Harold Hall

Workshop Processes

First Page

A smaller casting can be seen being held in Photograph 4 and there is little to added beyond what has already been said. The unseen jaw is clamping onto the casting's non machined face and one point worth adding is that always clean the surface to be clamped with a file to remove any locally high points.

Photograph 5 shows an example of using toolmakers clamps by a method that should be considered taboo, well in almost all cases, that is using just the outer few millimetres of the jaw to clamp the parts. At first it may be thought that the clamps, one can just be seen on the left of the photograph, are part of the assembly that holds the large casting to the vertical slide, this is not so. The casting is in fact solely held using the two plates, seen top and bottom, onto the vice's keep-plate rails. The two toolmakers clamps are there just to hold the vice's moving jaw in place so that its base can be very lightly skimmed to the same level as the keep-plate rails.

Used for Drilling

Photographs 6, 7 and 8 display a single clamp being used but acceptable as the operations taking place are only light duty ones. The reader may though understandably ask why use the clamp, why not place the parts directly into the vice? There was though three sets of two parts all requiring a hole to be placed at precisely the same height from one surface. The post, best seen in photograph 6, was held in the vice and used as a locating face for all six parts ensuring that the hole in each one was in the same place. The vice is of course fixed to the drilling machine table so that it could not move.

The hole was first positioned in each one using a centre drill (7) and then replacing each one in turn drilled to size (8) making 12 operations in all. The process ensured that the holes were all in the same place and lined up perfectly for the second operation.