Accuracy I can expect from a RF-45 or similar cnc conversion? Bang for $$ point? - Page 3


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Thread: Accuracy I can expect from a RF-45 or similar cnc conversion? Bang for $$ point?

  1. #25
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    Default Re: Accuracy I can expect from a RF-45 or similar cnc conversion? Bang for $$ point?

    I think I have arrived at 4 alternatives I need to choose between, I am liking the bang for buck for option 1 / 2. Any advice is appreciated. Servos look good but are pricey for me.

    1) Leadshine open loop 3 phase steppers $255 AUD used with a motion controller and encoders on the axis
    https://tinyurl.com/y9zhucyg

    2) Leadshine closed loop steppers - $270 AUD
    https://tinyurl.com/ybwxl3w4 . Can these be used in conjunction with an encoder on the load for positional feedback though? Sorry I do not know from looking at the diagram.
    Also most other stores are $50 more, makes me pause.
    Or this 'easy servo' - https://tinyurl.com/yc6pmfsr - $280

    3) Chinese servos - $422
    albeit from a reputable Aliexpress operator BST Automation: https://tinyurl.com/yck8br4l
    The more powerful servos don't go up by much more in price, and thus I would think you could overspec and re-use in another machine if upgrading.

    4) DMM 400w servo - $441

    Also 3/4 servos need belt drive setups which adds to the cost I guess.
    Sorry I made another thread related to this but after a fair bit more research and stumbling across some people with success stories these seem like good options.

    Last edited by j3dprints; 12-14-2017 at 09:01 AM.


  2. #26
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    Default Re: Accuracy I can expect from a RF-45 or similar cnc conversion? Bang for $$ point?

    I just discovered a company that manufactures drives with glass scale feedback - https://www.ebay.com.au/itm/CNC-Holy...-/322393653446
    Aussie too! I had an awful lot of trouble ebay'ing / aliexpress searching for DC servo motors but I came across these from the US - https://www.automationtechnologiesin...-dual-shaft-2/
    Perhaps I could pair the two? Looks like a good option, they also offer normal dc servo motor drivers.

    In the meantime I've been scraping my column and table with the help of a club and a BIAX. Another new world, but a lot easier to understand than the electrical servo drive side for a novice.
    https://imgur.com/a/DNdXd

    Last edited by j3dprints; 12-26-2017 at 01:53 AM.


  3. #27
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    Default Re: Accuracy I can expect from a RF-45 or similar cnc conversion? Bang for $$ point?

    The DC motors from Automation Tech don't appear to come with encoders. So there's another cost.

    Also, they have a no-load speed of 3200RPM - significantly lower than the DMM Tech you were considering earlier. Plus they need a power supply - more money (vs. the DYN4 drives).

    (Assuming I didn't miss this in a different post) I think you might figure out what motion control system you want first (Motion controller, controller software, BOB, etc.) and then pick a set of axis motors/drives after that.

    If you choose a system that permits linear encoder feedback to close the loop to the trajectory planner - then you can use 'dumb' axis motors & drives to achieve the accuracy you indicated you wanted earlier. (i.e. Galil controller and Jim Dawson's software)

    If you choose something that doesn't permit closing the loop to the planner, then you may need to purchase axis motors/drive that have their own error correction system (servos, closed-loop steppers, etc.).



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Accuracy I can expect from a RF-45 or similar cnc conversion? Bang for $$ point?
Accuracy I can expect from a RF-45 or similar cnc conversion? Bang for $$ point?