An advantage of making ones own is that they can be economically made in a wide range
of widths and lengths. Photograph 3 shows some typical clamps and would suggest a
minimum of 4 of each size made. Also shown are some T nuts, also shop made. Of particular
interest are those on the extreme left and right, front row. These it will be seen
are tapped off centre and provide some flexibility in the positioning of the stud
providing greater reach or spacing. This I find gets me out of an otherwise difficult
situation where the limited size of the average Mill/Drill table can sometimes make
mounting the workpiece, or larger machine vice, more difficult than anticipated,
occasionally, even impossible.
I am not including dimensions but obviously the thickness should be greater the longer
the clamp. As a rough rule, up to 50 mm long 25 x 6 mm section, 75 mm long 32 x 8
mm and over 75 mm long 35 x 10 mm.
Studs will be required in a range of lengths but suggest you standardise on a thread
size of M8, or say M10 if you have a large size machine. When I purchased my machine
and making my own T nuts, I equipped it with both M8 and M10 sizes, the latter now
Studs are one area where I consider it worthwhile you purchasing your requirements
as they are not overly expensive and would suggest at least four of each length,
normally 63 mm, 100 mm and 160 mm. Alternatively, a length of studding could be
purchased and cut into lengths. In this case, take a pin punch and distort the threads
on the underside of your T nuts. This will prevent the stud passing through and hitting
the base of the T slot. The commercial studs have a short length of thread at one
end and a plain portion then a longer thread at the other. This prevents the stud
passing through the T nut.
Much has been written regarding the principles of workpiece clamping and I am therefore
going to keep my comments very brief.
1. The packing must be slightly higher than the workpiece.
2. Arrange the clamping stud nearer to the workpiece than to the packing wherever
3. Do not use a single clamp unless the task is a light duty one and that the workpiece
is further restrained by supporting pieces. At least two and preferably three clamps
should be aimed at.
4. The clamp must be thick enough to prevent it noticeably bending.
5. Do not use an unstable pile of odd size pieces of material as packing.
6. When using slotted clamp bars do support the nut with a heavy duty washer, say
25mm diameter by 3mm thick for an 8mm stud, rather than standard washers. This equally
applies to fixings in angle or face plates.