How to Build a Torsion Box Workbench Top

Determine the correct proportions. To build a workbench that is best for you, it must be the right height, width, and length, strong, durable and have features that make it user friendly. These features are things like a good vise or two, being a face vise or an end vise.

• Other elements that make it user friendly are things that relate to your style of woodworking: boat building or just piddling in the shop. Tool tray, bench dogs, bench slave and cabinets or shelves under the bench. One note here: a woodworking workbench is to work wood, so build it to meet that need. If you add shelves or cabinets below the top; be sure you can still use your bench dogs and hold fasts. You should also be able to use a clamp under the top. Tool trays are handy, but get in the way when you need to add a clamp on both sides of the bench to hold your work. Think about how you will use this bench and what you need to make it work with you. Think about your seven "P's": "Prior proper planning prevents pee poor performance".
• One word of caution here: don't build a workbench that is too large for your shop. Be sure you have room to work around the bench. If it is not what works for you, than it's not going to make you happy or productive.

Understand that it will need to be strong, heavy and durable. All torsion boxes have one thing in common: they have small grids or boxes inside one large box. This grid is what gives the torsion box it's strength. It is also one that will hold its shape and not twist or bend under normal workbench use. But you have to build it to fit the type of work you do and for its intended use. This will determine the size and shape of your torsion box top.

Make a level surface. Making a level surface to start building is the first step. Level a set of boxes or saw horses or an area large enough for your project. Set rails or long 2x4's on top of them and level those.^[1]

Now lay your first sheet of mid grade plywood or MDF on top of the 2x4's. This will be the bottom of your workbench top, checking again to ensure that all is still level. This will make for a nice flat top when the torsion box is finished.

• The 3/4" plywood or MDF should be slightly over-size to the top you want. This lets you lay out lines for your grid pattern and have room to trim it's flush with the main inside box. Lay out lines around the bottom plywood or MDF for the top size less the thickness of the outside hardwood trim boards that will rap around the top when done.

Start laying the inside grid of squares. With the outside lines laid down, you can start laying out the inside grid or squares on the side of the outline. These squares should be of equal size along the length and width of the top. Here we will be using 1x2 lumber for the inside squares, so allow for the 3/4" thickness of each piece, all the short 1x2's across the width of the top should be the same length as should the long strips. This will ensure a strong and square grid pattern. Note: All the 1x2 lumber should be planed or run through the table saw to ensure they are all the same height.^[2]

Build your outside box frame, use the 1x2 lumber, pre-drill holes or use a brad nailer and glue. Lay out the outside edge lines of the bench top on the MDF or plywood. Fit the frame together on these lines you laid out. Use screws or brad nails only long enough to pass through the width of the 1x2 and about 3/4 of the way into the plywood or MDF. Check the outside frame to ensure its square, measure from corner to corner in a diagonal manner. This outside frame will be glued and screwed or brad nailed to the bottom plywood or MDF. From here all is dependent on the squareness of the outside frame.

Cut your 1x2 lumber to the proper lengths for the grid, use long pieces the length of the bench and short 1x2's across the width.

Place the short strips at their pre-determined location of the grid against the outside frame along the length of the bench. A carpenters square should be used on each short and long strip to ensure its square. Remove any excess glue, neatness is important to good craftsman like work.

With the short strips in place for the first row, you can now add a long strip in the same manner, glue and screws in pre-drilled holes or brad nails. Place the long strip into place making sure it touches all the short strips and touching the outside frame at each end. Brad nail at the intersections of the short strips and the long strips. You now have one row of your grid done, check to ensure that all remaining rows will be of the same width across the bottom.

You can now place more short strips into place as you did the first row of short strips, glue and screw or brad nail them in place making sure they are square to the long strip. Here you will have to toenail them to the long strip.

Now you can place another long strip in the same manner as the last long strip and then add the short strips as the previous row with glue screws and or brad nails. Use glue at the intersections where the short strips meet the long strips, this makes everything strong.

• Your last row of short strips should fit not too tight but touching the last long strip and outside frame as the first row of short strips. Check to ensure everything is square and the last row does not bow the outside frame member out.

