bits, twist bits, and brad point bits are also quite common, at least, I have them in my arsenal.

[jking]

Could you drill out most of the mortise with a twist bit & then clean up the bottoms with the forstner bit?

[Wood_workur]

I cleaned off the bit with mineral spirits (quite a job to get it into some spots) and that has seemed to take care of the issue. I don't know what I removed from the bit (it looked clean before and after), but now the chips aren't sticking and packing up in the bit.

Thanks for the help.