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MK3 Preassembled has some issues  

Trusted Member
MK3 Preassembled has some issues

Hi there, recieved my MK3 prebuilt yesterday and did some fair bit of testing.

Some things were off, like the Y-pully screw not being tightened (the pulley was hanging), some other loose screws but that was it.

Now in prints, I have some noticable errors in print quality and I just cant seem to get rid of them.

Using stock settings on Slic3r with the MK3 preset and the silver rapunzel PLA which came with the printer.

First off the most noticable problem while printing: The nozzle seems to scrape infill layers, no matter what I do.

Completly reset the calibration and did everything from scratch, retightened the belts, checked everywhere for loose screws (only 1 loose screw under the heatbed left, but have to take the heatbed off to reach it, it rattles a bit when the bed moves sometimes).
Looked if the extrusion is off, calibration cube in vase mode with 1 perimeter has exactly 0,44 - 0,46 mm thickness, which matches the extrusion width of 0,45.

No matter what STL I slice, most of the times the nozzle starts catching the infill.

Another problem is just "horrible" print artifacts all over prints, which I cant seem to get solved.

Im not getting much further like this, hope you guys now some answers before I have to consult the support.

In the attachments you can see my problems with the prints.

Maybe its just the slic3r, but there isnt a preset for S3D yet to test it out.

This isnt the quality you expect from a prebuilt machine to be honest.

Edit: Well, tried to take the heatbed off to access the loose screw on the Y-axis, no chance.
2 of the screws are pretty much stripped before I even went there.
The more I look into this printer, the more stuff I find to actually return it....
Now how the heck am I supposed to do maintence on this thing with 2 stripped screws?

Edit edit:

I somehow got the 2 stripped screws loose without damaging anything...
Someone knows what kind of screws they are?
Definetly not using the stripped ones again.

Posted : 17/12/2017 1:32 am
Eminent Member
Re: MK3 Preassembled has some issues

Thanks for the post, I can't help with this, but I ordered mine Preassembled as well. If anyone else posts about these issues, then maybe theres an assembly problem, paying $250 US extra for Preassembled and having issues is not what we paid for.

Pre-assembled MK3 Black with Bondtech
Zaribo 420 MK3s 10mm Deep Cherry Red with Bondtech
Many other small upgrades for these printers as tinkering never ends.

Posted : 17/12/2017 4:12 am
Eminent Member
Re: MK3 Preassembled has some issues

Just curious, have you tried printing any of the included gcode files to verify they have the issue as well? If the problem persists, then you can cross slic3r off your troubleshooting list. The pre-sliced gcode on the SD uses z-hop, so it probably won't catch the infill, but I'm guessing the print quality issue is hardware and so you'll still see it.

I haven't seen that kind of problem before exactly, but I wonder if there's a problem with the extruder temperature. It might be swinging more than it should or you may have a poor connection somewhere in the temperature probe connection. The bondtech seems extremely capable of driving filament into the extruder, to the point where it might still extrude in slightly low temperature conditions where other drive systems would strip the filament.

Posted : 17/12/2017 6:49 am
Honorable Member
Re: MK3 Preassembled has some issues

I would have said things could have gotten rattled in shipping but screws don't get stripped inside the box. If you're unhappy, contact support and work something out. You paid a premium to receive a built, tested, and calibrated printer.

Posted : 17/12/2017 6:50 am
Trusted Member
Topic starter answered:
Re: MK3 Preassembled has some issues

Fixed the rattling Y-Axis, got the heatbed back on, trying to calibrate everything.

Good nows, nothing rattles anymore, not the z-axis, not the y-axis, everything perfectly silent and smooth.

Bad news, when I try to PID calibrate, it starts calibrating for 1 second and crashes / restarts the printer.

Basicly I cant PID calibrate, but that seems to be a firmware problem, nothing to do with hardware.

Lets see, if the print results are any better.

@Steven, good point, I think the g-codes which came with the printer had the same issue but not sure.

Doesnt have anything to do with z-hop, I have it enabled on all of my prints and it still scratches the infill while printing, not travel movement.
Basicly the first and second layer is fine and then it starts scratching up the prints.

My guess is, either the slicer fucks up or my z-axis is shot/has some major problems.

Posted : 17/12/2017 12:29 pm
Eminent Member
Re: MK3 Preassembled has some issues

Yeah, I noticed that problem with the PID tuning as well. It won't work by triggering it with gcode either. Hopefully the new firmware coming it soon will fix it.

Posted : 17/12/2017 4:40 pm
Trusted Member
Topic starter answered:
Re: MK3 Preassembled has some issues

Yeah, Im going to email the technical support.
Im not getting anywhere.

