We asked Steven Roberts, the venerable “high-tech nomad,” best known for his net-connected, gadget-laden Winnebiko and BEHEMOTH bike projects from the 1980s, to write a series of articles on the amazing new mobile projects lab he’s building, dubbed Polaris. This tricked-out trailer will allow Steve to be ready-to-make wherever he parks, with all manner of maintenance, fabrication, and repair machines, tools, and supplies on-board. It’s a hackerspace on wheels. You can read the other installments of the series here: Part 1, Part 2, Part 4. — Gareth
Make it anywhere, part 3: Mobile lab fixtures
By Steven K. Roberts
This a continuation of the mobile-lab series (please see the Introduction for background). At the end of our previous installment, we had an insulated trailer prepped for use, ready to accept fixtures that will provide work surfaces and inventory stowage without falling apart on the first bumpy road.
Harsh environments like this are a challenge, although I’ve found it almost relaxing compared to building systems for the marine environment (water corrodes; salt water corrodes absolutely). The problem here is movement: lateral acceleration, high-frequency vibration, cyclic loading over time, and abrupt shock. Cheap office furniture will shake to pieces, inventory drawers need to be held shut, and high-mass items on moment arms will eventually fail.
Every mobile lab project will be shaped by the needs of its owner, so rather than any kind of recipe, I’ll offer a little smörgåsbord of methods that have worked for me.
The first challenge is simply finding suitable furniture. Forget laminate kits from the big box and office-supply stores; what you want is good stuff from the days when things were built to last. Pieces from grand old brands of the last century (Steelcase, Steelmaster, Cole Steel, and others) can be picked up at surplus places, auctions, and if you’re lucky, just for the effort of hauling them away from someone’s office renovation project. In my mobile lab (Polaris), steel units include an 8-foot steel work table, 5-foot standing workbench, file cabinets and drawer units, a gorgeous old desk… all of which work smoothly. The only large item that diverges from the theme is a hulking 10-foot wooden multilevel table that I got for free about 20 years ago, almost dumped because it was too hard to move.
The newfangled way to arrange all this, of course, is to model your space in Google SketchUp… but I just cut Post-It notes to scale and played with them and “Mr. Template” on a piece of graph paper until it made sense. However it shapes up, things start to get interesting when you drag the first piece of furniture into your mobile platform and have to figure out how to keep it in one place.
The Wells Cargo EW2024 trailer that I use has a plywood floor with steel joists underneath; it’s easy to crawl under there with a socket wrench. Many things (like the old workbench) are simple jobs, as long as they have legs or surfaces that can be mounted either directly or with angle brackets:
I similarly bolted down the air compressor (removing wheels and handle, then adding a block to level it), floor-mount drill press (3/8″ stainless bolts with acorn nuts on top), most of the steel furniture, the massive wood table, and a few minor items.
Attaching things to the walls gets a little trickier, with only thin plywood sheathing and steel ribs that you can hit with self-drilling sheet metal screws. I don’t trust this with significant loads, and suspect there may even be some flexion in rough conditions.
If you have a chance to specify E-Track when buying a trailer, by all means you should do so — it’s a standard with lots of readily available fixtures. An “industrial” rig like a container or big truck doesn’t need this, since you can tack-weld brackets where needed… but on a lightweight machine like mine, the additional wall structure simplified mounting throughout. Here’s a good example:
There are actually four instances of E-Track in this photo. The little ring hanging by itself at the left is used by a short webbing strap when underway, angled down across the drawer faces of the low cabinet to an eye bolt in the floor. The Honda generator (which moves outside to a shelf on the tongue when needed) is snugged against a foam pad on the wall by a strap that wraps around the unit and through the handle. The tall tool cabinet is likewise kept under control by a ratchet strap, and yet another provides a backup to floor bolting by wrapping around the 8-foot long bench barely visible to the right. Easy solutions are the best, and redundancy is cheap insurance.
I also use simple strapping to keep the folding Bosch table saw from wandering around:
This untidy bundle includes a small ladder and shock-corded roller stand in addition to the saw. That sloppy towel keeps screw heads on the wall from scratching the saw table (yes, I learned the hard way).
Atop that, by the way, is a folding work surface next to the drill press. The steel cables allow it to still be useful when the saw has been moved outside.
There were a few subtleties here and there, but the process of keeping furniture and other big stuff under control was mostly straightforward. But drawers, bins, and doors proved to be trickier.
