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Cnc Conversion On Small Knee Mill

Discussion in 'MACHINE BUILD LOGS' started by Al3xander, Feb 2, 2016.

  1. Al3xander

    Al3xander Canada Iron Registered Member

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    Hey I am hoping someone with a little more experience can help coach me on a successful CNC conversion of my knee mill. I have lots of experience machining and almost no experience with electronics. This is the mill I have. It is also sold by grizzly with the name g3617
    20160131_140408.jpg

    I found a kit someone has purchased for a CNC conversion that they never finished. It was really cheap so I just bought the whole set up with out researching it or testing it. 20160118_191052.jpg 20160118_191423.jpg
    I have a computer with mach3, a break outboard, 3 drivers and a power supply that is all wired up but nothing is configured properly and is still untested. This is what I was thinking for driving the original acme lead screws. The 2 biggest questions are will the stepper motors be big enough? and how do I set up the drivers? plus any suggestions on my construction would be appreciated.
    20160131_204423.jpg
    This is a mock up of my timing belt. you can see it is a 2:1 ratio because I suspect I may not have enough torque with these motors? 20160201_203359.jpg
    The steppers and the drivers are made by Wantai. I don't know how I am going to do Z yet? I suspect I may need to CNC the quill and move the knee manually
     
  2. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Looks like a fun project.

    It would be helpful if you could post the details of the drives, motors and power supply. You should be able to look up the model numbers on the Wantai website and download the specs.

    Jay
     
  3. Al3xander

    Al3xander Canada Iron Registered Member

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    Hi thanks for your reply. The power supply has an output of 48v and 7.5A, The drivers say they are 2H micro stepping drivers and the highest RMS I see on the chart on the side is 5.6RMS, does this mean they are 5.6A drivers? The motors are 2 amp and produce 4.4nm of holding power.This is the breakout board I have it is from CNC4pc C10 - BI-DIRECTIONAL PARALLEL PORT INTERFACE CARD.

    BOB:c10 parallel port interface card
    driver: Wantai DQ860MA
    power supply: S350-48
    Is there any info that I missed?
     
  4. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Welcome Aboard!

    It looks like the hardware you have should work. The motors might be a bit light, but you can change them out later if needed. The 2:1 gearing is the right way to go. There is a lot of support information on-line for Mach3 and CNC4PC, so you are well covered there.

    As far as setting up the drives, set the DIP switches to match the motor amps. I would start out 400 steps setting on the DIP switches also.

    One thing that might be a problem, I think X axis motor might hit the knee then the table is to the far left. Normally the motor sticks out to the right. The Y axis motor can be tucked in beside the knee. Powering the quill is the way I would do it.

    Looks like a fun project please keep us posted on your progress.
     
  5. Al3xander

    Al3xander Canada Iron Registered Member

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    I will try 400 steps thanks for the tip. I checked the clearance between the knee and the back of thr motor. It is just going to fit there .
     
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  6. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    You may also find the system under powered with a single power supply for three drivers.
     
  7. Al3xander

    Al3xander Canada Iron Registered Member

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    I finished everything for the X axis. I set the driver to 2 amps and the step rate to 400 on the driver. I tested the axis using Mach3. The movements seem accurate but the actual feed rate the machine is moving is much faster than the controller thinks it is. Also I need to go slow when moving the axis or the motor will just buzz and not move at all. I have attached a picture of how my motor is set up in mach3. Where did I go wrong and what are those 2 boxes for near the right? Step pulse and Dir pulse image.jpeg
    I need 20 revolutions of the stepper motor to move the machine 1"
    image.jpeg
     
  8. JimDawson

    JimDawson Global Moderator Staff Member Director

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    One thing I see is the steps per seems a bit high. 400 steps x 20 rev per inch = 8000 steps per inch. Then start out at acceleration =1. That should eliminate the decouple (buzz). Then bump it up a bit when you get things under control. Step Pulse is the step pulse width in micro seconds, not exactly sure why there is even a direction pulse width setting, normally it's either on or off for an extended time. Don't forget to Save Axis Settings after you make a change, I have forgotten that more than once.
     

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