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    Question Select electronics for my raptorxz

    I am getting a 36x48 RaptorXZ. Now i want to find a good electronics setup for this machine. And as i finally found a setup which suited me i get confused again on details... The leadscrews are x:2010 and Y:1610

    My requirements are:
    To be able to use the machine as a 3d printer, Cutting plotter, LaserCutter, MDF and Aluminum mill.
    Fast rapids - I Imagine a good speed should should be about 600-1200 IPM
    Descent speed working with Aluminium, maybe 50-100 IPM
    Good speed working with high density MDF maybe 90-180 IPM

    My workflow is as follows:
    AutoCAD 2014 for 2D design
    Solidworks 2014 for completing my assembly
    I intend to use HSMWorks Express for CAM/G-Code gen.

    Now what?!? There are so many options....

    There seems to be a mainstream choice to go with Mach3/4 ->DB25 (Paralell) -> Gecko G-540 -> Steppers

    I have looked at the following combos.

    - SmootieBoard(Kickstarter(dot)com and smoothieware(dot)org/smoothie-on-a-breadboard) and custom soldered 4xGecko G201V
    Can Mach3 feed this baby?

    - SmoothstepperUSB-> breakoutboard -> 4x G201V

    - SmoothstepperUSB-> breakoutboard -> 4x Wantai dq542ma (in this combo)

    The last was suggested to me as a get started kit but without specifying my requirements fully. I believe the suggestion is a good one and that it will do all i ask of it but still i feel the need to understand the numbers coz my calculations say it will not be sufficient as the motors max speed has to be 1500-3000rpm and the calculations made using an online calculator tell me it would do about 45. Now I might have input the wrong voltage coz using 80volt instead of 3 in the calc tells me it would do 1200 which is more like what i would expect for a suggestion. How do i calculate this right?

    I used this calc: Stepper Motor Calculator and the numbers below:

    Part No.: 57BYGH627
    Frame Size: NEMA23
    Step Angle: 1.8 degree
    Voltage: 3.0V
    Current: 3.0 A/phase
    Resistance: 1.0Ohm/phase
    Inductance: 3.5 mH/phase
    Holding torque: 19Kg-cm 270oz-in
    Rotor inertia: 480 g-cm2
    Detent torque: 0.6 kg-cm
    Number of wire leads: 4

    That would give me the answer to the question about Max RPM No Load rapids (yes..minus weight of heavy gantry etc but still).
    Next up is to know if it would be up for the task cutting in alu but here i give up for now and turn to you with experience. All the chipload, number of flutes, rpm, subject quality, bit quality, bit diameter etc just makes me comfused. I will eventually have to deal with this but atm id rather break a few bits on experimenting than doing the math before. The Requirement of running 50-100IPM into aluminum would be with a smaller bit (6mm diameter and a cutting depth of 2-3 mm.

    If the steppers are up for alu i guess they will do MDF at 1,5x alu speed too.

    Now im looking for suggestions on what to get...

    Is the last option sufficient or is my math correct?
    Are there any advantages using another option?
    Is there a better option for combining with (suboptimal) 3D Printing and using a plotting cutter)?
    I really like the smoothieboard but the smoothstepperUSB seems to be a better supported option. Also the wantai kit is a steal @ < $250 + smoothstepperUSB.

    Any help/recommendations/calculations/other input is appreciated!

    Similar Threads:


  2. #2
    Member ger21's Avatar
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    You're never going to get 1200ipm with those screws and stepper motors. In most cases, stepper motors have a maximum usable rpm of about 1000rpm. Absolute best case would be maybe 1500rpm, but that's very difficult to calculate. Depending on your acceleration rate, you might be limited to 400-500ipm with steppers. Acceleration rate is actually what determines your maximum speed. Steppers lose torque as rpm's increase. Acceleration requires a specific, constant force. To accelerate at a given rate, you can only accelerate up to the point where you run out of torque. The faster you accelerate, the more force that's required. Which means you'll reach your available torque limit sooner, resulting in a lower top speed. SO basically, the faster you accelerate, the lower your top speed will be. Most machines I see that can rapid at 1200ipm use rack and pinion, and don't accelerate quickly enough to even run at 1200ipm. As soon as they get to 1200ipm, they need to start decelerating to come to a stop before they run out of room.
    Maximum no load rpm is meaningless, because your motors would need to see the maximum load to get to that rpm.
    It's very difficult to choose the peerfect stepper motor for a given application. Mainly, becuse it's nearly impossible to get an accurate torque curve for the spcific motor/drive combination you might be looking at. Without an accurate torque curve, you really can only guess at how much torque you'll have at any given rpm. This is the most important information in choosing a stepper motor, and you really don't know what it is.