Where possible, of course, I took advantage of existing locking schemes (steel desk, file cabinet, and the tall tool box). The wood desk has a drawer that’s easy to lock with a pair of screw eyes and a pin. But there are three major “inventory regions” that involved special challenges.
Large parts and some tooling clusters live in an array of 32 Rubbermaid bins that slide into homebrew shelving atop the 8-foot steel bench. To keep these in place on a hard right turn, there are eight wooden bars that lock in place with a protruding screw in the bottom (engaging a hole) and a hook and eye at the top. Simple, but solid:
Smaller but still bulky parts reside in a pair of steel cabinets with a total of 63 drawers mounted to my desk (and held to the wall by an E-Track strap at the bottom and bookshelf brackets at the top). This one was kind of annoying, and my preferred method involved serpentine line, pulleys, and cam cleats. But somewhere between gathering parts and drilling holes, I discovered that it would have to come off the desk for surgery… and being fundamentally lazy, I dropped back to a simple-but-ugly solution:
The spring clamps at the top are at their limit, and keep the strapped-on boards from wandering off at funny angles while helping with the task of keeping them in place. In the photo, you can also see the bookshelf… this continues another couple of feet forward to a bracket on the forward wall, and is mounted to the side wall by two very heavy brackets encapsulated inside foam-core veneer-skinned sandwiches (to be nice to adjacent books). A shock cord runs the full length, keeping the library from taking a dive on an abrupt tack to port.
But the most ambitious drawer-retention challenge was the Wall of Inventory — 755 small-parts drawers. Their cabinets are all screwed to the wall and tightly constrained between a top shelf and the base, but a hundred thousand or so bits of hardware would be a nightmare if they got out of control:
To solve this problem (and provide a useful brainstorming surface), I made a hinged 93×32-inch framed whiteboard with a couple of additional 9-inch wings that cover the cabinets above the speakers. This latches down with marine-grade slide bolts (which glide across the mounting shelf and drop securely into receivers with a satisfying clunk). When I need access to inventory, the whiteboard swings up and latches to the ceiling… and a little nacelle of leftover space handily holds the Metcal soldering station base unit. Here it is in both modes:
(Popping this open always elicits an “oooohhh” from lab visitors.)
The whiteboard itself is Melamine “tileboard” or “shower board,” which is around $10 for a 4×8 sheet at the big-box home improvement stores. It’s 1/8″ thick and very easy to cut, though the edges bump easily and framing is recommended. This stuff behaves well with standard dry-erase markers, but will eventually stain if you leave drawings for a long time. A proper whiteboard material of Ceramicsteel would be tempting for its magnetic properties and greater longevity, but weight and cost are issues.
The hinging structure was critical; in order to provide a stable and strong mounting edge, I had to bring a top shelf out from the wall. This ensures that the four hinge pins are colinear, and carries the static load of the whiteboard as well as any dynamic loads encountered on the road. It also provides additional support by encapsulating the stack of cabinets… they’re not going anywhere!
I haven’t said much here about shock-isolation, but that is an issue in mobile systems. Anything on a long moment arm needs particular attention; in my case, the item most likely to be a problem on a rough road is the drill press. This is getting a pair of angled struts to the wall, with slots at the machine end to allow occasional recalibration. At the small of the spectrum, I stabilize wobbly parts (like wire-lead electrolytic capacitors and inductors) with dabs of hot glue or silicone.
In that spirit, I got a little carried away with the base unit of the Icom 706mkIIg ham radio. This is made for mobile use, so my solution is overkill… but I already had a shock-isolated platform, just the right size, that once carried delicate circa-1990 hard disk drives on an early version of my BEHEMOTH bicycle. The rig now floats luxuriously on bonded-rubber Lord mounts atop a dedicated shelf near antenna and power resources (its remote front panel is at the lab bench):
So there’s a grab-bag of mobile-lab fixturing techniques to get you started. This is by no means complete, even in my case — I still have to tie off or other otherwise protect loose items ranging from the desk chair to lab instruments that I’m not ready to bolt down. All these steps are collected in a preflight checklist pinned to a bulletin board by the door.
Enough with the carpentry! In our next installment, we’ll turn to the power system… as much a “substrate” as the trailer itself.
- Make it anywhere with a mobile lab
- Make it anywhere, part 2: Mobile lab substrate
- Make it anywhere, part 4: Mobile lab systems