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AndrewP

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Here I am declining into galoot-hood, and I come to think about making some draw-bore M & T joints. Dowels are all metric, but non of my brace bits are! Anyone found a neat solution that doesn't involve a lathe or a lot of sandpaper.
Andrew - who's only a beginner but doesn't want to stop! :?
 

Alf

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Up the proverbial creek
Andrew,

Nearest metric size and then drive it through one of these. However, a word of caution. Unless your augers are dowel bits they won't be bang on size anyway. They were usually made a fraction (1/16"?) oversize for easy installation of metal fittings and such. Test a few metric dowels with the bits you have and see how they go - you might get lucky.

Cheers, Alf
 
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Anonymous

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Not to worry! Draw boring requires the holes in the mortice piece be offset from the hole in the tenon. You'll have to taper or chamfer the end of the dowel before you drive it in to pull the pieces together.
Auger bits aren't quite that oversize, Alf :lol: . They come in numbered by 1/16" increments and the area of the spurs are 1/64" oversize. Dowels are usually out of round and that makes them fit tightly enough for most purposes.
If you need precise dowels and holes (drawboring doesn't) there are dowel augers as Alf mentioned or some chucks will accept round shank bits such as brad points. Dowels can be trimmed with a rounder plane (sometimes called a wichet) or driven through a dowel plate for a precise fit.
 

Alf

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D'oh. I'm always confusing my 16ths and my 64ths. :roll: Occasionally there is something to be said for the metric system...

Cheers, Alf
 

Wendell

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In Jim Kingshott's M&T video, he recommends not using commerically available dowels. These dowels are turned so they can contain short grain along the side. Mr. Kingshott recommends riving a short pin blank from a block of wood so that you get continuous grain for the length of the pin. He trims it to rough diameter then pounds it through a dowel plate to get the final diameter. If you can find or make a dowel plate, it might be the solution to your problem.

Good Luck,
Wendell
 

Argus

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Making your own dowels is easy and gives you a dowel that matches the material it joins if you wish, or contrasts with it if not.
An exact fit of drill and dowel is not necessary, in fact the dowel needs to be a little over sized so that it compresses in the hole.

I agree fully with Wendell and Roger. The late Jim Kingshott’s video showed how simple it all is to do. But the point Jim made was that the fit must be exact both on the sides and at the bottom of the mortise to maximise the strength of the joint. A sloppy M & T joint is inherently weak, however many dowels it has. My understanding is that the strength is in the fit and proportions of the joint, the dowel just stops it sliding out under load. A draw bore dowel pulls the joint into tight alignment.

I use oak a lot and use draw-bore dowels all the time, almost always without glue.
 
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Anonymous

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Originally the M&T joint was used in green woodworking. Drawboring ensured the shoulders of the joint would remain tight even though the tenon would shrink inside the mortise over time. Some great pictures can be found here.
Today we use a lot of kiln dried wood and furniture is often in climate controlled houses so a well fitted M&T that is glued can last a long time even though it involves a cross grain gluing situation. I'm with Argus, I drawbore without glue whenever possible.
Yes, Alf. those fractions are pesky. I'll be happy when we 'Muricans finally join the rest of the world with metric measurements but I'll still be using inches and fractions with my old tools.
 

Argus

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Roger Nixon":13vtjlsk said:
Originally the M&T joint was used in green woodworking. Drawboring ensured the shoulders of the joint would remain tight even though the tenon would shrink inside the mortise over time. .
One refinement is to use a combination of green/ semi dry timber.

The way it works is that the tennon section is drier than the mortise. As it dries the mortise shrinks onto the tennon, which also expands a little as it absorbs moisture. For a really, really permanent joint, saw a small vee groove in the sides of the tennon cheeks at right angles with the grain. The mortise sides will expand into it giving a permanent lock. You won't need dowels.

We seem to have gone right off-topic, but it’s interesting enough.

One advantage of non-glued joist is that they can be dismantled if necessary.
 
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kygaloot":37xqi5xi said:
Roger said,

I'll be happy when we 'Muricans finally join the rest of the world with metric measurements

........<sigh>.........
OK, we'll go way off topic on the thread here. :lol:
Jeff, I crunch thousands of numbers each day. I work on water and wastewater treatment plants where I deal with civil, mechanical and electrical engineers and architects. Civil engineers design in feet and decimals of a foot (i.e. 1.25') except on structures where they may revert to feet, inches and fractions, mechanical engineers work in either inches and decimals or inches and fractions. Architects work in feet, inches, and fractions.
These groups produce drawings from which I have to calculate quantities. Plans are produced where the civil drawings are in "engineer scales" ( 1"=20', 1" = 30', etc.) and the structural and architectural drawings are in "architect scale" (1/16" = 1', 3/32" =1', 3/4"=1', etc.). Not only do we get to take all these dimesions (based on the foot) and turn them into quantities based on feet (linear foot, square foot and cubic foot) but we have the joy of turning them into other units such as square yards, cubic yards, acres and gallons.
Then we have "enlightened" governments such as the state of Kansas where I reside that has declared all state funded projects shall be metric. Now all those formulae we have carefully developed and stored in our estimating software are worthless because we have all those conversions in there such as "length (in feet) x width (in feet) / 9 = square yards" whereas metric is simply length (m) x width (m) = m2.
As a woodworker, I don't care about measurement systems as most dimensions are transferred from piece (or tool) to piece but, as an engineer, this antiquated system sucks on ice.
 
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Sounds to me not so much a metric vs. non-metric issue Roger, but the fact that you're using 2 different systems. If everyone you worked with did it all one way, everything you mentioned would largely be eliminated.

That said, even though I'm one of the 'Muricans, I wouldn't have a hard time switching because I'm a math(s)/science kind of person. Metric makes "sense" to me from that standpoint. But then again, changing to a decimalized "inch" system would work just as well. =D
 

kygaloot

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Roger,

Though I promise to throw the occasional barb, I will not further clog this forum with any more lengthy fulminations on this subject. So far as I am able to practically do so, I will do my utmost to retain our cultural heritage in my own humble work shop. :)

Jeff

Member of the Society For the Preservation of Slotted Screws
 

AndrewP

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Thanks guys
(BTW that's a non gendre specific "guys")
That's given me several options. I think that a dowelling plate should go on the list for my next Axminster order, though that list is getting alarmingly long :shock:
Andrew
 

Midnight

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ummmmm..... Andy...

ye dinna need t buy the entire list at once... :p :wink:
 

Argus

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Andrew,

It's very easy to make your own.

All you need is a metal plate, mild steel will do, and a drill.
You need to preserve a sharp edge on the side of the hole.
 

Wendell

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There is a nice article from David Charlesworth on making and using a dowel plate. Lie-Nielsen has a link to a pdf file with article on the webpage for their dowel plate.

Wendell
 
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