# Gluing two huge timbers into a workbench



## jcleave (Aug 13, 2021)

Hi, first time poster here.
Last fall I bought a pile of culled timbers at auction from a sawmill. Two I am making into a thick workbench. They are bone dry probably doug fir, with some substantial knots. I've jointed and planed them. One is about 9x6 inches, the other 12x6. They're about 84" long, I'll trim the ends later. Legs will be M&T joints up into the timbers.

I put both thru the 8" jointer and planer at work, but machine size limitations meant I could only cut the narrow faces on jointer and the wide faces on the planer. So I had to square and finish it with a bunch of hand planing back home.

The glue joint is pretty close, but there are some gaps. Since these won't flex like laminating thinner stock, I may loose some surface area.

What glue and procedures would you all recommend for gluing these together? Maybe there's some glue (like Liquid Nails?) that can fill the gaps. Maybe Titebond, with 1" oak dowels. Maybe route long grooves and make some giant biscuits.

Thanks!


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## JohnGi (May 9, 2019)

I'm going to guess these timbers haven't been through a dry kiln. If they are air dried, one year of conditioning isn't going to get them ready to glue. Have you checked them with a moisture meter? At that thickness a pin type meter won't tell you what the interior m.c. is. Conditioning timbers is a slow process that can't be rushed. Doug fir mostly comes from damp, coastal forests. If that's your climate, I'd get them indoors in dry, heated space with air circulation all around them for a couple of years. No glue line will resist the forces inside those large pieces of wood if they decide to move.

Get as much wood to wood contact as you can. That above all is what makes a good glue joint. Dowels or biscuits help with alignment but won't add much strength unless is it a really uneven joint.

At 6" x 84", you have about 500 square inches of glue joint. 20 heavy bar clamps capable of 1,000 lbs of force each will give you about 40psi of pressure. That's a bare minimum, nothing to write home about. Twice that would be good for a heavy joint like this.

I'd use Titebond. I've heard several variations of the difference between mastics (Liquid Nails) and adhesives (Titebond): mastics adsorb force, adhesives transmit force; mastics allow movement, adhesives permit movement; mastics should be flexible, adhesives should be rigid. This job calls for an adhesive.


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## jcleave (Aug 13, 2021)

Thanks JohnGi.

I should have clarified, the timbers had been sitting in a pile at the sawmill in the semi-desert of western CO, for who knows how long. They're bone dry for sure.


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## Bob Bengal (Jan 2, 2021)

I haven't done something comparable. You mention M&T, how much of a traditional look do you want? I wonder about boring holes and using 3/4" threaded rods. If you don't like the look maybe counter bore enough for wood plugs.


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## jcleave (Aug 13, 2021)

Bob,

My first "real" workbench is laminated 2x lumber that I glued with titebond and 3/8" threaded rod. While its worked fine, I don't want to use metal on this one - for a more traditional experience and so there's no metal to hit when drilling dog holes.

I could put a horizontal member underneath the top, but since the timbers are different thicknesses, I'd have to cut a groove thru the thicker member. That's something I may do.

The leg faces will be in plane with the edge of the bench, so boards can be secured there with holdfasts for edge work.


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## DrRobert (Apr 27, 2015)

Difficult to joint thick boards. BTDT, not that huge, but 3” thick. I used a light behind the boards, constantly check with a square and winding sticks. One of the issues is planing a twist into the edge.

It has to be perfect since you can’t clamp out any gaps.

On mine, I used 1/2 splines.

BTW, you can fix a bad glue joint by routing a groove over the line and filling it with insert. An accent piece makes it creative. 😀

If I may mention, a trestle is just as strong. Through mortising legs is quite a lot of work, for seemingly little return. Personally I’ve never seen the logic in it, I wonder if the Roubo popularity and Chris Schwarz are responsible for that. And if you flatten the top with hand planes, you’ve got endgrain sticking up there…….


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## jcleave (Aug 13, 2021)

Dr Robert,
A trestle could be attractive since I could make the monster possible to disassemble. 
I'll just have to figure out some dowels or something to pin the trestle and top together.
Maybe it wouldn't be crazy either to not glue the top timbers together at all. One is all I can lift myself as is.


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## jcleave (Aug 13, 2021)

By popular demand, or otherwise, here are some pictures of the work in progress.
Here are the other ends of the timbers. Note the one on the right has a gigantic knot - more of a branch running diagonally along it. No wonder they were in the cull pile.
But they did dry pretty straight.

You all talked me into setting the timbers separately on trestles instead of gluing the top. That way I'm done jointing, and there's no glue joint to fail.
Plus I just scrounged up a couple more boards to use for the trestle top. The trestle members and legs are about 3x5, maybe 4x6. I'll try to get pictures up as the project proceeds, but it may be awhile.












Here's a test of the joint fit up. Kinda hard to throw these around by yourself.










Here's my "power planers" hard at work.


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## jcleave (Aug 13, 2021)

Here it is, assembled - no glue, no modern metal fasteners - just wood.
There's about a 1-3/4" gap between the two timbers. The leg frames at either end are mortise and tenon, and drawbore pinned. The long stretchers are mortise and tenon locked in with wedges. The top timbers can be lifted off tenons that don't go all the way thru, and are a little loose (so you can lift it off). So the whole thing breaks down on the rare occasion it needs to be moved.
Now that its put together, off the floor, the subsequent steps can happen here and there - flatten the top, dog/holdfast holes on top and on the sides, build a fence to drop into the gap, a built in planing stop, and finish with linseed oil. On this build I used a mix of hand and power tools as available and convenient, including using the 8" jointer and 16" planer at work.


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## woodnthings (Jan 24, 2009)

That turned out great! I like the gap between the timbers, but maybe it's just a deep tool storage tray?
Now that I see it, I would have made the gap wider and filled it with a removable spacer, supported by rabbets on the inside of both of the timbers. You could hide your good chisels down there away from the kids...... ?


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## jcleave (Aug 13, 2021)

That's just a 1-3/4" gap between the timbers. I'd make it a bit wider "next time" since when lifting those timbers in by myself, there isn't really space for my hand on the back side. But it is wide enough to put a wide 2x on edge, wedge it in, and work on the edge. And I'll make a fence to drop in there eventually. We'll see how the use of the gap evolves. But I don't plan to put tools in there.


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