Draw boring

[jlandis]

Hello,
  I am building a Queen Anne chair following Norm Vandalls book. In the directions he says to pin the legs, and describes the process. The way it reads to me is that he pins the legs well after the glue up.( it didn't sound like draw boring to me, just pinning) Is the proper way to apply these pins by draw boring or by simply running a pin thruogh the joint during the final surfacing of the chair?

                                                    Thanks for your help,

                                                                          Jim

 

[rococojo]

Hi Jim, The joint (draw Boring) was developed on roofing work, when a sash cramp could not be used, it is a means of drawing the joint shoulders together, the tenor hole is drilled offset by a say  1/8” to pull the joint up, but these days cramps are available and used, so a simple peg can be used, as the glue is holding the joint.

                                                                Joseph Hemingway
                                                                  Sharing the trick's of the trade.

 

[Adam Cherubini]

Jim,

I don't think anyone knows the answer.  I've asked this same question several times. The problem is, the chairs as they stand today don't seem to have evidence of draw bored holes. The other problem is, they wouldn't.  I think this is an excellent application for a draw bore.  I'll probably draw bore my chair.  But we have no way of knowing for certain at this point if this was common practice or not.  The guys who would know don't.

Adam

 

[rococojo]

Jim,

I don't think anyone knows the answer.  I've asked this same question several times. The problem is, the chairs as they stand today don't seem to have evidence of draw bored holes. The other problem is, they wouldn't.  I think this is an excellent application for a draw bore.  I'll probably draw bore my chair.  But we have no way of knowing for certain at this point if this was common practice or not.  The guys who would know don't.

Adam

Re: Draw boring
« Reply #1 on: Today at 03:00:22 AM » Reply with quote Modify message

Hi Jim, The joint (draw Boring) was developed on roofing work, when a sash cramp could not be used, it is a means of drawing the joint shoulders together, the tenor hole is drilled offset by a say  1/8” to pull the joint up, but these days cramps are available and used, so a simple peg can be used, as the glue is holding the joint.

sorry Adam But some do.

                                                                Joseph Hemingway
                                                                  Sharing the trick's of the trade.

 

[Bob Mustain]

I'm not sure I understand the statement the drawboring was developed in roofing.  Drawbored joints predate virtually all glued joints and have been used in buildings and furniture construction for centuries.  Peter Follansbee and others have written extensively on the subject.  This joint was used almost exclusively in early jointed furniture built with green wood.  The amount of the offset of the hole in the tenon has to be consistent with the size of the joint and the relative dryness of the wood.  A 1/8" offset in a chair joint in relatively dry mahogany or walnut would either be impossible to assemble or, if you used enough force to drive the peg it would simply explode the chair leg.  The pegged chair legs I have examined use relatively small pegs, some, in the crest rails of windsor chairs are almost toothpicks, but seldom much larger than 3/16".  I would expect the offset to be no more than 1/32" and the peg to have a conical end to assist it into the hole.  A pegged joint certainly adds to the strength of a chair, particularly where the back leg meets the rail but I would try a couple of practice joints using the same wood before I tried the actual chair.  Also, I would suggest splitting the pegs and then whittling them roughly round rather than using any kind of dowel.  This will help both in having less chance of breaking while being driven but also because the riven peg is better able to follow the path through the offset hole.  Good luck!

 

[rococojo]

Bob,
  Why are early chairs Draw Bored? Could it be the lack of a different, good clapping method?  Quite possibly?
“To draw”, up the joint? “A chamfer is cut down one side of the peg” (to compensate for the offset). “Making the peg longer”, by the chamfer length. This makes drawing the joint easy.” This is trimmed off later”.
(But sometimes left on the inside of antique chairs)
The pegs are better hand made, usually ¼”  to 3/8"round, and sometmes tapered. but Hand cut to hold firmer.
Do we agree? “Houses were built before furniture”. I think that is correct.
  This joint was developed first for roofing, (unless they had 20’00” sash cramps) to pull up the purling joint. (For example)
One last point: “I stated a small offset ” depending on hardwood or softwood, this would alter to compensate for any differences, in texture and hardness of the wood.
"Are we furniture makers"? Or not? I leave some thinking to the person designing the piece. Or are we incompetent, to think for ourselves? I’m hoping not.

