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  1. #1
    Join Date
    Aug 2015
    Posts
    4

    Larken replacement parts

    New member here. I bought a Larken 24/24 back in I believe 2004(?). I must say it has performed incredibly well. My only problem is once in a while the X or Y axis will get "stuck". I have read that the machines this old had Pacific Scientific steppers that were almost under powered for the machine (100 oz-in. torque). I have two questions:

    1. Does anyone have the replacement part number for the X and Y lead screw nuts? I believe Larken uses Kerk Leadscrews (Now Haydon?). I could take the nuts off and figure out the lead, etc. but I would rather order the nuts and then replace and not have to be down for a week. I think Larry has stated that he specially machines the Z nut. I really can't complain - almost 11 years and I have not changed or had to replace anything on this CNC router. (I have rebuilt 2 Bosch routers on the spindle).

    2. To address the potentially under powered motors, has anyone replaced their motors? If so what brand, holding torque, phase current (amps), and voltage. I believe the motor drivers in my controller are only rated for 2 amps to drive the motors. The Pacific Scientific motors are labelled P224RHS-LNN-NS-02 with 1.8 degree step, 3.1 amp, bipolar parallel. I have great success with this machine and would like to boost the motor power without changing anything else.

    At some point I know I will have to update to a windows based controller. For now I am OK with windows 98 for my controller. Any help would be greatly appreciated. Thanks.

  2. #2
    Join Date
    Aug 2015
    Posts
    4

    Re: Larken replacement parts

    After looking at the most recent build pics of the Larken shop, I have found what appears to be the X and Y lead screw nut part number. There is a bag of the nuts with Kerk part numbers on them.

    ZBX-ANR-050-0333-8200

    ZBX - anti-backlash style
    A - Triangular Flange Mount
    N - No lubricant
    R - Right Hand thread
    050 - Lead Screw Diameter - 1/2"
    0333 - Lead Screw Pitch - 0.333"
    8200 - Not sure - I think it is a customer assigned number to make ordering easier for Larken

  3. #3
    Join Date
    Aug 2015
    Posts
    4

    Re: Larken replacement parts

    OK.....I have another question. Larken had told me I could go to new motors and drivers and told me to set the drivers to 800 steps/turn. I checked my Larken 24/24 today in regards to the lead on the leadscrew. I measured the linear motion on one motor turn and it was .333 in. This does not seem to compute with Larry saying to set the drivers to 800 steps / turn. There is no gearhead or gearing so wouldn't a 1.8 degree step motor and a 0.333 in lead equate to 600 steps / turn?
    Any input would be appreciated. Thanks.

  4. #4
    Join Date
    Mar 2003
    Posts
    35538

    Re: Larken replacement parts

    Maybe he means set the drives to 1/4 step, or 800 steps per motor revolution.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  5. #5
    Join Date
    Aug 2015
    Posts
    4

    Re: Larken replacement parts

    Quote Originally Posted by ger21 View Post
    Maybe he means set the drives to 1/4 step, or 800 steps per motor revolution.
    I believe you are correct - Thank you!

  6. #6
    Join Date
    Feb 2007
    Posts
    962

    Re: Larken replacement parts

    Quote Originally Posted by ger21 View Post
    Maybe he means set the drives to 1/4 step, or 800 steps per motor revolution.
    Yes, the drives are set to 800 steps/rev so the x and y axis (3tpi screw) has 2400 steps/inch. On the Z axis the screw is 5tpi so its 4000 steps/inch.

    Larry
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

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