Chris Schwarz's Blog

Thanks Be to Mongo

For this Roubo workbench to work, I’ve got 16 joints that have to come together all at once. There is not an option to glue things up in stages and still guarantee success.

As a result, I tried to give myself some wiggle room. I fit the edge cheeks of the tenons a little looser than normal so they could shift around. I made my tenons’ face cheeks a shade thinner than when I build a typical door, for example. And I cut the through-tenons so that I will have to wedge them.

That said, getting this bench together for a dry-fit required Mongo, the 2-pound English mallet. I tried my other wimpier mallets first. I would have been banging all day with the little guys.

But Mongo made it happen.

Each leg had to be pounded about 20 times to get it to seat. Then I clamped the lower stretchers to the legs to see how all the shoulders looked. The shoulders on the front stretcher look good. The side stretchers each have a gap I need to tend to. The rear stretcher is just going to have to learn to be different. (Like the kid in my high school who had a weird affection for live poultry.)

Next up: Fix the shoulders (if the workbench will come apart), start drawboring the joints and select a glue with a two-day open time.

But I’m about to hit a wall. This weekend I’ve got to build a birdhouse. Yup, you read that right.

- Christopher Schwarz

32 thoughts on “Thanks Be to Mongo

  1. Keith

    Chris,
    Here is a different way to seat the legs. Start them in their mortises then turn the bench right side up. Lift the assembly by the bench top and drop it so it’s own weight drives the joint home. Should only take a couple of lifts per side.
    Keith

  2. Christopher Schwarz

    Adam,

    That might work. It might not. Once you start adding more and more joinery surfaces, you increase what some people call the "dynamic tension" of a piece. Lots of parts interacting with one another, making the tolerances tight and tighter.

    Because you want the leg-to-top joint perfect (it’s the strongest int he bench) you want those joints dead-on perfect. Once you make that decision, you really have no choice as to how to assemble.

    Plus, this isn’t a machine-made project. Every joint is individually fit, so fitting the top to an assembled base would be a difficult task. Nothing in this bench is perfectly square.

    Hope this help explain my approach.

  3. Thomas J. Hamernik

    How is the stability? Do I recall correctly that you had wondered about it since the bench top is narrower than what you build typically?

  4. adam

    Amateur question: If I had to glue up something like this, i’d do it in two steps: 1) glue up the legs to their stretchers, clamp them together and then just tap the tops of the legs an inch or so into the bench top to make sure they were oriented reasonably well with the mortises there. 2) after the legs were dry, I’d then glue/pound/drawbore the legs into the top.

    Seems like it’d save me a bit of urgency doing it in phases but i’m a tyro so perhaps missing something.

    By the way, I think the whole thing is lovely. the contrast of the pine vs old cherry is really striking, and the joints into the table are really cool. it’s going to be anice piece of furniture for the shop!

  5. Tommy

    Is there any clue as to how this bench would have been assembled in the pre-clamp days? Such as drawbores or wedged tenons on any of the old drawings?

  6. John Walkowiak

    Chris,

    Forgot to add, if you put a couple of 2×4′s directly on the floor, then put the benchtop on them, seating the legs will be much easier. As you have it the picture, the saw horses and rubber matt are absorbing much of your mallet blows. And, being lower, you can use a huge Commander, like were used to drive in the pins on post and beam barns and like Roy is using on the end of his shows.

  7. John Walkowiak

    Chris,
    I don’t really think you need glue. About 15 years ago I built an assembly table, 36"x66". I used doug fir 4×4′s for the legs, and the stretchers are construction 2×4′s, all were cleaned up a bit. I used drawbored M&T joints, 1-1/2" pin for each tenon. I drilled thru the legs and left the pointed ends protrude on the inside. I used no glue as it would have to be taken apart to get it out of the shop. It has been in constant use, being pushed around the shop to make room and it is as solid as when it was built. As long as there is tension on the shoulders, which the drawbored pins provide, the the joint will remain tight and the glue is really doing nothing.
    Live on the edge – go glueless!

  8. Eric R

    Well, if there is another Whopper earthquake, anywhere near you, I bet that sucker won’t even tip over!!!

    And a two day open time sounds about right for that bad boy!

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