Hi Jay, you first wrote
The extra length gets the tapered end outside the joint and also allows you to trim the striking end of the trunnel, should it start to "mushroom," or "split apart," before you have driven it all the way through.
I replied
Jay wrote earlier about driving pegs and mushrooming and splitting and cutting off the damaged end, In my view that is completely wrong, damaged on the end means the peg and bore are injured, drive it back out and replace. So use good technique, regard setting the draw bore peg as setting a spring, over driving defeats the purpose and weakens the system.
You answered
I will have to challenge you on your view that this is "completely wrong," because just because a tenon has begun to falter at the striking end, does not mean you have damaged the entire trunnel. Quite the contrary, if a trunnel is beginning to falter and you continue to strike it without the repair, you will damage it to a point that it will have to be replaced. Nor does it mean you have damaged the bore. The goal is not to smash a trunnel into place, but we all know that some do fail. If they present with shear failure, of course they should be removed. However, if the trunnels is well made and of sound wood, trimming the striking end a wee bit is of no great concern. For your second point, "over driving defeats the purpose," I may be reading your meaning wrong. The trunnel should be sound of nature and not damaged. If so, then it does need to be remove and replaced.
Challenge accepted. So what's behind mushrooming and splitting?
1. Mushrooming--cause, driving force too high--reason, peg to thick, offset too great--conclusion, reject
2. Mushrooming--cause, weak peg, such as high ring count ring porous hardwood, unnoticed decay, wrong species--conclusion, reject
3. Splitting--cause, grain runout, flaw in grain--conclusion, reject
4. Splitting--cause, off center hard face hammer blow--conclusion--possible parallel and horizontal shear, reject and strike with a soft face hammer or a mallet
So that is where the completely wrong conclusion stems from.
I also wrote
When driving the pegs, I align the bores with a erectors spud wrench, drive the peg making certain the joint seats continue driving until the peg tightens in the bore and stop once tight.
Jay, you replied
Why wouldn't you use the tool that was meant for this, and in the manner it was meant to be used? Iron draw pins are driven to the point of seating the joint. Now, if there are two trunnel holes, you may drive the second peg with little effort. If only one hole, you remove the draw pin and replace it with a peg, and because the drawn pin has seated well the joint, you trunnel does not work as hard entering the joint.
Try making an effort to understand the other guy. Here is a link to an identical erectors wrench that I have been using about fifteen years
http://www.service.kleintools.com/Tools/...CH/Product/3214The wrench is completely handy, hangs on a hammer loop, and is specifically designed for aligning bore holes, sorry it's not traditionally proper. Tomatoes Toe-Mahh-Toes
I must admit to peevishness so night night
