Tuesday, December 07, 2010

Workbench: Floating Bases

One of the key features of my workbench is the ability to take it apart and store it away quickly.  Like every guy with a small shop, I am trying to put all my stuff on wheels.  I came up with the idea of using base cabinets under my workbench instead of the more typical sawhorses.  The bases are an important part of this design, both for workholding and for stability.  They needed to be mobile but still sturdy enough to support the benchtop with all the forces from planing and pounding.

The retractable wheels on the bases allow me to quickly roll the cabinets under a stretch of countertop and get them out of the way.  When it's time to use the bench, I just wheel them out again.

I have two cabinets, one slightly smaller than the other.  Here is a picture of the small cabinet, with a bunch of drawers.  The height is just right for me, so that adding on the top slabs makes a workbench that is 34" from the floor.

Here is how the retractable wheels work, courtesy of SketchUp.  Way easier to show you this than to flip over the real thing!

I made a few changes when I built the cabinets, but these pictures give you the general idea. Underneath each base cabinet is a recess that is about five inches deep.  Inside, there are two casters on each side, mounted to a pivoting board.  This "wheelie" board is attached to the bottom of the cabinet with a couple standard door hinges I had laying around, but any strong hinge will do.  The hinges are shown in red above, and the yellow circles are there to remind me that the casters need to be able to spin freely. Don't put them too close to the corners.

Here it is right-side up, it is easier to see how the levers work in this view I think.

The levers are mounted with a couple bolts through the front apron of the cabinet and into the "wheelie" boards.  When you want to lower the wheels, just step on the end of the lever and the wheels get forced down which also raises one side of the cabinet off the floor.  These have a surprisingly strong lever action, and are able to lift up very heavy loads - at least a couple hundred pounds.  I suppose it depends on how much force you can get into the lever by stepping on it, but I have been eating my Wheaties and am well over 200 lbs.

But what keeps the wheels down?  Aha!  Take a look at the next picture.

Scrounging my pile of spare parts, I put a couple of door latches into the bottom apron.  When you step on the levers, they move down and the latches pop out to hold them in place.  Now you can wheel the cabinet around and when you are done, just give the latches a kick with your toe to drop the cabinet back down onto the ground.  These latches are cheap, and you can also buy just the latch at the big box stores.

In the picture above, you can see a hint of the arc that is cut out of the apron around each bolt - above bolt #3.  The bolts for the levers just pass through the apron and into the "wheelie" board.  You may also notice that one of the levers is lower than the other.  There is some flex in the wheelie boards, so when I was ready to add the latches I just cranked down on the levers until there was a quarter inch of clearance all around, especially in the back of the cabinet.  I then marked a line and this is where the latches ended up. I also made the apron removable in case things sag over time and I need to make a new one.

I have mentioned before that my garage floor has more waves than the Atlantic ocean.  In order to prevent the cabinets from rocking when they are dropped, I made them with three feet.  You can see that in the SketchUp pictures above, or in this picture of the back corner.

Once the cabinets are dropped down in place, they are very stable.  Not necessarily level, but stable.  This was pretty important since I don't want the bench to rock back and forth.  These things aren't going anywhere, since they are both pretty heavy.  The larger cabinet is about 30 inches wide and has my 13 inch planer mounted on a flip top, so that cabinet has to be almost 200 pounds with all the plywood and the planer.  The drawer unit is lighter, but I would still estimate it at over 100 pounds.  Add in 90 pounds for the top slabs and I've got a 400 pound bench that wheels away easily.

Here are some things I learned when building the retractable wheels, in case anybody wants to try this.  The drawings show the "wheelie" boards as 3/4 plywood, but this has a lot of flex when the wheels are up.  I had to do some weird stuff to stiffen the boards like you might do along the front edge of a shelf.  I recommend gluing up a double-thick board that is 1 1/2" thick, but I would use plywood again with no problems.  In order to do this, you need a slightly deeper recess under the cabinet.  I was trying to save every last bit of vertical space, and it got a little tight for me.  It's based on the height of your casters - with a 1 1/2" thick wheelie board, your recess should be at least 2 1/2" deeper than the caster height.  Plan to get the wheelie board roughly level with the floor when the wheels are down, though a little tilt is fine.

Next time I'll talk about some workholding stuff.  With a few accessories, I don't even care that this bench has no vises.

What next?  I've got more to talk about with the bench, but do you have a question?  Put it in the comments!


Jay said...

Very clever, man. Nice job, looking nice.

Aaron said...

Thanks Jay! Glad you stopped by.

Dyami said...

Great explanation about the wheels. I've been wondering how those handles worked. You truly are a SketchUp master to put even a shop project like this through the software. Nicely done (I can't wait to see you wall hanging cabinet model).

I understand how 3 feet keep the cabinets from wobbling, but I have 2 questions about the feet:

1) Are 3 feet stable enough when using the power planer?
2) Is it hard to get the tops of the cabinets co-planer so that you can drop the bench top on them?

Thanks for sharing your bench. I should have more about the one I'm building up soon too.

Aaron said...

Dyami, I'm not sure if I'm a SketchUp master, but a lunatic I would agree with. My wife thinks I would brush my teeth in SketchUp if I could. :) It really was helpful to model these for me, since I tried out multiple ideas for the retractable feet. I also wanted to get the planer flip top sized correctly the first time. These cabinets actually turned out to be pretty complex.

As for your questions, the bases are very stable when the wheels are up. Even with the planer flipped up the 3 feet are plenty. Each foot is about 12 inches long so there is plenty of contact area.

Getting the tops co-planar is a crap shoot, depends on how good the floor is in your shop. In the spot I typically use for the bench, there is a slight gap under the bench top, maybe 1/8" at one end. Other spots in my garage are worse, up to 1/4" out of whack. but the good news is that the top still sits on the bases very tightly and never rocks. There is a lot of forgiveness in the setup. The most important part is to get the two top slabs even with each other so the top is flat at the middle seam. So far, this has been easy to do.

Adam Van Sickle said...

Me so smart! Please disregard my last comment (asking where I might find this very post!)

I like this design... I'm planning on making my existing bench moveable. flip down wheels seem the best way to go. I have a trestle base currently. May need to modify my base to accommodate wheels - plus I want to flush the legs up with the edge of the top anyway so it's a good opportunity to do both.

Minbari said...

This is truly genius! I have been designing a work bench for myself and this is going to fit the bill. being able to put away the bench when not in use and being able to move it through a door way when needed it crucial since I rent.

what are all the holes in the sides of the modules for?

Aaron said...

Thanks Minbari. The bench is unusual, but it works well for me.

The many holes on the side of the cabinets are used to help hold long boards. They replace a feature of traditional benches called a sliding deadman. If you want to work on the edge of a cabinet door, you can pop a couple 3/4" pegs into the holes and then set the cabinet door on top of the pegs. A clamp will hold the door in place sideways, and the pegs support it from underneath.

I can't believe I haven't posted any pictures of this operation - something to be fixed!

Minbari said...

I dont know how to post a picture of it, but I adapted your floating bases idea to my table saw. it did not have wheels, now it does ;)