Harold Hall


Workshop Processes


Low Profile Clamps

Reference to an industrial supplier catalogue will show that there are a number of specialist clamps intended for the purpose of clamping relatively thin items to the machine table whilst still leaving the workpiece top surface free for machining, Photograph 16 shows a typical example.


The T nut itself is fixed firmly in place by the grub screw seen at the right hand end being tightened onto the base of the T slot to fix the nuts position. The head of the main screw is off centre from the thread and rotating it will, as a result of the head's cam action, advance the hexagon clamp piece to provide the clamping pressure. One advantage of these is that if a number of clamps are employed, irregular shapes can easily be held, as the clamping action does not need to be axially in line with the T slot holding the nut. However, for rectangular parts just two clamps will suffice when used in conjunction with a fixed jaw as seen in Photograph 17. Where batch work is being undertaken the clamps have the advantage of being able to cope with a fair range of variation to the size of the parts being machined.


Their main benefit is that they make some tasks easy that would otherwise be very difficult to perform without them, perhaps impossible. Photograph 18 show 5 types for construction in the workshop, see my pages relating to these for details. Of course, not all five types are necessary and the viewer can choose which one that suits his or her needs best. I would though suggest a minimum of four, all the same type or two and two.


The requirements for mounting workpieces onto the machine table are very varied and the suggestions in this article can only cover a small number of them. However, the basic principles will be the same for almost all situations so hopefully will help to give the workshop owner some confidence about even the most complex set-up.


For more examples of workpiece clamping see my pages on the

Alternative to the Four Jaw chuck. And  Machining Cast iron



Low Profile Clamps
Low Profile Clamps
Low Profile Clamps, 5 shop made