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Thread: Some advices for my CNC router build = Appreciating!

  1. #13
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    Default Re: Some advices for my CNC router build = Appreciating!

    oh wow , it would look like flow charts charts of turbo turbines ,

    so the lowest inductance with let the motor keep his torque chart more evenly equally thru a wide rpm range because the low Inductance is more free flowing current , more efficient. this is related with the amps rating specs

    Seriousy Gerry , you are really helpfull . Your knowledge is really shared nicely and understandable all the listings of specs on the sellers product pages are confusing a lot when not knowing everything !



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    Default Re: Some advices for my CNC router build = Appreciating!

    i am tripping balls right now !

    Some advices for my CNC router build = Appreciating!-design-de-milling1-jpg

    Attached Thumbnails Attached Thumbnails Some advices for my CNC router build = Appreciating!-design-de-milling1-jpg  


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    Default Re: Some advices for my CNC router build = Appreciating!

    Quote Originally Posted by Letomoto View Post
    oh wow , it would look like flow charts charts of turbo turbines ,

    so the lowest inductance with let the motor keep his torque chart more evenly equally thru a wide rpm range because the low Inductance is more free flowing current , more efficient. this is related with the amps rating specs
    Sorta. The first thing to realize is that steppers are not really motors in the sense of a brushed DC or induction AC motor. Steppers have electromagnets that turn on to orient rotor poles to the electro magnet. Once the coil is turned the rotor steps into position and is held in that position for as long as that coil is turned on.

    Inductance affects how fast the current can rise to the rated value, this along with mechanical factors in the rotor affect how fast the rotor can turn. To get the quickest turn on time possible the voltage applied to the coils is very high relative to the amount of current that needs to flow. Thus to prevent the stepper from catching on fire the electronics in the stepper drive switches that voltage off when the rated current is achieved. The drive can do this real fast keeping the coils saturated at the rated current.

    This is profoundly different than other motors where current is largly the function of back emf. It is also the reason why stepper drives should be set as closely as possible to the rated current of the stepper. Torque is a function of current and the drive regulates the current precisely, so you need correct driver setup to realize manufactures operating performance.
    Seriousy Gerry , you are really helpfull . Your knowledge is really shared nicely and understandable all the listings of specs on the sellers product pages are confusing a lot when not knowing everything !
    Gerry is the man!

    I’m hoping I didn’t confuse things much with my explanation above but I think it is important to understand what a modern driver does when connected to a stepper. In simple terms the driver is responsible for current regulation.



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    Default Re: Some advices for my CNC router build = Appreciating!

    yep i am now looking at Closed Loop stepper and Hybrid driver 3N.M but it is looking pretty more expensive than the basic steppers , i read quite a lot of things and it seems like a very good choice but it is 2X price ... my project is already raising the expected budget !

    i set up all the mechanical motion parts lenghts that i received today in the Fusion 360 , i need to design the gantry plates , exact mounting points of the linear rails , adjust the table widths to align gantry plates and have correct clearance to fit the motion components , clearance under the grantry beam etc .... it is a pretty hefty job , it is actually my first machine design but i did played a lot for 3D printing a second 3D printer but it wasnt the same level !



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    Default Re: Some advices for my CNC router build = Appreciating!

    I would not bother with closed loop steppers. Instead look into AC servos if you want something “better” than steppers.

    I quoted the word better because we need to remember what we are making here. In my opinion it takes far more effort to build a machine that can really justify something other than steppers. Even if your only goal is speed you still need a well designed machine to operate well at high speeds.


    Quote Originally Posted by Letomoto View Post
    yep i am now looking at Closed Loop stepper and Hybrid driver 3N.M but it is looking pretty more expensive than the basic steppers , i read quite a lot of things and it seems like a very good choice but it is 2X price ... my project is already raising the expected budget !

    i set up all the mechanical motion parts lenghts that i received today in the Fusion 360 , i need to design the gantry plates , exact mounting points of the linear rails , adjust the table widths to align gantry plates and have correct clearance to fit the motion components , clearance under the grantry beam etc .... it is a pretty hefty job , it is actually my first machine design but i did played a lot for 3D printing a second 3D printer but it wasnt the same level !
    Yes this is something that is very often underestimated. Doing a machine where 100% of the design work has been accomplished befor the first tool hits metal takes time. This even more so if you Do the mechanical analyst to verify that the machine will operate within well defined specs. This is why many with buy plans or wing a build. Building on the fly is doable if you have the machine building skills but maybe shouldn’t be suggested for everyone.

