Eventful morning....

Did some paying jobs, then started messing with the BP, it turns out I have the 1.5Hp / 1450rpm motor :( and top speed is 3500rpm although the vari-speed won't turn past 3000 or below 500 so I'm guessing something is wrong inside the head for a start.

I tweaked the VFD a bit, luckily the front panel pot was still programmed as speed source - it was just set at 50Hz.

After a few tests I finally set max to 100Hz and min to 15Hz, it was on default 25-75Hz.

The head was then wound to 1450rpm so it was at 1:1 ratio. Using the VFD this gave me a range of 430-2860rpm in high and 52-346rpm in low.

I made a test cut on one of the batch parts I was making earlier - these are moly steel and use I use a 1/2" HSS tool at 450rpm, I'd made loads so I knew what the machine sounded like when running them and there was no noticeable difference. With the tacho on the spindle while cutting the speed dropped from 450 to 420rpm but the chances are it did that anyway.

There are some issues up top as the sheaves are flapping like hell at speed.

I think a fixed conversion at 1:1 might be worth doing rather than repair the sheave bushes etc. At least that will give me the most of my meagre 1.5Hp at the spindle rather than lost in the pulleys.