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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.

Additional Information:

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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)
    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:
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    Additional Information:
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    Click the link to respond:
    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

  • 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.

    Link to the lead screw and other mechanical parts needed:
    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.

    Additional Information:
    20

    Click the link to respond:
    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

  • 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.

    Click the link to respond:
    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.

  • when cutting patterns with my cnc router there is significant chatter in the cut-I've replaced the router-what else should I try?

    Do you use the same bit?? If so, check if it is not dull or worn. Maybe it is time for a new bit. Additionally, I would check if the z axis mounts are tightened correctly and the router has no wiggle room. If that doesn't help, check all of the play that may be in the structure and where the bearings run along the rails and tighten all loose connections that may be present.

    Additional Information:
    So confused....is backlash and chatter the same thing or are they completely unrelated?

    Additional Information:
    Chatter and backlash are different. Backlash is a condition where there is play in the mechanical parts (i.e. a nut not tight against the treads, or two gears not meshing together tightly). Chatter is a phenomenon caused by many possible conditions including vibration, resonance, springiness and flexibility in the system and certain types of end kill and machine movement scenarios.

    Additional Information:
    Meant to say end “mill” at the end there.

    Click the link to respond:
    when cutting patterns with my cnc router there is significant chatter in the cut-I've replaced the router-what else should I try?

  • For cutting with the BlackTooth, what is the best type of clear plastic/acrylic to use, and can you recommend a source?

    The blackTooth will cut acrylic very easily. The type of acrylic (cast or extruded) is not important since the acrylic itself has 100% absorption with CO2 lasers. Any plastic retailer, even the home improvements stores will have sheets of acrylic.

    Avoid using plastics that will off-gas toxic and corrosive fumes. One example is PVC which is Polyvinyl Chloride. The burning of that material will exhaust chloride into the air and combine with the hydrogen in the air causing a chemical reaction yielding hydrochloric acid which is corrosive and highly toxic to humans.

    Always read the MSDS (Material Safety Data Sheet) for any material that you intend to burn with the CO2 laser.

    Click the link to respond:
    For cutting with the BlackTooth, what is the best type of clear plastic/acrylic to use, and can you recommend a source?

  • 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
  • Whats the maximum recommended speed to lase (engraving not cutting) a shape (say triangle) using the greenBull hybrid?

    The feedrate at which to engrave using a CO2 laser will depend on the material, depth of engraving and intensity of the laser output. For instance, if engraving plastic, you can run the machine at a very high feedrate (i.e. 100-500 ipm) and a very low intensity. In converse, anodized aluminum will require high intensity and moderate feedrate. Engraving woods will require fast or slow feedrate and high or low laser intensity depending on the result desired.

    With the greenBull, be careful with changes in direction at high feedrates as there is a very high amount of inertia with all of the components on the gantry. It is good to test raster vs. vector for some engraving patterns.

    Additional Information:
    I should have specified my exact question better. Sorry. Where you say "be careful with changes in direction at high feedrates as there is a very high amount of inertia", what is the maximum allowed acceleration (conversely deceleration) you recommend using.

    Click the link to respond:
    Whats the maximum recommended speed to lase (engraving not cutting) a shape (say triangle) using the greenBull hybrid?

  • 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.

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

    Additional Information:
    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.

    Click the link to respond:
    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".

  • 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).

    Click the link to respond:
    What's the maximum speed at I can machining reliefs without lost steps with BlueChick?

  • 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.

    Additional Information:
    20

    Click the link to respond:
    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

  • what are the different (feed, travel,rotation) speed to use with planet cnc and a 5x10 greenbull to cut mdf please?

    The feeds and speeds for cutting MDF will depend on the end mill that you are using and at the depth you are cutting.

    The feedrates below are based on 18,00 rpm and using a spindle. Routers will not be able to handle these feedrates.

    Our Onsrud end mills will cut MDF at 3/4" depth per pass at around 300 ipm using the compression end mill. A standard Onsrud single flute will cut MDF at 3/4" depth at 120-140 ipm.

    A general purpose 2 flute end mill at 3/4" depth can cut at around 80 ipm from our experience.

    Click the link to respond:
    what are the different (feed, travel,rotation) speed to use with planet cnc and a 5x10 greenbull to cut mdf please?

  • I'm looking to upgrade my X-Carve with one of your vfd spindles, can you reccomend which one to use to replace the dewalt 611 router?

    If you would like to replace a router that outputs a relatively low HP (horse power) such as the Bosch PR20EVSK or Dewalt 611, both having about 1-1.25 HP, the 1.5kW spindle would have more than enough power and will also provide constant torque where the routers are unable to achieve. The 1.5kW spindle outputs 2 HP and is water cooled to keep the dust out of the air!

    Click the link to respond:
    I'm looking to upgrade my X-Carve with one of your vfd spindles, can you reccomend which one to use to replace the dewalt 611 router?

  • I have blacktoe 4.1 with porter cable 890 router.To convert to spindle(2.2kw) can I just change the mount?

    If you would like to use a spindle rather than a router on your existing CNC, we will send you another set of components that will allow the spindle to be mounted properly which includes the z-axis rails, rail support, spindle mounts and the dust shoe components. You can find this item to purchase here: https://www.buildyourcnc.com/category/z-axis

    Click the link to respond:
    I have blacktoe 4.1 with porter cable 890 router.To convert to spindle(2.2kw) can I just change the mount?

  • 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.

    Click the link to respond:
    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?

  • I HAVE BLACKTOE 4.1 WITH PORTER CABLE 890 ROUTER.TO CONVERT TO SPINDLE(2.2KW) CAN JUST CHANGE THE MOUNT?

    If you would like to use a spindle rather than a router on your existing CNC, we will send you another set of components that will allow the spindle to be mounted properly which includes the z-axis rails, rail support, spindle mounts and the dust shoe components. You can find this item to purchase here: https://www.buildyourcnc.com/category/z-axis

    Click the link to respond:
    I HAVE BLACKTOE 4.1 WITH PORTER CABLE 890 ROUTER.TO CONVERT TO SPINDLE(2.2KW) CAN JUST CHANGE THE MOUNT?

  • 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.

    Additional Information:
    20

    Click the link to respond:
    can I control the speed of a 2.2 spindle through your 5 axis breakout board with relay?

  • What all is included in the GreenLean kit (sold with RedSprout and spindle/inverter)?

    The greenLean with the redSprout and the spindle option has everything you need excluding the spoilboard and the end mill.

    Click the link to respond:
    What all is included in the GreenLean kit (sold with RedSprout and spindle/inverter)?

  • 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.

    Click the link to respond:
    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

  • 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.

    Click the link to respond:
    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?