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  1. #31
    Quote Originally Posted by Jonathan View Post
    Maybe create a thread about using these motors?
    Yes please!

    There was an article in MEW (Feb 2008 issue, No 135 ) about making outrunner motors but there wasn't much about how to power them. I'm guessing that the 'servo tester' provides a PWM pulsetrain and the speed controller (is this aka an 'ESC'?) sees the pulsetrain and uses electromagick to provide a 3-phase supply to the motor.

    John

  2. #32
    [QUOTE=z3t4;14653]Yes please!

    it will be a while before i can report any findings on mine... i cant wait to see how jonathan gets on with that monster motor of his and what he gets with the "star/delta" wiring (i have no idea what that is and im just about burnt out on research)
    Last edited by blackburn mark; 05-08-2010 at 04:32 PM.

  3. Quickly sketched this to show aircraft vs cnc application for those interested:

    (You could probably delete the 4.8V supply if using a BEC ESC)
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    Last edited by routercnc; 05-08-2010 at 10:25 PM. Reason: updated sketch
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  4. #34
    nice one... im not so good with the electronics but all this stuff is nice and modular,, for those that dont know BEC is just a set of 5v power leads coming out of your Electronic speed controller to run your servo tester

    anyone using small motors (engraving) might get away with an old PC power supply... they have 5v and 12v coming out of them

  5. #35
    Quote Originally Posted by blackburn mark View Post
    anyone using small motors (engraving) might get away with an old PC power supply... they have 5v and 12v coming out of them
    If you're careful you could even put the computer PSUs in series. Just need to make sure they're isolated. I considered doing this for my stepper motors since I've got plenty of 350W (or so) PSUs from the local car boot and if I put 6 in series that would have given a nice 72v for my stepper motors. I decided against this as 6 of those would have been a bit bulky and a good toroidal transformer came up on eBay.

    A cheap way of providing the 5v supply is just using a 5v voltage regulator. Any would probably suffice since it's only providing a few miliamps in this application.

    With regards to my big motor I think I could get away with the 100mm shaft collet holders. I'd probably get the 1/2" one and reduce it down to 12mm. The motor contains 4 bearings, 3 of which are 2112 bearings and one big 6089. I shouldn't be too difficult to change them but it is worth it? The biggest external diameter bearing that would fit without doing something imaginative is maybe 24mm. I can't find any angular contact bearings that would fit there.
    I've been thinking of using this motor for a 4th axis / lathe but I wont go too off topic!

  6. #36
    yo jonathan,

    i was terrified of turning down an over sized shaft so i spent weeks looking for the right size, its being shipped as we speak

    im gutted you didnt find a 150mm one, im convinced it would have been easy to stick double row A/C on the nose in a shallow housing,, ill find out as soon as my shaft turns up ill start doing a bit of turning

    im not totaly convinced a double row A/C bearing will be tight enough for ally, the ones iv got dont feel like they have that much pre-load, i might end up stacking the two of them

    4th axis... mmmm im thinking a 100mm rotary table with my 5th stepper melded to it

    im not sure anything is off topic,, is it?

  7. #37
    Quote Originally Posted by blackburn mark View Post
    i was terrified of turning down an over sized shaft so i spent weeks looking for the right size, its being shipped as we speak
    Hah, I was pretty scared dismantling this motor. It was all glued/loctited together and needed some persuasion with a hammer.

    Quote Originally Posted by blackburn mark View Post
    im gutted you didnt find a 150mm one, im convinced it would have been easy to stick double row A/C on the nose in a shallow housing,, ill find out as soon as my shaft turns up ill start doing a bit of turning
    There are 150mm ones, but they're more than twice the price of the 100mm. I could probably extend the 100mm one if it came to it - definitely some thinking to do before I buy anything!

    Quote Originally Posted by blackburn mark View Post
    im not totaly convinced a double row A/C bearing will be tight enough for ally, the ones iv got dont feel like they have that much pre-load, i might end up stacking the two of them
    I see, so you don't think the ones that are currently in my motor would be up to it? Maybe I could link this motor to the existing milling machine spindle via a pulley...then I needn't worry about angular contact bearings. Having said that I don't know if the bearings in the spindle of my machine are up to 6000rpm.

    Quote Originally Posted by blackburn mark View Post
    4th axis... mmmm im thinking a 100mm rotary table with my 5th stepper melded to it
    Yep, that's what I did except with a 150mm vertex rotary table. It's excellent for making pulleys:

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    And making 4th axis'

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    Quote Originally Posted by blackburn mark View Post
    im not sure anything is off topic,, is it?
    :) well in that case this is the 4th axis/lathe design I've started making:
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    I'm using two tapered roller bearings in that. The gold things are solenoids to create a sort of disk brake which I'm hoping will hold it steady enough for me to mill will it aswell as using it as a lathe by swapping to a bigger motor...the brushless one.

  8. #38
    SWEEEET!!!! im intimidated,,, and its not just a drawing, youve made a start

    are you not happy with the rotary table?

    are the solenoids air?

    EDIT: iv just spotted the wires

  9. #39
    Thanks!

    I'm happy enough with the rotary table - it's very well made. If you get one I'd advise a vertex one as I've used this and a bigger one at school and they're both good. It's good in that it uses a worm gear (90:1) which means it wont move when milling but equally the worm gear is bad as it severely limits the rpm I can run the table at. I'm making the new axis because I want it to double up as a CNC lathe. My mini lathe (C3 from arc euro) isn't up to much so I'm hoping this will be sturdier.

    I've machined the shaft of the axis the same as the mini-lathe so it can take the same chucks. Ideally I would have gone for bigger than 80mm diameter for the shaft...but turning that down to 35mm for the bearings took long enough and annoyed my teacher at school a bit... any bigger would have been pushing my luck I think!!

    Any ideas for materials to use for the disk brake are welcome. The brake will only be used to hold in position, not for stopping, so heat build-up isn't an issue.

    I'll go and take another photo...

    P.S. Someone's bound to point this out, so before they do...If you look carefully on the renders of the 4th axis you'll see the disk brake is impossible to assemble! I've since fixed that by putting the disk the other side of the flange.
    Last edited by Jonathan; 05-08-2010 at 10:09 PM.

  10. #40
    Ah, im with you on the speed issue, i think i get you with the large motor to,, im guessing you would be fitting a rotory encoder for position feedback if you use the large DC motor ? (im no expert with these)

    for the brake i would be looking at a motorcyle cluch plate maybe, im not sure youll get the force with electric solenoids to lock it for milling though but thats my guesstimation... id be tempted to consider an actual disk brake and caliper... the caliper would have to be beautfully fitted and have oposing pistons (you couldnt have it floating like you do on a vehicle)
    im really not sure though im just thinking out loud :)

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