Saturday, 12 December 2015

I'm making a note here: Huge success (relatively)

After last time's successful measurement, I adjusted the extrusion speed to match reality. Time to find a test print!

Since I didn't get the kit, I don't have a presliced Android gcode file on the SD card. Instead, I go to Thingiverse to find some plain test cups. The first few I try don't get accepted, but the stack trace from Python is so long it takes me a bit before I realize that it's just not finding Skeinforge. Setting the external commands to point to the proper place helps. Grab a test cup, and slicety!

Slice... slice... slice... and boom! " object of type 'NoneType' has no len()". Hum. Could be a bad STL, let's try an egg cup. That one worked, but is estimated to take an hour. I was hoping to be home earlier than that. Grabbing a simple vase instead. 12 minutes, using 65 cm of PLA. Sounds good. I grab about a meter and switch out the small piece I tested extrusion with.

Pressing print! Things are moving! Things are printing... but not really sticking to the surface. Most likely forgetting to heat the bed is the problem. Resetting, homing, heating, printing again. It goes all the way out to the max corner when printing, that's silly. Let's see how to get things to the middle.

Aside: The Ubuntu version of the Arduino software has a weird bug that scrambles the text some of the time. It gets better if I resize, but worse again when I scroll or type. Annoying.

Changed to

#define X_HOME_POS (X_MAX_LENGTH * -0.5)  
#define Y_HOME_POS (Y_MAX_LENGTH * -0.5)

That did not help. Also, the clamps in the corners get in the way when Z is low. Trying with brute force:

#define X_HOME_POS (0)  
#define Y_HOME_POS (0)

Now centering is proper, but it won't go any further. 

Let's do this properly. The centering seems to go to (X_MAX_POS - Y_MIN_POS) * 0.5, so set X_MIN_POS and X_HOME_POS to 0, similar for Y. Now it homes nicely to 0, 0, and centering brings it to center, while allowing movement over the whole surface. Final settings:

#define X_MIN_POS 0
#define X_MAX_POS 190
#define Y_MIN_POS 0
#define Y_MAX_POS 200

#define X_HOME_POS (X_MIN_POS)  
#define Y_HOME_POS (Y_MIN_POS)

Note to self: Printing doesn't wait for the extruder to heat up.

Printing again, and this time it (mostly) works. The outline got loose, but the base seems to stick ok, even though it printed over some of the loose strands. However, the walls were trying to build on some of the initial loose stuff, which doesn't work too well. It also seems to slide in the negative Y direction. Then partway up, it either decided to just shift itself sideways, or X got stuck on that loose thread sticking up and got out of sync.

I can reasonably stop this here:)

Trying again, the outline gets loose here, too. Aborting. 

Applying Kaftan tape just to see if it makes a difference. Last print for the evening, but it's definitely sticking better. This might work. It still leaves that little gap between the outline and the bottom, though. Huh! It actually goes back and (sorta) fills in that gap once the rest of the bottom has been laid. How odd. But again it offset on the X axis, while the filament was bonking against the frame. I'll leave it be for the rest of this filament and see if it happens again while the filament is standing free.

I wonder if that odd jump before was due to the filament getting stuck up top and putting too much resistance on the X motor. I should probably set up the filament holder. And order some filament of my own.

Here are my first four prints, in printing order left to right:


Things I should probably do next:

Order some filament of my own and mount it on the reel holder.
Mount the fan.
Adjust the potentiometers for the X and Y motors in particular to make sure they have appropriate power.
Somehow calibrate the layer height.
Print more!

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