MODEL ENGINEER TIPS – USES FOR CLAMPS
David demonstrates how versatile a simple tool can be...
Toolmakers’ clamps (sometimes called toolmakers’ parallel clamps) are basically for ‘what it says on the tin’, clamping things together, but I have also found them very useful for work holding. They come in a range of sizes, imperial and metric, I have examples with 2-inch, 2½-inch and 4-inch jaw lengths.
First a tip for absolute beginners (not so long ago for me!) in the use of these clamps. The most important thing is to end up with the jaws as parallel as possible, otherwise the screws may become bent, and/or they will not provide the best clamping action. When I am using them I tend to tighten up the inner screw first, to leave them slightly off-parallel, then I do the final tightening with the outer screw to bring the jaws parallel, using a Tommy bar if necessary.
The other mode I use them more frequently for, is work holding. Sometimes with an awkward-shaped workpiece that needs some filing or whatever, it’s not possible to directly hold the workpiece in the vice. But by using a toolmakers’ clamp to hold the workpiece nearest to the work to be carried out, the clamp itself can then be held in the vice, providing a secure way of doing the job.
Photo 1 shows the cab of a 3½-inch gauge loco that needed some filing work, with the toolmakers’ clamp holding the job near to where the work is to be carried out.
Other jobs have necessitated the use of two toolmakers’ clamps, one holding the job, another, larger clamp holding the smaller one, and the larger one held in the vice.
Photo 2 shows the clamps being used on an loco axlebox that needed some grinding work to provide enough clearance against the valve gear. Here I could have probably just used the larger clamp, but I needed to hold the job a certain way up so I employed two clamps so I could then carry out the work satisfactorily.