Harold Hall

Workshop Projects


Drilling the six holes around the outer face can be done using a hexagon screw or nut for indexing.  This is held in a vice which is fixed to the drilling machine table in such a way that the hole is drilled in the correct position, using first a centre drill and then a drill of the required diameter.  As the grip on the hexagon will not be sufficient support the part being drilled by a suitable block of metal placed below it. Photograph 6 should make the whole process clear.


In the case of the Securing Nut (3) an M6 screw and nut will suffice, for the Head (4) take a large nut and turn a short spigot on this to fit in the 16mm bore. This can then be held in the part using an M6 screw and nut, see photograph 6.


Finally make the recess for the Clamp Pad (2) and drill and tap the hole M4. On the basis that the Back Stop is being made without access to a milling machine and that a vertical slide is also not available the following method will overcome the limitations quite easily.  Even so, such operations can still be rather fiddly but the following method, if unconventional, largely overcomes these problems.


First mount the part onto the angle plate the only consideration being that the area where the recess is to be made is available and not covered by any fixing clamps, for ease this can be done away from the lathe. The angle plate is then fitted to the cross slide but rather than directly as is normal, space this up above the slides surface using studs and nuts, Photograph 7. This assembly can then be raised and lowered so as to get the recess in the correct position. It would be a little tricky to measure if the position of the recess was critical but providing it just clips the central hole that is all that is necessary. Photograph 8 shows the process, in this case though it is for the Setting Piece (2). The purpose of the recess is to take the Clamp Pad which prevents the Stop Bar (6) being damaged by the ends of the clamping screws, see Photograph 9. The Head can now be secured to the Body using a two part resin adhesive.


The reader may be uncomfortable with the method of mounting the angle plate shown but I can assure you that it was more than adequate for the machining being carried out and would therefore be capable of much heavier machining tasks. If also a rectangular component was involved it would be very easy as measuring the result would much easier than with the round component in this article.