Drill bit drifting in Douglas Fir

Gilman · April 08, 2009, 04:00:56 PM

When drill peg holes in douglas fir I've been having a problem with the drill bit drifting from it's desired location. The sloped annual rings can push the bit quite a bit when starting an auger bit. Anybody have a method(s) for fixing this problem?

David

Dave Shepard · April 08, 2009, 07:10:27 PM

Are you using a screw lead bit? I'm surprised that it would wander. Perhaps one of the cutters has been damaged?

Gilman · April 09, 2009, 12:43:43 AM

Yep, it was a screw type lead. I ended up with a shear failure in one of my braces from an extremely misplaced peg hole. I conveniently didn't take a picture of that joint.

I don't have the clothes line wires strung yet

Oh, I forgot to mention that I found my drain field when drilling the post holes. >:(

Jim_Rogers · April 09, 2009, 07:47:39 AM

And/or one of the bit's wings could be sharper then the other..... which could cause the bit to wander off....
Also, what device are you using to bore the holes? boring machine, bit and brace, power drill?

Jim Rogers

Gilman · April 09, 2009, 11:17:50 AM

power drill

Rooster · April 09, 2009, 12:18:54 PM

Are you using a ship auger bit with one flute? How long is the bit?

matt eddy · April 09, 2009, 07:13:19 PM

I have good luck drilling with the Irwin double spur ship auger bits. I use a Milwaukee drill to power the 18" long bit. Drill stands help, however I have recently been proved wrong of there accuracy. Sometimes in squirrelly wood I will drill my mortises from both sides. Without a stand I drill tenons after there cut, but still draw bore them. If using Scott Northcott pegs I drive all pegs with caution, hence why I try to make all my own now. With a hand made peg you can always find one that will fit in the hole. Good luck...

Keep making sawdust!!
Matt ..... Pine Tree Timber frames

Jim_Rogers · April 10, 2009, 07:54:27 AM

Gilman:
Were you drilling peg holes or hogging out wood for a mortise?

Gilman · April 13, 2009, 05:24:17 PM

Both Jim,
But the problem part was with the accuracy of the peg hole locations.

Jim_Rogers · April 13, 2009, 06:32:33 PM

Well, of course, I hope you know, that all peg holes should be drilled from the layout side of the timber.
That way they should stay straight and true as it goes through the first side of the mortise, and then beyond the mortise it really doesn't matter if it does wander off.....

And if you're draw boring, then place the tenon in the mortise after the mortise peg hole is bored and just poke a tip point into the tenon to show you where exactly the hole would be if you were boring straight on.

Then offset the hole in the tenon, correctly.

This is the standard procedure and if the peg hole beyond the mortise isn't totally in the right place then, again, it really doesn't matter that much.

Also, all pegs are inserted and driven in from the layout side/reference side of the timber.

Jim Rogers

ljmathias · April 19, 2009, 07:30:35 AM

Hey, I didn't know that about drilling peg holes- you probably told us already and I just forgot. Another reason to keep reading what's on the forum- memory relapses and rebuilding...

Lj