Tried every calibration process avaible (except PID Tuning), 2 different versions of Slic3r Prusa Edition, retightened every screw, both belts, extrusion is calibrated pretty good (first extrusion was underextruded by 5mm, second one by 1,5mm, thats not really impacting the prints.

I still get ugly artifacts every time at the same places.

You can see it clearly.
The only thing I didnt try yet is different filament, but I highly doubt that its the completly newly unpacked silver filament from prusa.
At least not if the problems always occur at the same places with the same prints.

Posted : 17/12/2017 6:56 pm
Eminent Member
Re: MK3 Preassembled has some issues

I am having a lot of the same print issues with my kit build too; the included gcode prints perfectly but the Slic3r profiles just do not give me very good results.

I get some blobs in infill and the nozzle seems to catch on the infill quite a lot. You can see the whole extruder assembly bouncing around while printing infill. I also have first layer issues when slicing my own stuff but never an issue on the sample prints. It's a rather rough and frustrating process.

Obviously because the included gcode works beautifully with the same printer and filament my problem is in the use of Slic3r. It would be helpful to know what some of the common setting tweaks that people are making to improve the print quality. I am printing sort of ok with the .2mm layer preset changing only the perimeter alignment, reducing infill to 15% and then on the printer i dial down flow to about 90% and speed to 66%.


Well a couple of things of interest to other newer users like me: Slic3r does embed its settings in the gcode files so I am able to look at the settings used by the sample gcode files and what I was producing. A couple things of interest:

The distribution file for the mk3 for mac includes a version of Slic3r that does not support the conditional gcode in the included filament profiles. So linear advance never gets set by the "out of the box" profiles. You should download the latest Slic3r Prusa Edition 1.38.4 or newer from the github releases. This results in the linear advance parameters not being set during start which I think is probably the biggest problem here. The telltale sign of this happening seems to be the little blob at the start of the brim, so I am hoping this will also fix the blobbing infill and allow me to resume printing at 100% flow and speed.

Other important parameters such as various extrusion widths and infill overlap are varied a bit between the profiles used to generate the samples, the profiles shipped in prusa3d_mac_2_0_0 and the profiles built into the most recent Slic3r release, and the MK3 branch of the Slic3r-settings. I am not sure which to treat as authoritative so at the moment I am going to test again with the profiles from the Slic3r-settings merged branch as they are newer than the config bundle in the most recent Slic3r release. Prusa needs to do a better job of putting profiles in a single authoritative place.

Posted : 17/12/2017 8:02 pm
Vojtěch Bubník
Re: MK3 Preassembled has some issues

For these thin walled objects it will likely help to switch to a grid infill and to enable the "detect thin walls" feature at the Printer settings -> Layers and perimeters page.

We are currently extending our Slic3r team, so I will hopefully have time now to improve this issue.


Posted : 21/12/2017 7:34 pm
Trusted Member
Re: MK3 Preassembled has some issues

I found a way to make the mk3 totally silent...shut it off until they fix the biuggie firmware

Posted : 22/12/2017 1:02 am
Eminent Member
Re: MK3 Preassembled has some issues

Issues so far with my pre-assembled MK3:-

  • 1. Plate was not sitting down at front right corner, so removed plate and found 2 screws sitting proud of heated bed. Had to countersink both holes substantially to get them flush.
    2. Cables from bottom of the rambo box, were rubbing against the edge of the heated bed, so had to re-route. May be a shipping problem?
    3. Cable exiting filament sensor, was catching on the bottom of the single Filament spool holder, so re-routed.
    4. Using latest firmware, I got a change filament request during a print, although there was no requirement for me to do so, but carried out the request and print carried on without another hiccup.
    5. Spiral wrapped cables at rear clunk into each other at certain positions. (I also still don't like the exit/entry points of the cable wraps; too much bending back and forth. Would prefer a rubber sleeve like on domestic appliances).
    6. Single spool holder was 1.5 mm too small to fit on frame, so had to file to size.
  • Posted : 22/12/2017 3:59 am
    New Member
    Re: MK3 Preassembled has some issues

    I had ordered also a preassembled one. Also the Y-pully screw not being tightened (the pulley was hanging), there was a square nut in the box I could not identify. The bolt/nut on the heatbed connenction comes lose. I used the square nut as a contranut so now it stays good.
    Damaging your print can be done by the nozzle ventilation. the circulair blowing shape is connected with a bolt on the lefthand side. It can come down on the right hand site and than it hits your layer (mine did) maybe its bent by the heat.

    Posted : 24/01/2018 8:29 pm