Some questions about custom printer hardware and Duet WIFI



  • Hi Guys,

    Let me use the opportunity to present myself. My name is Boyan. I am almost a Pro DIYer 🙂 , mostly building CNCs till now. So recently i dived into the 3d printing with an Original Prusa MK2, meanwhile just to be learning, while i was designing my 3d printer.
    After long search and considerations i have decided that the Duet will power my printer . So i am building 2 prototypes. Long story short it will be fully enclosed Cartesian , not very big, fully able to upscale and Hiwin linear. It will be open source, reprap style, and IMHO will become the preferred build for people who want to spend some $$$ on building a extremely capable printer. I will be happy to share here on forum the build as it progresses.

    So excuse me my bragging, i am right into deciding and buying the mechanical stuff and motors.

    I know it sounds very dumb as i have read and answered that same question many times on CNC forums for Nema 23 motors, but reality is i am not very good with motors and considerations especially when have not tried personally, so just a quick check of my decisions and some help? In case i have accidentally missed some consideration.

    My exact questions are :
    1. The fastest available Nema 17 motors?? /20t GT2 10mm steel belt and pulleys/ for:
    -X - single X no heavier than Titan extruder, nema 14 motor and e3d V6 hotend , most possibly only the hotend , possibly Vulcano pack .
    -Y double motors that will move 1-2 kg heated 6mm aluminum bed / in my case 1.2kg for now/

    Aim is 150mm sec steady with good acceleration at least 3000mm/s2 with perfect print at that speed, better if even faster.

    I have looked around for motors and from here http://reprap.org/wiki/NEMA_17_Stepper_motor i see that maybe the most suitable nema 17 could be the
    42BYGH W811 47.0 N·cm 3.1 V Ø 5 mm 1.8° 48 mm 2.5A 1.8 mH

    Now the question is if the Duet could drive it at best possible scenario for that motor, i assume, yes? Given specs i have read for motor drives. What is the exact PSU that i should buy for the Duet? bed will be 230VAC powered. 2xZ +2xY+1X+1xE motors.

    Also i am not clear why this sudden desire for high micro stepping in 3d printers? I would never drive CNc more than 1/8, as more is just pointless

    2. Am i assuming right that i could remap one of the extruders drives and slave it to the Y for double Y motors? I wish this board had 1 motor driver more integrated for double extrusion without daughter boards, as i dont see myself driving / except the Z/ 2 motors on 1 drive.

    3 I am assuming also that i dont need very serious motors for the Z, as there will be 2x so i am wondering if to buy lead screws separately and fix them to 1.5- 1.7A motors or just buy 2 motors with lead screws from Banggood? http://www.banggood.com/JKM-42mm-Hybrid-Two-Phase-Stepper-Motor-40mm-Length-For-CNC-Router-p-1011710.html?rmmds=cart Gantry will weight less than 1 kg but as all will move very fast i dont want vibrations occurring due to flimsy Z motors

    Or just point me to the most used motors for that purpose please

    4. Any known source for that motors? I have found them here http://store.amberspyglass.co.uk/48mm-nema17-stepper-motor-200step-per-rev.html

    Thanks !


  • administrators

    A lot of your questions are answered on the wiki. See the pages on choosing stepper motors and choosing a power supply.

    Steel core belts are a bad idea unless you use a large pulley radius.

    Yes you can use a spare extruder driver to drive a second Y motor. However, connecting the two Y motors in series may be adequate. The page on choosing stepper motors says how to work out the drive voltage needed per motor at the top speed you want.

    The use of higher microstepping improves resolution up to about 16x. Above that, the main benefit is to make the printer quieter.

    If you are looking for a supplier with a large range of motors, try stepperonline.com. The 2.5A one you mentioned would be a good match for the Duet WiFi.



  • OK, thanks. I have read the wiki and have done the calcs more or less, just last check if i was missing sth.

    About the steel belts. Has anyone that knows how to properly tighten to specs belts tested that? Or its just an assumption?
    Anyway, i am willing to test and report, as its 20 euros for 10m belts.

    I meant how many amps should be the 24vdc PSU to operate reliably say 8 motors at 2A current? In fact isnt it preferable to be non regulated with some big caps? How do the drives draw current? Directly from the PSU


  • administrators

    Regarding steel core belts, here https://www.duet3d.com/forum/thread.php?id=615 is an example of them giving trouble.

    I cover the calculations for rated PSU current in the wiki page on choosing a PSU. You won't easily find a 24V unregulated power supply because switching PSUs are invariably used these days to avoid the cost of a large transformer.



  • I did quite the search yesterday especially contemplating the idea of finding some 24v ~200w PSu similar to, or from some laptop. I mean, obviously it will be a good quality, silent and outside printer, so i dont have to worry about other things.

    I found some 24 8,4A ones DigiPos Digi-PSU250 3 Pin power supply +24V/8.4A which seem very promising to me.

    There are also some Protek PM200-14C 24V 8.4A 200W . at ebay

    Both of the above are used but seem very good quality for the money and seems they have quantities.

    There are some 24v laptop uninversal PSus that claim 160-150w, but i am not sure if that is at 24W.

    Anyone know of something similar ready available? It would be nice the supply to be good quality at reasonable price.

    /i am talking 230VAC heated bed/


  • administrators

    If you are using a 230V AC heated bed then a 200W power supply should more than enough My delta also has a 230V heated bed and I use a 120W (5A) PSU to run everything else. But I have only 4 stepper motors and a single hot end heater.



  • a) Do not over-engineer the solution.

    b) consider your audience's skill level.

    c) also very important, wallet size, both of these last are frankly limited.

    d) Do not make the design mistakes others have made, and learned from "stand on the shoulders of giants"


 

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