Monday, 28 December 2015

The key to success: Tighten your gear shafts!

Got a suggestion to print from an SD card instead of over the USB link, so I acquired a plain 32GB card, and after poking a bit at Linux got it to work. Except that the Marlin doesn't recognize it at all (and the USB connection resets whenever I insert the card).

Looking a bit more at what the two jumpers do. JP14 atop the board appears to be the Autoreset, necessary when uploading firmware, but might interfere with the SD card reader due to a shared reset pin. Taking it off doesn't change the reset behaviour, though, so I'll leave it on.

JP15 switches between power from USB and power from the PSU. According to this, having it away from the connector blocks means USB power, and I have it towards the connector blocks, so that should be OK. But just because I'm paranoid, I'll try a print with the opposite JP15 setting.

Once again, the extruder gets set to 200C and the bed does not get set. Also, the X axis got stuck moving towards home. That is with an admittedly slack belt. Tightened somewhat and restarted.

An annoying thing about Slic3r taking over the heating and homing is that it does the heating pause by inserting a long pause. During that time, the print cannot be aborted.

X axis problems got worse, now it can't home at all. Time to check if the motor rod is properly attached. Inspecting a stuck Home command with a flashlight shows that the rod does turn while the gear doesn't. That's one mystery solved. Unfortunately, I have no small enough hex wrench in the house. Fortunately, a tiny Philips works in a pinch.

I expect the motor would be more stable if the rod has a flat side, but alas it doesn't. I suppose I could grind it down with my Dremel (leaving tiny pieces of metal all over the place:) For now, I will just retighting and see what happens.

Again the heated bed takes quite a while and/or several attempts at setting it before it started heating, and the extruder temperature got set to 200 despite the Slic3r settings. The result looks unsurprisingly somewhat soft in the corners, presumably because there's time for a little bit extra filament to ooze out:

Tried running Slic3r on the command line, inspecting the resulting gcode. Even there, it ignores the settings, but running the Slic3r UI takes it into account. Noticed that the --load command allows multiple files to be specified, adding the ~/.Slic3r/filament/Simple Mode.ini file got the temperature right. So apparently the presets section doesn't load the right thing. But there's also a simple.ini that gets generate along with the slic3r.ini, which contains all the right settings. Pointing at that instead.

Found a hex bit set that was a gift from Ric a year ago, which contains tiny hex bits. Tightened X and Y considerably. Thanks, Ric! I still think a flat-side shaft would be better.

Took a couple of tries before I got this right - turns out it now heats the bed first, then homes and heats the extruder. Except sometimes the bed seems to get confused and either not heat or keep heating. Also, using simple.ini is not a good idea, but pointing at the three Simple Mode.ini files works (as long as you quote the arguments with spaces instead of backslash-escaping them). The entire command line is

/home/lars/Slic3r/bin/slic3r $s --load "/home/lars/.Slic3r/filament/Simple Mode.ini" --load "/home/lars/.Slic3r/printer/Simple Mode.ini" --load "/home/lars/.Slic3r/print/Simple Mode.ini" --output "$o"

Ok, so now it heats up the bed first, then the extruder, then waits for a minute before printing. Also, it's harder to trick into not printing in the middle. Ah, well. The skew is utterly gone now, to be replaced with a stringiness that I at first guess would say temperature or extrusion amount problems.

The temperature is easy to test, and I got decent results with 200 before, so let's go there.

Stringiness persists. Odd. Looks like too little filament. Tried extrusion multiplier of 1.1:

This was abandoned partway through as no filament was coming out. I marked the filament and made it extrude a set amount, but nothing came out.  Then I turned off the motors and pulled out the filament. It was stripped along one side:

Reinserting it and running again gave pretty nice results:

It looks a little blobby in the corners, and the top layers hang down a bit. I'll try at 190. After that I can attempt increasing the acceleration. This time, since it's been a bit hard to get off the print, I'm adding a raft, just to see how that works.

Raft was hard to get off. Not trying that again until I see a real need for it.

Upping the acceleration to 1/2 of the original:

#define DEFAULT_MAX_ACCELERATION      {1000,1000,150,2500}

#define DEFAULT_ACCELERATION          1000

This definitely helped on the corners, I'll try putting it all the way back up. The lid of the cube still sags a bit, and there are gaps between the lines. 

I wish I could add more skirts, it only barely gets to start extruding, and if any drooling happens while it waits for a minute in the corner, that's likely to get stuck in the main print, as can be seen in the bottom-left corner above.

Trying with a 1.1 extrusion multiplier.

Apparently the thing I can add is a "brim", but that actually connects to the object, not what I want. Also in this print tried lowering the temperature to 180 (185 for first layer) to see what effect that has on the corners and top sagging. It still has one corner with issues, and there's a bit of ridginess to one side:

Reducing extrusion multiplier again. And because it's getting late and this will probably be the last print of the day, I'm doing an actual useful thing: A wire clamp for the back of some LED tubes, with a nut-and-bolt arrangement for affixing a back plate. It's a continuation of the earlier design by Thomas Riedl. Also looks slightly like a space ship:

And finally, a progression of the prints that have brought me here over the last few days:


  1. Congrats! That looks significantly better than your first, uhm, experiments :-)

    BTW: I print PLA at something like 220°, since it appears to result in noticeably
    better layer-to-layer adhesion while still not yet smelling too bad.

    For printing I use Cura, e.g. as it give me all nice things like skirts, rafts,
    brims, fan control etc. while using slic3r for slicing;
    funny things are its layer display mode, the nice zooming/ rotation/ flipping/ Xraying/ copying/ ... , and a comprehensive set of settable parameters (nozzle diameter, filament diameter, max. speeds X/Y/Z, with hovervcards explaining most of this plus recommendations, aso asf.

    Extra points in my POV for running under Linux (apt-get & friends with Ubuntu),
    and that you can hack its Python implementation (w/o needing to follow a certain
    Style Guide :-)

    The Recent Owner Of Chocolate Calipers

  2. YES!!!!!!!!!

    Well done

    Sorry for the last drunken posts (I deleted em because I couldn't understand them)

    Lookin good