The Virtue of Vices

The Portable (??!!) Workbench, equipped with twin screw chain linked vice

A dissertation on Stopping Things Moving, and the Virtue of Vices…

One thing I discovered when teaching martial arts was that when an impact technique moves a person around, it substantially loses power and accuracy. This led to a principle I apply in many areas, which I call ‘Apogenik Circuits’ (for more on Apogeniks see http://www.apogeniks.com).

An amazing amount of power is absorbed in ‘pushing’ a person with a technique, which is generally a useless drain. Thus the ingenious forms of martial art use a rather harder to master method called ‘reverse hip’, which projects the limb at high velocity like an arrow from the string, and transfers energy to the target as a percussive wave, without moving it – like dropping a pebble in a pool, or striking a drum.

When I started working with wood, this issue of not moving things around became a preoccupation. What I found was even a small amount of spring or racking in a bench had a considerable impact on speed of work and accuracy. For example, if cutting with a chisel resulted in a small deflection in the bench structure, the point at which the cut actually happened would be unexpected.  Further, there is a tendency to push harder, to overcome the spring, so when the cut actually happens the resistance to the spring goes, and the bench boings back.  The result is inaccuracy and unnecessary effort.

If the workbench structure is completely rigid, the amount of spring is negligible and the cut happens precisely and under perfect control. The energy of cutting goes into the cut, rather than deflecting a spring.

So in working accurately, possibly the most important aspect is first of all to immobilise the workpiece, and reduce any ‘slack’ in the circuit between me and the immobilising structure. Metalworkers know this, and require great rigidity in their machines. Slack in (for example) metal lathes will produce vibration, leaving a chatter pattern on the workpiece. Something similar happens when planing wood in a wobbly vice, where the plane chatters and sticks as power is repeatedly sucked away and then sprung back. Unwanted oscillations of all kinds come from a similar principle – something is ‘slack’ in the circuit, acting as a spring.

A decently equipped workshop will have a good workbench that has minimal spring, good mass and is bolted to the floor. The vice will be a serious affair, securely held to the bench. The happy woodworker using such a device will be pleased to note how easily his plane functions, how swiftly his saw cuts, and how thin and accurate are his chisel parings.

But here is the problem. What if one is *not* at the workbench? What if one is obliged to shift location, to move the work area to the project, like working on a boat?

The Knock Down Bench

One of my past projects was the knock-down workbench.  But this takes up a bit of floor space, and is impracticable on board a boat.

Sjobergs SmartVice – not bad, but too small (I felt)

About a year ago I saw the Sjoberg  Smartvice.  The idea was good – a clamp-able vice with small worktop.   But I felt the vice was too small, the mass of the whole thing was too low, and the table was only about a foot square. Was there a way of translating my twin screw ”knock down’ vice into a similar portable format?

Well I happened to come across a second hand but unused Veritas Twin Screw Vice kit on ebay for a song, and snapped it up.  And it has been sitting in my workshop waiting for an opportunity to build my version of the portable workbench.

Veritas Twin Screw chainlinked Very Nice Vice kit.

The Veritas twin screw vice is a serious and very nicely made piece of kit – two long 1″ screws linked by a chain, heavy cast iron fitttings. And the finished version of my bench ‘grew’ out of the vice specifications.

I spaced the screws at 16 3/4 inches, the maximum for the chain size, and ended up with  a 23″ wide vice, 6 inches high.  The front face is 2″ thick, the back about 2 1/2.

As a base I used a piece of very good quality birch plywood, and for the table and table supports I used 40mm thick keruing – tough, dense, heavy, and plentiful, as I have a large pile of it!

When I build things I have a preference for putting minimal load on fastenings.  This can usually be accomplished by decent joinery.  For this job I decided to use shallow housings to locate the components. These housings would take any sheer forces and torque between the clamped baseboard and operations on wood held in the vice.

Rear view, you can see the housings for the table supports

The two perpendicular table supports were housed into the birch ply and held there by screws, and also into the rear vice face and the work surface.  The worksurface was glued up from three pieces of keruing, and housed into the rear vice face. The work surface was coachbolted to the rear vice face, and also the supports.  The ply extends to the front of the rear vice face, so the front vice face is free to move.

Then I drilled the front face of the vice and the table with 3/4 inch holes to take bench dogs – I happened to have some Veritas ones from long ago, some of which have a neat screw, useful for clamping irregular shapes.

Finished table, sporting fancy Veritas bench dogs.

The resulting table is 23 inches wide and 17 inches deep (including the rear vice face), and just over 1 1/2 inches thick.  The vice is excellent, with good depth (6 inches) and a substantial gap between the two screws.  The gap between the base and the work surface is enough for a hefty clamp to fit easily (I use the Irwin variety).  And in all it weighs about 25 kilos!

Obviously it will be necessary to adapt it to each situation – some places it can be clamped, in others maybe temporary bracing will be needed to secure it.  I will have to see…