@Pete. Thanks To be honest I am not sure what rpm I just go by ear I was aiming for around 200 rpm it's cast I am cutting not mild steel and I am not totally happy with what the rpm readout is telling me
I was just listening to the cutter rhythm and it seemed to be about 7-8 turns a second. If you can get that down to 1-2 turns a second it would be much better, or you can buy a cheap laser tacho for less than a tenner off eBay.
I have one fitted it's reading 550 in the video bought of eBay that's the top read out in red I will try and slow it down nextime but what I am finding on the mill is that if I try and run it to slow it thinks it's a overload and drops out thanks for the advice Pete