Upgrade my spindle motor

[madmachinst]

Have V2XT CNC. Thinking about upgrading the Motor on the spindle.
Have a Mitsubishi 10 amp VFD running it so thinking of going with a 2.2Kw Black max Marathon motor. Model AVH-182THTL7726BBL. Name plate says that thing can safely go up to 5400 RPM which is an improvement over my existing motor. I was thinking that thing can safely be pushed beyond that limit for say 1/2 hr at a time max ? I was thinking 8000RPM at about 300Hz. Have a buddy who works VFD and motors at the oil fields in Midland Tx and he said the bearings in that motor will take it, the core that is another question. What you all think? I want to be able to run up to say 10,000 RPM on the spindle for those small 1/8" or smaller endmills and drills on the spindle so no need for a heck of a lot of torque. Gonna run it on my existing bearings till they go bad and then change out to ceramics.


Plan on getting rid of the speeder system and just use a solid 1.5:1 pulley drive between motor and spindle. Yes will have a lot of work to reconfigure the motor in there but I think well worth it. I will maintain the back gear system for high torque in the lower RPM's. Thoughts ideas?

 

[plastikdreams]

Try it and report back

 

[Milland]

I'm not qualified to say anything about VFDs, so here goes:

I think you'll need a more powerful VFD if it's just 10 amps, as presuming you're running 208V that's going to give a nominal ~2kw output, and I think you need some overhead available. So perhaps at least a 3kw VFD, maybe more?

One of the guys who actually knows this stuff will hopefully pop by.

 

[memphisjed]

Can the mills bearings take the rpm? Is the bull gear balanced enough? The only thing I wouldn’t worry about is the motors bearings.

 

[Billtodd]

You may run out of voltage at high speeds . Faster the motor spins the greater the back emf, so you need more volts to drive the current through the windings (also at higher frequencies the eddy current losses will start to mount and increase the heat generated) .

It might work for you, but typically anything over twice the speed, is sketchy.

 

[BT Fabrication]

why screw with what works, mill isn't ridged enough to put anything bigger on there anyways to utilize it.
2hp continuous is fine and push a little more for 3 hp, which unless you are taking a massive face mill to it, you will get more vibration then any hp limit.

 

[Jonathan Smith]

Over speeding a vfd has limits. Torque starts dropping after 60hz. There probably won't be much at 300hz. Better check specs.

 

[madmachinst]

I'm not qualified to say anything about VFDs, so here goes:

I think you'll need a more powerful VFD if it's just 10 amps, as presuming you're running 208V that's going to give a nominal ~2kw output, and I think you need some overhead available. So perhaps at least a 3kw VFD, maybe more?

One of the guys who actually knows this stuff will hopefully pop by.

Got 240 coming out of the wall.

 

[lr harner]

i have a VFD on my on my BP its 2HP rated i dont run it over 60hz tho. i am lucky tho cause my mill came stock with a 3650 rpm motor so top speed stock is around 5600. great for smaller cutters. i have a belt grinder that is also 2hp that i do boost Hz to 80 cause i dont want to bog my grinder when im really hogging off knife steel. i dont think i woudl ever bump to 120hz for either tool. my BP is a step pully drive while my grinder is direct drive. in the case of my BP i dont think the spindle woudl be happy at all at 8-10K speeds. i thought there was a spindle speeder thing that you can add to the the mill. more less you clamp it on the quill and put the belts on

 

[CarbideBob]

Why?
Something you read somewhere says this RPM or tool SFM better?
This spindle and bearings have design limits.