    In the end routers, at least most of the builds discussed here, are light weight machine tools. As such your expectations have to match the machines capability.



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    Default Re: Some advices for my CNC router build = Appreciating!

    this is also a big project for me to get experience points , learning a lot of things and developping skills further . Challenging me alot and exciting ! For steppers i am not looking for the fastest speed i could reach but i would like to never skip a step somewhere and wreck a big stock where a production of maybe 20 parts was started and the toolpath got offset half way in the job and not telling it .

    I do not have a lot of knowledge on closed loops and zero knowledge for AC Servos . i was thinking the closed loops were normal steppers but acting like a servo with their encoder and driver. A way to reduce the price of a servo but if you tell that the closed loop doesnt worth much i will dig more on their comparisons




    Edit : I am searching/reading the comparisons and i am reading a reply from Gerry !

    Re: Are Chinese servos a gamble? Servos vs Leadshine closed loop
    I've heard that those chinese servo's work well, if you know how to set them up. I've heard that documentation is severely lacking.
    I opted for DMM servos, as the price is only slightly higher, and they have better documentation and support. They would probably be much more expensive in Australia.

    Comparing an AC Servo to the Leadshine "Easy Servos" is comparing apples and oranges. The AC servos are much more powerful. The Easy Servos are still stepper motors, with a torque curve that drops off as rpm's increase. AC servos have a flat torque curve, up to 3000 RPM

    Gerry


    Went to search on Aliexpress for 3N.M servo and ouch it doubled or tripled the 3NM closed loops prices



    I also found there is an expansion board for the Smoothstepper ESS to add encoders input . and also dual shafts steppers ... if i get simple steppers and having troubles with steps at some point maybe i could upgrade them with encoder if needed . Right now the price i found for the closed loops 3n.m on Aliexpress it would cost me almost 600$usd for 4-axis but simple steppers 4-axis with BOB , psus 273$usd shipped

    And Gerry suggested a 450oz-in for my setup and the Nema34 are rarely under 890oz-in in the market , So should i focus searching for 23 or 34 ? sorry i am a bit ADD


    Here for Nema23 425oz-in 4 axis 4.2A rate

    https://www.aliexpress.com/item/NEW-Free-shpping-motor-CNC-Router-4-Axis-kit-4pcs-TB6600-Stepper-motor-driver-4pcs-Nema23/32854609719.html?spm=2114.search0104.3.49.15ef1885DwzVZX&ws_ab_test=searchweb0_0,searchweb201602_2_10065_10130_10068_10547_319_317_10548_10696_453_10084_454_10083_10618_10139_10307_538_537_536_10059_10884_10887_100031_321_322_10103,searchweb201603_51,ppcSwitch_0&algo_expid=a9df58a0-dde4-4243-bee5-88ba0f936251-7&algo_pvid=a9df58a0-dde4-4243-bee5-88ba0f936251

    then a kit of 890oz-in Nema34 it jumps up to 455

    https://www.aliexpress.com/item/Good-quality-Wantai-4Axis-Nema34-Stepper-Motor-85BYGH450D-007-890oz-in-Driver-DQ860MA-7-8A-80V/32821205632.html?spm=2114.search0104.3.79.2f234b4ezifqYA&ws_ab_test=searchweb0_0,searchweb201602_2_10065_10130_10068_10547_319_317_10548_10696_453_10084_454_10083_10618_10139_10307_538_537_536_10059_10884_10887_100031_321_322_10103,searchweb201603_51,ppcSwitch_0&algo_expid=5a56a75d-da1f-4d8f-ac8a-e6c0c4aca240-13&algo_pvid=5a56a75d-da1f-4d8f-ac8a-e6c0c4aca240




    Last edited by Letomoto; 12-21-2018 at 03:02 PM.


  7. #19
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    Default Re: Some advices for my CNC router build = Appreciating!

