Just thought I would throw out a heads up for something I found. Still trying confirm it at all rpms but it looks consistent so far. I discovered this while looking at some full sized mills and their belts systems and rpms.
I have the newest motors on mine at this time, the new ones that drove the cost up. They are 1400 rpm at 50hz. As you know you adjust the little dial by Hz to change speed. If you are like me you make a little chart and stick it next to the dial so you can see the actual rpm.
Knowing the rpm is obviously critical for working out SFPM on both lathe and mill operations, drilling also of course.
So I read the little tag on the motor itself and was looking at the 1400rpm at 50Hz, (not 1500 at 75Hz as the manual says that was the old motors). Then looked at the power 1.1kw or 1.5hp, not 2hp. This cause some emailing back and forth until it was cleared up. Now all their marketing and ads specify the 1.5hp true number. It's not lower than the old 2hp, the new motors are 100% efficient (hence the price bump), whereas the old 2hp where only 75%. Both made the same power, but the Chinese didn't understand the marketing aspect of the change. All fixed now so no big deal.
Anyhow as I was looking at the motor and the drive on the mill I realized that the pulley's where not the same size. So if the motor is turning 1400 rpm the mill won't be the same. Larger pulley on the mill so slower actually. The 1400 rpm is the advertised number so thought I should do some checking.
After measuring the pulleys I came out with a ratio of 1.74:1 for the mill. I then ran the motor at the first few Hz where I could actually watch a large mill end rotate and count the turns. It's was consistent at all the speeds.
For instance at 3Hz which should be 84rpm at the motor (1400/50 = 28rpm per Hz, 3x28=84). So I counted 49 at the actual mill end. 49x1.74=85rpm at the motor, or basically exactly as it should be for the Hz. I don't have a tachometer to test higher speeds. Looking around for one.
So now I need to redo my whole table so I can figure out my SFPM correctly. Also need to take the side off and do the same math for the lathe motor and pulley's and see if they are the same or some other ratio.
Obviously the CNC ramifications as far as threading and such or CNC spindle control could be large although I think the pickups for the signal are on the spindle pulley itself not the motor so might be ok. Haven't actually taken the side off to look.
Might have to have another fix it on the advertised motor speeds. Will drop a line to JT and fill him in at some point but I figure I can't be the only person of the last shipment to figure this out so I assume he is aware of it. Just thought I would throw out a heads up for the new owners.
EDIT: I know this is not specific CNC related but if there is a Shopmaster user forums I don't know where it is. The official one looks like it gets posts about once a year so not really thinking that is very useful.