Harold Hall

First Page

With care, relatively heavy machining can be undertaken with just a single clamp and some support pieces. It is though essential that these are positioned to oppose the forces created by the cutting action. In Photograph 9, the rotation of the cutter will attempt to force the part towards the bottom of the Photograph and if a sufficiently wide cut is taken, to pull the part from under the clamp. The two supports being positioned to resist these forces the task was undertaken without undue concern, even though there was a fair amount of material to be removed and relatively heavy cuts were taken because of this. You may consider that this would have been a natural candidate for using a vice but this method was just as quick as adding the vice to the machine table.

Photograph 10 shows a part requiring a recess to be made around three sides and illustrates that clamp bars make excellent supports. They are essential for supporting a part across the width of the table as their slots provided the adjustment to suit the width of the part being supported.

Compact clamps

Another form of bar clamp that I developed, initially for use on the lathe’s faceplate, is also very useful on the confined space of an angle plate, as Photograph 11 shows. Details of these can be seen on my web page relating to the method, do view the drawings on that page (Sk.1, 2 and 3)

However, note from the photograph that I have again incorporated a fence into the assembly and am sorry to keep referring to them but they do make it easy to position the part for machining, even in the case of a one off.

Step-less Clamps

Step-less clamp is the name given to this form of clamp in my catalogue but I am sure that other suppliers will have other names for them. Their main feature is that they avoid the need for packing, achieving this by virtue of their shape. Whilst they are made in a number of forms they all work on the principle illustrated in Sk. 1. They are also made to suit a number of stud sizes, but with 12 mm appearing to be the smallest are best suited to heavy duty applications. In the case of the 12 mm size the maximum height clamped is around 40 mm, though this can easily be increased by adding a substantial packing block at the non workpiece end.

Metalworking

Workshop Processes