Myford ML7 lathe leadscrew handwheel pointer

thingiverse

As an option, the revered Myford ML7 lathe can be outfitted with an engineering handwheel on the right-hand end of the leadscrew, a most valuable enhancement. With the carriage lever engaged, one turn of the leadscrew moves the carriage one eighth of an inch. The handwheel is graduated in 125 divisions, thereby moving one division moves the carriage one thousandth of an inch. The handwheel is readily available from numerous fine Myford parts and salespeople (check UK eBay) as well as other sellers, but it may not always come with the small plastic pointer block and fixing screw. This pointer block is molded from hard black plastic, and the cheesehead screw is believed to be 2BA of about five-eighths inch in length. It is thought that all ML7s have a pre-threaded hole for this in the bed just below the end of the front slideway and above the right-hand leadscrew mounting. This thing is a facsimile pointer block, originally drawn in QuickCAD then scripted in OpenSCAD, and was basically done as another learning experience in OpenSCAD modeling. To be honest, with my current OpenSCAD experience, I think it is not the most suitable solid modeling application for items that are chamfered or filleted. In this script, I used two different ways of producing the top and lower fillets: 1) Addition of adjacent small cubes then placing a cylinder 2) Cutting out a cube from a corner then placing a cylinder A more drawing-oriented approach used in other CAD programs would involve simply marking the corners or faces then applying the fillet, a much more straightforward operation than adding and subtracting solids. Ideally, it would be best to find an original pointer from a supplier but in a pinch this should work just fine. Although I have only printed test pieces in black PLA (at 100% infill), I think black ABS or PETG would be more durable. Instead of painting the white marker line and risking paint seepage between layers, the vintage vehicle restorer's trick of enhancing dashboard knobs and switches with a white crayon and rubbing off the excess should do the trick. The OpenSCAD script is included if you want to see how the pointer solid model is cobbled together.