This is 4th modification of my lathe (11 x 26, bigger brother of Grizzly G0602).
In order to have the lowest speed of around 100 RPM, which is acceptable for threading operations (at least for me), I decided to make new, bigger spindle pulley.
Bought a piece of aluminum round bar, dia 180 mm, length 70 mm and made new spindle pulley. As mentioned earlier I expected to get around 100 RPM but due to the fact that the lowest speed was wrongly declared as 125 RPM, I got the lowest speed of 116 RPM. Even that is much better than original lowest speed of 147 RPM which I had earlier with smaller pulley and which I have used for threading. Little bit too fast and scary but manageable.
Pictures are here just to show progress of pulley making. New and old pulley at picture 07 for comparison. A lot more about pulley making can be found at youtube. Observe amount of chips at picture 11. Picture was taken near the end of this job. Little bit more chips were there at the end, but picture was not taken.
Also did not take pictures at the very beginning of pulley fabrication when bored
40 mm hole with boring head. Before that I drilled 10 mm hole at distance of 20 mm from the center. That hole was used later for the keyhole.
Found that picture and posted it below.
Hope that this info will help someone to find out what lowest speed can be expected by installing bigger spindle pulley.