Soft jaws for your vice, cut to your jaws and your bars

Measure one steel jaw of your bench vice — how wide it is, how tall its face is, how deep its top is — and the thinnest and thickest round bar you want to hold. We cut a pair of plastic caps that drop over your jaws and hook on, with a sideways and an upright V groove sized so that, by our sums, every bar in your range sits on the sloping sides of the groove in both caps — below the edge, clear of the floor, with the caps still apart. Prints upside down, no supports.

What you need before you start

What it will take

Jaw width: 40–200 mm
Height of the jaw face: 10–80 mm
Depth of the jaw top: 8–80 mm
Thinnest round bar: 3–60 mm
Thickest round bar: 3–60 mm
Groove angle: 6 to choose from
Lip down the back of the jaw: 0–10 mm
Magnet diameter: 0–20 mm
Magnet thickness: 0–6 mm
Nozzle size: 5 to choose from
Filament: 2 to choose from

As it comes

Sideways groove, depth at its point4.69 mm

Caps still apart on your thinnest bar, at worst1.48 mm

Vice opening the caps take up12.1 mm

Filament for the pair, roughly68 g

Build plate: 107 mm as it comes, never more than 256 mm.

What you need to hand

A caliper or a rule for one jaw of your vice: its width, the height of its face and the depth of its top.
The thinnest and thickest round bar you want to hold.
Optional: the size of any round magnets you have.
Your nozzle size and the filament you will print it in.

The part, drawn to your numbers

Side cut through both caps as they sit on the build plate, top of each cap down — with the sideways groove

Drawn from the numbers in the form below, off the same geometry the file is cut from. It is not a photograph, and there is no photograph — every part that leaves here is a different size.

One jaw of your vice

Measure one steel jaw with a caliper or a rule; the two jaws of a vice are normally the same. The caps hook 5 mm down over both ends of the jaw.

Jaw width

Across the top of one steel jaw, end to end. The caps hook 5 mm down over both ends of the jaw, and that is what keeps them in line with each other.

Height of the jaw face

The flat steel face you clamp against, from the top of the jaw down to where it stops. The cap covers all of it, and the sideways groove sits half way down it.

Depth of the jaw top

From the front face of the jaw straight back across its top to the back edge — the part the cap rests on.

Lip down the back of the jaw

How far the cap hooks down behind the jaw. Measure how far the back of the jaw top drops before anything else on the vice is in the way, and use that or less. 0 means no lip: then the cap rests on the jaw by its own balance, or on magnets.

The round bars you want to hold

Rod, tube or round bar. Both grooves are cut for the whole range; the narrower the range, the more there is to spare.

Thinnest round bar

The smallest diameter of rod, tube or bar you want these to hold.

Thickest round bar

The largest. By our sums every size in between sits on the sloping sides of the grooves, not on an edge or a floor, allowing for printing error and for the caps sitting a little out of line. Out of line, a bar may bear on just one side of each groove, or on both sides of one and one side of the other; our sums do not say which, so we allow for either. A narrower range leaves more to spare.

Groove angle

The angle across each groove, 90° to 140°. A narrow groove is cut deeper and suits thinner bars; a wide one is shallower and suits thicker bars, and thin bars sink to its floor. If yours does not suit your range, we say which one does, when one does.

Magnets, if you have them

Optional. Round magnets sit in two pockets under the top of each cap, on the top of the jaw. Leave both at 0 for none.

Magnet diameter

Optional. If you have round magnets, their diameter: we add two pockets under the top of each cap, so the magnets sit on the top of the jaw. Leave at 0 for none.

Magnet thickness

The thickness of the same magnets. 0 when you have none.

The printer it will come off

These two are facts about your bench. Both start at the most common answer; change them to match your printer. The nozzle decides whether the thinnest walls print, which is why we ask.

Nozzle size

The nozzle you will print with. It does not change the model — it decides whether the thinnest walls come out the way we drew them.

Filament

Sets the weight estimate. It does not change the model.

Finer adjustments

Clearance over the jaw

How much bigger than your jaw the inside of each cap is drawn, front to back and end to end. Printed parts come out a little tight, so we need at least 0.5 mm; more makes them easier to drop on but lets the two caps sit further out of line.

More for the workshop

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A wall rack for the screwdrivers you already own, with each hole cut to its driver and spaced for its handle.
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A block with a row of holes for your drills, smallest to largest.
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A block of hexagonal pockets for screwdriver and drill bits, in the grid you choose, drawn from the bit you measure.
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