To gain the maximum benefit of having toolmakers clamps in the workshop I feel that
it is essential to have a pair of most if not all sizes listed below. I also think
sometimes, that in my workshop it would be good to have a pair larger than 150mm,
maybe 200mm, and readers who work a lot on large components may like to consider
Whilst budget priced clamps are available and not overly expensive at the smaller
sizes, making all the size suggested in the workshop is worth considering, especially
as it is a quick and easy task.
As they are one of the simpler items to make my comments will be brief.
Photograph 1 shows a set of conventional clamps, whilst those in Photograph 2 are
much less common, being made, as far as I know, by just one firm. Unfortunately,
they do not have a website that I can link the viewer to. They also only make smaller
sizes. Therefore, if you consider they would be useful in your workshop it is a
case of make your own.
Sketch 1 gives the main dimensions for a range of five sizes, 50mm to 150mm nominal,
for both types. I have also suggested alternative thread sizes, using either a standard
metric thread or the finer 32 TPI and 40 TPI model engineer's threads. Personally,
I prefer the finer thread as this makes it possible to just hand tighten the clamp
in many cases.
Another alternative to the more normal design that I would offer is to use the method
shown in Sk. 2 to make the central screw captive in the jaw, as this also would reduce
the work involved. The sketch also shows how simply the hole for the screw can be
positioned using a simple jig.
Making the screws from a single piece of bar will involve the reader in a substantial
amount of turning in reducing the bar to the thread diameter over most of its length
and then threading using a normal hand die. As an alternative, it is suggested that
a piece of studding is threaded into a separate head and fixed in place with a cross
drilled pin. Studding can be purchased in long lengths and the time saving will be
appreciable. Even if the model engineer threads are to be used lengths could be shop
made and fitted by the same means. This would still save time but not to the same