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### Question #: 855

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?

Current Solution

The best way to determine the cutting speed is to determine this with respect to the edge quality you desire. This recommendation generally comes from the major end mill manufacturers.

The feedrate (travel speed) should be determined by the chip load of the end mill, the number of flutes, material of the end mill (Solid Carbide, HSS - High Speed Steel, Cobalt, etc.) and the RPM of the spindle. You will need to see the manufacturer's specifications of the end mill to determine this information.

Formula:
Chip Load = (feed rate IPM)/(Spindle RPM x Number of Flutes)

or

Feed Rate IPM = Chip Load x Spindle RPM x Number of Flutes

Once you find this information, apply this to the material at the full depth of the end mill. If you find that your edge condition is aberrant, pull back on either the speed, or the depth per pass. If the edge condition is acceptable, then push the speed higher until the edge condition starts to deteriorate in quality and then pull back to the accepted level.

Using this method, you will be able to reduce the wear on the end mil which will be the most expensive consumable on the machine.

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### Other Possible Solutions to this Question

• 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

• 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

• I would like to know what the lowest rpm that can be acheived with the 2.2kw spindle and inverter and still have enough torque to drill

According to the supplier of the 2.2 kW spindle, the safest operating speed for the spindle is 6000 RPM. The supplier also stated that theoretically, the spindle can operate from 0 to 24,000 RPM. I am continuing a dialog with the supplier to delve deeper into understanding the configurations and ramifications of such configurations for operations outside of the safe boundaries into the "theoretical" ranges.

20

I would like to know what the lowest rpm that can be acheived with the 2.2kw spindle and inverter and still have enough torque to drill

• can I control the speed of a 2.2 spindle through your 5 axis breakout board with relay?

Yes, you can control the speed of the 2.2 kW spindle, and the other spindles we sell, through Mach3 software. It requires making some changes to the settings in Mach3 and in your inverter. It also requires an additional part, which is called a USB to Serial Converter, found on our site here:

https://www.buildyourcnc.com/item/Interfaces-newbiehack-Interfaces-TTL232R-USB-UART-Serial

I have some additional instructions, that I will send upon request, by email. I will also be adding a complete tutorial and video, to the website, on how to do this soon.

20

can I control the speed of a 2.2 spindle through your 5 axis breakout board with relay?

• Can I wire in a 5vdc relay board to the spindle relay for my router. Gnd would be negative and the arrow would be positive right?

Yes, a 5v relay board can be connected to a spindle. Relays generally have terminals labeled S, O and P and you will want to pass one of your main wires "through" the P and S terminals or the P and O terminals depending if you want normally closed or normally open function.

Refer to Step #8 on this page to get the full instructions on how to use a relay to control the spindle or router.

https://buildyourcnc.com/item/electronicsAndMotors-parallel-breakout-relay#prettyPhoto

User response:
I have the USB board. I was thinking of wiring a 5v relay board to the breakout board labeled (spindle) using the GND and (arrow) which i think is 5vdc. I will need this relay board to operate my router. Thanks

Buildyourcnc response:
Yes, those terminals are to control the relay (engage the relay). On the switch part of the relay, the router main poser wire (say, the live, black, wire) would pass through this switch portion of the relay.

Can I wire in a 5vdc relay board to the spindle relay for my router. Gnd would be negative and the arrow would be positive right?

• Hello what is the thread size of the water cooling fittings on the 2.2kw spindle? I am wondering if I can replace the fittings with standard pc liquid cooling fittings, which are G1/4".

They do have a similar looking thread as the G1/4”, but I will confirm in the morning. We use the G1/4” on the pump and radiator so it will be easy to determine this fit when I get into the office.

Another FAQ says it is an M8, but I will confirm.

These are M8x1 thread. I was able to find M8x1 3/8 barb fittings on Ebay. I plan to drill and tap my spindle to G1/4 though.

Hello what is the thread size of the water cooling fittings on the 2.2kw spindle? I am wondering if I can replace the fittings with standard pc liquid cooling fittings, which are G1/4".

