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Harold Hall

Metalworking

Workshop Projects

The variable stroke mechanism (5) as seen in photograph 19 could be replaced with a single disk of steel having holes at different distances from the centre enabling the ball race position to be modified and thereby the stroke length. Do note though that there is no room above the ball race for the head of a fixing screw so the screw would have to be fitted from the rear and with counterbored holes. The major disadvantage of this suggestion is that the machine would then need to be partially dismantled to permit the adjustment to be made. As the design is presented adjusting the stroke length is very easy.

 

The other possible simplification is to mount the variable stoke mechanism onto a mandrel that is mounted directly into the three jaw chuck eliminating the Input Drive Spindle (2).

This would necessitate the machine being packed up on the lathe bed or the posts increased in length. If this method was employed then the simplified variable stoke mechanism would be a more practical proposition. For me, the disadvantage of the arrangement is that it moves the machine back over the bed and into a less comfortable operating position. Incidentally, the Input Drive Spindle is included in the design as it is an essential item if being belt driven from a separate motor.

 

I subsequently decided to include a hold down feature to prevent the work lifting and this starts on the next page.

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