                                                              Joseph Hemingway
                                                                Sharing the trick's of the trade

 

[Adam Cherubini]

If Jo gets to make wild guesses then count me in! 

I've seen evidence of what I think are Jo's "cramps" indicating the crest rail may have been clamped down to the rear seat rail.  I'd bet New England craftsmen would have used draw boring more readily than Philadelphia craftsmen.  Philadelphia craftsmen sometimes left pegs out of front legs altogether.  The back legs were the problems, especially on Philadelphia chairs that lacked lower stretchers.  The through tenons were just about always wedged from the rear.  This was pretty clearly done at construction, not a repair.

About the history of drawboring, I'm seeing Jo's guess about roofing and raising- I think the Egyptians invented draw boring and I have just as much proof as Jo has.  I think the draw bore is the next logical step from a tusk tenon.  Saw an Egytian bed at the University of Pennsylvania Museum that IIRC had tusk tenons. Either that or it was the guy's foot who was laying on it.  He'd been there awhile and part of his foot had actually fallen off (I hate it when I do that!)

On a serious note and a question for Dr. Jo, I find if my shop is cold, my hide glue can congeal on my tenon shoulders, preventing me from pulling the joint up. On a complex assembly like a chair back, I feel like I either have to put less glue and rely on the pegs, or fire the pegs in quickly to pull up the glue.  Clamps are in some ways slower, especially for irregular parts like those found on chairs.  I have some of those "Quick grip" clamps in my shop which are one of the few modern indulgences I allow myself.  Period craftsmen didn't have such nice clamps. 

Adam 

 

[rococojo]

Adam, I'll rephrase my 1st answer? From "Developed" to "Utilised" as I seem to be working hard at this.

Hi Jim, The joint (draw Boring) was developed on roofing work, when a sash cramp could not be used, it is a means of drawing the joint shoulders together, the tenor hole is drilled offset by say 1/8” to pull the joint up, but these days cramps are available and used, so a simple peg can be used, as the glue is holding the joint.

All, I must object to Adams, wild Guess theory, my knoledge is built/based on fact, however early in world generations we  quote, one needs to think, Homes structures, came before any contents (Internal Joinery, or Furniture), what Guess? thats a Fact.
Adam is  quite correct in his theory, The Tusk tenor came from Draw Boring; same-wedged pin to drive in to tighten the joint. Great news?we are thinking and learning.


                                                                Joseph Hemingway
                                                                   Sharing the trick's of the trade.

 

[Bob Mustain]

I think we have a problem with nomenclature.  I think of purlins, along with the bents in a barn frame and other parts of the structure as framing, not roofing.  Certainly building framing was more developed in Europe earlier than furniture.  But some of the Egyptian furniture was very advanced.  Pinned joints were used for all of these when glue would be out of the question.

 

[rococojo]

Bob, Sorry, being in England? Not the USA. I should explane.Our roofs usually have: No 2, A, frame trusses per house, with 2 purling spanning between them each side; Its there joint connections that use tenons, into the A frame, this is where, Draw Boring is used. Roofing spars cross over the purling, etc.
Sorry for any confusion.
                         
                                                  Joseph Hemingway
                                                       

 

[albreed]

Jim- Your chair should be draw bored. It eliminates the need for a bunch of clamps when putting chairs together and will pull the joint together. Do it as follows:
Make your mortise and tenon. With the mortise empty, drill a 5/16 hole 5/16 in from the shoulder through the mortise and out the other side. With a chisel trim off any blowout inside the mortise.Slide the tenon into the mortise and take a sharp pencil and reach into the hole and trace it on the tenon. Remove the tenon and drill the hole within the pencil circle, but to the shoulder side so that your pencil line is visible on the part closest to the end of the tenon. You'll "erase" the arc of the pencil circle closest to the shoulder with your drilled hole.
When you slide the tenon in, you'll have a thin crescent of wood towards the end of your tenon. Your pin can be octagonal with a tapered point. When you drive it in it will wedge the tenon deeper into the mortise as the holes try to line up.
Draw boring is not a substitute for glue, although it can be glueless.I always glue the joint.-Al