Trying to find good stepper motors or servos

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legere

Legere
I've been putting off things because I can't seem to find stepper motors that are even close to accurate that don't miss steps and lose their spots. I was looking at servos but they're $2,000 everywhere I look. I was just converting a Grizzly G0704 for my son to use. The Longs Stepper motors weren't any good at all, constantly losing their position. I was using a Nema 34 for the Z axis and Nema 23s for the X and Y.



Is there anything you would recommend? I can raise and lower the Z axis and be off more than 5mm almost every time or move X and Y and it will be off by 3mm and steadily move to one side.
 
masso-support

masso-support

MASSO Support
Staff member
@legere stepper are great systems and just like any other system they have limitations and the right way of setting up and using them, we have clients running production jobs on machines with steppers without any issues.

Here are quick points that might help:
  1. Check the size of the motor and drive and see if its got enough torque for your application.
  2. Make sure the drives are powered as per the optimal voltage recommended, low voltage or current will reduce the performance and the motors will miss steps. Also make sure that the voltage to filtered DC.
  3. Finally even if the above are ok but your acceleration settings in the controller are too high or the maximum feedrate is too high still the motors will miss steps.
 
L

legere

Legere
It turned out to be the power supply. I swapped it out and it's not losing steps anymore while trying to calibrate things
 
testyourdesign

testyourdesign

testyourdesign
Quote from Legere on August 15, 2018, 11:53 pm

It turned out to be the power supply. I swapped it out and it's not losing steps anymore while trying to calibrate things
Click to expand...

The G0704 has been successfully modified by many people using steppers. I have scratch built several CNC machines and successfully used stepper on most of them since they are so much cheaper. I my experience if you want reliable steppers then you need to research the specifications for the steppers, the power supply, and driver then choose a power supply with an output of about 16x to 20x the rated voltage of the stepper motor so a 3V stepper uses a 48 to 60V DC power supply. You want to make sure that the maximum amperage of the motor does not exceeed the maximum output of the driver and the total amperage of all three does not exceed the capacity of the power supply. Many people are also incorporating Teknic or DMM Servos on the G0704 but my budget did not allow me to try them yet. I have been very pleased with the performance of the Hybrid Stepper Motors and Digital Drivers from www.automationtechnologiesinc.com . They have kits perfectly sized for the G0704 which include options for either Stepper based systems and Teknic Servo Systems. I believe he even they even offer a ready to run turnkey CNC G0704. Also CNC4PC.com is also a good source for CNC components.

Just remember that a CNC build is journey that can take years to fully experience. Expect many problems that will need to be resolved over an extended period of time. Try to focus on fixing one item at a time and keep it simple to start. Expect premature failures of items that have cost you allot of time and money. The remember you set out to make something that can literally make itself so its pretty special and complicated. There is great community of hobby and professional machinists out there that are willing to lend a hand or share their experiences. You can try CNC Zone for hundred of posts in their forums and YouTube for more videos on this topic than you will ever need.

I think is honorable that you are sharing this experience with your son. Have fun and be safe.
 
masso-support

masso-support

MASSO Support
Staff member
that is great @legere

There are so many things that need to work perfectly in a CNC system that checking each part and step is very important and even small things can make a huge difference.
 
evermech

evermech

evermech
Well here's my 2 cents. I build systems that will be used by my customers so when I really need to be in position I go with servos. I also have built many pieces of equipment that use stepper motors, but if they happen to miss steps there is no consequence from it. For me it's worth the extra money to hit the target and know I have hit it. I get my servos and drivers from Automation Direct

Guy
 
M

machinedude

machinedude
Quote from evermech on July 23, 2019, 6:05 am

Well here's my 2 cents. I build systems that will be used by my customers so when I really need to be in position I go with servos. I also have built many pieces of equipment that use stepper motors, but if they happen to miss steps there is no consequence from it. For me it's worth the extra money to hit the target and know I have hit it. I get my servos and drivers from Automation Direct

Guy
Click to expand...

automation direct is one place I do not go to for servo needs. it's one of the few things I skip over when I'm shopping, the steppers are a different story those are priced decent. but I have always used gecko drives with them. DMM has some good prices on servo motors and they are nice as well. they just don't carry they anything over a 1.8kw if I remember correctly. so if your looking for something bigger than 2.5 hp on a servo they are not the place. just my 2 cents as well even is this topic is resolved for some time by the original poster. the key to steppers is tuning so you don't miss steps and making sure the stepper is large enough and then some to give you a safety margin for operation without lost steps. then they work well and are accurate :)
 
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