[jduke]

I know motor selection has probably been beat to death, but I’m new to servos, so here goes.

The following is what I know about factory ac servos on the mill that I have.

Apparently reusing them is a pipe dream even with replacement encoders.

Now what parameters do I need to match or slightly exceed to get a decent sized motor.

I know with steppers the stall torque is a good place to start, but I don’t know enough about servos to be dangerous.

So please help me understand what I need to be looking at to get servos that will move this mill well.

Thanks
Duke


X-Y axis
HA40CS
Rated Torque
30.0 kg/cm at stall (2687 oz.in.)
27.2 kg/cm at 1000 RPM
24.4 kg/cm at 2000 RPM
Max. RPM 2000
Weight 8 kg

Z axis
HA80CS
Rated Torque
60.0 kg/cm at stall (5375 oz.in.)
54.4 kg/cm at 1000 RPM
48.7 kg/cm at 2000 RPM
Max. RPM 2000
Weight 12kg

Motor HA40CS 3Phase
Input in 100% (kVA) 1.0
Input in 100% at 170V 3.4

Motor HA80CS 3 Phase
Input in 100% (kVA) 1.6
Input in 100% at 170V 5.4

[Jim Dawson]

Take a look at the DMM servos. https://store.dmm-tech.com/collectio...0Servo%20Motor

1kW for X and Y axis, 1.3 or 1.8kW for the Z axis. I would match the motor frame to the original motor frames, makes installation easy, just bolts in.

I have 4 of their 1.8kW units on my CNC lathe and they have been operating flawlessly for the last 2 years running production every day, and have used them in other applications also.

[jduke]

Take a look at the DMM servos. https://store.dmm-tech.com/collectio...0Servo%20Motor

1kW for X and Y axis, 1.3 or 1.8kW for the Z axis. I would match the motor frame to the original motor frames, makes installation easy, just bolts in.

I have 4 of their 1.8kW units on my CNC lathe and they have been operating flawlessly for the last 2 years running production every day, and have used them in other applications also.

Thank you for the suggestions.

For my own understanding what in the specs of my originally fitted motors led you to suggest the 1kW for X-Y and 1.3 or 1.8 for Z

Thank you
Duke

[Jim Dawson]

Thank you for the suggestions.

For my own understanding what in the specs of my originally fitted motors led you to suggest the 1kW for X-Y and 1.3 or 1.8 for Z

Thank you
Duke

First you look at the torque required, then the RPM. Then I also looked at the drive specs you provided. So that, plus my general refitting experience led me to those motor sizes. In general, a 0.75kW servo will be in the range for axis drives on a Bridgeport type machine. A larger bed mill may be more happy with a 1kW X/Y axis drive, and with the higher mass of the Z axis, normally you would want to step up to a larger motor. Also, you may want the Z axis motor equipped with a brake, for power off position holding, depends it the Z axis is counter weighted or not.

[jduke]

Take a look at the DMM servos. https://store.dmm-tech.com/collectio...0Servo%20Motor

1kW for X and Y axis, 1.3 or 1.8kW for the Z axis. I would match the motor frame to the original motor frames, makes installation easy, just bolts in.

I have 4 of their 1.8kW units on my CNC lathe and they have been operating flawlessly for the last 2 years running production every day, and have used them in other applications also.

Thank you for the suggestions.

For my own understanding what in the specs of my originally fitted motors led you to suggest the 1kW for X-Y and 1.3 or 1.8 for Z

Thank you
Duke

[dazp1976]

Thank you for the suggestions.

For my own understanding what in the specs of my originally fitted motors led you to suggest the 1kW for X-Y and 1.3 or 1.8 for Z

Thank you
Duke

For another option. I bought a Lichuan A4 & 1.8kw motor for my mill spindle.
Once I got my head around the wiring, it's a nice bit of kit.
(Wiring wise, the B2 diagrams look easier).

https://lichuanmotor.com/
https://www.aliexpress.com/store/1907567

I often see other folk with servo's of 750w on X / Y and 1-1.3kw on Z.

[jduke]

For another option. I bought a Lichuan A4 & 1.8kw motor for my mill spindle.
Once I got my head around the wiring, it's a nice bit of kit.
(Wiring wise, the B2 diagrams look easier).

https://lichuanmotor.com/
https://www.aliexpress.com/store/1907567

I often see other folk with servo's of 750w on X / Y and 1-1.3kw on Z.

Thanks for the suggestion


These machines at one point were sold with steppers with a belt reduction
With specs as follows

200 steps/rev
140 oz. in.
125 watts
Parallel: .13 Ohms 4.6 A
Series: .52 Ohms 2.3 A
Shaft: .375" x 1"
Size: NEMA34

I’m thinking that since they were such anemic steppers, they went way overkill with the servos that they put on it.

After looking at the price of 750w and 1kW I may go back with closed loop steppers since I can get 12nm nema 34 closed loop steppers for about 1/2 the price of 1kW servos.

Duke

[jduke]

For another option. I bought a Lichuan A4 & 1.8kw motor for my mill spindle.
Once I got my head around the wiring, it's a nice bit of kit.
(Wiring wise, the B2 diagrams look easier).

https://lichuanmotor.com/
https://www.aliexpress.com/store/1907567

I often see other folk with servo's of 750w on X / Y and 1-1.3kw on Z.

