Intro: An Assembly Table From a Hollow Core Door
Some years back, I decided to set up a modest workshop in the corner of my basement.
I started with a workbench: Building a real woodworkers workbench
And then I got distracted and did nothing while my basement filled up with assorted junk. This last winter I decided to put some work into making my "shop" more functional and organized. Starting with a new assembly table, so I'd have some place to put things while I was working on my bench, and with a system of french cleats along the wall, so I could place cabinets, shelving, etc., where ever was most convenient to store my tools. This I'ble describes the assembly table.
This was inspired by Norm Abram - Season 14, Episode 7 of the New Yankee Workshop: Work Table and Clamp Cart
Norm's table is built around a torsion box, made from 3/4" ply, with a sacrificial MDF top, 3/4" ply legs, and a clever mechanism for some pull-away casters, to make it easier to use.
I made two significant changes.
First, instead of making a torsion box, I built mine around a hollow core door, with a layer of 1/2" MDF on each side. Hollow core doors are torsion boxes, and they're cheap, if you can work with their limited size selection. The only problem is that their skins aren't very tough, but the 1/2" MDF should fix that.
Second, instead of screwing a 1/2" sheet of MDF over the top, to provide a sacrificial work surface, I used a sheet of hardboard that's simply held in place by raised lips of MDF screwed around the edges. I vaguely remember reading about this idea, decades ago, but I don't remember where.
Because my basement floor is uneven, I also put levellers in the the legs.
Step 1: Laminating the Door
Hollow core doors have very weak skins. This is intended to be an assembly table, not a workbench, so it's not going to hammered or chiselled on, but I needed something tougher than the bare door. My choice was a sheet of 1/2" MDF, top and bottom. I'm using a 24" wide door, and MDF comes in 49" widths, so simply ripping one sheet down the middle gave me what I needed - and the home store was happy to do it for me.
Laminating sheet goods is simple, if you have a vacuum press. If you don't, you make do with clamps and weights. Once done, route the edges of the MDF to match the door. (This makes a lot of very dangerous dust - wear a mask and use whatever dust collection you have.)
After you've laminated a sheet of MDF to one side, and routed it to fit, flip everything over, and do the same with the other sheet of MDF.
Step 2: Building the Legs
Norm Abram's plans specify different widths for the various parts of the table that are made from 3/4" ply, The two pieces that make up each leg, the skirts, the aprons, etc., all have specific widths specified in the plans.
I'd misplaced the plans. So I just ripped a piece of 3/4" ply into 4" wide strips. I don't have a table saw, but I had joined Twin Cities Maker, and hence had access to The Hack Factory. Their panel cutter was out of commission, waiting for parts, but they have a very nice cabinet table saw.
I cut them to length with my circular saw and the cutting guide I made, back when I made my workbench.
Each leg consists of a pair of 3/4" ply boards, joined at a right angle. Norm used glue and a biscuit cutter, to join his. I don't have a biscuit cutter, and I couldn't see enough future products to justify the price, so I used Kreg pocket hole screws, and glue.
After I'd drilled the holes, but before I joined them together, I rounded the corners with the router table extension I'd made for my workbench.
Kreg makes a 90-degree Corner Clamp, that works well when you're making joins like this. Without a clamp of some sort, the screws tend to pull the joint slightly out of alignment.
Step 3: Adding Levelers to the Legs
My basement floor is anything but level, and if I expect anything with four legs to sit level, I need to add levellers.
Norm's design lacked these, but they seemed to be easy enough to add. Or they would have been, if I'd been more careful running the table saw, when I ripped my boards.
I wanted to add a square piece, filling the angle at the end of each leg, through which I could mount my levellers. I'd not bothered to make sure the blade was set square, so my edges weren't quite square, and hence the two parts of each leg didn't join at exactly a right angle. So my "square" pieces needed a little bit of work with a block plane. Once I had them fitted, I glued and screwed a couple of pieces of scrap, to provide support, then glued and screwed my end pieces.
Then it was just drill a hole and mount the leveller.
Step 4: Popup Caster Assemblies
I've never been much of one for measuring. It seems that when I rush things, I'm inaccurate. When I take the time to measure precisely, it turns out I was measuring the wrong thing. So I like to lay out pieces physically, when I can.
The feature of Norm's table that I found most fascinating were the casters, which he'd mounted to a hinged board that could be held down so that they took the weight of the table, or rotated up so that the table set on the feet. I was determined to include this feature in my table.
Calculating the proper positions from measurements and diagrams seemed like too much work, so I just put all the parts together in the way that seemed best, marked, drilled pilot holes, then screwed everything together.
Step 5: Mounting the Legs
I mounted the legs to the corners of the table, using glue and screws.
With the legs in place, I mounted the caster assemblies, and the positioned the long stretchers so that the braces would just fit.
Next, I cut aprons to fit between the legs, around the top, so that the edges of the table would be flush.
This is a work table, I don't much care about finish, but unfinished wood picks up grime, so I added a quick coat of danish oil to fill the pores.
Finally, I added some hooks and eyes, and some parachute cord to make it easier to manage the braces.
Step 6: The Sacrificial Hardboard Top
I wanted a top I could glue on and paint on, which means a top I can replace. Norm's design used a sheet of MDF. I thought hardboard would work better.
First step in adding the hardboard was to route the high points of the legs and the aprons so it would lie flat on the table.
Then I clamped a piece of slightly oversized hardboard to the top and routed the edges so it would match.
Next, I cut some strips of hardboard, screwed - but didn't glue them to the aprons, then routed them to match the top of the hardboard. In the end, the hardboard top is held in place mechanically, without screws or glue.
Finally, a couple of coats of danish oil and beeswax.