Steps per motor rev.

[beebee]

Finally got all the details regarding the axes. I was hoping someone could help
me determine the steps per .

Ball screw 5/8 .25 lead.
Z axis 3 to 1
X axis 2.5 to 1
Y axis direct drive.

US Digital Encoder. E2-250-250 EG. It is 250 line count, which will provide 1000 pulses per revolution using x4 quadrature counting.
Update 1/8/2020

Gecko 320 x driver. Update 1/8/2020. Step Pulse Frequency is 0 to 300 kHz

DC brushed Servo. Max operating speed 4800
Continuous torque OZ-IN 170
Peak torque 850
Terminal voltage max 90VDC. I’m supplying the motors with 72 VDC

[Richards]

We need to know your encoder's count per revolution. For example, with a quadrature encoder that has 1,000 counts per revolution, on the Y axis, you would enter 4,000 in the Wizard's Steps/Revolution (1,000 X 4 = 4,000). You would enter 0.25 in Overall Turns Ration (turns/in.). X would be 4,000 X 2.5 = 10,000 in Steps/Revolution. Z would be 4,000 X 3 = 12,000 Steps/Revolution.

[beebee]

Update 1/15/20
Encoder has a line count of 250 so I used 1000 Us digital.
X= 1000 x2.5= 2500....10 turns
Z= 1000 x 3= 3000......12 turns
Y=1000 direct drive....4 turns
Even with these numbers if I command a move of one 1 inch. The axis moves 1.75.
Not very close. Used the formula to correct the issue. The new number didn’t have much of a effect.

[swissi]

beebee,

this is the Wizard Axis configuration screen:

Wizard Axis Configuration Screen

• In Steps / Revolution, you would enter the number that matches the configuration settings of your driver

• In Overall Turns Ration you enter the number of full 360 degree turns of your servo motor axis required to move 1 inch

Your Z-Axis is geared 3 to 1 and your lead screw moves 0.24 inch per revolution, so the turn ratio would be 1/0.25x3=12
Your X-Axis is geared 2.5 to 1 so the turn ratio would be 1/0.25*2.5=10
Your Y-Axis is direct 1 to 1 so the turn ratio is 1/0.25*1=4

-swissi

[beebee]

Thanks just got the software installed and the acorn running . Now I have access to the wizard.

[cnckeith]

i heard that 320's with DC brush motors are pretty complicated to setup and get working well..?
you might be better off with modern AC brushless motor drive package that is made to work together like Clearpath or DMM or Estun. opinions?

[Richards]

I agree with Keith. I have a G320 and a brushed servo with a 200 line quadrature encoder attached. I got it to turn. I get it to turn the distance that I specified, but I never got it to work smoothly. I don't use it anymore and I don't recommend it to others. I do use ClearPath servos and I have a DMM DYN4 driver/motor that I also recommend.

A quadrature encoder is a type of encoder. (Quad)rature means that you multiply by 4 the line count of the encoder. If you have an external encoder on your motor, it probably has some kind of label that gives you the line count. Finding the line count by trial and error can be done, but it is tedious. My encoder uses 5VDC to generate count pulses. By hooking up power to the encoder and an oscilliscope to the encoder and then turning the motor's shaft very slowly, I can count the pulses. It's not ideal and is prone to error, but it will get you in the ballpark.

A stepper motor needs to be stepped X number of times for the motor to turn the shaft one revolution. X might be 200, 400, 800, 1,600 etc., depending on the stepper driver and how it is configured or preset by the manufacturer. Each time the stepper driver sends a pulse, the shaft rotates a small distance, again depending on the driver and how it is configured.

A servo motor works just the opposite. The motor is turned on and the driver counts the number of encoder counts coming back from the encoder. When the desired count is reached, the motor is turned off. In my case, the encoder would send back 800 counts per complete revolution. If I had a 500 count encoder and if it was a quadrature encoder, then the encoder would have sent 2,000 counts per revolution. It if was a 1,000 count quadrature encoder, then it would have sent 4,000 counts per revolution.

With my DMM DYN4 motor, I can choose the encoder count. I set that driver/motor to 500 counts. Because it is a quadrature encoder, I have to set the Wizard to 2,000 counts.

Googling "quadrature encoders" will help you understand the terminology.

Understanding why you need to know the counts per revolution and the distance traveled per revolution is just as important. We can't tell a controller to move and axis 1" when using step and direction signals and expect the axis to move 1" unless we tell the controller what 1" means. The Acorn needs two pieces of information before it can calculate distance. It has to know how many pulses/counts equals one revolution. I has to know the distance that the axis will travel per revolution. Then, if we tell the Acorn to move 1", it can calculate how many pulses/counts are required to move the axis 1". If 1,000 pulses equates to 1", then the axis will move 1". If 1,000 pulses equates to 0.25", then the axis will move 0.25". We need to give the controller enough information so that it can compute the numbers necessary to do the job expected.

[beebee]

I’m a bit concerned that it was difficult to get the motors working well. With my
bob Campbell breakout out board, Mach 3 and the smooth stepper board. My system
was working fine.

[Richards]

beebee,
If I recall correctly, the Bob Campbell system used the stock Oriential geared motors, the Gecko G201 or G202 stepper drivers, a 48 VDC power supply and Mach 3 (and in your case, a smooth stepper board).

The Acorn can do anything that Mach 3 can do and do it better. I have a licensed copy of Mach 3 that I was using until I bought the Acorn. Once I understood how to set the parameters for the Acorn, I've never used Mach 3 again.

Sometimes we ask, "How far is up"? That's a philosophical question. If we need to know the height of something, we need to know the units of measurement. For the Acorn, the units of measurement require that we know how many steps per revolution a motor requires and how far the motor moves an axis in one revolution. Without that information, the Acorn can't do its job.

[martyscncgarage]

I’m a bit concerned that it was difficult to get the motors working well. With my
bob Campbell breakout out board, Mach 3 and the smooth stepper board. My system
was working fine.

If it was working fine, then it should work fine with Acorn. Keep the motors paired with the G320's that were controlling them. They are likely already tuned.
The only caveat is you should use the DB25 on Acorn to hook them up.

I agree with Keith, I would not use DC brush servo motors any more, there are many hybrid closed loop drives and motors out there that are matched up with each other.

Marty