Mill motor recommendations and sources

[mariner3302]

Because I don't really understand this - instead of the 2hp motor I linked to above, what would going to a 3hp of the same specs do? Same speeds, doing belt changes, and a vfd. Curious what changes other than torque and what is the net benefit or drawback?

 

[mksj]

Typical convention would be to go with an 1800 RPM motor and overspeed to 120 Hz. Torque is constant below the motor base speed of 60 Hz based on the constant torque ratio of that model. A typical "Inverter Rated" motor would have a constant torque ration of 10:1 so down to 6 Hz, although Hp drops off in a linear fashion below the base speed. Above the base speed Hp is constant out to 1.5-3X the motor base speed depending on the design and specifications. Torque does drop off in a somewhat non-linear fashion above the base speed, but in a mill this is not an issue because you are turning a smaller cutter. If reducing the speed via belt/gears, then you are compensating for the lower motor torque through the ratio of belting/gear drive (mechanical advantage). If you look at factory VFDs on mills they use 1800 RPM motors and overspeed them, such as on my mill which the motor covers 20-200 Hz with a direct belt drive and just a back gear.

As far as motors, I would suggest either a 2 or 3 Hp inverter rated motor, it really depends on the size of your current motor, the shaft size and the mount. Many mill motors have an extended shaft and often a unique mounting bolt pattern, so it may be difficult to get a drop in replacement. I would remove the current motor and see the current shaft dimensions and mounting flange. You will want a flange mount motor either TEBC or TENV. A vector motor is an inverter motor that is designed to only run off of a VFD, they have much higher top speeds with full Hp rating, and also a constant torque ratio of 1000:1 or better.

This is a motor that I found for another person who is going to use it in a lathe, he offered $250 and it was accepted. This is a $1200+ motor, it is also very heavy but it is a a 182 frame which is the same as a 184 other than the foot mounting hole locations. This would be a hard motor to beat, but it is a beast being over 100 lbs.

Allen Bradley Bulletin CM202-FC00318AXZCC Vector Duty 3 HP AC Motor NEW NIB | eBay

Constant Torque 1000:1 Speed Range (0 to Base Speed). FASTRAC AB MOTOR NOTE. Synch Speed. Torque Speed. Final Descriptor. C-Face Foot Mounted. Mounting Options.

www.ebay.com

A Teco L510 (3 Hp) are inexpensive and work fine for mill use. There are several "US" vendors that also provide support. Dealers Electric also has decent surplus motors and sometimes some motor VFD combinations.

Teco-Westinghouse, L510-203-H1, 3 HP, Variable Frequency Drive 230 Volt, 1 Phase Input, IP20, at Dea

Purchase Teco L510-203-H1-N 3 HP Variable Frequency Drive from Dealers Electric

dealerselectric.com

L510-203-H1-U

VFD, 3HP, 230V, SINGLE PHASE, IP20,

www.wolfautomation.com

 

[DavidR8]

I don't have a dog in this hunt but I just completed a 3-phase conversion on my mill/drill.
I used replaced a 1 hp with a 1.5 hp motor and used the 2hp version of the Teco VFD. I am very impressed with the VFD.
@mksj helped tremendously with the overall and final VFD programming.

 

[mariner3302]

Since I know jack about this stuff, I take all I can get! lol

Finally got the pulley of the old motor. The mill was built in April 1962. So she was a tad ... ummmm... attached to the shaft. Nothing broke so the outcome was favorable!

 

[mariner3302]

How do you find out what the shaft size and length is? It is probably shown in a spec listed but I do't know what it is..

The pulley pack is for a 1" shaft with a 1/4" slotted keyway.

 

[Buffalo21]

All you have to is measure the shaft on your existing motor, how much shaft is sticking out out the motor?? What diameter??

Post a picture if you can

 

[mariner3302]

1" shaft, 1/4" keyway, 3 3/4" length but 4" will work well. I meant how do you determine those dimensions when looking at motors online..

 

[Janderso]

Top spindle speed with pulleys is 12000rpm

Did you say 12,000 RPM?

 

[mariner3302]

I did say 12000 rpm, yes.

 

[Janderso]

Holy Toledo.