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  1. #1
    Hello guys, my name is Juan Pablo from Argentina, I am building my first Cnc and I need help deciding the electronic components for the CNC. I can spend about 600 dollars in my proyect (shipping included) and I am trying to choose wisely what to buy. I was researching because I do not know much about electronics. So let me ask you a couple of questions: first, is the Am882 driver good? Is it difficult to make it work? Because I have read on this webpage that there have been problems with its installation. I am planning to use them with a nema 34 1200oz or a 1600oz I really need help because I donīt know which power supplies and breakout board I should buy if the c10 works fine with these drivers or if I have to buy another. Well guys thank you! I really appreciate if you could help me with this! THANKS

    These are the products I can get in my country:

    3PCS CNC NEMA34 Stepper Motor 1232OZ-IN,6A,118mm,4leads 257uss
    3 pcs am880 180uss
    1pcs 6 axis cnc breakout board DB25/ interface board adapter milling engrave c10 18uss
    Power supply :
    350w 36v 10a 38uss
    350w 60v 5,9a 41 uss
    400w 48v 8,3a 44uss
    420w 60v 7a 59uss

  2. #2
    Hello Juan and welcome.

    First the Am882 drives are excellent drives and easy to setup. Most people having troubles has been because of user error and nothing to do with drives being complicated or faulty. In there basic setup they work just like any other drive with simple Dip switches for selecting appropriate motor settings and Micro stepping. Where they shine above other is the fact you can fine tune them to match and get the best performance from your system if needed or desired by using the tuning software.

    BUT.!! . . I think your making a mistake often made by going for Big Nema 34 motors.? Bigger is often not better in CNC and it's important you match motors to machine. . . . . So what machine are you building or converting.?

    Problem with Nema 34 motors is they need high voltage to get best performance and your proposed largest 60V supply will be far to small and really the AM882 drives Max 80V would be the lowest you'd want to run at and really I'd recommend getting high powered drives like these 2M2280N Digital microstepping driver to get the best from those motors.

    Unless your building very large heavy router or converting a large milling machine you probably won't want those motors.?
    Give more information on what your planning and we can help guide you to what will work best. Give details like linear rail type and drive system IE Ballscrews or Rack & pinion etc.
    Last edited by JAZZCNC; 11-10-2013 at 02:09 AM.

  3. #3
    Jazz, first of all I would like to thank you for your help, I really appreciate it because I have not received any help from these forums and I do not know how to get started. I have decided some things but before buying any products I would like to be certain so as not to regret it later.
    I need a CNC to produce aluminum moulds and be able to produce products with less hard material such as poliacetal or mdf. I am an Industrial Designer and I work with software such as Solid Works and Rhino which help me to verify movements and assembly. I know a little about dimensioning structures but I do not know anything about electronics. I am trying to use the tools I have and reading a lot to be able to build the CNC.
    You asked me about the measures of the CNC, and I believe that with the axis X 1m, axis Y 1m, axis Z 0.3m I will be able to manufacture the pieces I need.
    I did a 3D model to verify the dimensions of the metallic frame, I will attach some pictures so that you can give me your opinion, because I have problems starting with the linear movements and the electronic, but regarding your observations I will be able to change them.

    Axis X :
    HIWIN Brand linear guide rail 2PCS HGR20-L1000mm+4PCS HGH20CA HGR Series Narrow Carriages ZH075 - 337 uSs
    RM2005 Ballscrews L1150mm with ballnut with end machining+1set BK15/BF15+coupler - uss 164

    Axis Y:
    2pcs SBR20 -L 1000 mm Linear shaft Support + 4pcs SBR20UUBearing Blocks - uss 179
    1antibacklash ballscrew RM1605-1020mm+BK/BF12+coupler - uss 149

    Axis Z:
    2pcs SBR20-L300mm Linear Bearing Rails + 4pcs SBR20UU SY1860 -uss 69
    1pcs antibacklash ball screw 1605 -L300mm-C7+BK/BF12 + 2pcs 6.35*10mm couplers - uss 83

    Electronic:
    As regard Electronics, I have read that the nema 34 has a good torque that I why I thought of using them, but I am not sure if they are appropriate for what I have in mind. There are several kits advertised on ebay for example this one:
    Electronic kit on ebay:
    3 PCS Nema 34 Stepper Motor with 1090oz-in (7.7N.m) holding torque,5.6A current,99mm motor body length,
    3 PCS Stepper Motor Driver DQ860MA,24-80VDC,7.8A Peak Current, 256Micostep replacing MD882,
    3 PCS 350W, 60VDC,5.9A Power Supply.
    1 PC Breakout Board & 1 Parallel Cable
    Uss 480.

