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  1. #11
    Quote Originally Posted by Lloyd View Post
    anyway, I'll take your advice regarding the brackets, positioning, and screws, - but this could change should I decide to invest in more expensive digital drivers?
    You don't have to take my advice and by all means go for the larger screws etc but you will regret I guarantee you that.!!

    Your doing the classic BIGGER IS BETTER approach and that's a sure fire way to waste money and build an under performing machine. Digital drives won't make any differance if they are sized wrong and mismatched to screws.
    Even with the stuff I suggested I recommend you use Digital drives but this as nothing to do with giving more power but more to do with being smoother running and resonance handling capabiltys.

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  3. #12
    Quote Originally Posted by Lloyd View Post
    . . . it would be good to see anyone's idea of what percentage of your budget you' should allocate to which part of the machine... e.g. 15% on base structure, 35% xyz hard wear 50% on power, control, motors etc....
    For my machine http://www.mycncuk.com/forums/gantry...eady-eddy.html the breakdown was roughly this;

    mechanical 1600
    electrical 1500
    spindle + vfd 1000

    I've listed the spindle/vfd seperate bacause most people here seem to buy the Chinese 2.2kw model but I went for an Elte spindle and ABB vfd.
    Last edited by EddyCurrent; 06-05-2014 at 09:48 AM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

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  5. #13
    Quote Originally Posted by Ger21 View Post
    The cheapest way to get a good machine is to spend more money. Any places you try to save money will usually result in spending more money later to replace the cheap components. Or you live with an inferior machine that still cost 80% of what a good machine would have cost.
    Missed this last night but Excellent reply that Gerry best way I've seen it said yet.!! . .
    Last edited by JAZZCNC; 06-05-2014 at 04:05 PM.

  6. #14
    Quote Originally Posted by JAZZCNC View Post
    You don't have to take my advice and by all means go for the larger screws etc but you will regret I guarantee you that.!!

    Your doing the classic BIGGER IS BETTER approach and that's a sure fire way to waste money and build an under performing machine. Digital drives won't make any differance if they are sized wrong and mismatched to screws.
    Even with the stuff I suggested I recommend you use Digital drives but this as nothing to do with giving more power but more to do with being smoother running and resonance handling capabiltys.
    I understand what you're saying- I have received advice saying I should get large screws on my X,Y and Z and I should get 800w digital drives... But here, collaborative experience dictates otherwise...

    as for the bigger is better approach; no, I just want a good solid reliable machine and I'm willing to invest the time and effort in researching the best equipment - you guys seem to know what you're talking about, and I'm just trying to understand the reasoning behind, which for all intents and purposes you've so far done well to justify.

    My general philosophy when it comes to building stuff is to keep it simple and functional, I hate things that are over engineered unnecessarily.

    So with the machine, I would like to use only the best possible parts for the required cutting area and material.

    based on what you've told me (and off the top of my head)

    profiled rails are best on all axis.
    20mm ball screws on x, 16mm on y and z.
    the ball nuts should be reinforced more than I have.
    the position should be better placed, to avoid chips and being knocked
    i should use digital drives correctly sized and I should not get poor motors with high inductance. (Have to get the maths out for the lads!!!!)
    the bed should be adjustable, so when I cut alu, I should be as close to the y gantry as possible.
    to help reduce resonance, I should use pullies this will also enable me to adjust ratios...
    pitch on the ball screws should be 10mm on x and y and 5mm on z...
    And dont waste money - unless I really want to ;)

    did I miss anything?

  7. #15
    Quote Originally Posted by Lloyd View Post
    did I miss anything?
    Yes, you mostly just listed the mechanical items.

    the PC to machine interface
    breakout board / spindle speed control
    Emergency stop / limits / homing switch strategies
    the rest of the electrical stuff like power supplies, what voltage to use, amps required ?
    the spindle and cooling system if water cooled
    the variable frequency drive
    type of wiring to use
    cable drag chain
    fan assisted cooling of control panel
    software to use, Mach3, Linux, other ?
    material and construction of bed surface.

    must be something I've missed now ?
    Last edited by EddyCurrent; 07-05-2014 at 10:17 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  8. #16
    with a name like eddy current... no wonder you've listed everything Electro-related :) so far, i can find a Foucault with your list... excuse the worst pun ever!

  9. #17
    Quote Originally Posted by Lloyd View Post
    with a name like eddy current... no wonder you've listed everything Electro-related :) so far, i can find a Foucault with your list... excuse the worst pun ever!
    i mean cannot**

  10. #18
    Jazz mentioned the nema 23 motors... These CNC kits seem cheap... What's the deal with them? Are they any good?

    When it comes to this side of the machine, I have to admit, I'm a bit lost thus far...

    eddy current - you mentioned you spent 1500 on electrical... What was your breakdown? Or shopping list?

  11. #19
    Quote Originally Posted by Lloyd View Post
    Jazz mentioned the nema 23 motors... These CNC kits seem cheap... What's the deal with them? Are they any good?
    Good motors, but the rest of it is sub-optimal. Those motors need about 75V to run well - see here (and here if you want to see investigate the mechanical equations). Read some more of the build logs on this forum as everything mentioned so far in this thread has already been covered.
    Last edited by Jonathan; 07-05-2014 at 11:51 PM.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

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  13. #20
    You don't want regulated power supplies, linear type are best for this application.

    Quote Originally Posted by Lloyd View Post
    eddy current - you mentioned you spent 1500 on electrical... What was your breakdown? Or shopping list?
    See here, http://www.mycncuk.com/forums/gantry...html#post56144
    Last edited by EddyCurrent; 08-05-2014 at 09:43 AM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

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