    Stepper motor maximum voltage should be no more than 32 x sq rt of the motors inductance. Any higher results in excessive heat and no performance gains.

    If you're going to use motors rated 3 amps or less, then there is no need to use Gecko G201's. A Gecko G540 can deliver 3 amps and is a much cheaper option.
    It's also the most popular option here.

    The most popular option you'll find here is a Gecko G540 with 380oz motors that are a good match for them. They are a pretty good fit for most applications in the size you have. If you want to go faster, you have two options.
    1) Larger Nema 34 motors in the 450 oz range, rated at 6 amps, and Gecko G201 or G203 drives. These will usually have more torque at higher rpms than the Nema 23's at 3.5 amps.
    2) Servos. If you want to spin your screws at 3000 rpm, then servos are the way to go. However, if it were me, my preference would be ballscrews with a 20-25mm pitch, geared 2:1.

    I'd stay away from the Kickstarter stuff. I'm not familiar with that specific board, but I've neve seen any high performance CNC components coming from Kickstarter. Most Kickstarter projects are geared towards low cost for the masses, not high performance.
    If you decide to go with a Smoothstepper, the ethernet version is a much better choice than the USB version, which is very sensitive to electronic noise.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Ok, thats one beefy reply - I got a lot smarter but still have no clue as to what steppers i should get. :P

    Since i found info on many forums about 3d printing with mach3 i guess Smoothstepper Ethernet is just fine. My only consideration is that it might limit my software choices versus using another type of connection. Im probably going to have some hassle setting up the temp monitor and control stuff but for a multipurpose machine i expect to have some fights with setup etc.

    So 1200Ipm for rapids is fantasy when using steppers and 10mm lead ballscrew? What is a realistic number to aim for?

    I want the 10mm lead due to precision/accuracy requirements - by which i mean steps/mm not using microstepping which is 0.025 and i am aiming at 0.05mm.
    0.05mm precision is for really small work with small bits.

    I have been looking for low inductance steppers but best i can find are 12, 15 and 22mH NEMA 34 motors... What is a good value to aim for? I have understood that 2.8mH is a good value for NEMA23:s in the 320oz/in range. Im still confused about my calculations... The calc (see first post) still just gives me ridiculous numbers when inputting the motors voltage rating. For the kind of speeds im looking for i´d be looking for motors specified for 80v and that sounds wrong given that I only find motors in the 3-12v ratings.
    So what am i doing wrong? Can anyone help me out and tell me how to calculate this or give me some hints towards which are good kombination of values in stepper specs for my application.

    There must be a good formula to use...

    One E-bay finding... Could these be any good?

    CNC Milling Machine 3 Axis Nema34 PC Mach3 Micro Step Motor Kit Stepper 637oz In | eBay



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    As I said, I think a realistic number is in the 400-500ipm range.

    While I haven't used them, these would be my choice for Nema 34 sized motors.
    NEMA34 465 oz/in 6A Stepper Motor (KL34H260-42-8A) | Automation Technology Inc

    You don't run steppers at their rated voltage. If you did, you'd only get a few rpm out of them. The higher the voltage, the faster the current can flow through them, which gives them more top end speed. Typically, voltage is proportional to speed, up to a point. Which is the formula I posted above for max voltage.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    OK... Maybe im getting the hang of it...

    From the perspective of "Oh I found this on e-bay is it any good?"