    Jazz thanks again for everything and I hope to be able to assemble the Cnc and learn something about electronics with your help!

  4. #4
    Here are some old frame renders

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  5. #5
    Pleased to help you Juan,

    Let me say from the beginning that your requirements to cut multiple materials causes conflicts with design and component selections.
    To cut aluminium correctly with accuracy and still give quality of finish required for moulds requires a very different design and components compared to a machine designed for wood and softer materials. Now It is possible to build such a machine to cut all materials but you have to realise it will only ever be average at all of them.!! . . . . It will also require certain design features to successfully achieve this. IE Adjustable Bed.

    The problem comes from the fact Aluminium requires a very very stiff machine with shortest possible tool and Z axis extension to reduce chatter and give best finish quality. The resolution required, esp for detailed work like moulds is high. Also feed rates are relatively slow along with spindle speeds. On top of this to give best tool life and finish quality coolant is required.

    Now softer materials like wood don't require high resolution but they do require high feed rates. This causes component conflict number one.! Ballscrew pitch Selection.?
    High resolution requires fine pitch so 5mm or less ballscrews but this fine pitch makes achieving high feed rates required for correctly cutting wood difficult. To achieve feed rates needed for woods/plastics etc requires ballscrews with larger pitch 10mm or more but this reduces resolution required for Aluminium.!!
    Now this is also where stepper selection plays a big part and why new CNC builders often fall victim to "Bigger is better" .? Larger Nema 34 size steppers spin much slower than smaller nema 23/24 and this lowers feed rates even further.

    Now you have selected the Worst combination for Cutting softer materials.? Having 5mm pitch and larger Nema34 motors will mean you won't be able to achieve feed rates for cutting woods and plastics correctly. This will mean poor finish and poor tool life.

    To cut aluminium doesn't require massive torque and the smaller Nema 23 motors easily handle it. They spin much faster and cost less, they don't require expensive high voltage drives.

    Now thru experience I know the best combination for cutting both types of materials at the size of machine you require is 16mm Dia 10mm pitch ballscrews connected with timing belts and pulleys to 3.1Nm Nema23 motors running between 65-70Vdc using 80V drives.

    To get round the higher pitch screws lower resolution causing problems when higher resolution is required is simple.? just change the ratio of the pulleys. Changing to 2:1 form 1:1 doubles the resolution and doubles the torque but half's the speed, Remember we don't need speed for Aluminium so this is no problem and gives best of both worlds.
    In reality you will find you rarely need to change ratios has 10mm pitch will be fine for most aluminium jobs except when really high detail is required.
    But with this combination you have the option.! You also have the option to go other way with 1:2 ratio and cut even faster if required or any in between ratio that may suit your requirements.
    Also on top of this using timing belts has the added benefit of eliminating the negative affect resonance from machine has on the motors.

    Regards the Frame design to allow best possible compromise for hard and soft materials then you need high sided with gantry sat direct on rails design along with adjustable bed. Look around the Forum and you will see both Jonathan and Me posting designs using this design.

    I'd also look towards using profiled linear rails on all Axis has they are much much better than SBR rails and will handle cutting Aluminium much better and last far longer.
    Hope this helps and forget the Nema 34 motors they are wrong for your needs.
    Last edited by JAZZCNC; 12-10-2013 at 01:14 AM.

  6. #6
    Quote Originally Posted by jpsicilia View Post
    Here are some old frame renders
    Hope this is just initial draft because You will need many more supports and bracing adding before this design is usable.
    Also it's too wide for a central ballscrew and you will never successfully cut aluminium, or wood for that matter with this design. ABSOLUTELY must have TWIN ballscrews.!!
    Last edited by JAZZCNC; 12-10-2013 at 01:28 AM.

  7. #7
    How are you Jass? You are amazing! You have clarified many doubts for me. I hadnīt considered the pitch before and the quality it brings. As you said, it is true that we think that the bigger the engine the better. It is very interesting your idea of changing the ratio of the pulleys to get more resolution or speed and considering the torque. With all the information you gave me I have decided to restart my project. I will remodel these aspects with the solidwork software and I will most probably ask you some questions if you do not mind. Thanks a lot!!

