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Question #: 14277

Question: When we simulate cutting a part, the part is 40% larger than it should be. Why?

Current Solution

What software are you using to simulate the CAM machining operations?

Additional Information:
I drew my part in ViaCad, opened part in CamBam to produce GCode, then Mach3 to simulate cutting part. Everything worked as it should but part was too large.

Additional Information:
It sounds like steps per unit is not calibrated properly. Use the Mach3 to calibrate the axes. In the settings tab, there will be axis calibration labeled just above the reset button. There is a button just just below axis calibration called set steps per unit. When the button is clicked, mach3 will present you with a dialog box asking for a measurement of how far to move the specific axis you need to calibrate (use a number that will not make the machine over run the axis). The machine will move to a certain length. Measure that length and enter it into the next dialog box that Mach3 presents to you. Do this for each axis.

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Other Possible Solutions to this Question

  • 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.

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

  • Under what conditions should the LED on the 3d printer driver be lit when the driver is connected to the MB?

    The driver's LED serves to indicate a fault condition. The driver chip has built in protection for overheating and over current. If the LED is on, most likely, the driver will stop until the condition is resolved. If you see the LED on, adjust the vref trimmer. First, connect a multimeter to the pads just next to the trimmer potentiometer and adjust until the voltage is lowered a bit. Alternatively, even though the PCB contains a vast amount of thermal vias and a relatively large ground plane connected to the belly of the driver, there still may be a need to cool the driver chip using a small heat sink. Do this only if you are not satisfied with the performance of the motor at the torque require.

    Click the link to respond:
    Under what conditions should the LED on the 3d printer driver be lit when the driver is connected to the MB?

  • When Blacktooth is powered on the motors get power but will not turn. What should I do?

    The motors could be wired incorrectly causing them to lock up. Make sure to check the wiring to make sure the X and Y are connected to the correct terminals.

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    When Blacktooth is powered on the motors get power but will not turn. What should I do?

  • Is the Greenlean capable of cutting soft metals like aluminum or brass? Thanks

    Yes, the greenLean can cut metals such as aluminum and brass. The gantry and Y carriage was designed to be rigid enough to handle these types of metals. The typical metal cutting techniques should be used, such as high feedrates to reduce heat buildup at the end mill, or the use of cutting fluids or cold air used at the end mill as is necessary with most machines that cut similar metals. This is necessary since the aluminum has a rather low melting point and can clog the end mill.

    Additional Information:
    All of our machines are capable of cutting many metals, including steel and aluminum as long as the proper CNC machining operations are used like light fast passes, and if desired, using air cooling for better performance.

    Here is a video of one of our customer demonstrating aluminum cutting using air to cool the end mill.
    https://www.buildyourcnc.com/tutorials/tutorial-milling-cutting-metal-blacktoe-mark-gottschalk

    Additional Information:
    how do I hold down material on a greenlean

    Click the link to respond:
    Is the Greenlean capable of cutting soft metals like aluminum or brass? Thanks

  • Do you have a laser kit that is larger than the blackTooth?

    We have one in the works. It is a 4'x8' machine that will house the 80w laser tube on the gantry. The machine is bout 2 months out as of 1/7/2014.

    Click the link to respond:
    Do you have a laser kit that is larger than the blackTooth?

  • When connecting homing switches, should I use more than one input?

    It is ok to connect the limit/homing switches to the same input.  The machine will go through a procedure that will start with the first axis, hit the switch, pull off, move more slowly for better accuracy, then pull off again.  This procedure makes sure that the input is always in the correct state while homing.

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    When connecting homing switches, should I use more than one input?

  • Where is the best place to see projects made with BuildYourCNC CNCs? I would like to get an idea of carving capabilities and cutting Baltic Birch plywood. Thanks.

    You can always come to our offices in Katy TX. If that is not an option, we can do cut in our shop and record video for you. Specify what you would like to cut and we can consider doing this for you.

    Thanks. I've reviewed the gallery and think my question comes down to this- Can I do hardwood carving like Mike M.'s guitar display cases and cut 3/4 inch baltic birch plywood with the same machine?

    Absolutely, the cutting and machining is more a function of how the machining operations are created and specified. Baltic birch is not a tough material and you will be able to cut very aggressively with any of our machine kits.

    Click the link to respond:
    Where is the best place to see projects made with BuildYourCNC CNCs? I would like to get an idea of carving capabilities and cutting Baltic Birch plywood. Thanks.

  • Does the 2X4 ft CNC model allow cutting a 2X4 ft board or what is the cutting demeninsions? Thanks

    Yes, the 2'x4' CNC router (blackToe) cuts within the full 2'x4' dimensions and a tiny bit more.

    Link to the machine:
    https://www.buildyourcnc.com/item/cnc-machine-blacktoe-v4-2x4

    Click the link to respond:
    Does the 2X4 ft CNC model allow cutting a 2X4 ft board or what is the cutting demeninsions? Thanks

  • Why should I use a spindle rather than a router?

