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### Question #: 14163

Question: hello there, i am using servo motor for my X and Y Axis but i dont know how to calculate steps/mm for that, the lead screw i am using is have pitch of .5 mm. please helpme on this i have done everything only this point is pending.

Current Solution

The formula for finding the steps per mm is found in the units itself. First, you mentioned that the motor is a servo. This needs to be clarified as a servo is different than a stepper motor. Some servos behave similar to a stepper motor, so I will continue with this in mind.

The formula is (steps/mm):

You need to find the steps. The stepper motor has a natural number of steps per a full revolution. This is typically 200 steps per revolution.

The driver for the stepper motor allows you to increase the number of steps per revolution by adding a specified number of steps between each step. For instance, if you set the driver to 1/4 microstepping, then instead of having 200 steps per revolution, you would have 200 x 4 = 800 steps per revolution.

So now we have the first part of the formula:

Steps / mm = (200 x 4) / mm

Lets determine the mm side of the formula:

You mention that the pitch is 0.5 mm. Check to insure that the lead is also 0.5 mm. This could be a multiple start lead screw where the pitch is different than the turns per mm. If in this case, that the 0.5 mm is the travel for one full revolution, then you can simply plug this into the formula as:

mm = .5 mm

Otherwise, determine how fat the travel is for one complete revolution.

Therefor, with what we know and the driver is set at 1/4 microstepping and the stepper motor has a natural step count per revolution at 200:

steps / mm = (200 steps x 4) / 0.5 mm = 800 steps / 0.5 mm = 1600 steps / mm

If your travel for one revolution is not 0.5 mm, then plug in your travel distance instead.

i know about steps/mm calculation for stepper motor, because i am using servo motor that why i asked about that. please tell for servo motor.

because its my first time with servo motor i have no idea about calculation of parameter with servo.

Have you attempted to contact the manufacturer or seller of the servo? We typically respond to customers of our products on this customer service area, unless we have extensive knowledge of the subject and can answer the question efficiently.

Respond:

### Other Possible Solutions to this Question

• On the Book Build: I'm changing the 13TPI 1/2" lead screw with the 1/2" 10 TPI Acme screw with the anti backlash nut. This is for the Z axis only. What should I know about installing it and what are the numbers I need to plug into the motor tuning area.

The settings that will have to be change will be your steps per inch in motor tuning (mach 3), or settings/axes(planetCNC). But we do not have the actual numbers/specs that will fit your 10 TPI 5 start lead screw, here is a tutorial video which explains how to get the exact numbers you need! (

).
Here is a default setting that you might be able to tune and adjust accordingly: 1600 steps, accel 400.02, velocity 5.

• I have an engine NEMA 34 from Y axis on my green bull that do not response, I already check connections and everything seems to be OK, how can I check that the motor it's working properly or not?

If one or more motor is not responding, please follow the troubleshooting directions below:

For parallel Bob only! Make sure both the parallel and USB are connected.

Re-check wiring, and connections for continuity (no breaks in the wires) and check for correct wiring locations from driver to BoB.
Check dip switch settings on the driver.
Check components, by swapping the motors (ex. y-axis motor to z or x-axis driver and z or x-axis motor to y-axis driver) to check if motor functions on another driver.
Depending on software check step low active (mach 3) or invert pulse (planet-cnc) for the axis which is not responding.
Mach 3 - config/port & pins/motor outputs / Planet-CNC - file/settings/axes

I have an engine NEMA 34 from Y axis on my green bull that do not response, I already check connections and everything seems to be OK, how can I check that the motor it's working properly or not?

• How to determine lead screw length needed. My Thomson 1 1:4 rails are 60 inches long roughly for the router I’m building. I know I have to have it long enough to couple up with the stepper motor of course but does it matter if it’s a little long on the other end

It generally does not matter if it is longer at the other end as long as the lead screw provides the desired travel for that axis. The lead screw will only need to be long enough for the travel, plus any structure and lead-nut positioning.

For example:
- The motor that will turn the lead screw will need to be mounted at some position (generally at one end of the axis). In many cases, this positioning will be mounted where some of the lead screw will not be used (the lead nut will not be able to moved close to the coupling of the lead screw to the motor shaft). Add some of the length of the lead screw to be inserted into the coupling.

- If the lead screw will contain bearings at either end of the travel, that portion of the mechanical assembly will need to be considered in the lead screw length.