    E-Bay item specs:

    Size: NEMA34
    Step Angel ( ° ) 1.8
    Motor Length L(mm)113
    Rate Voltage (V)2.6
    Rate Current (A)6
    Phase Resistance ( Ω )0.43
    Phase Inductance (mH)2.5
    Holding Torque (N.m)4.1
    Lead Wire (NO.)8
    Rotor Inertia (kg. cm2)2.7
    Motor Weight (kg)3.6

    Use: Calculator with following input:

    IMax 6 A (Rated Current from above)
    L 2.5 mH (Phase Inductance from above)
    Voltage 50 ( use formula from above suggested by ger21 and also found on gecko site 32 * sqrt(Phase Inductance) -> 32*sqrt(2.5) = 50.6 )
    Result is Maximum speed = 8.33 rev/s (10mm lead on ballscrew directly connected to stepper then moves 10mm*8.33rev/s*60sec = 4998mm/min = 197IPM)
    Yanking up the voltage to 70 gives 276IPM

    This is theoretical speed not taking inertia or gantry weight in to consideration...

    Given i have no experience at all but just looking at the torque curves common for Low inductance motors id guess that 120IPM->150IPM Rapids would be possible.

    Am i right?



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    Now comparing the kit that was suggested to me (?USA Ship Free Ship TO US?3AXIS NEMA23 Wantai Stepper Motor 270oz 3A 2PHASE CNC | eBay)
    The steppers would run on 60volts producing 14.3 rev/sec
    Drivers max out at 50v -> steppers producing 12 rev/sec

    Compared to your suggestion
    steppers would run 10 rev/sec @ 43v

    Putting these numbers to the real world the e-bay kit would run cooler and faster @ 12 rev/sec and 50 volt theoretically. BUT ... Mounted in the router taking inertia and gantry weight and friktion in to account speed would be same or slightly better with your motors during rapids. Also the ones you suggested would be faster as soon as you put load on them and also having the option to crank up the voltage a little bit to gain a little more speed if steppers are provided a little cooling... And also drivers would not run @ max voltage and have double the torque at low speeds...

    The only other thing that differs is the frame size NEMA 23 vs. NEMA 34

    PHEW!

    Did i get all that right?

    Last edited by Bx3mE; 12-20-2013 at 04:55 AM.


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    Member BanduraMaker's Avatar
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    A G540/381oz setup will do just fine for you. You should be able to rapid around 400ipm with a setup like that. I have a 24x26 raptor and while I'd love it to go faster, it's plenty fast as it is. I routinely cut at 400ipm for certain things and usually keep it around 100 to 250ipm for deeper cuts.

    A few days ago I cut part way through my aluminum corner fences on accident at a .200 depth of cut, .125" stepover with a 1/4" bit at 200ipm and the machine didn't even notice.

    -Andy B.
    http://www.birkonium.com CNC for Luthiers and Industry http://banduramaker.blogspot.com


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    What lead do you have on your ballscrews?

    Sent from my GT-I9505 using Tapatalk

    Still Learning..... :D


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    Also 10mm on all Axes. I have a rapid of 400 on the X, 450 on Y and Z. Yours should be similar. I could go a little faster on the X but I'd have to drop my acceleration more which already is on the low side for reliability

    -Andy B.
    http://www.birkonium.com CNC for Luthiers and Industry http://banduramaker.blogspot.com


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    Could you give me specs on your motors? And is it g-540 you are using?

    Sent from my GT-I9505 using Tapatalk

    Still Learning..... :D


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    Member BanduraMaker's Avatar
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    G540 with the 381oz-" motors from Automation Technologies: G540 3-Axis NEMA23 381oz in PSU48V/7.3A | Automation Technology Inc

    I'm using a linear PSU but that kit's got the same motors I have.

    -Andy B.
    http://www.birkonium.com CNC for Luthiers and Industry http://banduramaker.blogspot.com


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    Thanks for the info! Im also running a thread on this build from 3D printing perspective here:
    Woodworking router with BulldogXL Extruder [Build]



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    Ok My findings so far:

    For 3d Printing it is an advantage it the setup is max 36V (not getting into detail here...) so i have been looking for a combination which gives good speed and torque On my 36x48 machine and still enables it to in a simple way (both useabillity and design wise) ti do some 3d Printing.

    Not to forget, The machine must perform well cutting Aluminium!