    The spindle is quieter and has more consistent torque (It doesn't get "bogged down" when it starts cutting into material). It can be used with collets of varying sizes (not restricted to imperial sizes). It is water cooled and so it does not blow air downward to cool the spindle like the router does. The spindle is also machined with much higher precision than typical routers and will have a much longer life.

    Click the link to respond:
    Why should I use a spindle rather than a router?

  • 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?

  • should i be getting power from the parallel port? the green light is on without the usb and i think it might be causing a grounding issue.

    Yes, there is a small signal level voltage coming from the parallel port out of the computer. If the pin is high, then it will be outputting 5v and if the pin is low, it will be pulled to ground. It may appear that your parallel breakout board is powered, but will not provide sufficient voltage to properly operate the drivers. The USB power is vital for proper operation.

    Click the link to respond:
    should i be getting power from the parallel port? the green light is on without the usb and i think it might be causing a grounding issue.

  • i want to make a cutter laser machine with 4kwatt power so i want to buy all this laser components can you list the parts and cost thanks

    We can lower the price for just the hardware and also for the structure. However we do not have any files, dimensions, for public access.

    Additional Information:
    Would there be any/enough measurement or info on the instructions to extrapolate the dimensions? What would the new pricing be?

    Click the link to respond:
    i want to make a cutter laser machine with 4kwatt power so i want to buy all this laser components can you list the parts and cost thanks

  • Should I have recieved documentation on any of the parts? No connection diagrams or pin callouts were included. No motor spec sheet either.

    All of the information and instructions for kits and products are shown on their respective product pages. If you need personal assistance, please give us a call and it will be our pleasure to guide you and solve any problem that you may have.

    Click the link to respond:
    Should I have recieved documentation on any of the parts? No connection diagrams or pin callouts were included. No motor spec sheet either.

  • What kind of cooling system should we set up for the Blacktooth laser cutter laser tube? Can tap water be used? Is water temperature critical?

    The blackTooth's 40 watt laser tube can be cooled with simple tap water. A bit of anti-freeze keeps the tap water clean and free of algae. The cooler the water, the better output you will get from the laser. A great source of information can be found here: http://www.buildyourtools.com/phpBB3/viewtopic.php?f=8&t=3452

    Click the link to respond:
    What kind of cooling system should we set up for the Blacktooth laser cutter laser tube? Can tap water be used? Is water temperature critical?

  • WHEN SHOULD INFLUENZA (THE FLU) VACCINE BE GIVEN?

    You can begin offering vaccine as soon as vaccine becomes available. Early vaccination of children younger than age 9 years who are first time vaccinees can be helpful in assuring routine second doses before the influenza season begins.

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    WHEN SHOULD INFLUENZA (THE FLU) VACCINE BE GIVEN?

  • WHEN SHOULD INFLUENZA (THE FLU) VACCINE BE GIVEN?

    ACIP recommends annual influenza vaccination for all children age 6 months and older who do not have a contraindication to the vaccine.

    Click the link to respond:
    WHEN SHOULD INFLUENZA (THE FLU) VACCINE BE GIVEN?

  • WHEN SHOULD INFLUENZA (THE FLU) VACCINE BE GIVEN?

    ACIP recommends annual influenza vaccination for all children age 6 months and older who do not have a contraindication to the vaccine.

    Click the link to respond:
    WHEN SHOULD INFLUENZA (THE FLU) VACCINE BE GIVEN?

  • Can a sample be sent and or brought to you for confirmation of the end results when cutting carpet tile and or hard surface tile?

    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:
    Can a sample be sent and or brought to you for confirmation of the end results when cutting carpet tile and or hard surface tile?

  • Why is my 4x8 blackfoot not cutting shapes correctly. I have ran the moter test in Mach 3 and still cuts terrible

    Dealing with the machine not cutting the design you may have correctly, could be a variety of things.
    Most common, is the machine is not properly calibrated or tighten correctly (in specific areas).
    To calibrate the machine, go to the settings(alt-6) page, and click the set steps per unit(right above the reset button). You will receive a tab which asks to select the a axis, once selected it will ask how much you plan on moving. Here you will enter a value of inches/mm's. The machine will move what it thinks is the correct length and might be dead on or might be off, we recommend doing this about 2-3 times per axis, and in long distances. (ex: for the BF you may do 2-4Ft on y-axis and 5-8Ft on the x-axis)

    Make sure the v-groove bearings are tight, on the y-axis plate and z-axis, as well as the v-groove bearings on the gantry legs. (test: try moving them with your finger, if tighten correctly they will not move)
    Also having the chain too loose will not move the machine enough to create your design, the chain should have about a 1" - 1"-1/2" of slack in the middle of the table when the gantry is in either of the far ends of the table. (larger machines will have a bit more slack).

    Trying to run the machine faster then the bit can cut, or running with a old endmill/router bit.
    This is a rare occurrence but is seen, having the correct endmill, feedrate, and RPM will have a great impact on your cut. They all work together in one complete conjunction, if one is off they will all be working incorrectly.
    Each endmill will have its manufactured specifications.

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    Why is my 4x8 blackfoot not cutting shapes correctly. I have ran the moter test in Mach 3 and still cuts terrible