Let the glue dry overnight before doing anything else. After the grid has set overnight, attach it to the bottom plywood. This is the bottom of your workbench.^[3]

When the glue has dried overnight, get help and turn the bottom and grid over placing it back on the 2x4s you used to make a nice flat level surface. Check to ensure all is still level and square. Lay out lines on the bottom to match the centers lines of the 1x2's on the underside. On these lines you can add brad nails from the outside. This makes for a very strong box.

When the brad nailing on the bottom is complete, you can again turn over the bottom, again check for flatness and square. Place the top layer of plywood or MDF onto the grid. If you intend to use the torsion box for a very long time and intend to replace the top piece of plywood or MDF when its worn, than don't glue it in place. This can be done by laying out the center lines again for the grid below the top piece. Using pre-drilled holes, screw the top to the grid below, you can use nice brass or bronze screws and let them show for a nice contrast. Steel screws can be used if counter sunk and the holes plugged. Use enough screws into the grid and along the outside edges to make it very secure. No moment or giving of the top here. With this method you can replace the top plywood or MDF and have a new bench top again for very little money.^[4]

Once the new torsion box is together, you can trim the outside edges of the top and bottom plywood or MDF flush with the outside edges of the outside 1x2 frame.

The outside trim is a hardwood of 1" to 1-1/2' thick and the width of the thickness of the torsion box. The corners should be mitered or use a nice box joint here. Glue and screw the outside trim into place, do not glue it to the top plywood or MDF. The hardwood outside frame top and bottom outside edges should be rounded over to prevent splintering. Your torsion box is now done and should be about 3" thick by what ever length and width you have chosen.

After rounding over edges and sanding the entire top, you can put a nice oil finish on the torsion box to keep it looking good and prevent any other problems from water or whatever may come in contact with it. Oil finishes as 1/2 boiled linseed oil and 1/2 tongue oil,about 3 coats.

You should build a nice strong 2x frame with 3 layers of 2x6 material for legs. This new torsion box top is not just strong, stiff and durable but heavy and should have a heavy frame to hold it.

The frame for your top can be very inexpensive and still look like a million dollars. At your local lumberyard, pick out the best 2x6's and 2x8's you can find. The grade and quality of these depend on your budget. Yellow pine is really good for this and still much less than any hardwood.

Trim the outside edge of the 2x6 and 2x8's, cut the rounded edge off, about 1/4"-5/16" will square the edges.

Cut the 2x6's to length for the legs, this is up to you as to how high you want your bench top. It should be high enough that you don't have to bend over to work and not so high that you have to reach up.

Cut one of the 3 2x6 lamination shorter by the width of the bottom trimmed 2x6 foot and the top trimmed 2x8 rail.

With the 2x6's cut to length and trimmed to width, glue and screw them together making sure you leave the right amount of space for the foot at the bottom and right amount at the top for the top rail. You can use scrap pieces for this to ensure proper location of the short leg lamination.

Cut 2 trimmed 2x6's the length of the width of the base frame plus about 3" over on each side of the legs. These pieces are for the foot, they should have a small amount of material removed from the center bottom section of each foot to let it set level.^[5]

Glue and lag screw the foot (trimmed 2x6) to the legs at the pre-determined end for the 2x6 foot. Use a framing square to make sure that the legs and foot fit square. This should give you a nice inletted look for the foot. All lag screws should be long enough to pass through the foot/rails and about 2-1/2" into the legs, just don't let go completely through.^[6]

The next piece to add is the top rail, this should be just the length of the width of the bottom of your base frame. As with the foot piece it should also be glued and lag screwed into place. This to should give you an inletted look.

Now that the leg assembly is complete, you can attach the long trimmed 2x8 side rails with glue and lag screws. These should be the length of your bench less the amount of overhang used for mounting vises. The long side rails should overlap the end rails at the corners of the legs.

A stretcher between the foot pieces can be added if wanted. Two trimmed 2x4's attached to the top edge of the foot will also make a good base to build shelves or storage cabinets under your new workbench.

The base frame can also have a nice oil finish after rounding any edges that are subject to splintering and sanding it all smooth.^[7]