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### Question #: 849

Question: I received the electronics for book build cnc machine. I need to know how much weight the z-axis motor can hold since my (craftsman) router seems to be heavy. It is 2HP with variable speed

Current Solution

The motor is helped by the mechanical leverage of the screw. The 425 oz-in motors that are included in the standard electronics combo has very high torque for that type of machine. You will have no problem using that motor for the book machine.

We use that motor for very heavy spindles on the blackToe and blackFoot CNC Machine kits.

You will need to do the mechanical leverage calculation along with the torque of the motor to determine the actual weight it will lift. The calculation will need to consider the type and pitch of the screw and it would also consider the gravity constant of 9.8 m/s/s.

If you need me to determine this formula and work out the calculation based on the screw you are using, please let me know.

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. 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

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### Other Possible Solutions to this Question

• Since I am using normal all-thread lead screw 13 TPI 1/2" for the book build cnc, what can be the maximum feed rate of machine and how can I change the mechanical setup in mach 3? I am using 1/4" steel carbile endmill with 2 flutes and router is 2 HP with variable speed

Book build (scratch build), feedrates and recommendation.

Using standard allthread will provide around 20-30 ipm using 36 volts. Although it allows for a working CNC machine, the RPM of the spindle/router will need to spin at the lowest setting to provide the beat efficiency and life for the end mill at 1/4" cut diameter and higher. The speeds may be fine for smaller end mills.

If you would like faster speeds, you should change the lead screws on the CNC machine to the 1/2" 5 start 10 TPI which translates to 2 turns per inch which means, the stepping motor will not need to turn as fast to produce faster motion. That is to say, the stepping motor will only need to turn two revolutions for the machine to travel one inch and with the allthread, the stepping motor will need to turn 13 times to reach one inch.

https://www.buildyourcnc.com/CNCMachineMechanicalParts.aspx

To change the lead screws you will need (for each axis):

1. The lead screw for that axis.
2. Two 1/2" collars to keep the lead screw axially stable.
3. One Antibacklash nut.

20

• 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

• If I purchase the [blackToe 2x4 v4.1 CNC Machine Kit - USB Electronics - Table Included] all I would need for this CNC to be fully operational is a laptop with mach 3 software and a router. Is this correct?

if you purchased the USB interface, you will need planet-cnc software rather than Mach3, and you will need a usb cable to connect the usb interface to the computer.

The blackToe 2x4 CNC Machine Kit with optional table will need wire to connect the electronics. Don't forget to get some end mills to use for cutting the intended material.

• I just made the book build Cnc machine with the feed rate of 11.19 inch/min as suggested in book. Can I increase it to 20 inch/min? I have 2hp of router attached

The book (scratch build) will be able to cut at very high rates of speed, but the speed is partly determined by the mechanical setup. Cutting wood is generally recommended between 60-200 ipm depending on the end mill and spindle being used. The larger the end mill (with increased chip load capacity) the faster the feedrate.

The stepping motors need to turn 13 times to travel one inch using standard allthread (1/2-13 TPI - threads per inch). The higher lead leadscrews shown in the link provided will move one inch with only two turns allowing the machine to move many times faster.

These speeds are especially important if you are cutting materials that have low melting points like aluminum and thermoplastics like acrylic, Plexiglas, etc. These materials require high feedrates and smaller depth per passes.

20

I just made the book build Cnc machine with the feed rate of 11.19 inch/min as suggested in book. Can I increase it to 20 inch/min? I have 2hp of router attached

• I need to replace the fried electronics box for my 6090 wood router. Do you offer a play and play, no wiring required, kit? If yes, how much? If no, can you recommend one?

Yes, we offer a CNC electronics assembled package called the redFly, redLead and redSprout. If you already have a computer, I would recommend the redFly. You would still need to add connectors to the ends of your motor cable.

https://www.buildyourcnc.com/item/cnc-computer-system-redFly

I need to replace the fried electronics box for my 6090 wood router. Do you offer a play and play, no wiring required, kit? If yes, how much? If no, can you recommend one?

• I bought a Blacktoe 2 x 8 three years ago and have always had a problem with the Zid axis. No matter how tightly I've calibrated the axis it always cuts to deep. Can I put a larger Stepper motor on Z-axis using the same motion electronics that came with the original machine.

Modifying the Z-axis to accommodate a larger motor will be a worth while task and is possible, however we have not calibrated the z-axis therefore using the 1600 Steps-per inch in the motor tuning on our machine in our shop. We have not noticed any significant depth increments from not calibrating the z-axis but only from zeroing the z axis too close to the material. Also in your design did you specify the actual depth and the length of tool (end mill/ bit) that you are using?

• I just finished building my first CNC with the electronics I purchased from you and I am already thinking about improving it. I would like to build a 2 motor X axis solution. Is it possible to attach 2 parallel motors and drivers to the BlueBrew Breakout Board? If so, how?

Attaching two motors in parallel is possible, but you will need another motor and driver for the opposite side. Each motor must have its own driver to work accordingly and fluently. The two can be wired together, to the same pins on your breakout board and set the dip switches on the driver to match the ones on your x-axis(ex). But remember to view the orientation of the motor and which way it spins, since it is on the opposite side it will have to be orientated correctly to move in sync with the other motor.

