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  1. #51
    Quote Originally Posted by Boyan Silyavski View Post
    closing the loop with servos definitely makes machine faster.
    But is this a function of the closed loop or is it the fact that the drivers are part of the package and this stops cheapskates buying inadequate hardware and then blaming low speeds and step loss on open the loop?
    ;-)

    - Nick
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  2. #52
    I thought selecting a stepper or servo should bee easy, but it seems like nothings easy here. So for each person I ask I get a different recommendation. Steppers, open loop, closed loop, no only servos is good enough. The common thing is that everyone recommends servos if I want to use the money. But they are waaaaaaaaaaay more expensive than normal steppers. And all the cheap servos and closed loop steppers is a pain to get information on, since the datasheets and torque curves is not easily available and I have to ask the sellers for it for every motor. But my logic is as follows, if open loop steppers is good enough for Tormach it's good enough for me. First to comment on how this is not a mill. Then I can use some higher quality steppers instead.

    By the way can someone remember the good reason to not use overkill steppers like 8nm nema 34? It's not like they are a lot much more expensive. I read it somewhere but I can't find it.
    Last edited by PotatoMill; 23-06-2016 at 09:08 PM.

  3. #53
    With nema 34 you will need mains voltage drives to get any decent results You won't go far wrong with decent 23,s from Zapp or CNC4you

    With AM882 or similar drives and 68V power supply non linear
    Last edited by Clive S; 23-06-2016 at 09:59 PM.
    ..Clive

  4. #54
    Quote Originally Posted by PotatoMill View Post
    By the way can someone remember the good reason to not use overkill steppers like 8nm nema 34? It's not like they are a lot much more expensive. I read it somewhere but I can't find it.
    I think Nema 34 steppers would be too large for your machine. The Load/Motor Inertia Ratio would probably be below 1:1 and therefore you're using more energy accelerating the motor shaft than you are accelerating the 40kg load!

    I'm not sure about Steppers but for Servos a 5:1 Load to Motor Inertia Ratio is pretty normal, with 2-3:1 being higher performance and even 1:1 is used for super speedy machines.

    A belt reduction gives you flexibility in the gear ratio. If you happen to under size the motors you can lower the gearing and get more torque with less speed, but if you over size the motors you can get some free speed!

    I'm sure you can see how this becomes a hobby for many people... Haha!

    Cheers,

    Fenza

  5. #55
    How about fixed screws and rotating ballnuts?
    No problems with whip from the screws and reduced rotating mass ;-)
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  6. Quote Originally Posted by magicniner View Post
    ...or is it the fact that the drivers are part of the package and this stops cheapskates buying inadequate hardware and then blaming low speeds and step loss on open the loop?
    ;-)

    - Nick
    I couldn't have said it better.
    project 1 , 2, Dust Shoe ...

  7. #57
    Quote Originally Posted by magicniner View Post
    How about fixed screws and rotating ballnuts?
    No problems with whip from the screws and reduced rotating mass ;-)
    I'll just need CNC router to make it first

  8. #58
    Quote Originally Posted by PotatoMill View Post
    I'll just need CNC router to make it first
    Jonathan has made them for people in the past - worth an RFQ?
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  9. #59
    Do someone have some opinions on this stepper http://www.aliexpress.com/item/Nema-...999.264.8phZye? 1.8mh seems nice, but the seller dont looks so professional.

  10. Quote Originally Posted by PotatoMill View Post
    Do someone have some opinions on this stepper http://www.aliexpress.com/item/Nema-...999.264.8phZye? 1.8mh seems nice, but the seller dont looks so professional.
    https://www.cnc4you.co.uk/Stepper-Motor

    https://www.poscope.com/nema23
    Last edited by Boyan Silyavski; 28-07-2016 at 06:25 AM.
    project 1 , 2, Dust Shoe ...

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