    So i found a 4 axis kit giving me best of all worlds. Again using the calc in first post i get the following:

    stepper is 1.6mH/phase (6wire) --> 32*sqrt(1.6) = 40.5volt optimal power
    stepper is 3.0A/phase --> 21.1 rev/sec @ 40.5 volt
    leadscrew is 10mm --> 211mm/sec --> 8.3inch/sec --> 498IPM

    now powersupply is 36v for reason above:
    stepper is 3.0A/phase and 1.6mH Ind. --> 18.8 rev/sec @36v
    leadscrew is 10mm --> 188mm/sec --> 7.4inch/sec --> 444IPM

    What I still do not understand is consequenses/effects of having a 6 wire stepper and the different ways i can connect it.
    Anyone?




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    found the answer...
    --> UniPolar vs BiPolar wiring schemes for 2-phase Stepper Motors

    Each phase is 3 wires, beginning, middle, end.

    Following this guide you connect beginning and end as wire1 and center as 2 and same for next phase as 3 and 4 and for the rest follow the setup as if it was a 4 wire motor.

    For future reference if link above goes dead, the wireing above is called "Bipolar Halfcoil" and does not affect specifications of motor (as if it were a 4 wire).



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    The more i learn the more i fall to the understanding i know now nothing....... -

    Im trying to find a stepper to go with my 10mm ballscrew. it will move the gantry (est. 15Kg). I needs lots of acceleration. I want it to reach 350+IPM speed within 3 inches or so. It needs only torque enough to handle the weight of the gantry at these speeds (3dPrinting) but at the samt time have torque enough to do aluminium routing at lower feed. I have been calculating for days now using online calculators etc. but everytime i find something new i get setback with new info.

    Any suggestions?



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    You have conflicting requirements. G540 at 48v with the motors I recommended should exceed the speed/accel requirements you've stated. Dropping the supply voltage to 36v will hamstring your drive system.

    Since you've bought a Raptor, I have to think that 3D printing is less of a priority than milling as there's no reason to go with something this rigid for 3D printing. So, decide what's important to you and the solution will become more clear.

    -Andy B.
    http://www.birkonium.com CNC for Luthiers and Industry http://banduramaker.blogspot.com


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    Yes - BanduraMaker - I am slowly realizing that. lol ...and Yes Milling is a priority but having a print speed less than 150mm/s will force me into having two machines where one always is standing still. This is the reason I am willing to spend a lot on one machine, and also two machines will not fit in the area designated for the task.

    After another 3 hrs of reading during the day my conclusion is that the size / weight of the machine will require about 50v or more when using NEMA 23 steppers. The printer solution will have to be some custom built controller board using external voltage supply and the drivers incorporated into the board.

    So I dropped the 36v target and now I will try to find a 50v system to keep the driver price down. G-540 looks promising but so does DQ542MA. The Gecko G-540 has spindle outputs but that should not matter since i will use a smoothstepper Ethernet and can break out the nessesary outputs from there.



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    I believe that the setup from suggested by BanduraMaker is up for the task if he says so, but I cannot get my head around the math. Using the known formulas these motors should Max out at 12.2RPS = 732RPM and with 10mm Lead This translates to 288IPM @48v cranking up the voltage to 53v would result in 312IPM.
    To meet requirements i need at least 355IPM = 150mm/s. BanduraMaker says the combo does 400IPM on his with 10mm lead, so what am i doing wrong?



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    AAAARGH! Just sead into a thread on DSP Drivers.... Another all new world *sigh* More reading... Just realizing - by the time i have all the info on what i need i´ll be able to write a book on the subject. - Still cant make out the math.....



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    Several days ago I ran my numbers through that calculator and came up with the same 288ipm (or something close to it) but I can tell you for sure that my big axis is running at 400ipm with an accel of 30. The smaller axes are at 450ipm with accel around 50.

    I can only guess that the calculator is a very conservative estimate. Don't forget that units like the G540 have micro stepping and other tricks up their sleeves to work the motors harder.

    With the larger size of your machine, it probably won't get quite to the performance of mine (I've got the 24x36) but you should be able to come pretty close.

    -Andy B.
    http://www.birkonium.com CNC for Luthiers and Industry http://banduramaker.blogspot.com


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