hybrid Closed Loop Stepper vs dmm servo

[rmachinist]

2 types of motors hybrid Closed Loop Stepper vs dmm servo, if anyone here had personal experience with both motors i would like your opinion. whats best value for the money? asking cause i don't want to be disappointed when i buy mind i was look at these on ebay https://www.ebay.com/itm/428Oz-in-Cl...c7ae075e8d4b1b
Thanks

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[mick41zxr]

No comparison really. The DMM is a far superior product.
It really comes down to your budget and what you are trying to achieve.
Please don't mix up the torque ratings when comparing motors. Steppers are generally advertised at peak torque (at low rpm with torque falling off rapidly).
Whereas servo's are rated at constant torque.
Also consider the rest of your drivetrain. No point going for servo's if you are going to use ebay special C7 ballscrews with single ballnuts.
Welcome to the Rabbit Hole.
M

[rmachinist]

I'm using Ebay ball screws from chai there double nut
More Torque with lower feed rates don't plan on feeding more then 40 - 50 ipm and maybe rapid no more then 150-200 ipm

No comparison really. The DMM is a far superior product.
It really comes down to your budget and what you are trying to achieve.
Please don't mix up the torque ratings when comparing motors. Steppers are generally advertised at peak torque (at low rpm with torque falling off rapidly).
Whereas servo's are rated at constant torque.
Also consider the rest of your drivetrain. No point going for servo's if you are going to use ebay special C7 ballscrews with single ballnuts.
Welcome to the Rabbit Hole.
M

[CL_MotoTech]

At those speeds steppers will be more than adequate.

I run my G0704 at exactly those parameters. Z is 160ipm, X,Y, at 180ipm, but I've run them faster.

The vast majority of cutting is 60ipm or less. I've read about some have issues with preloaded double nuts and steppers though (i.e. stalling), they have a fair amount drag as I understand it. My machine is on single nuts, but I've repacked them to get down to around .0015" or less backlash on all axis.

Closed loop steppers seems like a waste of money to me, simply because once everything was tuned up and working as it should my machine never loses steps. There have been pages of debate and flaming on the topic though.

[Jim Dawson]

Another vote for DMM. I've had good luck with their products, and they have great tech support. I haven't used the hybrid stepper systems.

[JerryGarcia]

The downside with servos is that you’re looking at reduction of some variety, and of course, cost. It also seems somewhat dicey to run a non linear rail machine at those speeds, and while I know many have done it and done it well, there certainly has to be some consideration for machine type and build. Hardened ways I imagine would be desirable for greater rapids.

[rmachinist]

I have PM-25MV I’m converting, know servo are better I’m trying justify paying around $500 for closed loop stepper vs. $1000 for servos they really worth it? I don’t want to be disappointed in my purchase

[CL_MotoTech]

I personally think servos are a waste of money on a PM-25, G0704, etc.. Unless you install linear rails. Closed loop steppers are also an unnecessary expense. Start with spending your money on better ball screws, a kick ass spindle motor, oil setup, full enclosure, flood coolant, PDB, ATC, etc.. Even when I run my G0704 at 8k (2.2kw) I rarely cut over 90ipm (4 flute cob rougher in 6061). So asides from torque and faster rapids what do the servos gain you? Speaking practically, not too much, especially for a hobby machinist. For the record, as a hobby machinist myself, I make lots of money with my machine. I've done the cost benefit analysis, as well as dreamt about servos, many, many times. It just doesn't pan out, not for me anyways.

Here is my machine.

[mick41zxr]

Completely Agree with CL_MotoTech. I have two machines one with closed loop steppers the other with DMM. While I think the DMM better it is also overkill on this class machine.
The biggest limitation I find with the PM25 is the rigidity of the column. From the closed loop steppers I have it running 40ipm easily. These combined with 1.1kw 3 phase motor are enough to induce deflection in the column on heavy cuts.
Photo of my setup below.
Regards,
Michael

[eldata]

I have PM-25MV I’m converting, know servo are better I’m trying justify paying around $500 for closed loop stepper vs. $1000 for servos they really worth it? I don’t want to be disappointed in my purchase

I have the kit you show on https://www.ebay.com/itm/3NM-Nema23-...oHbalgQQ%3D%3D, the motors are good but the drivers are not. Using the motors and these drivers https://www.automationtechnologiesin...-servo-driver/ I get 420IPM on a PM-25MV.

You can adjust acceleration etc., to get what you want.

[arizonavideo]

I have both the DMM and closed loop and regular steppers. The closed loop are a nice product. Get the 2.2Nm for the X and Y and the 4Nm for the Z.

The DMM are faster and quieter but the closed loop are much quieter then regular steppers and dont loose steps.. For the smaller mills the 400 watt 60mm DMM are just over kill.

Dave