I have had a Multico PM12 for over twenty years and it has faithfully served me both for mortising and as a drill press. My workshop is not big enough to fit in both.
Very recently I needed to use a 45mm diameter Forstner bit to cut 12mm deep recessed holes into solid oak. I tried this in the mortiser and this works OK for a few seconds (say 2mm depth) but after that it gets too hot and burns the sides of the hole being cut. I can cut them very slowly letting the bit cool down but with 24 to cut it takes ages. If I cut for too long, cleaning up the burn marks is very time consuming and difficult, but a drum sander in a electric drill does help.
This burning is obviously because the mortiser speed is around 2500 rpm which is ten times too fast for such a large diameter bit (250 rpm max for 45mm Forstner bit in hardwood).
Does anyone have any experience of using an AC frequency reduction device to slow such a machine down. If so can they recommend a make and model. How slowly would I be able to run the motor and what would the current increase to?