New servo selection?

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

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.

Quote:

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Originally Posted by 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.

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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

Quote:

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Originally Posted by jduke

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

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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.

Quote:

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Originally Posted by 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.

---

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

Quote:

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Originally Posted by jduke

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

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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.

Quote:

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Originally Posted by jduke

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

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See my post #4 above

Quote:

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Originally Posted by Jim Dawson

See my post #4 above

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Sorry I double tapped accidentally posted same thing second time

Quote:

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Originally Posted by dazp1976

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

Quote:

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Originally Posted by dazp1976

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

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

Quote:

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Originally Posted by 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

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

Quote:

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Originally Posted by mactec54

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

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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

Quote:

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Originally Posted by dazp1976

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

Quote:

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Originally Posted by jduke

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

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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;

Quote:

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Originally Posted by Jim Dawson

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;

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Thank you , I’m still trying to wrap my head around wiring differences between steppers and servos.
Are there any good videos that you can recommend on the basics of wiring servos to either Mach3 or uccnc ?

Also from measurements it looks like the ac servos on my machine are nema 51 frame while the steppers used on previous dyna dm4400 were nema 34 steppers.

Thanks
Duke

Quote:

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Originally Posted by jduke

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.

Quote:

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Originally Posted by jduke

Thank you , I’m still trying to wrap my head around wiring differences between steppers and servos.

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By definition, a servo system is a closed loop system. The term servo does not define a motor type contrary to what the marketing types would have you believe. Your home heating/AC system is a servo system, the loop is closed by the thermostat and you, as the user, define the comfort level parameter by setting the thermostat. Another common example of a servo system is your car. You, as the controller, take various inputs from what is going on around you, process the data, and output the appropriate (we hope) actions to the steering, throttle, and brakes. On a machine tool, the loop is closed by the encoder feedback to either the servo drive or the controller.

Servo motors can be brushed DC, brushless DC (also called AC servos), or closed loop steppers, there may be some other variations, but not common. The common theme with all of these motor types is a permeant magnet rotor (armature)


On the low end there is the open loop stepper stepper system, this is the most popular for many hobby uses because it's inexpensive. In this case the controller sends out a pulse train and direction signal to the stepper drive but there is no feedback and the controller just assumes that the motor is doing what it is commanded to do. But the controller has no idea what is actually happening. Not the best for accurate work, but it does work pretty well.

The primary wiring differences are that on a closed loop system there some kind of position feedback device (encoder) tied back to either the drive or controller. Other than that, the wiring is pretty much the same. You would connect the command signals to the drive (step & direction or analog). Then most likely also have an enable signal.

Quote:

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Originally Posted by dazp1976

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.

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What makes you say replace the ha40cs with the 1.8kW?

I was just looking at the 1kW and it says it’s rated at 4nm which is a little higher than the 2.94nm that the HA40cs rates as it’s stall torque of 30kg-cm.

I have used the 12nm closed loop steppers on a 4x4 router, and like them for that application, but I can understand that my familiarity doesn’t make them right for this new application.

That’s why I am trying to wrap my head around the use of servos on mills so frequently while routers still commonly use steppers.
I am assuming it has to do with the opposition to movement that cutting metal provides that causes the need for more torque at higher feed speeds.

I also have avoided servos in the past due to what I assumed was complicated wiring. Apparently that is not as true as it once was, they don’t seem substantially more complicated than a closed loop steppers from what I have read recently.

Price has always, and will continue to be a deciding factor, as this is entirely a hobby for me, but again the price of some of the lower cost servos is not so far above closed loop steppers as to make them out of reach.

Although I could get a couple of the 12nm Nema 34 closed loop steppers for $165 each vs $430 for a 1kW servo.

Duke

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.

Jim,

Thank you for the definition of servo.

I’m using servo interchangeabley with AC servo, and probably should be more specific.

Duke

Quote:

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Originally Posted by jduke

......../.../

That’s why I am trying to wrap my head around the use of servos on mills so frequently while routers still commonly use steppers.
I am assuming it has to do with the opposition to movement that cutting metal provides that causes the need for more torque at higher feed speeds.

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In normal conversation a closed loop system running any machine tool can be called a servo without regard to the exact motor type. So when we say servo motor, it can include any motor type and still be understood. Just language shorthand, but not entirely descriptive.

It really depends on the machine and machine manufacturer. Also it's about price point, steppers are cheaper. Some smaller mills do come with steppers, my little Emco Concept 55 has steppers, as do the Tormach machines, and the old Bridgeport Boss series came with steppers also. Where my Eagle (BP clone) and Haas have servos, as does my lathe. Most of the higher end and higher performance equipment comes with servos, both routers and mills. More accurate and more power. Steppers loose torque rapidly as the RPM increases and this can cause them to lose steps, where any of the servos, with the exception of closed loop steppers, have a nearly flat torque curve from 0 to their rated RPM. The closed loop steppers are kind of a special case, if they lose steps, the drive will attempt to correct the error. Where a more conventional servo drive will just keep adding more power to the motor until the torque limit is reached. At that point the encoder error will become too great or the internal drive electronics or controller will simply throw an error and shut the system down. Or the tool bit will just break, which is normally the case.

