I have followed the advice of everyone on the Yahoo 9x20 lathe group and made my compound 4 bolt plate. This replaced the very weak 2 bolt plate that comes with the lathe. As you can see I also added a 2" dial indicator. This attaches to the ground ways, and can be moved out (right) for use and back (left) when not in use. I need to get a larger 3 jaw chuck to hold larger diameter projects. I need to buy a blank chuck plate and thread it to fit the M39x4 metric spindle. Next I will need to make a crank handle for the spindle. This will make single point threading possible.
Before I could start making my back plate for the new chuck, I needed to be able to cut threads. With this lathe the best way to cut single point threads is to make a crank handle. My crank handle was made from 1-1/4 x 1/8 thick steel bar. I drilled and tapped two holes in the aluminum spindle pulley and used standoffs with allen head screws to attach the handle.
I also created a counter-bore that fit the spindle shaft and was 1/16 deep with a through hole. This allowed the steel bar to be supported at three locations.
This setup was with the old motor and pulley setup. I have removed this and added a varaible speed DC motor to replace this. See "More modification" below.
To the right you can see my setup for cutting 4mm threads. Use the setup to make 3mm pitch threads but substitute an 80t gear for the 60t one specified in the setup. My 80t gear has a flange on it so I could not use the keeper washer. Just keep an eye on the gear to make sure it stays in place when you start to crank out the threads. To sum it up again.
Position A= 80 tooth gear meshing with the large 127 tooth gear.
Position B= 30 tooth gear meshing with the smaller 120 tooth gear.
Selector handle in position 1.
Last make sure to use the thread engagement lever that is below the Y-axis feed screw.
Do not use the feed lever which is near the bottom of the carrage.
<--------- It is in the down position now and locked to the feed screw to make threads.
The first item I needed was an M39x4 threaded shaft. I would need this to test fit my female threads in the backplate. This was made from aluminum. I kept increasing depth of the threads until it fit into the face plate that came with the lathe.
Now I was ready to start on the blank back plate.
Here is the back plate threaded on the spindle. Once I got it here I could true everything to the spindle. I then turned the large OD down to 6.250" I faced the plate to get the thickness I wanted. I then added the step that fit the Bison chuck per there recomendation.
I drilled the bolt circle by using my Mill. and am now adding the locking hole so I can use the locking screw and clamp.
Well here it is all finished and ready to go. It fit like a glove on the back plate.