- The lead-nut will need to be mounted in a position on a structural member of the part that is to move. The distance from the part of the structure that will extend closest to the motor will have some distance to the position of the lead nut. This distance will need to be added to the lead screw length.

Add these discrepancies to the length of the lead screw and the travel length and you will have the final length.

• Hi there. I have an ex school Boxford HSRmi2 sat in my workshop, good condition and I'm assured it's all ok, but I want to rip everything out and go down the Mach 3/4 rabbit hole with servos. I need help at this point as I haven't done anything like this before and have no knowledge of controllers/motors etc. Could someone please point me in the right direction? Thanks.

If you are wanting to use servos, I would highly recommend using closed loop steppers and drivers. You will get the best features of both the servo closed loop and the exact digital positioning of stepper motors.

For controllers: the pokeys57cnc will work with either Mach3 or Mach4
https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach4-mach3-USB-ethernet-Board

Otherwise, you can use the Mach3 USB controller if you only an on using Mach3:
https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach3-USB-Board

• I'm using the big 651oz in stepper motor for X and Y and the smaller 325 for the z and X and Y keep tripping when I try to tune the motors on Mach3 but Z seems to work. I have to turn power on and off to reset....is this a wiring issue?

This is most likely a wiring issue. I would disconnect all of the power to the drivers and reconnect one at a time to isolate the problem.

that was not helpful. I already did that way before submitting this question. there are not that many wires here and I have already rewired this a few times. I actually think its a software or interface board issue because it does work sometimes but then trips (possibly a amperage / voltage issue) I am using the interface board that has a parallel port and usb for 5V. are there different settings that I need to setup?

• I just ordered a 1/2" lead screw and bearings, etc. But I don't see any 1/2" shim washers for those bearings. If you have any, please toss 8 of them in the shipment and I'll gladly reimburse you.

We will provide shim washers as a part of machine assemblies, but when purchasing lead screw and bearings, the shim washers must be purchased as well. Please give us a call and we can send them out.

I just ordered a 1/2" lead screw and bearings, etc. But I don't see any 1/2" shim washers for those bearings. If you have any, please toss 8 of them in the shipment and I'll gladly reimburse you.

• I wpold like to know how to hook up my water pump (12vdc 9 amp) to turn it on and off using Mach 3. I have your Blue Brew break-out board Rev. 2.8 dated 8-12. Explain how the three relay connections work for this application? Thanks.

Since the pump will use a standard 12v power supply, you will have two wires. One of those wires will be connected from the power supply to the pump. The other wire will be connected to the power supply and the pump, but cut that wire and connect one side of it in the P terminal and the other end in the S or the O terminal depending on if you need the connection as NO (Normally Open) or NC (Normally Closed).

Step number 9 in the instruction will have the relay connection information:
https://www.buildyourcnc.com/item/electronicsAndMotors-parallel-breakout-relay

• can you please specify how to connect the collar/nut and bearings to prevent the axial movement of lead screw. Do I have to put that next to the stepper motor /coupling assembling or on the other side where the lead screw comes out. Or is there any way I can make the flexible coupling rigid so it does not come out of the middle spider?

You would use a combination of bearings and collars to prevent your lead screw or rod from being able to move back and forth. Without it being able to move back and forth, you shouldn't have the couplings coming apart, because the motor is solidly mounted and unable to move as well.

I will try to draw a picture using symbols, with a key to define what each part is.

--CB|--------------|BC}{M

- = Lead Screw or Rod
C = Collar
B = Bearing
| = Wood, the frame of your machine
}{ = Coupling
M = Motor

On the example above you could replace the collar on the motor side with one half of the coupling, putting it right upside of the bearing to hold it in place instead. Like this:

--CB|--------------|B}{M

You could also place the bearings on the inside as follows:

----|BC----------CB|--}{M

• I am making my own CNC setup using all the electronics from your website and I have many questions. Please advise how to have my computer recognize the USB connection from my breakout board also I would like to use a water cooled spindle but I need to know the parts required for a 4x10 bed area used for woods and plastics

You will need PlanetCNC software for the USB breakout board and when plugging in the USB the computer should automatically recognize the board, however you can go into device manager to see if the USB terminal is working correctly.
The parallel breakout board; the USB is not a connection terminal rather than a power source, and the parallel port will be the communication terminal.
The items you will need for a water cooled spindle would be: water pump, silicon tubing(length desired by customer), a extension cord(from a hardware store(orange))(1 same gauge wire/length as extension cord).