Under most conditions, the properly sized axis drives are operating at a small fraction of their rated torque while cutting on any machine. Where the maximum torque is used is in accelerating and decelerating especially during fast rapid moves. Take my lathe for instance, it uses every bit of the max available torque (29NM) of the servo to rapid the 1500lb+ Z axis carriage at 600 IPM over a 6 inch move. It requires a lot of torque to accelerate that much mass to that speed and get it stopped again in that short of a distance, it's frightening to watch it.

Quote:

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Originally Posted by jduke

What makes you say replace the ha40cs with the 1.8kW?

I was just looking at the 1kW and it says it’s rated at 4nm which is a little higher than the 2.94nm that the HA40cs rates as it’s stall torque of 30kg-cm.
Price has always, and will continue to be a deciding factor, as this is entirely a hobby for me, but again the price of some of the lower cost servos is not so far above closed loop steppers as to make them out of reach.
Although I could get a couple of the 12nm Nema 34 closed loop steppers for $165 each vs $430 for a 1kW servo.

Duke

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I got pointed towards the wrong info by the looks of it. :rolleyes:
Just go with something thereabouts.
Also are you belted or direct fed from it to your axis?
Reason I ask is that your existing ones are 2000rpm yes?.

Well many of the new ones around your range are 3000rpm nominal.
So you could now get a pulley an extra 1/3 bigger than what you have..... which means you could get a servo a little smaller.
Bigger pulley / smaller motor / higher motor rpm - would be like having changed nothing. (need to do the math).
(If it's direct drive then the above doesn't matter).

Another good thing about servo's too though is you don't have to fork out for power supplies. Direct mains fed.
That's a chunk saved right there.

Quote:

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Originally Posted by jduke

I also have avoided servos in the past due to what I assumed was complicated wiring. Apparently that is not as true as it once was, they don’t seem substantially more complicated than a closed loop steppers from what I have read recently.

Duke

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Actually they're not bad at all. If you can read a wiring diagram you can get it quite easily.
I have to admit my servo's manual was a bit vague (my first ever servo unit). But if you look at other servo's schematics as well, there are many similarities between all.

I did ask for help and people on here are very helpful. I more or less had it right anyway from the diagrams. It turned out more a confidence thing.

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

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

Quote:

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Originally Posted by 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

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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

Quote:

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Originally Posted by mactec54

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

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Why is 2500ppr not suitable? How does it compare to the 16 bit single turn absolute encoder on the DMM?

Where are DMM made, I believe they are sold out of Canada but I assumed like most things they are China sourced as well.

I’m not opposed to spending the money on a better product, I’d really rather be an educated consumer that’s why I’m researching a bit before I buy

Thanks
Duke

Quote:

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Originally Posted by jduke

Where are DMM made, I believe they are sold out of Canada but I assumed like most things they are China sourced as well.

I’m not opposed to spending the money on a better product, I’d really rather be an educated consumer that’s why I’m researching a bit before I buy

Thanks
Duke

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Yes the DMM systems are sold out of Canada, and made in China to DMM specs. I suspect the quality might be better on the DMM units as opposed to the lesser cost systems direct from China, but I can't prove that.

But most important is the documentation, warranty, and tech support. You are paying for that, and it is worth every penny if you have a problem. I would only buy servos from DMM Tech, or Automation Direct SureServo2 (Delta) products. Tech support from both of these companies is outstanding.

Quote:

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Originally Posted by jduke

Why is 2500ppr not suitable? How does it compare to the 16 bit single turn absolute encoder on the DMM?

Where are DMM made, I believe they are sold out of Canada but I assumed like most things they are China sourced as well.

I’m not opposed to spending the money on a better product, I’d really rather be an educated consumer that’s why I’m researching a bit before I buy

Thanks
Duke

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Every part of the DMM system is designed in Canada as well as prototypes design changes and software, there system is manufactured by Dmm in there own Factory which is in China

With a Encoder count that low you would be better off with a closed loop Stepper system

16Bit is 65,536 PPR this does not compare with 2500PPR the higher the Encoder count the smoother the motor will run and have a faster reaction time which are all things a CNC machine needs

They have a 20Bit and a 32Bit Encoder also the 20Bit= 1,048,576 yes that is 1 million PPR which has been the standard for CNC machines for a few years now

The lowest PPR you can use is 14Bit= 16,384 anything lower you will have the jerk factor with your machine movement

Quote:

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Originally Posted by Jim Dawson

Yes the DMM systems are sold out of Canada, and made in China to DMM specs. I suspect the quality might be better on the DMM units as opposed to the lesser cost systems direct from China, but I can't prove that.

