Workbench on wheels build

I wanted a workbench on wheels for doing metal working in my big garage workshop.
The idea was to have a workbench I could wheel outside for some of the smokier work like welding or plasma cutting.

The plan was for this workbench to be structured much like most of the cabinets I've built lately, with a frame made out of 2x4 lumber. The wood is box joined at the corners for lateral stiffness. There's no face frame to leave maximum opening at the front for drawers or access to storage. I used this approach for this tool stand, bandsaw base, this and this dresser.

I bought seven 2x4s for the wood. At right, a sketch for how the frame goes together, the only "plan" I made.

I always do all the cross cutting with my table saw sled. I have a miter saw, but I don't have a good location for it. Besides, I prefer the accuracy of table saw cuts.

Pieces all cut. Also removing the staples from the end. I have cut into some of these staples before!

I stacked two 7 1/4" saw blades in my table saw, then used my screw advance box joint jig to cut 1/4" box joints in the ends. Rather than fiddle with getting a dado stack to cut exactly 1/4", I just make two cuts spaced such that the slot is 1/4". I'm cutting the joints in four pieces of 2x4 at once. I sized the cabinet so the pieces just barely clear the low ceiling in my shop.

Using a 48:12 (4:1) gear ratio, each turn of the crank gear moves the carriage by 1/4". I make one cut with the crank handle to the right (next to the other gear), then I turn the crank by about one third of a turn so the red tape is to the right and make the second cut. To save time, I make the second cut while pulling the jig back over the blade (cutting with the back side of the blade).

But the joints came out too tight. I think that cutting four 2x4s at once may have pushed the blades together a bit, making a narrower slot. So I moved the red tape marking by two teeth further along, which makes for 0.010" (0.25 mm) wider gaps, then cut the mating pieces. This resulted in a perfect fit with the pieces cut earlier.

A good fit! But I screwed up a little bit. I meant to make all the parts so that both ends were the same, but when I cut the first batch of short pieces, I accidentally oriented the joints differently on both ends. I can work with that by making the rest of the vertical parts the same way. But it means more to keep track of when assembling. These little mistakes can really complicate a project.

A vertical member goes in the middle. I could accommodate the box joint ends by cutting a series of slot mortises in the horizontals, but this would mean cutting away half the 2x4.

To avoid having to cut away so much of the frame, I cut away half the fingers of the middle vertical part.

Just an aside - I like to clean up little bits of wood on the bandsaw using my dust collector. These pieces just barely went through the hose, and some got stuck. With the cyclone and filter ahead of the blower, I don't have to worry about them damaging the impeller (not like a typical small dust collector).

This left just three mortises to cut, using my slot mortiser. I marked approximately where the mortises need to go to avoid making gross mistakes.

The 16 turns per inch threaded rod for the vertical adjustment makes it easy to get the spacing just right in 16ths of an inch increments. A "counter wheel" on top of the machine counts how many turns of the crank I have made. That way I can use the threaded rod for precise vertical indexing without worrying about mis-counting crank turns.

Now dry fitting the frames together. There will be pieces of 2x4 that connect the front and back frames.

I want to join the front and back frame with floating tenons. I started with some 1/2" thick maple and routed half-rounds on either side using my router lift.

... and chamfering the ends on my strip sander. I used to use my 6"x48" belt sander for this, but my strip sander is quieter, and sanding them right near the table gets the dust sucked into the machine effectively.

This shows where the floating tenon is going to be. It's like a Festool Domino, but bigger.

Cutting the mortise in the end of the 2x4. The motion I'm using is mostly side-to-side while plunging slowly. This allows the cutter's sides to mill away mostly side grain, which is much easier to mill than plunging into the end grain.

I then mark approximately where the mortises need to go with a pencil. The actual precise position will come from stops I set up on my slot mortiser.

I also label all the joints on the dry fit frames before taking them apart so I can put them together again the same way.

This time, I mill mostly by making a series of plunge cuts. Plunging into the side grain is easier than sweeping side-to-side, because the side sweeps would cause the cutter to have to mill end-grain in the wood, whereas plunging cuts into the side grain in this case.

From time to time, I'm asked about the relative merits of floating tenons vs integral tenons (By integral I mean a tenon that is part of the end of the piece, not glued into a slot in the end like a "floating tenon").

Both have their advantages. For this workbench, I'm using maple tenons, which will be stronger than the spruce. So the floating tenon will probably be stronger.

But if I made a floating tenon almost the size of the workpiece (as shown here), that would not be very strong because there wouldn't be enough wood around it to hold it. For an integral tenon, this wouldn't be a problem.

Checking for square as I assemble. The glue sets quickly in the joints, so I make sure individual parts are square. When the glue sets, I know they'll stay square so I won't have to worry about it when I add the last piece.

I applied the glue with a thin wooden split, with a glue container to dip it in. I didn't bother making a comb for applying glue in all the slots at once. But the splint fully loaded with glue is enough to apply glue to two or three slots before dipping it again.

After that, I glue the floating tenons in the ends of the rails. I'm careful not to get glue on the other end of the tenon.

Then mating the front frame. I need 8 mortise and tenon joints to mate at once. This is only a dry fit. I need to take this workbench apart again to move it to my other shop.

The font and back frames are connected by two 2x4's next to each other on the bottom corners. This will provide a bigger mounting surface for the casters.

Even dry fit, the workbench frame is quite sturdy. It survives the jump test just fine.

I took the frame apart and reassembled it in my big garage workshop, where I glued it together. First I glued the eight rails into the front frame (front down on the floor) and dry fitted the back to make sure alignment was good while the glue dried.

Then I took the back frame off again, applied glue to all the mortise and tenons and put it back on.

With eight mortise and tenon joints that have to come together at once, it can take a lot of force to close the joints if the glue starts to set. I didn't have any clamps long enough there, but pounding it with a heavy splitting maul made quick work of it!

Some of the casters came from a dumpster. Some with bad wheels, some with bad swivel bearings. So I had to combine two into one. I couldn't get the axle bolt loose, so I had to grind it off with an angle grinder. You can see the sparks flying on the right edge of the photo. You can also see the subjects of more than ten earlier videos in this photo.

This photo was taken with a Raspberry Pi running my imgcomp program to capture a motion triggered time-lapse.

An old table top mounted, and welder and plasma cutter loaded on the bottom. I'm wheeling it outside to see how well that works. I don't anticipate doing this much in the winter. My welding smoke extractor does well enough if positioned close to the weld, Though it's not effective with the plasma cutter.

A big problem with this workbench is that it came out much nicer looking than I had intended, which will make it mentally difficult to get it covered with welding splatter.

Update 2018:
A bigger problem with this workbench turned out to be that it just wasn't big enough. So two years later I made another movable workbench, but this one is designed to lift itself onto dollies.