let see i have a 1.5(spindle):1(motor) ratio so to get 4000rpm on the spindle i need ~2666 rpm on the motor. the motor runs 3600 rpm @ 60 Hz so 2666 is about 74% of 3600 so my frequency ought to be around 44 Hz. i have my VFD limited to 4000 rpm (you can limit the vfd by frequency or speed) so that would be about 66.6Hz my spindle speed at the frequency is 6000 rpm same as before . as for the max Hz on the VFD I think it says you can set it up to 999 Hz but it will not be stable and suggests that your max should be in the 300-400 Hz range if i remember correctly.
in the inverter i remember you could set the amount of slip, and overload torque. i always had the colombo at 20% overload cause it would get very hot at anything higher.
in ay case, i have $199 for the ironhorse motor. ive found an equal westinghouse motor, just cause its local. i expect it to cost more, but hopefully still acceptable. $283 for the delta drive. $221 for a 4" air cylinder, $20 for disc springs... we have solonoid valves lying around the shop.
just need a nice drawbar, pulley and belt set, TTS collet, and a few other bits and ill have a 7/10k rpm spindle with ATC ready to rock.
i also need a new X ball screw. the previous owner damaged it and it has .013" backlash due to damage bearings. i found a nice ground C5 thk model that will fit for $329.
perception is a funny thing...
i measured the novakon nm200 motor. its basically identical to the one i was ginna buy. its even 3600rpm. gah.
so, the key thing is that i wont gain any space. i have only 1.25" from the drawbar to the motor. grr.
at least i dont have to buy and ship a new motor though
i wonder what i can rig up to make more room. i could leave the stock pulley setup in there and make a separate 2:1 pulley kit on a platform pushing the motor back.
anyhow, ill make me a new thread for the nm200 overheal
the series 1 nm200 uses a 4 pole 1760rpm motor that they are running in the 120-140hz range in order to get 4000rpm. my motor runs at 4002rpm bang on. if you are not getting 4000rpm, test your BoB. it should be reading 10v when programmed for 4krpm. if not, adjust the trim pot until you get 10v, and you should have 4krpm. if not, then they may have set your vfd up different as perhaps your mill is earlier then the ones they advertised as 4krpm, but getting it is as simple as setting the max hz higher. also, check your motor tuning parameters. now that i have my mill running correctly within mach3, i have my step and dir set to 2us(this affects spindle motor tuning) with it set to 2us, i set the steps per to 1000 and accel at 1500. i get 4k rpm max and all other settings are within 25rpm. i am going to use the WEG motor that dynoray used. it is an aluminum frame 3hp 2 pole motor (3600rpm at 60hz) that can easily be run up to 7200rpm, 6000 no problem, and has all the same dimensions as my current motor, so the pulley and everything will transfer right over, and it will bolt right up as it is the same frame size and everything. then i can run 1:1 ratio as i currently have, and get 6k rpm with very little work or modification. i think my current vfd(sunfar c300) will run it just fine, just have to figure out how to change the max hz. i will be running the same WEG aluminum frame motor in 1.5hp flavor for my new nm-145 i have on order. the cast aluminum motors are much lighter then the cast iron. 29lbs for the 1.5hp. i will probably run a 1.5:1 ratio and set it to 8k rpm max spindle speed, so 5333rpm at the motor which it can do all day long. i will rebuild the spindle and use kluber grease to ensure the spindle will live at that rpm, might even send the spindle out for a regrind and balance to true it up.
well if they used the same motor on your machine as mine. i googled the part number on the motor tag (yvf2-90l-4) and that is the info i got from it. to get 4000 rpm out of that motor you would need 133.33hz not including slip. 133.33 hz on a 2 pole motor would yield 8k rpm. set your vfd to 100hz max, and you will get 6k rpm which the WEG will do no problem. you will go from 2hp to 3hp(current vfd is a 3hp or 2.2kw model) and a lighter weight motor which is always good for the stepper. shaft size is the same, and the frame size is the same, so should be able to slap your pulley on there, and bolt it in. i think you will need a face mount kit which dyno ray reported to be $18. the motor itself is about $375, a little spendy, but wouldnt be nice to have a high quality motor up there? plus it is the cheapest and certainly easiest way to get there all in. the 1.5hp motor is only $210 for reference.