Chris Schwarz's Blog

Do You Need Glue?

After three days of work, we are going to start assembling the workbenches we are building at the Marc Adams School of Woodworking tomorrow and are coming to a familiar fork in the road.

Should we assemble the benches using glue or not?

My gut says these benches don’t need glue. The legs are immobile in their mortises in the top – even during a dry fit. A couple wedges in each mortise will make them even more so. The stretchers that run between the legs will be drawbored into mortises in the legs. A drawbore joint doesn’t really need glue – if it is properly executed.

But glue makes sure that everything will hold tight. At least that is the way I was raised.

It’s a tough fight that I wage in my head. So far, the glue has always won its place in the joints in my workbenches. It is so inexpensive and I cannot come up with a downside to using it.

So check back tomorrow to see if the glue won again.

— Christopher Schwarz

14 thoughts on “Do You Need Glue?

  1. vinfonet

    Am building a Roubo style bench in my home workshop now. The sheer mass, gravity and the joinery (with the tenon and dovetail) to me make glue seem unnecessary. I can appreciate the reason for sticking with just the one straight through tenon; getting a true vertical dovetail tenon through four inches of hard maple has proven to be quite a challenge. If I were to start over, I would probably choose southern yellow pine which would have been much kinder to me.

  2. plato

    It’s a toss up in some ways…I was brought up watching my father using using horse’s hoof glue but later when he lost his factory (through capitalist skull-duggery)he went over to PV as he no longer had a place to use the glue pots. I see things I don’t like in the construction of these benches, though understand the processes make it easier…like having a mortise on the line of the lamination..I’d be a good inch and an half or two back into the plank before it. Loads of glue doesn’t make up for poor mortising but because timber may still be shrinking (depending) the joints may loosen over time though a workshop is a stable environment.

    My ideas would be to choose naturally dried timbers, as this is the underpinning recipe for a good bench…I doubt knotty pine but whatever it is…I’d use draw-bore or tusk-tenon and wedge joinery. The leg braces used in the examples shown add serious rigidity to benches (which to me seem a plank short in width) and as I reflect on it whilst writing………I wouldn’t use glue. Older benches were commonly braced just under the bench and towards he foot of the leg…often with a central brace as well and a shelf built across the lot.

    If the bench can be fixed to the wall then the legs can predominantly do the work legs are intended to do….ensure vertical resistance. As that is rare you get less problems if the bench moves than if the joints flex. If you want to fix the bench it should be fixed at bench height and preferably at both ends…admitting that this might reduce some access to those ends.

    Another comment, if you want to sight for out of true using a tri-square, or square…after checking itself for “true”….don’t do it as shown. You can see some light, if out of true, but you should be looking straight along the timber at contact level to see the ‘out of true’ or if obstructed you can use feeler gauges. As shown you have parallax error.The square itself should be no more than a couple of millimetres wide (say 1/16th inch’ish ) or you can have error introduced.

    A square may not show you uneven surface along the timber..for that us a good long spirit level tipped at 45 degrees to narrow the edge or work it across the timber using feeler gauges as you go.

    When mortising timber make sure you turn the leg around to find the grain so as to to cut the tenon in the correct direction of it.

    One thing about the traditional techniques still more commonly used in Europe than expediency neurotic America is that they are a very fine piece of sturdy joinery and adjustable. I was actually quite surprised to see the bracing for the roof overhang of some 6 feet I asked a builder to do to my old place in France when rebuilding the roof was draw-bored and wedged.It does the heart good and I think even non-woodworking types could feel that pleasure.

    On balance I wouldn’t glue…the bench can be tightened if ever it needs to be with tusk and wedge and if well mortised and braced will take the working on it with little complaint. I’d rather have a pair of wood face, wooden screw vyces than dogs too for planing and use the dogs only to steady when chiseling a mortise or tenon.Voila

  3. Hoj

    My friend and I wanted to take this class but we registered too late (maybe next year). If I were there, I would definately not glue mine as I need to partially disassemble it in order to manoeuver it into my basement which does not have walk-out access. Regardless, seems to me that the “knock-down” feature would be nice especially since the glue seems to be optional.

  4. John Walkowiak

    Considering that most benchtops just sit on dowels and function just fine I think these would not need glue. However, if the tenons are tight, and if you used yellow glue, you might need a press to drive them home. Liquid hide glue would at least make them slippery and go together easier. Good luck! IMHO these things are waaaaay overbuilt.

    1. Steve_OH

      One big difference, though, is that most benchtops are sitting on self-supporting bases (e.g., having stretchers), which is not the case here. For longevity, you have to be sure that the joints do not “work” over time. Glue is one way to accomplish that; mechanical reinforcement (wedges, drawbores, bolts) is another.

      -Steve

    2. Steve_OH

      Actually, I see from the next video that they’re drawboring the stretchers, which means that the base really is self-supporting, so that negates a lot of the rationale for gluing the tops to the legs.

      -Steve

  5. jwaldron

    It does seem the design has been “streamlined” from the “real Roubo” design with the dovetail pin and tenon on the top of the leg. I think we need an explanation for this heresy!

  6. renaissanceww

    Chris thanks for the constant video updates. I keep sharing them with the staff at the lumber yard. Everybody is lovin’ it. It is actually rare for us to get to see what is done with the lumber when it leaves the yard so the footage is much appreciated.

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