### Question #: 14023

Question:
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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
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**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.**

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### Other Possible Solutions to this Question

**BUILDING ONE OF YOUR GREENBULL 6X LONG AND 2.2 KILOWATT SPINDLE DOES NOT FIT. SEEMS LEAD SCREW YOU SENT WITH KIT IS SHORT 42" LOOKS LIKE IT NEEDS TO BE 5 OR 6 INCH LONGER. THIS CORRECT? WHAT THE NEEDED LENGTH FOR UNIT?**The leadscrew length for the greenBull long Z-axis is 47 inches.

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BUILDING ONE OF YOUR GREENBULL 6X LONG AND 2.2 KILOWATT SPINDLE DOES NOT FIT. SEEMS LEAD SCREW YOU SENT WITH KIT IS SHORT 42" LOOKS LIKE IT NEEDS TO BE 5 OR 6 INCH LONGER. THIS CORRECT? WHAT THE NEEDED LENGTH FOR UNIT?**Building one of your greenBull 6X Long and 2.2 kilowatt spindle does not fit. Seems lead screw you sent with kit is short 42" looks like it needs to be 5 or 6 inch longer. Is this correct? What is the needed length of lead screw for this unit?**The leadscrew length for the greenBull long Z-axis is 47 inches.

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Building one of your greenBull 6X Long and 2.2 kilowatt spindle does not fit. Seems lead screw you sent with kit is short 42" looks like it needs to be 5 or 6 inch longer. Is this correct? What is the needed length of lead screw for this unit?**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.**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.

Additional Information:

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.

Additional Information:

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

Additional Information:

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.**Click the link to respond:**

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.**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 have a Black Toe CNC with your optional table, and wish to extend the x-axis to 6' of cutting length. Is is as easy as ordering another section of table, longer x-axis chain, and longer x-axis rails? If so, would you sell these items?**The limitation of our machines lies with the width of our gantry, so extending the blackToe to 2' x 6' will not be a problem. Adding the required aluminum rails and chain is the essentials that we sell on our website(http://www.buildyourcnc.com/CNCMachineMechanicalParts.aspx). The table extension is something we do not offer. Please contact (customerservice@buildyourcnc.com) for custom requests.

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I have a Black Toe CNC with your optional table, and wish to extend the x-axis to 6' of cutting length. Is is as easy as ordering another section of table, longer x-axis chain, and longer x-axis rails? If so, would you sell these items?**I have a project very similar to cnc machine. I need 3 lead screws of 1.8 m with all set (supports, bearings...etc). and 3 NEMA 42 motors that I can connect with. if those are available, I need the information about shipping to Oman or UAE.**We carry several sizes of lead screw and stepper motors on our website, for example here https://buildyourcnc.com/Item/mechanical-leadscrews-lead-screw-!5-5-starts-10-tpi and here https://buildyourcnc.com/ProductSearchResults.aspx. Please call us at 281-815-7701 to discuss the particular lengths you would need and shipping options.

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https://buildyourcnc.com/ProductSearchResults.aspx is not working**Click the link to respond:**

I have a project very similar to cnc machine. I need 3 lead screws of 1.8 m with all set (supports, bearings...etc). and 3 NEMA 42 motors that I can connect with. if those are available, I need the information about shipping to Oman or UAE.**I am building a machine and don't know which steppers to use. Machine specs are: plywood frame, SBR25 rails, 96"X48" work area, rack and pinion for X and Y axis (2 motors with 2 racks for X axis), about 3:1 reduction ratio with belt drive. I plan to work on wood, acrylics and aluminum. Thank you!**We would recommend using the heavy gantry electronics combo, using 2 - 425 oz-in motors(NEMA 24) and 1 651 oz-in motor(NEMA 34), with a additional 651 oz-in motor/6.0 amp driver for the x-axis, and that will leave the two NEMA 24 motors for your y/z-axes. The larger motors will be beneficial for the x-axis for the dual motor control and increased torque.

**I need the calculation to determine the stepper motor torque to find the load that it can lift using a lead screw at 1/2" diameter with 13 TPI.**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)

R = radius of the lead screw

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

Additional Information:

Additional Information:

Additional Information:

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

Additional Information:

Pls

Additional Information:

1m 16mmdiameter ball screws calculations**Click the link to respond:**

I need the calculation to determine the stepper motor torque to find the load that it can lift using a lead screw at 1/2" diameter with 13 TPI.**I need the calculation to determine the stepper motor torque to find the load that it can withstand in horizontal position using a lead screw at 1/2" diameter with 13 TPI.**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)

R = radius of the lead screw

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

Additional Information:

Additional Information:

Additional Information:

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

Additional Information:

Pls

Additional Information:

1m 16mmdiameter ball screws calculations**Click the link to respond:**

I need the calculation to determine the stepper motor torque to find the load that it can withstand in horizontal position using a lead screw at 1/2" diameter with 13 TPI.**X AXIS STEPPER MOTOR STALLS AND SHUTTERS WHEN COMING FROM A STAND STILL WON'T MOVE WITHOUT PUSH BY HAND. I TOOK THE CHAINS OFF SPUN FINE WITH OUT LOAD. HAVE CHAIN HOOKED UP CAN MACHINE BACK FORTH HAND, NO HANG UPS OR ANYTHING, BUT TRY TO IT DOESN'T JUST SPINS OUT. ANY SUGGESTIONS?**If your axis shutters and will not move unless moved by another force, that sounds like your acceleration is set too high. Lower the acceleration until it works well, then lower it a bit more to have a margin of safety.