• Hi, I’m purchasing an ox build workbee cnc router from China but I need to purchase the spindle mount, router and all cables/wires. Please can you give a list and quote of what I will need? I am purchasing the electrical pack with it but it doesn’t come with the cables and all other bits I need. Thank tou

Hola puedo venderte una maquina nueva completa chocofrutfc@yahoo.es

• Can the vertical CNC router do about what a horizontal router can, like cutting out 3/4" cabinet doors from a 4'X8' formica clad sheet? If so, how do you hold it - with Vacuum? Is a vacuum system available?

Our hold down method is screws. For a 4'x8' 3/4" sheet, we use 6 screws around the perimeter of the sheet. This provides sufficient hold down for milling. For the vertically oriented machine, the sheet also rests on a small ledge, making it easy for the board to maintain position while fastening.

• I'm considering buying the 4 axis cnc combo. I have metal lathe with variable speed spindle. Can i somehow control the spindle with the gcode. like s values and ,m03,m04, m05?

Our spindle VFD's, have a multitude of different connectors that can be used for different operations. There is a manual that comes with each VFD, and you can refer to page 11 for different functions and descriptions.

We currently have a PWM, working with our machine, however it is connected via USB, and setup through Mach 3.
Also if you may have misplaced or lost the manual here is a link to the pdf:

I'm considering buying the 4 axis cnc combo. I have metal lathe with variable speed spindle. Can i somehow control the spindle with the gcode. like s values and ,m03,m04, m05?

• What's the maximum speed at I can machining reliefs without lost steps with BlueChick?

This will depend on the material, end mill that you are using, and whether you are using a spindle or a router. The stepping motors and the mechanics on the blueChick (and the other machines as well) can move the machine very fast (x and y about 700 ipm rapids).

You will need to refer to the manufacturer specifications for the speed on the end mill with the particular material. The Onsrud end mills sold here are of top quality and can generally go faster than standard end mills. If the reliefs are in wood, you will be able to machine around 200 to 80 ipm depending on the wood and the depth per pass. Generally, you want to rough out most of the wood with a roughing end mill then finish off with a finishing end mill with a small tip and a small step over.

If you are using a router, the speeds will be slower than a spindle since the spindle can handle more torque and the torque is compensated with the VFD (Variable Frequency Drive).

What's the maximum speed at I can machining reliefs without lost steps with BlueChick?

• I am building the 24" x 48" machine from the original book and i was wondering if anyone can provide me with the actual cutting area possible with that machine.

The cutting area is 20" x 40" for the book machine. This area is determined by the 2'x4' sheets that make up the bed of the machine. You can increase this area if you use larger sheets and adjust the gantry width by the same difference of the width of the sheets.

You can also use the plans from Woodsmith magazine to build a larger machine.
https://www.woodsmith.com/article/build-a-cnc-router-for-your-own-shop/

need cutting area of 25 x 49 what size of gantry

need cutting area of 25 x 49 what size of gantry

I am building the 24" x 48" machine from the original book and i was wondering if anyone can provide me with the actual cutting area possible with that machine.

• I purachased a bluechick from you in 2011. I am upgrading from a Porter-cable router to a 2.2kw spindle. Can you supply me with drawings for the spindle mount so that I can cut the parts?

We currently cannot release or sell any plans at this current moment! We apologize for this inconvenience, however if you email us at customerservice@buildyourcnc.com. We can help you get the current parts you will need, for a fully functional 2.2kW z-axis assembly.

I purachased a bluechick from you in 2011. I am upgrading from a Porter-cable router to a 2.2kw spindle. Can you supply me with drawings for the spindle mount so that I can cut the parts?

