HackSpace – September 2019

FORGE

You can make your own soft jaws, or buy them
ready-made for popular brands of vice. You can also
buy ‘universal’ soft jaws that fit onto existing vice jaws
using magnets or tape, although these are less secure
than replacement jaws that bolt onto the vice body.
Clamping tube or hollow stock is tricky, and you
really only have two good options to avoid deforming
the part. You can either use shaped jaws that match
the profile of the object you’re working with (a
dedicated pipe vice is an example of this), or you can
increase the rigidity
of the part before
you clamp it by filling
the hollow part with
something solid. Musical
instrument repairers
sometimes use low-
temperature plastic as a
packing material in brass
instruments. The plastic
is heated, pushed into
the desired section of
the instrument, and then
allowed to cool. When
the repair is finished,
they warm up the plastic
again and remove it.

DOGS AND COOKIES

Holding work flat onto a surface poses a different set

of problems, particularly if you need to work all the

way along the edge of the material. Clamps are an

effective strategy in some cases, but the jaws of a

clamp can get in the way of tools you’re using. If you

have a workbench, it might be worth investing in some

bench dogs. Although the name might not be familiar,

you’ve probably seen a bench dog before on a portable

workbench. Bench dogs are the small stoppers that

fit through regularly positioned holes in a workbench

and butt up against the edge of a piece of wood

to stop it sliding around. You can make these quite

easily with a 3D printer, or by gluing a piece of dowel

into a wooden block. Bench dogs won’t stop your

work from flipping upwards, but they will keep it in

position on the table when you apply a lateral force.

Above

A pipe vice typically

has different-sized

inserts that let you

hold different sizes

of pipe. They’re

relatively cheap and

are very useful if you

work with lots of

hollow stock

Silicone mats or

baking grips are

useful for holding

and moving hot

metal objects.

QUICK TIP

Left

This work area is

drilled with holes that

accept bench dogs

and holdfasts. It can

be removed from

the workbench and

replaced with a blank

piece of wood when

it isn’t needed

Threaded bar, bolts, and machine screws are very

difficult to clamp effectively without damaging the

threads, even if you are using soft jaws. Last month we

looked at how to make a stud clamp for just this

purpose, but another option is to use a split nut. To

make a split nut, you will need an ordinary nut with the

same thread as the workpiece that you need to clamp.

Hold the nut in the vice with one of the high points at

the top, and cut down to the middle with a hacksaw,

parallel to the direction that the bolt fits. Clean up any

rough edges, then screw the nut onto your workpiece.

Tightening one or more of these nuts into the vice with

the cut part between the jaws will deform it slightly,

gripping the threaded bar firmly without damage.

SPLIT NUT