IF that didn't work, try swapping the X and Y drivers. That way you will pinpoint if the issue is the driver. If the proplem persists, then there may be an issue with the motor itself.

The X and Y drivers can be easily swapped by swapping only the motor wires.

- Remove the x-axis motor wires from the X driver.

- Remove the Y motor wires from the Y driver.

- Insert the X motor wires into the Y driver.

- Insert the Y motor wires into the X driver.

Now the Y-axis will move the gantry. Test the Gantry movement by moving the Y axis using the up and down arrow keys (mach3).**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).

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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?**If i can get the autocadd drawings of the building mdf peices that need to be build are the plans detailed enough for me to make my own autocadd drawings? I have access to another machine to build my own.**Yes, the plans are detailed sufficiently enough to produce CAD drawings. If you wish to create AutoCAD drawings from the plans that we provide, we ask that the information conform to the creative commons license established on this site.

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If i can get the autocadd drawings of the building mdf peices that need to be build are the plans detailed enough for me to make my own autocadd drawings? I have access to another machine to build my own.**Building the 5x10 GreenBull, I went to install the ribs on the mid section of the gantry and you say in the video to skip a spot for the motor to sit, but I have 3 sections that are going to blank not just one like you show in the video. Do I skip more than one, am I missing ribs?**We apologize for the confusion! The current greenBull kit in the video is a 4' x 8' gB CNC machine, so we currently have a shorter Y-axis length, compared to the 5X/6X kits. However with the gB 5X you should skip every other section(or something similar so it is symmetrical), since we added the option for you to increase the number of ribs if you wish, but is not necessary for the CNC machine.

**I'm planning on using your 425 oz motors and need help on selecting the right interface and driver boards. The PoKeys57 CNC USB card looks good but I wonder if the 2.5 amp driver boards shown with it are enough for the 3 amp motors?**You can use the Pokeys57CNC board with our 3.0 amp drivers. The Pokeys57CNC has all of the headers necessary to provide the pulse train to any common stepper driver.

Here is the link to the Pokeys57CNC interface board:

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

Here is the link to the 3.0 amp stepper motor driver:

https://www.buildyourcnc.com/item/electronicsAndMotors-stepper-driver-3!0a**Click the link to respond:**

I'm planning on using your 425 oz motors and need help on selecting the right interface and driver boards. The PoKeys57 CNC USB card looks good but I wonder if the 2.5 amp driver boards shown with it are enough for the 3 amp motors?**I am converting a 12x36 lathe over to CNC, I am interested in a 2 axis kit. I would love one stepper motor to be no smaller than 1200oz. , and another at 6000z. Is this something that you could offer? I have two other cnc machines but this is my first converstion on my own.**We may be able to source those motors. Curious, the 6000 oz-in motor is pretty big. Do you mind explaining the application of the CNC machine and the structure that would require the large motor?

Additional Information:

The largest motors we can offer is 3900 oz-in without any mechanical help. 6000 oz-in can be resolved by mechanical means as an alternative.**With your 120v drive systems for your 2.2kw spindles, do you do something to limit the output to the spindle so that the current draw doesn't exceed the 80% limitations of a 20a circuit? I have a dedicated circuit for my router and I am considering a spindle upgrade, but I am curious how the configuration matches the math.**Yes. The VFD (Variable Frequency Drive) has a large set of parameters that can be modified. This is typically called "programming" the VFD. The parameters can be accessed using the front control panel of the VFD.

Since the VFD is the mechanism that control the allowable current draw from the spindle, there is a parameter that assigns the motor rated current; however, it is probably better to match the rated current of the motor and "up" the circuit breaker current instead. If the current limit is set too low, then there is a possibility that the spindle will cause a current overload error on the VFD and cause the spindle to stop.**I purchased hardware for my plasma table which included 3 nema 34 stepper motors and drivers, power supply,Blue brew BOB, and Mach 4 Control software with parallel port plug-in. In configuring the Mach 4 software it asks for a motion controler. Do I need another device such as a smoothstepper motion controler?**No, you do not need another motion controller if you have the parallel breakout board and you are using the "Legacy Parallel Port Plug-In" with Mach4. The motion controller is the parallel port.

**I am building a cnc router with twin ball screws on the long axis and I will have a rotary axis as well. I need a 5 axis breaker board using only 4 axis total. Can you help me?**Yes, we can make a redLeaf system that has all 6A drivers for use with the 651 oz-in motors. We can also wire the electronics in a way that two of the drivers will use the pins of the same axis so that axis will drive two drivers and motors.

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I am building a cnc router with twin ball screws on the long axis and I will have a rotary axis as well. I need a 5 axis breaker board using only 4 axis total. Can you help me?**How do I order 3 specific lengths of lead screws in one order? I could only order a single total amount via the shopping process. I require 36", 60" and 14". If I order 110", I will get 79" + 31". Do I have to order 115" and pay for an extra 5" to get around this?**Just specify the full length in the quantity field in the shopping cart and give us a call to inform us of the cut lengths (you can also email customer service - link in the contact us page - link at the footer). We are working on a way to do this at the product page, but won't be finished for a few more days.

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