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  1. #1
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    Mar 2009
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    8L X and Z directions...

    I'm setting up a non-tormach cnc lathe and want to emulate a tormach 8L for cad/cam purposes. I'm not new to CNC as I have 2 cnc mills, and 2 cnc routers, but I do not have a CNC lathe.

    Couple Questions related to the 8L: Assume you are standing in front of the lathe, with the spindle on the left hand side.

    1) When homing the Z axis, does the carriage go to the left or the right to find the home sensor?
    2) When homing the X axis, does the carriage go away from you (back of lathe) or to you (front of lathe) to find the home sensor?
    3) When you press the left arrow on the keyboard, does the carriage (Z) go to the left or the right?
    4) When you press the left arrow on the keyboard, does the DRO number for Z go up or down?
    5) When you press the up arrow on the keyboard, does the carriage (X) go to the back of the lathe or the front of the lathe?
    6) When you press the up arrow on the keyboard, does the DRO number for X go up or down?

    Thanks a ton!
    Scott...
    Instructional Videos for CNC Guitar Building
    http://www.rmgvideos.com

  2. #2
    Community Moderator Jim Dawson's Avatar
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    Re: 8L X and Z directions...

    Quote Originally Posted by sagreen View Post
    I'm setting up a non-tormach cnc lathe and want to emulate a tormach 8L for cad/cam purposes. I'm not new to CNC as I have 2 cnc mills, and 2 cnc routers, but I do not have a CNC lathe.

    Couple Questions related to the 8L: Assume you are standing in front of the lathe, with the spindle on the left hand side.

    1) When homing the Z axis, does the carriage go to the left or the right to find the home sensor?
    2) When homing the X axis, does the carriage go away from you (back of lathe) or to you (front of lathe) to find the home sensor?
    Depends on where the home switches are. Home normally would be in the right rear position.

    3) When you press the left arrow on the keyboard, does the carriage (Z) go to the left or the right?
    Carriage should move left,

    4) When you press the left arrow on the keyboard, does the DRO number for Z go up or down?
    Z moving in the negative direction (counting down)

    5) When you press the up arrow on the keyboard, does the carriage (X) go to the back of the lathe or the front of the lathe?
    The X carriage should be moving to the back (away from you)

    6) When you press the up arrow on the keyboard, does the DRO number for X go up or down?
    The X DRO should be counting up

    This is the case for all lathes.

    X G54 zero is normally tool tip on the spindle centerline. Z G54 zero is normally tool tip at the right end of the part.

    .
    Jim Dawson
    Sandy, Oregon, USA

  3. #3
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    Re: 8L X and Z directions...

    All of this is the way I set the machine up based on what I would have expected with a Mill... But, if you watch this video at 2:29, he turns a part down and measures the diameter. He uses that diameter to set the tool distance, in this case the diameter that part is at that tool position. Then sets X to that negative diameter. So, if I am understanding what he is doing then Zero would be closer to center and I guess that if you are going up in X towards the back of the machine, then entering a negative number here does that.

    Is that the way that everyone sets tools up? Do you do this every time you cut a part? I would have thought that you just drop a tool on the toolpost and change to that tool and based on your tool offsets it knows where that tool is.

    Scott...

    Quote Originally Posted by Jim Dawson View Post
    Depends on where the home switches are. Home normally would be in the right rear position.



    Carriage should move left,



    Z moving in the negative direction (counting down)



    The X carriage should be moving to the back (away from you)



    The X DRO should be counting up

    This is the case for all lathes.

    X G54 zero is normally tool tip on the spindle centerline. Z G54 zero is normally tool tip at the right end of the part.

    .
    Instructional Videos for CNC Guitar Building
    http://www.rmgvideos.com

  4. #4
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    122

    Re: 8L X and Z directions...

    The X axis of the 8L is reversed from the 15L

  5. #5
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    Nov 2007
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    2086

    Re: 8L X and Z directions...

    Quote Originally Posted by sagreen View Post
    I'm setting up a non-tormach cnc lathe and want to emulate a tormach 8L for cad/cam purposes. I'm not new to CNC as I have 2 cnc mills, and 2 cnc routers, but I do not have a CNC lathe.

    Couple Questions related to the 8L: Assume you are standing in front of the lathe, with the spindle on the left hand side.

    1) When homing the Z axis, does the carriage go to the left or the right to find the home sensor?
    2) When homing the X axis, does the carriage go away from you (back of lathe) or to you (front of lathe) to find the home sensor?
    3) When you press the left arrow on the keyboard, does the carriage (Z) go to the left or the right?
    4) When you press the left arrow on the keyboard, does the DRO number for Z go up or down?
    5) When you press the up arrow on the keyboard, does the carriage (X) go to the back of the lathe or the front of the lathe?
    6) When you press the up arrow on the keyboard, does the DRO number for X go up or down?

    Thanks a ton!
    Scott...
    imho i would follow cnc standards for x and z control! 8l does not and causes some confusion I bet

    1) right
    2) front
    3) left
    4) same as sbl15 up. and this is a cnc standard in g-code.
    5) back
    6) opposite of sbl15. tools in front of spindle have a x+ offset value not a cnc g-code standard. cnc g-code standard is x- for tools in front of spindle

    all tools reference a base tool that is used to set "work offsets". If base tool "tool offsets" are changed then all tools associated in tool table will require new "tool offsets" based on the base tool.
    otherwise use the base tool to set "work offsets " and then run code. all associated tools will use the preset associated "tool offsets" to move to correct "work offset" and cut.

  6. #6
    Community Moderator Jim Dawson's Avatar
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    Re: 8L X and Z directions...

    I edited the posts above to correct an error on my part. The Home 0,0 position should be in the top RIGHT position Z(I originally said left)

    On any CNC lathe you have at least two coordinate systems, Machine Coordinates (MCS) and Work Coordinates (WCS) The MCS 0,0 is at the home position. The WCS is an offset from the MCS.

    The WCS X0 is on the spindle centerline. When the tool offset is applied, X 0 should put the tool tip on the spindle centerline. So in the video when Joe set the WCS for the tool, he set -1.7527, negative because the tool tip was on the operator side of the spindle centerline.

    Normally, once you have tools set in the X axis, you should not need to change the offsets until you change the tool in the holder. The X tool offsets should stay with the machine, rather than the job.

    Normally in CAM, you will set the X 0 to the centerline of the part, and also set the tool orientation to set from which side the tool is approaching the work.

    I hope I haven't confused you too much. It took me a while to figure all of this out when I got my lathe.
    Jim Dawson
    Sandy, Oregon, USA

  7. #7
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    Re: 8L X and Z directions...

    Thanks everyone. All of this makes perfect sense. I'm getting close to making chips and wanted to start with the machine configured correctly.

    I've attached an image of the culprit for posterity. Looking a lot better since I knocked down the rust from setting about 8 years...

    Scott...
    Attached Thumbnails Attached Thumbnails lathe1.jpg  
    Instructional Videos for CNC Guitar Building
    http://www.rmgvideos.com

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