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  1. #1
    Join Date
    Feb 2004
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    38

    Cool excello conversion stepper to servo

    hi all i just recently purchased a xlo knee mill cnc model 602? for a great price but the controllers were shot it was a 1970's paper tape reader it had 1100 Oz-In slo-syne steppers installed at 200 steps per revelution direct drive, now here is my question there is about 2" of table travel per revelution on the leadscrew (ball type) if i use a dc servo (Continuous Stall Torque (Oz-In) 352
    Peak Torque 1760 (Oz-In) 1760.) that run up to 1700 rpm, should i use reduction belt an pully set up, or direct drive??



    thanks

  2. #2
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    Jan 2005
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    Stepper motors produce their torque at a low RPM range and servo motors produce their torque at a higher but broader RPM range. With that being said, I would use a belt and pulley reduction. Are the original steppers still good/ usable, you may be able to get away with changing out the controllers to a newer style.
    If it's not nailed down, it's mine.
    If I can pry it loose, it's not nailed down.

  3. #3
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    Feb 2004
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    38
    Quote Originally Posted by 2muchstuff
    Stepper motors produce their torque at a low RPM range and servo motors produce their torque at a higher but broader RPM range. With that being said, I would use a belt and pulley reduction. Are the original steppers still good/ usable, you may be able to get away with changing out the controllers to a newer style.
    the steppers are pretty old 1.3v 20amp dc i have a rutex controller just wondering how much reduction is needed for those servos 2:1?

  4. #4
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    Dec 2003
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    24220
    Quote Originally Posted by roonster71
    2" of table travel per revelution on the leadscrew (ball type) if i use a dc servo (Continuous Stall Torque (Oz-In) 352
    Peak Torque 1760 (Oz-In) 1760.) that run up to 1700 rpm,
    Should that be 0.2"? because 2" is heck of a high lead for a ball screw.
    My Excello's are fitted with 26 inch-Lb stall torque DC motors with 2:1 timing belt reduction.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  5. #5
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    Jan 2005
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    What worries me is that 2" of travel per revolution, that's an awful lot of movement. At that amount of travel you would almost have to go with a 10:1 or 20:1 ratio to get any kind of decent resolution. At that amount of reduction you IPM speed would be awfully slow.
    If it's not nailed down, it's mine.
    If I can pry it loose, it's not nailed down.

  6. #6
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    Feb 2004
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    38
    yep i guess i need to learn to read my dial it was loose its .250 inches per rev

  7. #7
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    That's much better. With a 1000 ppr encoder and a 2:1 reduction, that would give you a resolution of 8000 pulses per inch of travel. Now were cookin.
    If it's not nailed down, it's mine.
    If I can pry it loose, it's not nailed down.

  8. #8
    Join Date
    Feb 2004
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    38
    thanks!! that the info i was looking for do you know of any good (inexpensive) places for timing belts and pully's ????

    or any place for info on xlo mill's

    thanx

  9. #9
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    Jan 2005
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    As for the mill, I am not familiar with that one. Timing belts and pulleys can be found at McMaster-Carr, W.W. Grainger and my favorite Stock Drive Products. Stock Drive has a very nice section on engineering data to help you design your drive. As for finding stuff inexpensive, I've been doing some searching myself as I'm needing the same stuff. Ebay has been a waste of time, yesterday-only 2 auctions for belts and 1 for a pulley. I have started searching metal scrap yards for them, found some stuff that has been close but not exactly what I was wanting, a lot of more yards to go thru though.
    If it's not nailed down, it's mine.
    If I can pry it loose, it's not nailed down.

  10. #10
    Join Date
    Dec 2003
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    24220
    I have the mechanical parts manuals, and the last time I checked most mechanical parts are still available, I assume the retrofit on the 602 was Z axis on the quill? They had two types of knee, one was hand crank and the other powered for initial position only.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  11. #11
    Join Date
    Mar 2004
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    1543
    Looks like most of your queries are answerred.

    I'll just mention I have the Excello 602. First with Ahha control and now with a Camsoft control. I used 2:1 reduction for servos 1:1 for steppers. Most parts from McMaster Carr

    Its been a wonderful machine for me. Parts and manuals readily available from Excello in Michigan.

    Karl

  12. #12
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    This one of the 602's I retrofitted.
    Al
    Attached Thumbnails Attached Thumbnails Dscf0041.jpg  
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  13. #13
    Join Date
    Feb 2004
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    38
    Quote Originally Posted by Al_The_Man
    I have the mechanical parts manuals, and the last time I checked most mechanical parts are still available, I assume the retrofit on the 602 was Z axis on the quill? They had two types of knee, one was hand crank and the other powered for initial position only.
    Al.
    the x and y axis were converted and the z axis was some strange "quiltrol" hydrolic mechinism from seperior electric on it whith ajustable pre set depths for the spindle im gonna have to convert the z axis also probably later

  14. #14
    Join Date
    Feb 2004
    Posts
    38
    Quote Originally Posted by Al_The_Man
    I have the mechanical parts manuals, and the last time I checked most mechanical parts are still available, I assume the retrofit on the 602 was Z axis on the quill? They had two types of knee, one was hand crank and the other powered for initial position only.
    Al.
    do you have a link or phone number to some place that stocks xlo mill parts?
    i need a quill return spring

    i found a manual in pdf at http://www.deanq.net/aboutme.htm

  15. #15
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    Dec 2003
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    The last contact I had was EX-CELL-O machine tools Sterling Heights MI 810-722-1043
    I don't have a web site.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  16. #16
    Join Date
    Feb 2004
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    38
    Quote Originally Posted by Al_The_Man
    The last contact I had was EX-CELL-O machine tools Sterling Heights MI 810-722-1043
    I don't have a web site.
    Al.
    thanks Al you are THE MAN

  17. #17
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    Mar 2004
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    Diane Scott
    Parts Sales Agent
    EX-CELL-O Machine Tools, Inc.
    586-722-1017 Phone
    586-977-6283 Fax

  18. #18
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    Mar 2004
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    847
    Quote Originally Posted by 2muchstuff
    Stock Drive Products. Stock Drive has a very nice section on engineering data to help you design your drive.
    Thanks for the link as well, great resource there - and not too badly priced.

    How does one decide what pitch and groove count to use on the pulleys? Is it just arbitrary, or does it matter?
    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
    Check Out My Build-Log: http://www.cnczone.com/forums/showthread.php?t=6452

  19. #19
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    Jan 2005
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    javadog,

    On the smaller machines that use screws less than 3/8" a MXL (.080" pitch) belt works great. On anything greater than that an XL (.200" pitch) belt is ideal. Unless you had an industrial size machine using a 2" screw, using an L series belt (.375" pitch) would be a waste, IMO. You would be amazed on how strong these belts are for their size.
    If it's not nailed down, it's mine.
    If I can pry it loose, it's not nailed down.

  20. #20
    Join Date
    Dec 2003
    Posts
    24220
    Quote Originally Posted by JavaDog
    How does one decide what pitch and groove count to use on the pulleys? Is it just arbitrary, or does it matter?
    They used to send out a whole box of around 7 different catalogues ( I see they have compacted it to 2) One half of the book read like an engineering manual for design and selection, and all kinds of tables etc.
    The price was right.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

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