Need help understanding workbench design and build process

Question

I recently asked a question here regarding the use of 1x4s rather than 2x4s for a laminated workbench top and got some helpful advice. I decided to go with 2x4s, and now it's time to build. Before I do, I'd like to run my general plan past this community to see how it sounds.

I plan on laminating 16 5' long 2x4s to make a 5x2' bench top. I'll use a plane to skim the face of each board to help the gluing process, use my 6 5' long bar clamps to hold the glue-up together overnight, and then build the base.

For the base, I have 8 3' 2x4s to laminate in pairs for the legs, the depth of the legs being 3.5" each and the width being 3" each. I have enough material for two sets of pairs of laminated 2x4 stretchers, one at the top of the legs, to be tenoned into the leg mortises, and one at the bottom of the legs to be tenoned in. Then I have enough for 4 sets of 2 laminated 5' 2x6s to run the length of the bench, also tenoned into the legs.

So, I'll end up with a frame that is 2'x5' with fairly stout legs and good bracing across and along the depth. Then I'd like to use dowels to attach the top, so it could be removed to be semi-portable. Those would be between the top and the stretchers on the left and right sides, either one on each side or a pair on each side.

Is there anything wrong with this design? Most designs I see have the top overlapping the base by a few inches on each side, especially when considering the length. Is this a requirement?

Edit: here's a quick sketch of my idea:

Answer 1

I made a bench similar in construction to what you describe only a bit bigger ( 8' long with two 1' wide top slabs separated by 1 1/2" gap - roubo style split top). I made mine with 2x6 instead of 2x4s; I use it for hand planing so I wanted it to be a bit heftier. It also has a leg vise and an embedded wagon vise running along the front face of the top. I have several considerations for you:

• It's good to skim the boards in the planer to insure flatness. Do not plane the top and bottoms until your slab is glued.
• Do not try to glue up all the top pieces at once. I worked with pairs first and after they set I glued pairs of pairs etc. to get to the final width. When I got up to 12" width I ran the top through the planer to get the top nearly flat and get rid of the rounded edges of each board.
• My stretcher tenons (connected with the legs to a depth of 2" and were tight to insure maximum glue contact. I did not need to add an apron brace at the top of the legs. If the base needs more rigidity you can add a top brace later on the inside face of the leg ( see next comment).
• I made my legs 3 boards wide (4 1/2) so that the mortices for the stretchers could be 1 1/2" wide. I simply notched the middle leg board to the depth of the tenon and avoided custom chiseling.
• Keep the face of the legs and top front and back face flush. You can clamp larger pieces to the face that way.
• I routed a mortice on the underside of my top to snugly receive the legs as tenons to a depth of 1 1/2". The top just sits on the legs but because of the weight the top and legs act well as a unit. I would allow a little extra width on the mortices to allow the table top width to expand and contract against the fixed width leg structure. (My split top absorbs that expansion and also serves to hold tools and provide a stop for planing materials. (see roubo table designs on the net for details).
• Allowing the top to overhang the legs on the sides will provide good clamping opportunities and make the leg structure more ridgid due to the shorter spans.
• The 'workbench" tag wiki has a couple greate references books for design and construction details
• For me it's all about clamping my work so I included the vises, as well as strategically placed holdfast holes.

After you added your design sketches I want to add the following:

• You didn't clarify what you will use the bench for. In this answer, I assume it will be for heavier woodworking tasks.
• Although not to scale, I assume the 2x4s are long side vertical. This adds a great deal of strength to the bench. If the bench is only 1 1/2" thick it will not be as suitable for heavy loads or work such as planing.
• 2x4s will work at the lower level for all 4 sides. 2x6s are not needed. Keep the bottom of the 2x4s up 5"-6" (or more) so that you can get a broom under it.
• If the top is 3 1/2 thick then the 2x6 aprons should not be necessary if the legs tenon into the top 1 1/2".
• The tenons of the sides into the legs are shown smaller than the 2x4s. I made mine full sized to increase the gluing surface. This was easier to construct and added strength for heavy duty work.
• The top need only overhang the legs enough that you can use clamps at the full depth of the edges. 4"-6" each side should be more than enough for most wood clamps.
• When looking at your side view, note that the top will expand and contract while the legs assembly will not. Your connection between the two should allow for the differential movement.
• You can add a shelf on the lower leg supports for storage.

Good Luck

Answer 2

It will definitely help to have at least a rough drawing, but I don't see a problem with this. Workbenches for woodworking can be very personal and should match the work you do. It's a little small as benches go, but should be sturdy. There are advantages to having the top:

• overhang the legs at the long ends of the bench
• be flush with the legs along the sides

See books by Schwartz and Landis about workbench design for details. But generally, the overhang on the long ends - depending on the width of the bench - allows you to hang something like an entire drawer over it for working. The flush sides help you clamp/hold panels square to the top for edge work, either profiling or joinery.

Answer 3

I think it's worth saying upfront that entire books have been written about workbenches*, going into detail about their designs and build details so as detailed as the Answers you get here might be this will really only scratch the surface!

I'd like to use dowels to attach the top, so it could be removed to be semi-portable.

Good way to do it. This isn't the only way the top can be made easily removable but it's a simple, elegant solution.

Those would be between the top and the stretchers on the left and right sides, either one on each side or a pair on each side.

You should use centrally-placed ones and not a pair each side as expansion and shrinkage of the top will cause a problem with those, even with it minimised by the grain orientation of the wood in this type of top.

It may be overkill but might be worth going with hardwood dowels here. Unless they're large in diameter softwood dowels may not be quite strong enough.

Is there anything wrong with this design?

I refer you to my opening paragraph :-)

Most designs I see have the top overlapping the base by a few inches on each side, especially when considering the length. Is this a requirement?

It's not just a few inches in many cases, overhang can be considerable. 12" (300mm) wouldn't be unheard of.

Whether to have an overhang depends on what work you'll be doing and how — which methods of workholding you'll need to account for, and how frequently. But as a general thing I personally think an overhang is practical and actively desirable to make maximum use of clamps so a must-have on both ends, and possibly on the front and back as well. Depending on where you site the bench of course, if it's against a wall there's no benefit from an overhang along the side or sides in contact with walls.

If you're not going to be using clamps however but instead will rely on holdfasts, hold-downs and other traditional forms of workholding then an overhang may not be necessary at all.

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*See this previous Question if you're interested in reading up on the subject more, Is there a workbench "type" reference? although I don't think it's vital that you do so at this point. IMO it would be much better to build a bench and have it done and available and then read up on the subject if you want.

As many who have written about building benches have said already, even a bench that's not perfect is better than no bench at all. Numerous woodworkers have used a bench for years that didn't have all the features they wanted. But if it's solid and doesn't move about when work is being done on it that's what really counts most. Your proposed bench has all the hallmarks of being solid and dependable so with or without minor tweaks just go for it.