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Scot Ferraro
03-25-2009, 7:37 PM
Hi everyone,

I am in the process of making a new workbench and I want to draw-bore my mortise and tenon joints on the stretchers. I am making my bench out of hard maple and I wanted to know what types of wood you would recommend to make the dowels for draw-boring. I know that many prefer white-oak, but are there other viable options? Would Bubinga hold up (I really like the contrast to the maple)? I have a dowel-plate and I was thinking that 3/8 inch dowels 3.5" long would do the trick nicely (two per tenon). Any suggestions are very much appreciated.

Thanks!

Scot

Richard Magbanua
03-25-2009, 7:51 PM
I used white oak, but I suppose any hardwood, as long as it's bone dry with straight grain, should work okay. I also glued my stretchers in since it needs to be solid. I went without glue in one joint and I felt just a little wobble. Of course that was in S-Y pine.

http://www.flickr.com/photos/magbanua/3059768674/in/set-72157610497536990/

Robert Rozaieski
03-25-2009, 7:52 PM
Your pegs should be riven from dry stock with straight grain that splits straight. hence the typical use of red & white oak, ash and hickory for pegs. Bubinga in my experience has a lot of figure and grain runout which means weak pegs. You want straight springy wood for pegs. I'd stick with the typical ash, oak or hickory.

Wilbur Pan
03-25-2009, 7:52 PM
I've used the round wooden oak dowels that you can find at the borgs, and cut them down to the length that I want. They work very well for drawboring a workbench.

mike holden
03-26-2009, 7:49 AM
Scott,
Use ash or white oak for the pin, then make a bubinga button for the show surface.
Mike

Ken Garlock
03-26-2009, 10:14 AM
First, why do you want to ruin a perfectly good mortise and tenon joint by drilling a hole through it? :eek: Yes, I know Chris Swartz thinks the sun rises and sets on draw bore joints.:rolleyes:

The tests I have read in the past 6 months demonstrate that a simple M&T joint is stronger than a the draw bore. That leads me to think that the draw bore is a artifact of the days when glue was not nearly of the quality that it is today.

This past summer I built my 30X96 workbench of sugar maple, and did not use any metal fastener except those to hold the vises in place and a lag bolt at each end to keep the top centered (yes dowels would have worked.) Each and every joint is held in place by Titebond III, including M&T, bridal, and lapped.
I feel confident that the bench will not fail in my life time.

Whatever you decide to do, enjoy your work, and build it to your own satisfaction.:)

Adam Cherubini
03-26-2009, 10:43 AM
The tests I have read in the past 6 months demonstrate that a simple M&T joint is stronger than a the draw bore. That leads me to think that the draw bore is a artifact of the days when glue was not nearly of the quality that it is today.


We have 400 years of experience with draw bored joints like these. They hold up. How long has Titebond III been around again? By the way, Tite Bond's manufacturer only has strength data for clamped joints. For unclamped, unclampable joints, (like mortise and tenons) Titebond's strength is dependant on joint quality.



Each and every joint is held in place by Titebond III, including M&T, bridal, and lapped. I feel confident that the bench will not fail in my life time.


Let's hope that's the case, but if it does fail you're screwed. Even if you damage a component, you won't be able to get the bench apart without a saw and you can't practically reglue a PVA joint.

As an engineer, I've learned to trust real world experience over test specimens. I don't want to say your bench, Ken, is a train wreck or ticking PVA time bomb, but I think practically and scientifically, draw bores make sense.

Adam

Richard Francis
03-26-2009, 11:14 AM
Check out Peter Follansbee, joiner's blog; his recent posts on mortise and tenon in 17th century furniture illustrate Adam Cherubini's point - and add another 100 years of experience.
http://pfollansbee.wordpress.com/

Ken Garlock
03-26-2009, 1:44 PM
Sure, 400 years experience is a notable achievement for any type of construction. Consider what was the glue in use 100+ years ago, hide glue? However, the new glues and adhesives are as strong or stronger than the items they hold together. 3M even makes a tape to fasten steel parts together.

I don't want you gents to loose sleep waiting for my bench to fall apart. All the the stiles, rails, and spreaders are in one form or another mechanically interlocked to their mating piece. The only exception is the apron that is splined to the top which in turn just sits on the base. I estimate the total weight to be over 350#. Lastly my shop is air conditioned year around, low 60s in the winter, and mid 70s in the summer.

