[Blabber] Weird 3d Printing Asymmetry Flaw

Chris Stratton cs07024 at gmail.com
Sat Dec 16 20:17:08 UTC 2017


James' off-list insistence on a mechanical issue turned out to be
right - loose Y stepper pinion.

This may be in part a result of my putting it together a bit
temporarily, since I'm going to have to disassemble it back into the
box to get it to the ultimate install location.

Given how strikingly repeatable and rectangular the flaws were, I
really had trouble believing this until I saw the same problem with a
freshly compiled install of Marlin from house.

As least learning how to build Marlin was fun however, I'll probably
end up exploring that further to fix a few annoyances on my own
printer, though this one will probably stay stock since I don't have
time to fully dial in a custom build.

Thanks James and also Peter for the responses.

Chris

On Sat, Dec 16, 2017 at 12:10 AM, Chris Stratton <cs07024 at gmail.com> wrote:
> In a fit of holiday hubris, I purchased an inexpensive 3d printer kit
> to be given as a gift, thinking I'd assemble, test, and tune it before
> presentation.
>
> Alas, it has me stumped!   I figured out the belts of this direct
> drive extruder but otherwise ultimaker like contraption laser cut
> plywood cube, fabricated a base for the missing Y axis limit switch on
> my existing printer, and I learned about Z offsets.
>
> But much to my surprise, files that print fine on my prusa-style
> printer come out with a very odd Y axis asymmetry on this one.
>
> I'm not sure if the attached picture will come through, but
>
> X-oriented vector shell lines are about 3mm too positive in Y on the
> left side of the print, and 3mm too negative in Y on the right side.
>
> Contrastingly, the raster infill is either in the right place, or at
> least has much less error.
>
> And this repeats layer after layer stacking up in the same wrong place
> each time, so I don't think it can be a slipping or skipping steps
> issue.
>
> Is there some kind of acceleration or backlash settings that can cause this?
>
> Firmware is some mystery vendor build of Marlin, slicing is Cura.
>
> Anyone have any ideas?  Apart from missing parts the mechanism seems
> decent so I don't really want to send it back, doing a custom firmware
> build wasn't really in my plans for the coming week, but if that's
> what it takes to fix it...
>
> Chris


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