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Harold Hall

Workshop Projects

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The right hand blocks are a close fit (with adjustment) on the column ensuring that there is no up and down movement at the milling cutter. In addition to the adjustment, a means of fully clamping the blocks onto the column is provided to lock the assembly in place whilst machining is taking place. The left hand blocks are there to prevent the cutter moving back and forward. If these were similarly a close fit on the column then the two columns would have to be exactly parallel. So as to cope with a very small error, I am suggesting that these blocks should be bored 0.2 mm oversize. When closed down using the adjustment, the resulting oval hole should help to accommodate very small errors in the spacing of the two columns.

 

Photograph 2 shows the parts that make up the column.

 

Drive Assembly AS2

Using a conventional drive to the spindle having a fixed top mounted pulley driving a splined shaft moving up and down, as used on a drilling machine, was considered. However, whilst more easy to visualise, it was considered too involved to manufacture (especially as the workshop in which it is to be made  is unlikely to possess a milling machine) and difficult to incorporate with the existing spindle. Photograph 3 shows how the route that the belt takes enables the head to move up and down without changing the belt's length. Due to a lack of space for taking the photograph a mirror is being used to show the route.

 

Spindle Assembly AS3

This assembly is fitted with single row angular contact bearings numbers 7201B and 7202B. In my original (described in the above mentioned book) I suggested that, in view of the light loading that the spindle was likely to see, single row deep groove bearings would also suffice. However, with the spindle now being used for heavier duties the angular contact bearings are preferable.

 

Mounting Assembly AS4

The parts for this are not dimensioned as they will be required to suit the lathe on which the milling head is to be used. The assembly drawing should make the requirements clear but I will add that I have added two disks to locate in the bed space rather than a parallel web as these will be easier to make to a precise fit.

 

Large Collet Chuck Assembly AS5

This assembly will enable screwed shank cutters up to a shank diameter of 1/2" or 12 mm to be used. An adapter is used to permit the existing spindle to take these collets.

Milling Head, Lathe mounted, parts.
Milling Head, Lathe Mounted, Drive arrangement.
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 2

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 3

Photograph taken using a mirror