You have your opinions and I have mine, wouldn't it be boring for everyone thought the same.:)

Jameel Abraham
03-26-2009, 5:46 PM
Ken,

This is a great read about hot hide glue compared to carpenter's glue (Titebond, Elmer's). http://www.player-care.com/hide_q-a.html

I once read that furniture from King Tut's tomb was assembled with hide glue and it's still together after a few thousand years. I use Titebond for most of my furniture making just because it's convenient. But with musical instruments I use hide quite a bit. If I was more set up for hot hide I would use it for almost everything since it's such a nice glue. I was really tickled when I first got into using it, and unlike some people I kind of like the smell (I never let it get funky), it's kind of like woodshop incense. It gets me in the mood for making instruments and other fine things...

Chris Padilla
03-26-2009, 5:55 PM
That furniture in King Tut's tomb probably wasn't USED for few thousand years...may have never been used as a matter of fact! :)

Lottsa ways to put a bench together...I suspect they will all serve us very well for a long time.

Chris Friesen
03-26-2009, 6:24 PM
First, why do you want to ruin a perfectly good mortise and tenon joint by drilling a hole through it? :eek: Yes, I know Chris Swartz thinks the sun rises and sets on draw bore joints.

Nobody with any smarts is claiming that a drawbored joint is stronger than a joint with just glue. However, the drawbored joint is strong _enough_ , will continue to hold when the glue fails, needs no clamps once the pegs are inserted, and is more tolerant of certain sorts of sloppiness within the joint (but we're all too perfectionist for this to matter, right?).

If we trusted glue completely, then for ultimate strength everything should be joined with bridle joints or finger/box joints at corners. Dovetails and pegged/wedged M&T joints exist primarily to give mechanical support when the glue fails.

Scot Ferraro
03-27-2009, 1:42 PM
Thanks for everyone's replies...I guess I will resort to Oak for the pegs. I like the idea of draw boring and since I have not done the technique yet myself, I figured why not try it on my workbench? The mechanical interlocking will give me some piece of mind as I am not using any screws or bolts.

Thanks again for the feedback.

Scot

glenn bradley
03-27-2009, 2:34 PM
For unclamped, unclampable joints, (like mortise and tenons)

Uh, I do clamp my unclampable M&T's :confused: ;)

If you want the bubinga contrast you could certainly recess your structural dowel and put a flush bubinga plug in place for looks. I think it would look nice.

Robert Rozaieski
03-27-2009, 5:37 PM
Uh, I do clamp my unclampable M&T's :confused: ;)

If you want the bubinga contrast you could certainly recess your structural dowel and put a flush bubinga plug in place for looks. I think it would look nice.

Clamping along the M&T joint does nothing for the joint. What Adam means is clamping the cheeks to the tenon. As per the manufacturer's instructions, PVA glues require high clamping pressure on the surfaces being glued because they have zero gap filling ability. In a M&T, the cheeks of the mortise are being glued to the tenon therefore, you would theoretically need to clamp the sides of the mortsie. Doing so however would risk breaking the walls of the mortise, therefore, M&T are basically unclampable. Therefore, for a strong M&T you really need a perfectly fit joint. Clamping the shoulder tight does nothing for the strength of the joint as it's an end grain to long grain surface.

The drawbore solves these problems because it adds a mechanical strength to the joint instead of just relying on the glue which will one day fail, there's no avoiding that.

Chris Padilla
03-27-2009, 5:51 PM
Why not use a through-tenon that is wedged? That seems like it would be easier to take apart than a drawbore...if that is your goal, which it may not be.

Here is an example of what I mean: Wedged Tenon (http://emporiumindonesia.com/Woodworking-Project-Plans/joinery/038-wedged-tenon.htm)

I guess those tenons sticking out might be a nuisance but if things loosen up, it is easy to give 'em a good whack! :)

Bob Hicks
03-28-2009, 10:08 AM
Hi Scott, I used a walnut dowel because I incorporated some walnut in the top. It word great, pulled the joint together nicely and finsihed up with striking contrast. Use whatever you like, it will come out fine!