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  1. #1
    Hi

    I will be finally getting round to building machine I have had in mind, over the next few weeks, and could d with some advise. I want to build a strong machine, and can get the frame built up. I really want 1200mm or better Y. 2.2 or 3.2, on X, as much depth and can get on Z.I want the Y and Z to be strong enough to handle a B/C type head if needed, but will mostly be used for cutting stone.

    Opinions am looking for

    Gantry

    1. X configuration motor choices and design. Am Thinking Nema 42 single motor 2 ball-screws, or 2 nema 34s and 2 ball screws.

    1.1 Nema 42 bolted to end of machine, timing and gears to drive 2 ballscrews ( what problems will I face ),
    1.2 2*nema 34s, (driving direct or geared ? ) and slaved ( does this give accuracy problems )

    Table build.

    I can get steel at reasonable rates and ally if needed, and my brother makes gates and has workshop with tools and jigs, am thinking that for end accuracy and convenience, I am going to get it made in 5 bits at least ( unless advised otherwise, 2 sides, 2 ends and the bed ). and bolt it together and tack it on site. I know I am going to have to take a long time makings sure the frames level and accurate.

    2.1 any advise on what profiles, thicknessís or design am thinking 125mm box section, 2 oblongs about 1.2mtr high by 3.2mtr long, and 2 squares 1.2mtr
    2.2 am making the bed in three sections, very sturdy, ( 1 4th axis, plasma/laser, printing area ). any advice ?

    I will ask the other questions when I have finalised the design, am currently reading through the threads to get tips ) . Your opinions will not not be wasted, I have the funds to build this and I want to get the frame built next week, and the motors and heads ordered this Friday or Monday. Am thinking about 1200 for motors and electronics , 800 for the metal for the table ( cost price ), 600 or more for rails and screws. ( leaving 400 unbaked but can be increased ) .

    cheers

  2. #2
    found this thread, it answers nearly everything i was looking for

    http://www.mycncuk.com/forums/router...g-machine.html

  3. #3
    finally getting on with this.

    Going for a rig thats 2000mm double x 1200mm y 300mm z

    ordered this lot

    supported linear rails SBR20-300/1200/2000mm rails(6 supported rails+12 SBR20UU bearing blocks)
    4pcs of ballscrews RM1605-350/1200/2000/2000mm overall length-C7(4screws+4ballnuts+4end-machinings)
    4 SETS OF BK/BF12(with locknuts and cir-cplis)
    4pcs of flexible couplings 6.35mm*8mm

    am building a base similar to the above mentioned thread, with a few modds for rigid bed

    am going for duel x motors, so heres my first question.

    There now seems to be nema23 and nema24 motors, with the latter having more power eg
    4 Axis Nema24 Stepper Motor 567oz-in CNC Controller Kit With Display And Keypad | eBay

    so, is it worth the extra for the nema 24s, or is there something am not seeing ?

    I want the Y gantry to be heave duty so i can maybe strap a B/C head on,

    question 2 would a nema24 be overkill for a y axis at 1200mm travel, would i be better of with nema23

    Question 3, i want to build a heavy duty rotary table on part of the bed, for stone carving. would nema 34 cause me any problems with lighter weight things like wood or foam and what gearing would you recommend.

    i sort of need to order the motors over the next 2 days

  4. #4
    Sorry I can't advise on most of your questions but these motors are 4Nm (same as those in your link) but nema23, I got some and they run very smoothly albeit just on my bench at the moment.

    Nema23 4Nm

  5. #5
    Quote Originally Posted by george uk View Post

    am going for duel x motors, so heres my first question.

    There now seems to be nema23 and nema24 motors, with the latter having more power eg
    4 Axis Nema24 Stepper Motor 567oz-in CNC Controller Kit With Display And Keypad | eBay

    so, is it worth the extra for the nema 24s, or is there something am not seeing ?
    YES your not seeing plenty.?

    First the only difference between Nema 23 & 24 is physical outer Dim 23=57mm 24=60mm both have the same Bolt centres so both can be used on same mount.

