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  1. #41
    Mounting Y and X axis motors.

    - 9 x 50mm M3 screws
    - 3 x stepper motors with gears assembled

    Other parts:
    - 4 x bow_tie.stl (see previous steps for print info)

    Take one motor, two motor_mount_small parts and 3 50 mm M3 screws . Assemble and screw the screws in only couple of turns:

    Next, slip the assembly on the rack. If it doesn't fit, open the screws more:

    Tighten the screws until the mount needs considerable force to move. It's a good idea to move the mount back and forth while tightening the screws. Move the mount through whole length of the rack. Turn back the screws in small increments until the mount moves relatively easily. Don't expect it to be buttery smooth and move freely, there are no bearings here.

    Repeat the operation on the other side of the frame:

    X-axis can be assembled before assembling the motor mount for it, because the motor mount can be slid in and out freely.
    To mount the x-beam on the Y-mounts, first move the Y-mounts to the end of the racks:

    Then slide the x-beam on the tie slots on the Y-mounts:

    The bottom of the rack should be approximately on the level with the Y-mount top:

    Add bow_ties to the bottom of the Y-mount and x_spacer junction. Assemble motor mount for the X-axis same way as for the Y-axis.

    Moving the mounts might seem bit rough and that's expected. These are printed parts so there will always be some unevenness. But in this case things will get better; after a some time printing with Dollo, the parts will adjust to each other and he movement will get somewhat smoother.
    Last edited by spegelius; 02-25-2018 at 07:34 AM.

  2. #42
    Been modeling parts for bed and Z-axis. Previous version of the bed carriage was bit too flimsy, didn't use existing parts and also needed nuts and bolts for assembly. So for the new setup I'm going to be using the extention pieces which should make the carriage quite robust. Z-axis prototyping is also underway.

    Wanted to see how well my first Dollo build handles a bit more complicated model so printed a terminator skull. A 28 hour print, with two PLA colors. Enabled M600 command in Marlin so filament change was a breeze. Had some problems with the black PLA jamming. Got the base printed after cranking the speed to 150%.
    Result is actually better than I expected.

  3. #43
    Got the first working prototype of the Z-axis screw-mechanism. It works, but turning the screw requires a bit of force. But there's no slack so that's probably a good thing. Probably need to smooth out the threads with a file bit, because it seems that the seam is also causing a bit of unevenness.

    The screw itself is a V-shaped thread with a pitch of 3 mm, diameter 25mm. I didn't want to use simple nut, because of the wear that will happen. Wear in intself wouldn't be that big of a problem if it would happen evenly on the length of the screw, but unfortunately fost prints won't use the full z-length.
    So the nut uses side rollers matched to the screw shape and hopefully the wear will happen in the axles of the rollers and not in the screw.
    Side rollers are printed in PETG, other parts PLA. Again hoping that the different materials reduce wear. Also using some silicone grease inside the rollers.

    Also improved the mechanism for joining screw parts together using a keyed center part, same as I use for the z-rails. Keying makes sure that the screw parts are joined in proper way.

    Source code for the screw thing:

    Next, create motor screw coupler, integrate this thing to the bed carriage parts and try to print the whole thing. Who knows, maybe even get it working...
    Last edited by spegelius; 03-17-2018 at 05:18 AM. Reason: links

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