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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.

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• 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

• 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.

• 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.

• 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 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 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

• How can i get a complete list of all the components (electronics) I need for a CNC laser cutter with the laser controller? A wiring Diagram would probably be very helpful.

All the options for and variations of our blackTooth laser cutter/engraver are available on our website here https://buildyourcnc.com/blackToothLaserCutterAndEngraver.aspx#prettyPhoto. The wiring diagram is available here: https://buildyourcnc.com/blackToothLaserCutterAndEngraver.aspx#prettyPhoto/0/
We do not offer plans or a bill of materials for our machines at this time, but if you are interested in doing your own from scratch you can learn a lot about the design and build process from our tutorials. We wish you success in your endeavors.

• The instructions for the 3-axis combo at https://buildyourcnc.com/item/electronicsAndMotors-3axis-425-elcombo seem to be missing. Can you look into that.

To wire the CNC electronics, use the tutorial for the specific interface board you are using.

If you have the parallel breakout board, use this tutorial:
https://buildyourcnc.com/CNCElectronicsandWiring.aspx

If you have the USB interface board, use this tutorial:
https://buildyourcnc.com/tutorials/tutorial-Electronics-USB-Interface-Wiring

• 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?

• Is there a complete wiring diagram for the Medium Combo Kit with the usb board? Your USB tutorial does not cover the modular 2.5a drivers. https://buildyourcnc.com/item/electronicsAndMotors-3axis-100-elcombo

We are currently getting it completed for us to post it under the 2.5A stepper driver page. However here is the correct wiring procedure.

First: Wire the 24V power supply to the 2.5A driver, by wiring +V on the power supply to 12-24V on the driver. Next wire the COM on the power supply to Ground(GND) on the 2.5A driver. GND on the driver will also go to the GND on the USB board, for specific axis. (additional 3-4 wires connected to ground will be needed for the other axes as well).

Second: Wire the USB board to the driver(one driver per axis on the USB board):
CP on the driver will go to CP on the desired axis on the USB board.
CW on the driver will go to CW on the desired axis on the USB board.
5V will go to the VCC pin on the keyboard jog pins on the USB board (check schematic here: https://buildyourcnc.com/item/electronicsAndMotors-electronic-component-USB-Controller-Breakout#prettyPhoto/2/).
GND on the USB board to GND on the driver. (as specified in step 1).
EN is not used.

Personal Note:
I would recommend that you crimp the VCC pin to a wire which could be split for the other axes as well, each driver will need 5V.

Third: Wire the stepper motor to the driver, (using either the Nema 23 100-oz or the Nema 17 62-oz stepper motors, the wiring will be the same. For the Nema 23 the yellow and white is not connected.)
Black to A1
Green to A2
Red to B1
Blue to B2

Fourth: Repeat steps 1-3 for each driver/motor per axis.

Mention: Remember that GND on the driver will also go to the GND on the USB board for specific axis, and VCC pin on the USB board (keyboard jog) will go to 5V on all drivers for each axes as well, each driver will need 5V!

• I am almost done with the book build Cnc machine, but when I run the motors from mach 3, the 1/2" coupling comes out of the middle spider (the joiner which connects 1/4 and 1/2" coupling. How do I prevent this?

The lead screw must be held in position axially. In other words, you don't want your lead screw to move back and forth at all. This is the only way the coupling hub that is attached to the end of the lead screw could be moving away from its coupling assembly. Depending on the lead screw that you are using, the combination of bearings and collars/nut keep the lead screw in place.

• 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.

• I have the usb breakout board https://buildyourcnc.com/Item/electronicsAndMotors-electronic-component-USB-Controller-Breakout and need to run the A axis as a slave the software greys out the box how do I fix this?

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).

• Is it possible to order the mechanics, motors and electronics, in other words, order the kit without the wood? Reason being is I have aluminum and steel to make a machine out of.

We do offer all of the parts; but it is best to purchase them a la carte. You will probably not want the hardware since this would not conform to a design in metal.

All of the mechanical parts are available here:
https://buildyourcnc.com/CNCMachineMechanicalParts.aspx

All of the electronics you would need is available here:
https://buildyourcnc.com/electronicscombo.aspx

All of the laser components are available here:
https://buildyourcnc.com/LaserComponents.aspx

And the spindles and VFDs are available here:
https://buildyourcnc.com/SpindlesAndAccessories.aspx

• Is it possible to order the mechanics, motors and electronics, in other words, order the kit without the wood? Reason being is I have aluminum and steel to make a machine out of.

If you are wanting to purchase all of the parts for a machine excluding the structural parts, you will need to order the parts a la carte.

Electronics packages can be found here:
https://buildyourcnc.com/category/elcombo

Mechanical components can be found here:
https://buildyourcnc.com/CNCMachineMechanicalParts.aspx

• 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.

• Just purchased the book "Build Your Own CNC Machine". Can I get hardware and electronics kits and how?

The electronics (stepper motors, drivers, power supply and interface board) can be found here:
https://www.buildyourcnc.com/item/electronicsAndMotors-3axis-425-elcombo

If your computer cannot connect to the parallel breakout board (the interface card), just make sure to inform us that you need the USB alternative.