• I am having difficulty with the wiring on the White Ant. The latest electronics that I received don't seem to be anything like the book or even the tutorials. For instance, the three stepper drivers need 6 pin connectors and ribbon cable. How are they wired? There was no thermocouple wire included. Thanks,

The whiteAnt is no longer sold; the information on the website is to support legacy customers. We have spoken with you and are sending the materials that you need.

• Correct kit of motors and electronics, I bough a book in Amazons kindle to build a CNC, this book mention a kit of motors and electronics for parallel port, I want to use USB, can you suggest me the correct kit fot this machine.

Dealing with our scratch Build kit/BYO CNC Book Kit, you will use our basic 3 axis electronics kit (https://buildyourcnc.com/item/electronicsAndMotors-3axis-425-elcombo). Now dealing with the Breakout Board, the book specifies the parallel port BoB, but you can use the USB BoB and use Planet-CNC rather than using Mach 3 or Linux-CNC as your control software.

• I would like to design my own CNC router around one of your electronics bundles, either the 3 Axis - Heavy Gantry or 3 Axis - All Large Motors. Do you have the data sheets for the motors so that I can use the dimensions in my model?

You can find the datasheets to our motors be going to the the stepping motor category page https://www.buildyourcnc.com/category/nema and selecting the motor. This will bring you to the product page for the motor and all of the motor information will be found there.

• Hello. I am interested in the green bull 6X long z CNC machine with electronics. I live in NZ, where the voltage is 230 V and 50 Hz. is it going to be possible to get the inverter to run here? Thanks!

Dealing with our inverters, they are built with a bit of margin on the input power. For our 220V VFD the margin is from 170-250V 50/60Hz, so running our VFD in your location will not be an issue! Our electronics will not have a issue running at 230V as well.

Hello. I am interested in the green bull 6X long z CNC machine with electronics. I live in NZ, where the voltage is 230 V and 50 Hz. is it going to be possible to get the inverter to run here? Thanks!

• I build a 3 axis router CNC the gantry is heavy in aluminium plate, witch plug n'play kit you suggest me 1 or two motor on the longest axis this will be drive with chain?

What is the weight of the gantry, number of teeth on the drive sprocket and tooth pitch?

I build a 3 axis router CNC the gantry is heavy in aluminium plate, witch plug n'play kit you suggest me 1 or two motor on the longest axis this will be drive with chain?

• I'm trying to build my CNC router 3m*1.3m, but i'm not sure what is the type of stepper motor i should pay, all my CNC body is Al. I need to bay 4 Stepper motors, 4 drivers, spindle, inverter, and i don't know what is the type of controller ?

The size of the stepper motor is measured in holding torque, generally oz/in. You will determine the torque loads of your axes when selecting steppers. Once you know which stepper you need, the drivers and controller board are simple to pair with them.

• My Z-axis seems to be reversed on a fully assembled machine... I've tried reversing it in the config settings on Mach 3, but to no avail. What do I need to do? IS this a wiring issue that was not done correctly at the factory?

If your Z axis is moving in the opposite direction, go into Mach3, click on config, ports & pins, then click on the motor outputs tab. You will see the axes labeled on the left and the parameters labeled on the top of this dialog box. Toggle the dir low active for the z-axis.

What if I'm having the same issue on a different axis?

You can follow the same procedure as with the z-axis. When you get to the motors outputs tab, toggle the dir low active checkbox for the axis that you would like to change.

If you are using another control program, let me know and I will add the recommended action here.

Girbl

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• How do I get started I would like to build a cnc router. Making the machine I can do, but I am weak on cad,cam and mach3. I am thinking about a 4’x4’. Do you have plans I can buy?

We are developing plans for our machine, but they are not completed yet. Please let me know if you would like to be added to our list of customers wanting plans. Thanks,

If you have specific questions regarding CAD, CAM and Control, please add another question to the customer service and I will answer them in detail.

How do I get started I would like to build a cnc router. Making the machine I can do, but I am weak on cad,cam and mach3. I am thinking about a 4’x4’. Do you have plans I can buy?

• Building the 2'x4' CNC from the Woodsmith plans and want to use a router with 1/2" collet. Will your stepper motor kit with 2 NEMA-23 and 1 NEMA-34 be sufficient for a Bosch 1617 router motor, or will it be too heavy?

You will be fine with using 2 NEMA 23/24 (425 oz-in) and 1 NEMA 34 (651 oz-in) motors with the Woodsmith CNC build with a large heavy router with a 1/2" collet. Specifically, the Woodsmith CNC build uses lead screws for each axis and this will provide mechanical advantage allowing the motors along with the drive mechanics (lead screws) an increase in torque.

• ok I Build my CNC machine table and now need a complete set for motor and software how you can help me

Yes, I will need to know more specifics of the machine so I can recommend the correct electronics.

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• The electronics for my current cnc machine has a 36v 8.8 amp power supply. Is this power supply sufficient to power my new Mach3 USB interface?

The Mach3 USB interface card uses 5V (powered from the computer's USB) and a 24v to power the inputs, outputs and spindle control

the mach3 usb interface can be found here:

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

But the mach3 usb does not absolutely need the 24V supply. The 24v supply is only needed if you will be using limit switches (I1-4), VFD controlled automatically and for use with the outputs (O1-4)

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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.

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.

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