    I already gave my advise.
    Most of those kits perform very poorly, especially the ones with larger motors.
    there are a lot of threads here from users who bought cheap kit with big motors, and found that they are much slower than small motors.

    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

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

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


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    Yes i understand this part , having a hard time finding small oz-in 34s but i found 23s at the oz-in you suggested 425-450 are available so compare a few different amps rates and select the high rate .But you suggested a 34 would be good.

    So am i wrong in the logic or a high force 23 would be slower than a small power 34 ?



  9. #21
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    Default Re: Some advices for my CNC router build = Appreciating!

    , having a hard time finding small oz-in 34s
    I already gave you a link.

    So am i wrong in the logic or a high force 23 would be slower than a small power 34 ?
    The motor I linked to above should be faster than any similar sized Nema 23, provided that you run it at about 60V, with a quality drive.

    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

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

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


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    Default Re: Some advices for my CNC router build = Appreciating!

    All the best with your build



  11. #23
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    Default Re: Some advices for my CNC router build = Appreciating!

    That dual beam gantry is not going to be very rigid. Try to make the extrusions bigger, and put a thick solid plate on the back of them, maybe 10mm thick?

    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

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

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


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    Default Re: Some advices for my CNC router build = Appreciating!

    Quote Originally Posted by ger21 View Post
    I already gave you a link.



    The motor I linked to above should be faster than any similar sized Nema 23, provided that you run it at about 60V, with a quality drive.
    You are really damn right , you even sent me a link but i didnt knew your experience yet and i am reading so many things my brains are a bit oversaturated and we're on the page 2 now ... (i am actually in accident recovery post TBI and it brought up ADD ... im sorry i feel a bit like a 35 years old teenager )

    I will follow your stepper link to order them and i have a small last question before submit my order . i am wondering what is the weight moving good range for a 465oz-in stepper . i am using the mass calculations of my Fusion 360 (yes did set the materials properties of the aluminum parts and the steel ones to have the good calculations) and it is already at 23 KG but no gantry sides plates , Z-axis (rails and assembly) , steppers X-Z and the ATC spindle (the one i am looking at is 19KG) in the design yet but i would probably end up around 50KG (100lbs) and two Y-axis steppers/ballscrew to move it . Probably more weight than the screenshot of the El Beast build i showed in a previous post who is smaller than mine .


    Some advices for my CNC router build = Appreciating!-carriage-mass-without-z-jpg


    I am also still wondering if a 2.5kW ATC
    JGL-100/2.5R24
    spindle kit Jian-Ken (1900usd with water pump , VFD and shipment fees) would be very okay for my wood and Aluminum needs or a 4.2kW
    JGL-110/4.2R24
    kit from Jian-Ken (2115$ shipped, would be almost double power for only 10% price increase ) if it would be usefull or never need it at all ? I remember Wizard said a bigger spindle will drain more power amps from the electrical box but when not using 100% of the power available it would drain more ?


    i was also wondering if specs from the steppers called " HOLDING TORQUE " is their actual movement force or it is exactly what amount of torque they can sustain without skipping a step or moving out of position , like their "car handbrake" , not the real engine HP or something. I just fell on these info/explanations and the actual movement power is really related to the Amps rate like you told earlier .


    from a website i opened in my Google search , looks good infos !
    https://www.motioncontroltips.com/fa...olding-torque/

    Holding torque

    A stepper motor’s holding torque is the amount of torque needed in order to move the motor one full step when the windings are energized but the rotor is stationary. Holding torque is one of the primary benefits that stepper motors offer versus servo motors, making stepper designs a good choice for cases where a load needs to be held in place.
    Stepper motors can hold a load against an external force when the motor is stationary.
    Image credit: Oriental Motor U.S.A. Corp

    Holding torque is typically higher than running torque, and is limited primarily by the maximum current the motor can withstand. From a practical standpoint, holding torque is the sum of the magnetic force exerted by the coils to hold the motor’s current position, plus the detent torque. Once the motor is moving, the torque available at low speeds equals the holding torque minus two times the detent torque (because the motor has to work against the detent torque).

    Attached Thumbnails Attached Thumbnails Some advices for my CNC router build = Appreciating!-carriage-mass-without-z-jpg  


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