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  1. #71
    Technologist
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    Oct 2016
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    Actually it seems Prusa didn't mess with PSUs, they upgraded the heater cartridge to a more powerful. I remembered watching a clip about it in youtube, the PSU 14V mod was Tom's doing: https://www.youtube.com/watch?v=pRX_uvG9Z-w.

  2. #72

    so many choices

    Being new to this, I feel overwhelmed by the choices.... I'm going to need help, that's for sure

  3. #73
    Engineer Roberts_Clif's Avatar
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    Jun 2017
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    Washington State, USA
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    Add Roberts_Clif on Thingiverse
    Quote Originally Posted by dirtyknightsdolls View Post
    Being new to this, I feel overwhelmed by the choices.... I'm going to need help, that's for sure
    Choices are easy,
    They are dependent on what you can spend?
    How much space you have for a 3D Printer?
    What materials you want to 3D Print?

    When these choices are made then a list of choices can be derived to suit your needs.
    The more money the better the 3D Printer.

    Now some will say that the less expensive 3D Printers are no good. However I have two such Aluminum frame 3D Printers that have more than paid for themselves.
    Both cost around $200 US Dollars
    Now I went a little overboard with a Heat Chamber for 3D Printers, Spare Parts, Tools, air tight Storage containers with disentent moisture removal for filament and Filament $600 US Dollars.
    For a grand total of well over $1000 US Dollars invested.

    Not bad considering I have TWO 3D Printers, Enough variation of Filament as to print most anything and spare part to make repairs without any downtime.

  4. #74
    Technologist
    Join Date
    Oct 2016
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    101
    Got the frame stabilization done for the Dollo.2 build. It's quite rigid now. Printing all the screws, beams and center parts took quite a lot of time and material, so not sure if it's worth to do the stabilization with plastic when same thing could be done with threaded rods. But for science!
    For the models, I also did some experimental internal infill magic by adding 0.1mm holes through the bolts, beams and center parts. The idea is that slicer has to add extra parimeters around those holes, thus making the parts stronger. I have no comparison to parts without the extra infill features, so how much it helps is just a guess.

    To test the stabilized frame, I printed yet another vase, 330mm in height. 0.6mm nozzle, 0.35mm layers, 2 perimeters. The quality is quite good almost all the way, but at the top there's slight banding, which I think comes from the z-screws that aren't secured at the top and move around somewhat. But marked improvement to the previous vase, that showed quite bad artifacts due to the frame shaking around.






  5. #75
    Technologist
    Join Date
    Oct 2016
    Posts
    101
    So here's whats happened with Prusadollo:
    - the original 240W PSU started acting up, I had lowered the voltage to ~12.3V and now PSU cannot keep the voltage stable during load. So the overvolting might've caused some damage. Swapped in a 360W PSU from the old Dollo that I've been planning on upgrading for a while now. Had the design a slightly bigger PSU cover for it.
    - redesigned some of the corner pieces and added some 8mm threaded rods inside the frame parts, now it's quite a lot more stable. Probably still lacking a bit in stiffness, butt good enough for now. Need to test a tall print the see if there's any artifacts...

    2019-01-05 17.37.11-1.jpg2019-01-05 18.06.48-1.jpg2019-01-17 20.05.49.jpg

    - changed stepper drivers to DRV8825 with 1/32 microstepping. They are quite quiet, especially after the Trinamic drivers coil whine. But It seems that there's some problems with slow speeds, probably this problem: http://cabristor.blogspot.com/2015/0...steps.html?m=1. To fix that, I tried the diode hack shown on that page (TL smoother I guess) and lo and behold, it seems to work. At least partially, slow speeds are smooth now. But when the printer slows down from fast moves, it sounds like there's a sudden skipped step, even though the prints are fine. That doesn't happen with A4988 drivers, so not sure if I'm going to continue using DRV8825. The increased resolution (400steps/mm x and y) is tempting... made a box for the diodes, they get somewhat hot.

    2019-01-17 20.18.10.jpg2019-01-17 20.18.03.jpg

    - also tried printing ABS with 100C bed temp. Result = the bed belt holder came loose, because the bolts underside the bed heated enough to make the PETG bit soft. Shows in print quality quite drastically when belt position can shift ~1mm. So I need to reprint that part with ABS and also attach the belt holder to bed carriage with extra bolts other than those that are in contact with the bed.

    Todo is Raspberry pi box and powering it from 12V. Thinking about using 7V 5W zener diodes in parallel so the power draw won't be an issue...