That’s an attractive price point.

And you like the 1.8kW as a spindle motor?

Thanks
Duke

[dazp1976]

That’s an attractive price point.

And you like the 1.8kW as a spindle motor?

Thanks
Duke

Yes I do.
I realise that my little mill is no comparison to the one you're referring to (now I know what it is... VMC).
Bottom line is that they work well.
Take S/D signals and/or analogue voltage.
Position / speed / torque.. or hybrid modes.

You'd prob put the 1.8kw in place of the HA40CS' by the looks of it.

I wouldn't look at 12nm steppers. I've tried those out and binned them before now. They need drives with full AC mains voltage afaic.

[jduke]

For another option. I bought a Lichuan A4 & 1.8kw motor for my mill spindle.
Once I got my head around the wiring, it's a nice bit of kit.
(Wiring wise, the B2 diagrams look easier).

https://lichuanmotor.com/
https://www.aliexpress.com/store/1907567

I often see other folk with servo's of 750w on X / Y and 1-1.3kw on Z.

Do the lichuan motors take step/dir input? Or 0-10v input

[Jim Dawson]

Do the lichuan motors take step/dir input? Or 0-10v input

Based on the specs, they take both step/direction and +/- 10V analog.

From the web page:
1. Three control mode support, Position control, speed control, torque control

2. With Pulse + direction, CW/CCW, AB pulse three pulse modes;
3. Support pulse feedback frequency division function;
4. ±10V analog voltage control;

[Jim Dawson]

Thank you for the suggestions.

For my own understanding what in the specs of my originally fitted motors led you to suggest the 1kW for X-Y and 1.3 or 1.8 for Z

Thank you
Duke

See my post #4 above

[jduke]

See my post #4 above

Sorry I double tapped accidentally posted same thing second time

[Jim Dawson]

What machine are we talking about here? The steppers you list are a far cry from the existing servos.

[mactec54]

I know motor selection has probably been beat to death, but I’m new to servos, so here goes.

The following is what I know about factory ac servos on the mill that I have.

Apparently reusing them is a pipe dream even with replacement encoders.

Now what parameters do I need to match or slightly exceed to get a decent sized motor.

I know with steppers the stall torque is a good place to start, but I don’t know enough about servos to be dangerous.

So please help me understand what I need to be looking at to get servos that will move this mill well.

Thanks
Duke


X-Y axis
HA40CS
Rated Torque
30.0 kg/cm at stall (2687 oz.in.)
27.2 kg/cm at 1000 RPM
24.4 kg/cm at 2000 RPM
Max. RPM 2000
Weight 8 kg

Z axis
HA80CS
Rated Torque
60.0 kg/cm at stall (5375 oz.in.)
54.4 kg/cm at 1000 RPM
48.7 kg/cm at 2000 RPM
Max. RPM 2000
Weight 12kg

Motor HA40CS 3Phase
Input in 100% (kVA) 1.0
Input in 100% at 170V 3.4

Motor HA80CS 3 Phase
Input in 100% (kVA) 1.6
Input in 100% at 170V 5.4

What is the Mill, they are quite big motors are they 1:1 or have a different ratio

[jduke]

What is the Mill, they are quite big motors are they 1:1 or have a different ratio

These are for a dyna mechtronics dm4400m
And yes the steppers that they put on it were grossly different then the ac servos.
As I understand it the steppers did have a belt reduction but I’m not sure what the reduction is.
The ac servos are 1:1 on the belts but later ones may be directly coupled.

The head does have a counterweight.

Duke

[jduke]

I just checked another calculator online, and the 30kg-cm and 60kg-cm respectively came back as about 3 and 6Nm

So that would put the above advice of 1kW ac servo for x and y as well as 1.8kW for Z as pretty much spot on replacements.

[jduke]

Bill South, I tried to PM you but your inbasket is full and it won't let me send it.

Dazp

these are belt drive with a 1:1 ratio

I am probably going to try to bore out the pulleys that I have and keep the ratio same.

this machine even though it weighs in at almost 4000lbs, doesn't have a huge work area, so rapids don't need to be very quick or I am going to beat the heck out of some limit switches.

work area is only X-Axis 14", Y-Axis 10", Z-Axis 14"

thank you

Duke

[jduke]

just for the sake of whomever reads this thread later on, as of today 15 Aug 2021

DMM servos
to get 2 1Kw motors and drivers as well as one 1.3kw motor and driver directly from DMM would be $1810 not sure if this includes cables
from CNC4PC the same package with cables is $2181

for same spec motors from Lichuan shipped directly from china ordered on Ebay $1310
if ordered on Aliexpress $1324.44 both of these are from Lichuan factory store.

Thanks

Duke

[mactec54]

just for the sake of whomever reads this thread later on, as of today 15 Aug 2021

DMM servos
to get 2 1Kw motors and drivers as well as one 1.3kw motor and driver directly from DMM would be $1810 not sure if this includes cables
from CNC4PC the same package with cables is $2181

for same spec motors from Lichuan shipped directly from china ordered on Ebay $1310
if ordered on Aliexpress $1324.44 both of these are from Lichuan factory store.

Thanks

Duke

But do they compare almost anything from China is cheaper with no support and not the same spec product

The encoder spec tells you what you are getting 2500 PPR is not suitable for CNC machines