    The Difference you'll be seeing between them is Holding torque, Probably 3.1Nm and 4Nm.
    Now the thing you don't realise is that what's important is the Inductance rating and often the larger 4Nm motors have much higher inductance than the lower 3.1Nm and this means they don't perform has good.
    Now the Motors Eddy linked to seem quite Low inductance for 4Nm if that is indeed true.?? But most of the 4nm Chinese motors I've encountered have been quite High and IME the slightly lower 3.1Nm motors perform much better.

    Now it seems to me your Rushing and not really knowing what your buying or what Mass you have to move.? This is a recipe for disaster and you will end up buying the wrong stuff if your not careful.!

    The Kit you linked to is a prime example, it's Rubbish and completely wrong for your needs. The Drives are Rubbish junk, The PSU is way to Low voltage at 36V for those motors you'll end up with a very low performing machine. Thou this won't be too much of a problem thou has the drives will probably have died in short time so it won't be going anywhere.!!

    Honestly I'm not just being Negative or pulling down but please take a Step back put a foot on the brakes and assess what you need better otherwise you'll regret it and waste shit load of money.

    I'll PM you my number if you want to ring me and I'll try to help.

  6. The Following User Says Thank You to JAZZCNC For This Useful Post:


  7. The Nema24 motors are 4mH/phase and ideally need 60v but are shipping with a 36v supply and 42v drives . The Nema23s are 3mH/phase and ideally need 55v and ship with 38v supply and 50v drives.

    The Nema23 are the better option.

  8. The Following User Says Thank You to irving2008 For This Useful Post:


  9. #7
    Call Dean/JAZZCNC/ and cancel or put a hold on your order!

    Most sellers stock everything or can source it, so stop the order until its not too late. Later you can just order from them the correct things. And add some money to the bill :-)

  10. #8
    Best advice I can give is talk to Jazz. Could save you a whole lot of expense and agro. Have spoken and emailed jazz a fair bit and he certainly knows about cnc machines.I would grab his offer for help as it is a rare thing nowadays for someone to offer to pass on their hard earned knowledge.
    Jazz is extremely helpful and has a refreshingly no Bullsh*t approach. If you do take him up on his offer of help, please remember that Jazz and other knowledgeable members of this board impart their considerable knowledge and help at the expense of their own time so please respect that.

    Alan

  11. #9
    Hi

    Thanks all, exactly the info i needed, i was not thinking about these

    The Nema24 motors are 4mH/phase and ideally need 60v but are shipping with a 36v supply and 42v drives . The Nema23s are 3mH/phase and ideally need 55v and ship with 38v supply and 50v drives.
    and

    Now the thing you don't realise is that what's important is the Inductance rating and often the larger 4Nm motors have much higher inductance than the lower 3.1Nm and this means they don't perform has good.
    are both important bits of info, dont you just love proper hobbyist forums

    Honestly I'm not just being Negative or pulling down
    I like direct answers like that, and am listening and reading.

    Now it seems to me your Rushing and not really knowing what your buying or what Mass you have to move.
    AM not rushing, but am eager, i have the funds in the bank.

    The gantry i have planned will be below 40kg, fully loaded, probably closer to 35kg, I know how i will do the gantry, but have not finalised the design, as i need to think about what i might need to strap on to it.

    I want to incorporate a turret on the end of the table, and a rotary table or b/c head on the table. and a geared 4th axis

    I'll PM you my number if you want to ring me and I'll try to help.
    .

    I will write up fully on here what am doing and mp you, thanks.

    Thanks to all of you for your replies,

  12. #10
    Quote Originally Posted by george uk View Post
    AM not rushing, but am eager, i have the funds in the bank.
    Me also from a month/at last/, but as i have still not finished the detailed drawing i am not eager to spend hard earned cash.


    Quote Originally Posted by george uk View Post
    The gantry i have planned will be below 40kg, fully loaded, probably closer to 35kg, I know how i will do the gantry, but have not finalised the design, as i need to think about what i might need to strap on to it.
    George,
    i wonder how that really will be with the specifications /size/ you stated in the beginning? Are you sure you did not forget something? What type of gantry will that be?

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