• I have NEMA 34 motors for a GreenBull 6x12. After 2 weeks of use, my Y axis motor has developed play in the front but not rear of the motor. Is this a motor defect or has something come loose somewhere? Thanks,

If there is play within the motor itself, then that motor may be defective. Call us to provide us more detail on this issue.

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-1' OR 2+307-307-1=0+0+0+1 or 'HN9afNei'='

-1" OR 2+88-88-1=0+0+0+1 --

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• I WIRED MY VFD (2.2KW VERSION) AND TRIED TEST RUNNING THE SPINDLE. CONFIGURED TO YOUR SPECS ON THIS WEBSITE, ONLY ISSUE IS WE GOT AN ERROR CODE. ERR 02, DO YOU KNOW WHAT IS? OR HAVE A LIST OF CODES? THANK

Can you provide the model number of your VFD?

Yes, I have the "YL600 - 2S - 2K20"

It just came with a small booklet that is all in Chinese...

I WIRED MY VFD (2.2KW VERSION) AND TRIED TEST RUNNING THE SPINDLE. CONFIGURED TO YOUR SPECS ON THIS WEBSITE, ONLY ISSUE IS WE GOT AN ERROR CODE. ERR 02, DO YOU KNOW WHAT IS? OR HAVE A LIST OF CODES? THANK

• [575] Hi, I recently purchased this board and everything seems to be fine! But I am not being able to jog two axis at same time as I used to do on my older board. Did I do something wrong?

with parallel port controllers, you have the ability to jog using two axes at the same time, but with USB controllers, this is not possible.

[575] Hi, I recently purchased this board and everything seems to be fine! But I am not being able to jog two axis at same time as I used to do on my older board. Did I do something wrong?

• Can you preset an origin point on this cnc? How long does it take to jog over? (If I have the case that I using the same thickness of maple wood, and same jig everytime)?

Yes, you can preset an origin by zeroing the machine at the desired location before beginning your work. You can return to that exact point at any time, or you can specify an offset from that point to be the beginning point for the next machine operation (for instance when cutting several parts from one sheet of wood.) Jogging time varies by machine and application but would generally be a rapid move -- our default rapid setting is 400 inches per minute.

Can you preset an origin point on this cnc? How long does it take to jog over? (If I have the case that I using the same thickness of maple wood, and same jig everytime)?

• thank you for the reply. I would be really good to know the calculation. The lead screw is 1/2" diameter with 13 TPI. Please provide the calculation for determing the maximum weight motor can handle on Z-axis on book build cnc. And one more question. If I am cutting 18mm MDF with 6mm cutting bit (so 6mm pass), what can be the maximum speed rate of cutting and spindle speed of router? thank you

There are two main questions that we can answer with respect to motor torque and the mechanical advantage of lead screws, 1) What torque motor do you need to lift a particular weight, or 2) What maximum weight will my motor torque be able to lift.

This formula uses Newtons (N) as it's final unit. Use this with the included radius (R) to determine the torque. Newtons can easily be converted to lbs or ounces using online conversions.

Effort = Sf + (Load/(2 x pi x (R/p) x Se))

where:
p = pitch of the screw
Se = screw efficiency = Standard lead screw will be between 20% (.2) and 40% (.4)
Sf = static force. This is the force that is needed to start the movement. The number may be eliminated, but it is good to use a number in the 5 N to 20 N range.
Load = the expected load that the effort will need to carry (i.e., the router and the included axis assembly that the motor will need to lift)

This formula is based on the "law of the machine"

The final effort amount with its unit of newtons and R will be the torque. For example, if the effort comes to 100 N (newtons) and the R is .5 inches, then you can assume that the effort is 50 N-in since it would take twice the effort to turn form the one inch mark from the center of the shaft.

Example:

Load = 90 N (20.2 lbs)
R = 1 inch since that is the length from the center of the shaft that the motor is rated
p = 1 inch / 13 = .08 inches

Effort = 5 N + (90 N / (2 x 3.14 x (1 / .08) x .2))
Effort = 5 N + (90 N / (6.28 x 12.5 x .2))
Effort = 5 N + (90 N / (15.7))
Effort = 5 N + (5.73 N)
Effort = 10.7 N = 2.4 lbs = 38.4 oz-in

I am putting the oz-in on the end because the formula considers the distance from the center of the shaft to be one inch.

