Chris Schwarz's Blog

Do L-Brackets and a Leg Vise Mix?


Mark L. Wells writes: I’ve read your book and the extra chapterr.  Both are great. You provide so much more detail than anything else I’ve read, and I almost feel guilty for not having to work it out myself. 

Anyway, I am going to rebuild my bench soon and I plan to put a leg vise on the front.   When attaching the top, I assumed I would have to use mortise-and-tenon joints because of the tremendous shearing force generated by the leg vise.  I’m concerned that the vise would just push the workbench top right off the legs.  However, when I saw the simple L-brackets in this chapter, I started wondering if those would  be sturdy enough to resist the force of the vise.  The L-brackets would certainly be a lot less work! 

Have you tried attaching the workbench top using L brackets when the bench has a leg vise? 

Answer: Good question. My gut says that two L-brackets on the leg with the leg vise would probably do the trick. However, just be safe, I would probably put one stout 1″- or 1-1/4″-diameter dowel in the top of that leg. That should provide all the protection against shear forces that you need.

Hope this helps, and good luck with your bench design.

- Christopher Schwarz

6 thoughts on “Do L-Brackets and a Leg Vise Mix?

  1. Christopher Schwarz

    Mark,

    Your plan will work (assuming you give yourself a little extra meat on the front edge of the bench to plane away after assembly).

    However, lining up blind dowels is fairly easy with "dowel centers" — very inexpensive alignment aids from the Golden Age of Dowels.

    Here’s a link to Woodcraft’s version: http://woodcraft.com/family.aspx?familyid=783

    Get a 1/4" dowel center. Drill a *extremely* shallow 1/4" hole in the top of the leg with a Forstner – about 1/32" deep is all you need). Put the dowel center in the hole. Place the top on the base in position. The dowel center will mark the center on the underside of the top. Then carefully drill the 1" hole in the leg and the underside of the top for your dowel.

    Works great.

    Chris

  2. Mark Wells

    Thanks for the quick responses! I agree with Gary that this is a time to overbuild. I like Chris’s idea of the dowels, but I can’t figure out how to easily align blind holes in the top and legs. I could rest the top on the legs and then drill the hole in through the top and into the legs, but I prefer to not have end grain of the dowel exposed in the bench top. Here’s my current plan:

    I’ll laminate the top and legs all from stock that is the same thickness. The legs will be laminated from two pieces of stock with the glue line parallel to the front of the bench. On the front two legs, I’ll form a tenon using the offset gluing trick that Chris uses for the French bench. The tenon will be on the inside, so the shoulder will be closest to the front of the bench. The back two legs will not have a tenon. With that configuration I’ll assemble the base.

    Next I’ll glue up the top. I’ll form the mortise for the two tenons before the top is glued up. I’ll take one of the boards to be laminated for the top and rest it on the shoulders of the front legs. I’ll mark the two tenons on that board and then cut out to the lines. When I glue up the top, the board that I notched will be one board in from the front of the bench. Look Ma! Instant mortises!

    I’ll rest the top on the legs so that the front legs go in the mortises and the top simply rests on the back legs. The tenons will protect against the shear forces from the leg vise, even with no glue. Then I’ll attach the top to the legs through some mechanism that will allow me to lift the top and have the base come with it, probably L brackets.

    Thanks again for the thought provoking articles and blog.

    Mark

  3. Gary Roberts

    Jumping back to my days doing factory maintenance, it’s time to overbuild. I’ld either mount a T brace behind the leg, or better yet, slap a good solid length of stock under the bench top and directly behind the leg to accept the force applied by the leg vise. Make sure the brace is the full length of the bench top and anchor it well at the front and rear with angle braces. Don’t anchor it to the bench top or else you may find things splitting as the seasons pass.

    For the side braces, don’t bother with the light duty Borg homeowners variety and sniff out some of the heavier industrial grade angle braces. You can sink these in shallow mortises if you want a cleaner look. Anchor them with carriage bolts, hex head nuts and lock washers. Bore the holes for a tight fit, but not so tight that you risk splitting the stock. Tighten up the bolts, wait a week and tighten them again. And again until you have passed the wood compression stage.

    The motto in factory maintenance goes… overbuild it cause you never know what THEY are going to do to it. I once built a 5′ high by 25′ ramp out of standard grade stock. Three layers of marine grade ply on top of a framework of 4×4, 2×10 and lots of bolts and screws. It was never intended to carry more weight than a person rolling a flatbed. Then they decided to run a forklift down it, carrying a pallet load of sheet metal. The forklift made it, but the ramp flexed a lot and I didn’t breath for almost five minutes.

    Gary

  4. Christopher Schwarz

    Chris,

    My concern would be that pocket screws are (in general) thin and too short for my tastes. The ones we get are No. 6s and are 1-1/4" long. However, there is no harm in trying it – you can always beef up the joint with an L-bracket or large dowel if it comes loose in service.

    Chris

  5. Chris F.

    What about butting the pieces together with pocket screws? My workbench is currently dimensional lumber butted together with drywall screws. I am thinking of rebuilding it in the same form but with pocket screws in lieu of the brackets that hold the top on.

    Merry Christmas!

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