Hi Don & Jim,
The important thing to recognise from and engineering standpoint is that drawbores are employed in conjunction with tapered pegs (or is that pins) and so when a peg is being driven it pulls the joint together up the inclined slope of the peg. Driving home the peg is thus somewhat of a "musical" or resistance based process. Knowing when to stop driving is therefore very much an experience based affair in order to prevent tenon relish pop.
Regards
Ken Hume
Thanks for the input, Ken. After yours and others comments I think we can agree that draw boring is/was historically widespread...an old technology ("old tech").
As to your comments about tapered pegs... To my mind, the fact we see tapered pegs reinforces the theory of draw boring even further. Fact is, as we know, because holes are offset in draw boring, you need a tapered peg to align/fit through everything... Seems this is why we see tapered pegs. Otherwise a chamfered peg would have been adequate to get it in the hole.
I know some assert that tapering is just a result of drawknifing them on a shaving horse, but there are also rived and turned pegs out there... It would be interesting to see if joints pegged with these were drawbored. I would guess not, given you need the taper for draw boring, etc.
Most all pegs I've seen here in old barns are tapered... ~ 90%
As to your sloppy mortise assertion, it sounds like a good practice to allow for stress/movement, esp. wracking. Old buildings weren't on frost walls. And like you say, a tight shoulder is really where the strength of the joint is. Slop can be done w/out infringing on that critical factor.
Putting "slop" in a mortise is probably counter-intuitive, as well as more difficult to accomplish w/ today's power equipment, however.
