# Mill motor recommendations and sources



## mariner3302 (May 23, 2020)

I have a Gorton 0-16A that currently has a 440v 3 phase motor. I have 220v 1 phase. I am not going to do anything with the mill other than small projects. I got the mill for $1000 and I like it. I posted a thread here looking for help with rewiring the motor but the general opinion is a different motor will be the most economical route. The mill uses a 2 speed motor, 1hp at 1800 rpm and 2hp at 3600 rpm. It has 10 speeds by pulley per motor rpm.
So, what options are out there to find a motor?


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## mariner3302 (Jun 3, 2020)

Hi, I was wondering if you thought this motor would work with an appropriate VFD for my milling machine? The motor is inverter rated and 3600rpm. Would the VFD now run the motor from very slow up to 3600rpm with constant torque? That 3600 rpm at 2hp is the highest rated speed if I used the original pancake motor. The motor is inexpensive and ships free. I would just like to choose something and get it setup. Lots of projects, so little time! haha

https://www.automationdirect.com/ad...eneral_purpose/general_purpose/mtrp-002-3bd36

Thanks, Dan


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## Buffalo21 (Jun 3, 2020)

Personally I’d want a 1800 rpm motor, even with a VFD, you can only turn it down so far.


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## Reddinr (Jun 3, 2020)

I would go for the 3600 RPM (just to be contrary  ).    If you need the low-low speeds / lots of torque you can change speeds with your pulleys.
Would using an 1800 RPM limit your top spindle speed to half of what it was?  That motor would work well with a VFD.

BTW, I've used automation direct many times for business.  They have been great to work with.


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## mariner3302 (Jun 3, 2020)

Top spindle speed with pulleys is 12000rpm using the original motors 2hp 3600rpm setting. I figured an inverter motor would allow the motor rpm to come down to 1800 which is the original motor's 1hp setting. At least that is what I have read, I have no first hand knowledge or experience with motors generally. What I am trying to do is keep the original motor's capability without the cost of using RPC's and transformers.


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## Reddinr (Jun 3, 2020)

(Edited with corrections)

A VFD will run your motor at speeds above and below the "60Hz RPM" of the motor as you have read.  Buffalo 21 mentioned that the motor will lose torque when it is slowed down.  It actually loses available horse power when run slower but the effect is you have less cutting power.  

But you can "gear down" using your pulleys to get most of that back by running the motor as fast as possible with the spindle in the range you want.   I have a small gear-head mill and run it in two ranges, "fast" and "slow".  The VFD gives me good variation within those ranges while keeping the available horse power.

Here is a curve off the inter-web.    Slower than rated RPM, loses horse power, faster than rated RPM, torque goes down.


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## Buffalo21 (Jun 3, 2020)

As Reddinr, stated the true benefit to a VFD is when its used in conjunction with the pulley system of the mill, this allow speed adjustments and to be able to keep the torque and hp levels at the optimum for the work/process being done. A VFD, should never be considered as a way to never have to change belt position ever again.


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## mariner3302 (Jun 3, 2020)

Constant Torque Variable Frequency Drive Applications - Drives & Systems
					

Definition of a constant torque variable frequency drive application with regards to voltage current, motor power and torque



					www.drivesandsystems.com
				




I read this and understood about half of it and nothing on the graph. I am making the assumption that constant torque is required of a mill. Is that correct?


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## mariner3302 (Jun 3, 2020)

I am totally ok with changing belt positions. My hope is to get max torque at 1800 and 3600 because that is giving me stock motor capabilities.

Using the VFD to control the spindle speed is not what I am looking to do.

I would set the motor to either 3600 or 1800 as necessary. Belt changes on this mill are ridiculously easy.


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## Reddinr (Jun 3, 2020)

I edited my post with a couple of corrections.  You will have a nice capability with that motor, belt changes and a VFD.  One thing I've found with a VFD is that I can sometimes change the speed a little and improve some chatter issues I might be having on a cut.


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## mariner3302 (Jun 3, 2020)

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?


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## mksj (Jun 3, 2020)

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-U, 3 HP, Variable Frequency Drive 230 Volt, 1 Phase Input, IP20,  at Dealers Industrial
					

Purchase Teco-Westinghouse, L510-203-H1-U, 3 HP, Variable Frequency Drive 230 Volt, 1 Phase Input, IP20,  from Dealers Industrial, formerly L510-203-H1-N




					dealerselectric.com
				











						VFD, 3hp, 230V, Single Phase Input, IP20, Medium D
					

VFD, 3hp, 230V, Single Phase Input, IP20, Medium Duty, Speed Potentiometer, Easy to Program, Compact, 150% Overload, V/F Control, Auto-Torque Boost or Sensorless Vector, 3 Phase Output




					www.wolfautomation.com


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## DavidR8 (Jun 3, 2020)

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.


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## mariner3302 (Jun 3, 2020)

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!


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## mariner3302 (Jun 3, 2020)

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.


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## Buffalo21 (Jun 3, 2020)

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


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## mariner3302 (Jun 3, 2020)

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..


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## Janderso (Jun 3, 2020)

mariner3302 said:


> Top spindle speed with pulleys is 12000rpm


Did you say 12,000 RPM?


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## mariner3302 (Jun 3, 2020)

I did say 12000 rpm, yes.


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## Janderso (Jun 3, 2020)

Holy Toledo.


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## GunsOfNavarone (Jun 20, 2020)

@mksj It appears you have a good handle on the TECO L510 and I have a question I hope you can answer. My setup is running great, but I'd like to know how to manipulate the analog output. i.e I'd like to send a negative output to complete the circuit on my digital rpm gauge so it turns on when I kick on the VFD. Any advice? There are other ways of doing this, but I would like to know what these analog/digital outputs are and how to manipulate. I have the manual and I see they are all under group 4, but I see nothing like, "send - signal to S4" etc....


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