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Dual Direct Drive Extruders Concept

Discussion in 'Mods and Upgrades' started by Tony Janus, Nov 8, 2014.

  1. Tony Janus

    Tony Janus Member

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    So, could I actually just use an ATX PSU to power the whole printer? Cause I have an even better 750watt from an old gaming pc that broke down on me. I think it has multiple rails, I know the 1600w in my current pc has a bunch of them, but I think I remember that one has at least 2. Just plug those 2 rails into the 2 pairs of pos and neg terminals then? Sorry if that's a newbish question, but I have literally 0 electronics and engineering experience prior to what I've taught myself here.
     
  2. Mike Kelly

    Mike Kelly Volunteer

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    Right. You need around 10A on one 12v rail and 5A on the other.
     
  3. Tony Janus

    Tony Janus Member

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    Awesome, thanks. Those 2 hobbs are coming in today hopefully, and the fan extender on friday. I hope to have this up and running by Sunday at the latest. Once I've got it going, I'll update the thingiverse page with a BoM and instructions.
     
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  4. Tony Janus

    Tony Janus Member

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    Hey all, so because of the issues I was having with my wades extruder, I was unable to get a working version printed out. After this first real test run, I've noticed a number of flaws, and have a redesign in mind.

    At this point, anything I publish will solely be for geared steppers with Tatsu v2's. A standard nema17 and mk8 gear are not compatible. At some point in the future, I'll adapt, but no timeline for that. These Tatsu drives are beastly, and I'm using what was going to be my bowden extruder as my direct and even with the flaws, it's printing nicely with a .8mm nozzle at .4mm resolution.

    I'm probably just going to make the current design hold 2 bowden hotends and and make the hybrid a total redesign.

    What I'm thinking is taking the mounting plates and the heatsink fan brackets and combining them into one piece. That gives me more room for springs and screws for leveling while keeping the part strong, changes the carriage design into a more unique look, makes the whole assembly slightly more compact, reduces the number of parts, and further balances the carriage's center of gravity.
     
    #124 Tony Janus, Jan 6, 2015
    Last edited by a moderator: Jan 6, 2015
  5. Tony Janus

    Tony Janus Member

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    Hey Mike, I got a quick question for ya.

    This is the PSU I have:

    http://www.corsair.com/en-us/tx750w

    It's showing me 60a on the single 12v rail. Would I be able to use this as the only PSU for my printer? And if so, would I just take two 12v wires, connect those to the + terminals on the 11a and 5a inputs, and ground to the - terminals? Or would I need to connect 2 12v wires to each terminal to ensure max amperage per wire isn't hit? Or is this more complex than I'm seeing it? I'm worried that since there's only one rail, that I'll overload the system. But that rail can support up to 60amps, so that makes me think I'd be fine. I don't know enough yet to feel confident one way or the other.

    In the case I can't use it, I'm planning on plugging all my fans (that aren't firmware controlled) into this or a smaller psu and just using it to supplement the stock psu.

    Also, I took a piece of cardboard and put 2 layers of reflectix insulation tape on it, and then sealed it to the underside of the bed with silicone gasket maker. I am easily able to hit 110c now, and it's stable. I haven't tested 120c yet, but that simple mod ($5) boosted bed temps for me.
     
  6. Mike Kelly

    Mike Kelly Volunteer

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    Yup you could drive 2-3 printers off that beast.

    Running two 12v lines to the input power should be fine. With the wires it's more of a limit on how much amperage the wires can carry. I'm assuming the power supply has big enough wires to handle 10A. You should be able to run anything you need off that single power supply.

    Just be sure you removed the connector if it has one. I've seen too many of them fail out at high temps
     
  7. Tony Janus

    Tony Janus Member

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    Hey Mike. I'm running into an issue with the geared stepper on the extruder. I initially used one of the geared steppers and changed my steps per mm to 485.367. When I tried the 520 you suggested, I was extruding approx 150mm when set to extrude 100mm. Now I had a clog caused by the old extruder design and when I switched it with the new one, I used the second geared stepper. This stepper makes a very loud humming and rattling noise when extruding. The other stepper worked without the hum, but I noticed it got painfully hot to the touch.

    I'm wondering if there were any additional settings you changed in the firmware in order to get these motors to work. They are the same you linked to in another thread.
     
    #127 Tony Janus, Jan 9, 2015
    Last edited by a moderator: Jan 9, 2015
  8. Mike Kelly

    Mike Kelly Volunteer

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    Right it can vary depending on the particular printer. I probably suggested you start there and then do calibration.

    The heat is a function of the stepper driver current output. You need to tune it down (I probably mentioned this as well).

    Using the supplied plastic ceramic screwdriver, tell the printer to extruder 100-200mm of filament.

    While it's extruding get access to the stepper driver and turn the potentiometer counter clockwise until the filament stops extruding. Then slowly turn it back up until it extrudes smoothly again.

    [​IMG]

    If the stepper driver gets too hot it'll melt filament causing jams. It may be advisable to have a fan/heatsink on the stepper driver to pull the heat away if it still gets too hot after tuning.
     
  9. Tony Janus

    Tony Janus Member

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    Worked, awesome thank you!
     
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  10. Tony Janus

    Tony Janus Member

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    [​IMG] [​IMG] [​IMG]

    So here's my new idea. Looks bulky, but I feel this will make for a very rigid carriage. The 40mm fan heatsink brackets also provide the mechanism for holding the hotends in the carriage. To level the hotends, I'll be using blocks sitting under the heatsink brackets as seen in the second photo. Two M4 nuts and washers will be placed into both blocks, with an M4 hex head screw through each. There will be a 4.5mm hole in each side of both heatsink brackets that will allow the screw to spin, but also use the screw for stability. As you turn the screw, that side goes down. As I'm typing this though, I realize springs may still be necessary. I'm still working on it.

    The heater blocks are close to the carriage, but there should be a small amount of air from the fans coming through the bottom that should prevent the plastic from warping. I'm also encapsulating my hotends in ceramic fabric and then covering that in reflectix tape. I'm less worried about that airflow coming through affecting the hotend temps than I would be if I wasn't insulting them.

    I'd like to figure out a way to get a 50mm radial fan to blow *into* the carriage, which would lead to 2 pairs of holes, one pair on each side of the carriage, where I would then insert standard airline/aquarium tubing and direct that towards the hotends.

    I also have to figure out how to attach the extruder and motor without putting all the stress on the head of the hotend.

    I'm not sure if the flaws in my previous design are specific to my printer or if everyone that's printed the design is having issues as well. I've had no comments on thingiverse. My printer just hasn't been printing parts strong enough (namely, the x-carriage) and keep breaking, even at 100% infill. So I'm redesigning with this problem in mind, which results in all the extra bulk.

    Any suggestions would be appreciated. I have all the parts I need to make this happen, I just need the assembly designed and printed.
     
  11. Mike Kelly

    Mike Kelly Volunteer

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    You may need to increase the printing temp if you're not getting strong layer bonding.
     
  12. Tony Janus

    Tony Janus Member

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    Well, I'm going to give the old design another go. I'm printing with a .8mm nozzle now and have calibration dialed in for the most part. Seems to be producing much stronger parts.
     

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