But most important is the documentation, warranty, and tech support. You are paying for that, and it is worth every penny if you have a problem. I would only buy servos from DMM Tech, or Automation Direct SureServo2 (Delta) products. Tech support from both of these companies is outstanding.

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They are made in China in there own Factory, not by some other company to there spec's if you don't know then don't post incorrect Bs

Quote:

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Originally Posted by mactec54

They are made in China in there own Factory, not by some other company to there spec's if you don't know then don't post incorrect Bs

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Um, I think that's what I said.

Quote:

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Originally Posted by Jim Dawson

Um, I think that's what I said.

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No not by what you posted ( made in China to DMM specs. ) I replied to a post of yours a few years ago about DMM having there own factory in China I guess you forgot

Not a big deal, but there is a difference though of having something manufactured in China, and having your own factory in China
Apple is a good example of this, most Brand name Bearing Manufacturer's are in China the list could fill many pages of brand name manufactures in China that have there own Factories

Quote:

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Originally Posted by Jim Dawson

Um, I think that's what I said.

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Quote:

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Originally Posted by mactec54

No not by what you posted ( made in China to DMM specs. ) I replied to a post of yours a few years ago about DMM having there own factory in China I guess you forgot

Not a big deal, but there is a difference though of having something manufactured in China, and having your own factory in China
Apple is a good example of this, most Brand name Bearing Manufacturer's are in China the list could fill many pages of brand name manufactures in China that have there own Factories

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Put your claws back in you pair. :rolleyes: :argue:
1 of you will get (nuts) the other (wedge) lol.

Quote:

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Originally Posted by dazp1976

Put your claws back in you pair. :rolleyes: :argue:
1 of you will get (nuts) the other (wedge) lol.

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No need for your ridiculous post, (wedge) Jim knows where we are at :)

Mactec, it sounds like your pretty deep into DMM motors and sold on their benefits.

as a home hobby guy, I am still having difficulty with spending over $2000 on 3 motors when I still have to replace the spindle motor as well on this machine.

I had a Nema 34 12nm rated closed loop stepper motor that I popped onto the dm4400m this morning and was able to move the each axis with it well on X and Y I was able to get up to over 1000mm/sec^2 accelleration at 5000mm/min before the closed loop kicked the motor off

the cost of 3 12nm closed loop steppers is under $500 for the Mophorns that I have.


I can spend the $2000 on motors if it will really get that much better performance, but having never used AC servos in the past, I am having some reservations.

I am also probably only going to put a 2-3hp spindle motor on this machine, is having the excellent performance of AC servos going to be wasted with such a low HP spindle?

as it stands, I have 1800 in the base machine, and another 1000 in the spindle cartridge, so another 500 for a spindle motor
if I go with AC servos that would put me up to 5300 into the machine with the closed loop steppers Id be at 3800.

like I said, I am open to doing the AC servos if they would really up the performance, but I am having some reservations.

thanks for the input.

Duke

Quote:

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Originally Posted by jduke

Mactec, it sounds like your pretty deep into DMM motors and sold on their benefits.

as a home hobby guy, I am still having difficulty with spending over $2000 on 3 motors when I still have to replace the spindle motor as well on this machine.

I had a Nema 34 12nm rated closed loop stepper motor that I popped onto the dm4400m this morning and was able to move the each axis with it well on X and Y I was able to get up to over 1000mm/sec^2 accelleration at 5000mm/min before the closed loop kicked the motor off

the cost of 3 12nm closed loop steppers is under $500 for the Mophorns that I have.


I can spend the $2000 on motors if it will really get that much better performance, but having never used AC servos in the past, I am having some reservations.

I am also probably only going to put a 2-3hp spindle motor on this machine, is having the excellent performance of AC servos going to be wasted with such a low HP spindle?

as it stands, I have 1800 in the base machine, and another 1000 in the spindle cartridge, so another 500 for a spindle motor
if I go with AC servos that would put me up to 5300 into the machine with the closed loop steppers Id be at 3800.

like I said, I am open to doing the AC servos if they would really up the performance, but I am having some reservations.

thanks for the input.

Duke

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You use what ever you can afford to spend on your machine and you will be happy with it

I agree you have to look at the machine and see if it is worth spending that much on, you may have already spent too much, what is the condition of the machine the ways the Ballscrews Etc.

I used to use only Yaskawa and there cost is more than that for just ( 1 ) motor and drive plus cables Etc. so can easy spend $3K Plus per axis for the best there is

I just ordered DMM AC servos, going to be less expensive to build it this way from the start, than to go back and rebuild it later.

Late to this party.

Jim sold me on DMM servos for my mill rebuild a few years ago.

I ran into trouble with analog +/- 10V feedback to a galil card on my system. The vendor was GREAT with tech. help. NOT going to get that if you buy from china.

Anyway, just another person saying DMM is a good choice for a refit.