Timber Framers Guild Forums General General Forum Questions Auger Bits / Peg Holes

I know this topic has come up before, but I didn't find exactly what I was looking for when I searched this forum.

None of my peg holes are bored yet, I plan to do it on site and will most likely come a long everything together and bore straight through.

Can anyone give specifics on which brand bit to buy and where to buy them. I don't want to waste my money on a cheap bit, I would like to buy something a professional timber framer would buy. A single spur, I assume, is a must (many auger bits don't have a spur at all). Many specify that they're excellent for cutting nails........ there are just so many out there, please help narrow my choices. Also, something that will give a nice clean exit, no blow out, if this is possible. Advantage Drills keeps popping up, can anyone comment.

Have you considered using the draw bore technique to improve on joint tightness as the timber shrinks over time ?
Common practice to avoid blow out is to stop drilling when the bit tip emerges and finish the hole from the other end.

Try an IRWIN double spur auger (47716) Its 12" of twist, 18"overall. Available at www.bitsnbores.com.

Lee Valley tool provides good quality, well priced augers suitable for timber framing.

www.leevalley.com

JO:

We drill our peg holes in the mortises here in the shop where we have more control. It's hard to drill a straight hole when you're on a ladder or scaffolding. We don't drill the tenons until we're on site. Pull the frame together tight with ratchet straps. Then you can put the bit back in the mortise peg hole and the hole will guide you as you punch through the tenon. We will occasionaly use drawboring where the situation warrants, but in general, it's too much work to put things together twice. If you angle the drill a little toward the shoulder of the joint as you punch the tenon, you can get a simialr effect.

Emmett's tip about letting just the tip come through is right on the money. Pull back on the drill as you near the end of the hole. When the threads hit daylight, the bit will lose it's grip, and the drill will pop right out of the hole. Then finish it from the other side.

The tip about Jennings pattern spurs is also right on. You want spurs that hang down below the cutting edges. The spurs will score the sides of the hole before the cutters lift up the chip, making for a very clean hole.

I just got a flyer in the mail from Timberwolf Tools for a triple spur auger by Wood Owl. I already ordered one, but has anyone tried one of these? CB.

Emmett thanks for the reply. Yes, I have considered draw boring and will most likely draw bore some of the joints, such as th tie beam, collar tie and tongue and fork. Not all of it though, as Daiku mentioned it could take a very long time to do on site. Also, thanks for the tip on finishing the hole from the opposite side once the tip of the bit has just punched through. This is the technique I planned to use, but it feels good to hear it recommended from others, it gives me reassurance that I'm doing things correctly.

Daiku, thank you as well for the detailed reply. In a perfect world I'd be cutting the frame and then putting it right up, but since it's going to be sitting until June I wasn't comfortable drilling my peg holes in the shop. Believe me I wanted to, I'm dredding having to drill all those holes on site. I'll look into the bit from Timber Wolf they're not far from me.

Others, thanks you for your info also. This forum has been great to me. I truly appreciate. it.

I have 2 questions, first, when I did a workshop many years ago we drilled the peg holes at the time we assembled the frame on the first floor deck of the house, so we simply had a scrap of 2x4 as a backer for the drilling. How are you able to drill from both sides? what is the orientation of your frame when drilling? Second, could someone please give a description of the process of creation the offset holes for a draw bore, Many thanks!!!

Draw bore technique is really quite straight forward when you think about it. The purpose of offsetting the peg hole in the tenon is to force the tenon deeper into the mortise when you drive the peg. So much for the theory. Now the practice. The assumption is that both pieces of wood are accessible and the tenon can be set in the mortise, marked, removed, drilled, back into the mortise, pegged. Obvious is easiest on the ground. Now improve the details.
(for this illustration the tenon is entering the mortise from right to left so the purpose is to draw the tenon even tighter from right to left when pegged.)
1. insert the tenon tightly in the mortise (on some larger sticks a come along is frequently used).
2. Insert the drill bit (without the drill) into then previously drilled peg holes on the side of the mortise. Tap it gently to mark the center of the mortise peg hole on the face of the tenon. remove the bit.
2. disassemmble the joint placing the tenon bearing stick in a position to drill.
3. Find the mark you just made, For ease in visualization draw a circle around the mark about the same diameter as the bit. remount the bit in your drill. set the tip, by about it's own diameter (will vary with wood species and wetness, and how much you want to draw the tenon into the mortise by lateral peg pressure. yes you can split the tenon by drawing too much)in the direction (3 o'clock on imaginary clock face) away from the end of the tenon. Drill your hole carefully. don't blow out the other side.
remove your drill and bit.This places the center of the now drilled tenon peg hole slightly away from the end of the tenon compared to the center mark you made with the bit in the previous step. When you peg it the draw of the bore tightens the fit of the tenon into the mortise.
4. reassemble the joinery and peg em up.
(you may have done multiple marks and drillings depending on the complexity of the partially disassembled frame)
5. like in measuring before cutting read these instructions more than once.
work safe, have fun.
deralte

Emmett, If I'm reading this right, you say to "set the tip, by about it's own diameter"...Is this a typo? How would the holes ever line up to drive a peg? What you have explained so far is what I have always suspected. The one piece of info I don't quite know is how much the bore offset is, 1/4", 1/2", etc. on say a 1" peg?

offset is generally 1/8"
bigger tenons(2 1/2 or 3") go up to 1/4"
drawboring can be done on mortise and tenon in advance....