Therefore, a 425 oz-in motor would be able to lift a 20.2 lb Router with its accompanying assembly. If the assembly and router is heavier, plug in the numbers and determine the effort required.

With a bit of algebra, the formula can be rewritten to find the load:

Load = (Effort - Sf) x (2 x pi x (R/p) x Se)

Another formula that does not consider friction at all:

Effort = (Load x p) / (2 x pi x R)

Lets see if we get similar results:

Effort = (20 lb x .08 inches) / (2 x 3.14 x 1)
Effort = 1.6 / 6.28 = .255 lbs = 4.08 oz-in

The results from both formulas appear to be very small because a 13 TPI screw will have enormous mechanical advantage.

It is evident that the first formula that does consider friction that we are loosely estimating is far more conservative than the second formula. Either way, even the most conservative formula shows that the 425 oz-in motor will handle very large weights. If you are using a lead screw with only two turns per inch, .5 inch pitch, you can determine the requirements with the first formula.

Example for a 10 TPI 5 start (2 turns per inch) lead screw:

Load = 90 N (20.2 lbs)
R = 1 inch since that is the length from the center of the shaft that the motor is rated
p = 1 inch / 2 = .5 inches

Effort = 5 N + (90 N / (2 x 3.14 x (1 / .5) x .2))
Effort = 5 N + (90 N / (6.28 x 2 x .2))
Effort = 5 N + (90 N / (2.512))
Effort = 5 N + (35.83 N)
Effort = 40.828 N = 9.18 lbs = 146.88 oz-in

Customer Response:
thank you so much

how do i calculate torque of stepper motor if lead screw coupled to motor shaft and load applied by lead screw on plate is 100 kg by vertically

Pls

1m 16mmdiameter ball screws calculations

What is the max load that 2 NEMA 17 stepper motors (spaced 2 feet apart, both will be pushing up on the same gantry) can lift while using a rod with the following specifications T8 OD 8mm Pitch 2mm Lead 4mm for each motor.

1

• I am building your "Green Bull' 6 foot wide kit and I am at the stage of attaching the motor and drive chain. I would like to know if you have an modification kit available to put the 1/2" ACME screw on the Y-axis?

Currently we do not have that modification kit, our set up is fixed for our greenBull only modification kit we have for this model is the long z-axis kit(Designed for Foam cutting).

• Hello there, I am a beginner in trying to control a stepper with a pc, you can sell me a kit to control my motor from the pc. I already have a motor, driver, and power supply

All you need is a CNC controller like the following options:

https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach3-USB-Board

This controller is easy to connect using standard wire screw terminals and works with the mach3 control software.

https://www.buildyourcnc.com/item/electronicsAndMotors-electronic-component-breakout-Mach4-mach3-USB-ethernet-Board

This controller is a little bit more difficult to connect, but is a more feature-rich controller and will work with both mach3 and mach4 CNC control software titles.

Specifically, a CNC controller connects to the computer via a USB cable and connects to the motor drivers. These controllers also connect to the limit switches, spindle/router control, air/fluid/mist control, etc.

Hello there, I am a beginner in trying to control a stepper with a pc, you can sell me a kit to control my motor from the pc. I already have a motor, driver, and power supply

• I wired my vfd (2.2kw version) and tried test running the spindle. I configured to your specs on this website, only issue is we got an error code. Err 02, do you know what this is? OR have a list of error codes? Thank you

Can you provide the model number of your VFD?

Yes, I have the "YL600 - 2S - 2K20"

It just came with a small booklet that is all in Chinese...

• Downloaded Mach4 and pokeys57cnc software, hooked everything up according to videos and motor isn't turning, do you have to designate a pin number in Mach 4, for the step and dir. using motor 1 block as video described (3,5, and 9). Thanks for your help.

You don't need to designate a PIN. In the pulse engine, you may want to try inverting the step low active. You also want to make sure that the pokeys57CNC ID is correct. If you had a previous pokeys57CNC, Mach 4 may be using a previous ID. You can try removing the plugin and start again so Mach 4 can recognize it and reinstall it.

• Have you heard of the requirement to cut the Reset Enable trace on the Aruduino Mega for a Makerbot Thing-o-matic? Does this apply to the whiteAnt 3d printer? The trace on my Arduino board is definitely connected and I am experiencing issues with connectivity. Please advise.

I have not hear of this. This cold be an issue with using later firmware, but I have not come across having to cut the trace for the reset enable on the Arduino board.

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