Hi Everyone,

We were having a disscussion over our water cooler at work regarding the mixed opinions and methods of drawboring. ...And I hope I haven't missed a previous disscussion on the topic...

Anyone care to share their techniques?

Anyone have any empirical evidence about the effectiveness of certain methods?

What about the performance of a joint who was draw bored VS a joint who was pulled tight mechanically and then drilled straight through?

Acceptable offsets?

Thanks everyone!

Looking forward to a discussion,

Brock Smith

I think this has been covered somewhere, but I can't find it exactly.

What was the out come at the cooler? Pro or con?

Acceptable offsets depends on the size of the peg and length of the tenon and the amount of common sense. Mostly an eyeballed 1/8". My reasons for drawing the joint is a time factor. It is done when the joint is done, no more tools needed at raising time. you are right there doing the work, the peg hole is the least of the work. It would be risky to bore the holes right on with the joints apart, the risk is miss alignment and forcing the joint apart so that is not a choice. So reason would say draw the joint and have it done. Than there is the shrinkage factor. Basically its just the way I have always done it. Tim

yes to the draw bore
1/8 plus or minus is usual
works better in green wood
it is very risky to draw bore with turned pegs or sawn pegs -- they don't bend like the draw bore peg needs to.

As for empirical evidence -- since there aren't any 500+ year old timber frames with peg holes bored straight through, I guess we'll have to wait to see which is better.

To elaborate on Gabel's point: your client may want a pretty turned peg with only a slight chamfer for their finished look. Such pegs are not very compatible with draw boring. Also with regard to 500+ year old frames: The old timers didn't have access to inexpensive truckers' ratchet straps to pull their frames tight. I like to think they were practical folks who would have used them had they been available. CB.

Hi Gabel,

Not true. It is precisely on 500 year plus frames that one is liable to find non draw bore pegs where centre line mounted tentons for braces on wide posts require the use of parallel pegs. A draw bore will only work effectively when the tenon is offset towards and is fairly close to the reference face such that the peg manages to fill the gap and pull up the joint before it fills the driving peg hole and stops.

Regards

Ken Hume

Ken,

Perhaps my statement was over-reaching, but I am not yet convinced.

Has it has been verified that the peg holes you are referring to are not drawbored? If so, that is very interesting indeed, and raises quite a few thoughts about how they managed to pull the joints up tight enough to drill through them. Spanish windlasses? Drill them in situ after gravity has brought the joints home tight?

I feel compelled to mention that we have quite often and with no ill effects draw-bored centered tenons on posts as wide as 12". In fact, there are about 200 draw-bored pegs which pass through centered tenons on the frame we are assembling now. (These are all 2" tenons centered in 10" posts). I don't know of any reason why it wouldn't work unless your peg was too fat on the driven end to go into the hole deep enough (easily remedied) or your hole isn't deep enough to allow the peg to pass through the tenon enough to draw the joint up fully or your peg was too short.

I have wondered if the tendency to offset tenons/mortices to one side is so that the peg holes won't have to be drilled as deeply in order to drive them to the point that the joint is drawn up fully. I know that I have seen pegholes that were not drilled through in quite a few old frames. Having the tenon shifted over as far as possible keeps the required peg hole depth to a minimum and it keeps the required peg length shorter. Double time saver.



Gabel

Gabel, I have also seen the same thing. The bit wasn't long enough so the builder hacked at the exit side to expose to peg hole, the funny thing is he didn't expose the hole and gave up. In the repair of this tie beam to rafter connection, I finished boring and he was only an inch away. The tie was wider at one end than the other to save on a lot of hewing, they were like this through the whole building, flared ties.

It helps to keep your joinery closer to one side due to the chance that the deeper the peg hole is from the starting face the higher the chance of wandering of the bit and that could lead to a pushed apart or too tight joint. I also drive all pegs from the ref. face. Are you using a guide for the peg holes, or just a square. Tim

Hi Fellas,

Tim, we did not come to a conclusion at the cooler! We do seem to have a full range of opinions, though...

I'm the drawborer in our group, and when I do so, I poke the tenon, dissassemble the joint and re-dill. Gabel, I have been doing so for many frames now with sawn and turned pins with good success. Ken, we also pin center tenons on fairly large members with good success (and I DB them).

Our frames our generally cut from standing dead timber, through pegged, with a drill guide.

And what about offseting your hole by angling the drill with the joint assembled? Do you guys feel this is effective?


Brock

I will at times tilt my brace and bit to further enhance the draw, mostly when I have guessed on the shy side of my 1/8", so I am compensating. I don't prefit and redrill. I use my combo square as a guide to help until I'm into the further side of the mortice than let it go, checking the start and than the realignment in the mortice. I bore them horizontally not from the top as well. My shaved pegs have a fair bit of taper, I peek in the hole at raising and select an appropriate peg. Tim

Hi Guys,


been absent for a some time.
As far a being able to pull frames tight without the handy ratchet ties. The old times did know how to make use off ropes which were available then. Just tie around your framing members and tighten up. Sort of like tie wires for re-bar.
I never tried DB as I found that there is to much friction on large members to pull it tight relying on the peg only. I am always afraid that all I would accomplish is destroying the mortise.
Just my 2 cents.


Enrico