• Hi, I am thinking of making a CNC router that I can use in woodworking. I am very happy if you can help me with the necessary parts for this

Ok, sure. Let's get the discussion started. Please respond with your questions on this FAQ

Hi, I am thinking of making a CNC router that I can use in woodworking. I am very happy if you can help me with the necessary parts for this

• Hello. I like your vertikal router. Is then router stabil enogh for the need of a Carpenter? Are you using 21mm Plywood or 21mm MDF. What type of spindel (KW) is maximum allowed and whatbis the maximum feed (6mm cutter) in oak. Thank you, Veit

The greenLean vertical CNC is stable enough to handle large-scale production on a daily basis. We use 3/4" MDO plywood, which is equivalent to about 19mm. The gantry is designed to hold a 2.2kW Spindle, with a maximum of 24,000 RPM.

• I am looking at purchasing the greenbull 5X system with the laser/spindle combination. Can the laser do both rastered engraving as well as vectored cutting with the same breakout board and software? If I have this wrong please let me know what would be needed to accompish this.

You can do raster and vector engraving on the greenBull laser/spindle combination. The methods of this process is not accomplished in the same way as the typical laser machines where CorelDRAW is used. The Mach3 laser plug-in can be used for the raster engraving and standard CNC g-code can be used for vector cutting and engraving.

The raster method will not be fast on the greenBull since the z-axis is heavy and there are inertial limitation on doing fast raster back and forth movement. Vector is the best use of this machine.

• What 1/2" collet and nut do I use for the Greenbull with the 2KW spindle? I want to order the Onsrud Spoilboard surfacing cutter.

For the 2.2kW Spindle you would need the ER20 1/2" Collet.

What 1/2" collet and nut do I use for the Greenbull with the 2KW spindle? I want to order the Onsrud Spoilboard surfacing cutter.

• HEY ! I HAVE PURCHASED A VFD WITH MATCHING SPINDLE 1.5KW AND CONTROL PROGRAM UCCNC. MY INTERFACE CARD IS DB25, THE QUESTION HOW DO CONNECT TO DB25 SO THAT CAN SPEED UCCNC? SINCERELY "CNC BEGINNERS"

Identify the Control Signals: First, determine which control signals from the DB25 interface card are used for spindle speed control. Typically, these are PWM (Pulse Width Modulation) signals or analog voltage signals.

VFD Configuration: Your VFD should be configured to accept the type of control signal your DB25 card provides. This involves setting parameters in the VFD that correspond to the type of input signal it will receive for speed control.

Wiring: Connect the appropriate output pins from the DB25 card to the input terminals on the VFD. This usually involves connecting the PWM or analog output to the corresponding input on the VFD. Make sure to consult the manuals for both your VFD and interface card for specific wiring details.

UCCNC Settings: Configure UCCNC to output the correct type of signal (PWM or analog) that matches your VFD's configuration. This is done through the software's spindle setup section.

Test and Adjust: Run some tests to ensure that the spindle speed is being correctly controlled by UCCNC. You might need to tweak settings in either the VFD or UCCNC for optimal performance.

HEY ! I HAVE PURCHASED A VFD WITH MATCHING SPINDLE 1.5KW AND CONTROL PROGRAM UCCNC. MY INTERFACE CARD IS DB25, THE QUESTION HOW DO CONNECT TO DB25 SO THAT CAN SPEED UCCNC? SINCERELY "CNC BEGINNERS"

• Is the 4kv spindle constructed using two or four bearings and what size collets are included with the spindle/vfd combo?

Yes, all of the spindles come with collets. The collets have a 1/4" (6.35mm) bore for end mills that have a 1/4" shank. The ER specification is different for the 1.5kW (ER-11) and the 2.2kW (ER-20).

Is the 4kv spindle constructed using two or four bearings and what size collets are included with the spindle/vfd combo?

• what is the warranty period and do you repair these in house? 2.2 kW (kilowatt) Water Cooled Spindle with Inverter (VFD)

Spindles are generally covered up to 1 year after date of purchase. We do not repair them in house, but we do work with our manufacturer to replace defective units. Generally if you have a defective unit covered under warranty, we will issue a replacement.

what is the warranty period and do you repair these in house? 2.2 kW (kilowatt) Water Cooled Spindle with Inverter (VFD)

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