  8. #8
    Hello again! As I have told you before I have started with my CNC project from zero thanks to the tips you have given me. I thought of making a bigger CNC, use it to mill wood, plastic and aluminum, and later I want to buy a small mill and change it so that I can build mould in aluminum and if possible metal.
    This time I am bothering you because this week I am going to buy the components from China and I want to make sure that I am buying them correctly, and I imagine this happens to all of us when we build a CNC for the first time. I have a couple of questions regarding the hgr15 for the x axis, maybe they will work or will I need a hgr20?
    This is what I have thought for the CNC:
    Axis X
    2pcs RM1610-1500mm Full length 10 pitch with ballnuts and end machined.98 usd
    2pcs HGR15 -L1500mm Linear Motion Guide Rail with 4pcs HGH15 Narrow linear carriages 200usd
    Axis Y
    1pcs RM1610-1200mm Full length 10 pitch with ballnut and end machined.45 usd
    2pcs HGR15 L1200mm Linear Motion Guideway with 4pcs HGH15 Narrow linear carriages 176 usd
    Axiz Z
    1pcs RM1605-350mm Full length 5 pitch with ballnut and end machined. 26 usd
    2pcs HGR15 L=350mm rail with 4pcs (HGH15 Narrow linear carriages)108 usd

    Motors
    5PCS Nema 23 stepper motor 425oz-in,3A,2ph,1.8° CNC Engrave 241uss
    Timming Belts?
    Witch timing belts and pulleys do you recommend?
    Drivers and supply power?
    I have the same problem as before, I believe that you can help me with this. I have researched on these products, what do you think? Is it an analogic driver convenient or a digital one?
    1pcs 6 axis cnc breakout board DB25/ interface board adapter milling engrave c10 18uss
    DM542A
    Mt880.
    Same pictures of the cnc frame
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  9. #9
    Quote Originally Posted by jpsicilia View Post
    I have a couple of questions regarding the hgr15 for the x axis, maybe they will work or will I need a hgr20?
    Either is plenty stiff enough. Sometimes people go for the 20mm rails just to make it easier to to make the parts they mount to with minimal machining. You need to draw it and work out which is best before buying them.


    Quote Originally Posted by jpsicilia View Post
    Motors
    5PCS Nema 23 stepper motor 425oz-in,3A,2ph,1.8° CNC Engrave 241uss
    Don't get those. They're 3A/phase which means they're the higher inductance motors. You want motors with lower inductance to get more torque at higher speeds - just search this on the forum and you'll find more detailed explanations. Last time I checked, these were the best value.

    Quote Originally Posted by jpsicilia View Post
    Timming Belts?
    Witch timing belts and pulleys do you recommend?
    HTD 5m (i.e. 5mm pitch) and 15mm belt width. Don't get bigger pulleys than you need to as it'll adversely affect the acceleration. You can get them from Bearing Station, belting online or aliexpress.

    Quote Originally Posted by jpsicilia View Post
    Drivers and supply power?
    I have the same problem as before, I believe that you can help me with this. I have researched on these products, what do you think? Is it an analogic driver convenient or a digital one?
    The 'digital' ones should be better than the 'analogue' ones, but it's a bit of a misnomer as they're all digital to an extent. Drivers like the AM882 use better algorithms (e.g. field oriented control) to get slightly higher torque from the motors and detect stalling, among other things. However once you've tuned the system properly it wont stall, so if you can get enough torque with a cheaper driver (e.g. DQ860MA) I see no reason to get the better ones.

  10. The Following User Says Thank You to Jonathan For This Useful Post:


  11. #10
    Quote Originally Posted by Jonathan View Post
    I see no reason to get the better ones.
    I see a reason.!!!!. . . . They are better.!! . . . and the price difference is not enough to justify not taking advantage of there more advanced features like better resonance handling and stall detect. Has you well now there are other things beside incorrect tuning which can stall motors and on dual screw machine having the ability to alert and E-stop the machine is worth the slight extra cost IMO.

    Oh and from the few times I've used the DQ869MA the AM882 give much smoother performance from the motors at lower feeds.!!

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


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