  6. #76
    Technologist
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    Oct 2016
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    101
    Wanted to test how MK2Dollo handles a tall print and started, admittedly bit optimistically a 24h 23cm tall Nefertiti print. Progress after 13 hours of printing:

    2019-01-19 12.28.49.jpg

    You'll probably notice a quite prominent ringing artifact on the left cheek that I think might be caused extempore filament routing from the spool:
    2019-01-19 12.29.08-1.jpg

    It's chafing against the plastic and probably causes enough friction to affect the print quality. The point where the artifacts are, is just the point when the head yanks more filament from the roll when printing the perimeter. Need to figure something better for that...

    Other than that, the print is going along fine. 0.3mm nozzle, 0.17mm layers, 3 perimeters, gyroid infill 5%, Slic3r PE.

  7. #77
    Technologist
    Join Date
    Oct 2016
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    101
    Changed the filament feed mid print and no more chafing. I normally use that kind of spool container for all printers, but was lazy. Lesson to be learned: don't be lazy.

    2019-01-20 12.32.26.jpg

    Print finished fine, took ~27 hours. So the full 23cm is usable on the MK2Dollo build and seems no drastic problems with quality. There's the quite prominent ringin on the left cheek, but not quite sure if it's due to the filament chafing or just regular ringing... Also there's some small differences in layer coloration, which is probably the filament (Amazon basics Gold PLA).
    All in all, happy with the result.

    2019-01-20 12.32.34-1.jpg2019-01-20 12.33.04-1.jpg2019-01-20 12.32.43-1.jpg

  8. #78
    Technologist
    Join Date
    Oct 2016
    Posts
    101
    Finally got the heated bed installed on Dollo3D.2. It's a MK2B from Aliexpress, not the best option, but with a glass on top of it good enough. Added some insulation to the underside of the bed so it should heat bit better. Printed adjustment screw mounts that attach to the bed carriage and used long M3 bolts. Seems to be working fine so far, although the PCB does warp bit when heated and it's not fully in contact with the glass.
    2019-01-26 15.12.14.jpg2019-01-26 15.13.47-1.jpg2019-01-27 15.08.06.jpg2019-01-27 15.08.14-1.jpg

    MK2Dollo has now Octopi mounted on the frame. Also it's powered from the same PSU as the printer, so no need for the usb charger. Used buck coverter to get 12V->5V for the Raspi. The converter I had is bit overpowered, ordered some smaller ones and maybe swap it later.
    2019-01-27 15.08.55-1.jpg

  9. #79
    Technologist
    Join Date
    Oct 2016
    Posts
    101
    Now that both Dollo3D.2 and MK2Dollo are more or less finished products, I can finally star working on the first Dollo expansion. Step 1, take it apart:
    2019-01-27 18.13.07-1.jpg2019-01-27 19.06.05.jpg2019-01-27 19.06.07.jpg

    Step 2 is to sort out what I can reuse and what needs to be printed. The orange extension parts will go to trash can as will the corners and maybe some of the black extensions. Those are the very first parts I printed and they are bit too small on X and Y (printer wasn't calibrated) and they are also fragile and mostly broken, apparently printed with too much heat. Not sure how much off the breakage is because they are couple of years old...
    Probably going to use the metal z-screws for this build.

  10. #80
    Technologist
    Join Date
    Oct 2016
    Posts
    101
    Found the actual reason why MK2Dollo made that artifact on the Nefertiti bust: the bed carriage was bumping on the ziptie that holds the smooth rod in place. Not sure why, might be that I've slightly mispositioned the bearings too deep on the carriage.
    Fixed this by rising the bearings 2mm on the bed carriage model. For the already printed parts, I made spacers. Also fixed the y belt holder more firmly on the bed carriage so printing ABS should be possible again.
    2019-01-30 18.42.25.jpg2019-01-30 18.42.33-1.jpg

    For the Dollo rebuild, need to print quite a lot of extension parts and 4 corners. Bed carriage needs 8 and there's pieces missing from the frame. Also as I'm planning on using the full length of the 505mm threaded rods, I need to replace 4 60mm pieces from the corners. Ran out of black filament, now waiting for my order to arrive.
    Also as I'm going to reuse the z-rails, I need to modify some of the bed carriage/z parts. And there's also some bugs that I need to fix so some modeling work to do.

    Currently the max viable print dimensions should something like this: 320x320x450mm. Which means I need to get a bigger bed. I have some 3mm aluminum, just need to get heater for it. Or multiple heaters, I wonder how hard it would be to make a sectioned bed...

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