Things I have learned in the past three months

Hi internet, it's been a while. During this time I managed to figure out most of the major problems with the printer. Here's a quick summary:

1. Wet filament sucks
2. The weakest point in any system is the end user
3. Z couplers are much, much more important than I realized

Wet filament

So in a previous post I reported I was getting some inconsistent extrusion. During a routine extrusion to clear out filament, I noticed a popping sound and I saw steam escaping. This is apparently a telltale sign of wet filament since the moisture in the filament will be heated into steam and expand.

From what I can gather, the production of steam causes inconsistent extrusion since steam isn't plastic (duh). You can't get an even amount of plastic being pushed out if an uneven amount of plastic is present.

To solve this problem, I initially invested in a desiccant. Since the supermarket didn't stock silica gel, I had to settle for the more caustic calcium chloride (as Damprid). Problem is, it'd take months for it to dry properly. 

To speed up the drying process, I preheated an oven to the lowest temperature possible (~50oC) and turned the element off. It's important to keep the element off, since it will radiate heat directly onto the filament and is likely to melt it. I put the filament in the oven to sit in the warm environment for about an hour. I repeated the process once more to fully dry the filament.

Now I keep my filament in a box with a desiccant to avoid these issues in the future.

I thought wet filament was to blame for all my printing woes, but it was only a small part of the problem...

In summary:

• Wet filament ruins prints
• Kitchens are possibly one of the worst places to store filament. Only the shower would be a worse storage area
• Ovens aren't just good for baked goods. It's also good for baking filament.

Slicer settings

I'm a huge fan of KISSlicer. It seems to be a lot more intuitive compared to Slic3r in terms of printing movements and in settings. Only problem is, I started tinkering with some of the settings I didn't understand (I know, it contradicts the above statement), like the destring settings.

To quickly summarise what destring is, it's responsible for preventing hot plastic from trailing behind the hotend when it moves off the path. If you disabled destring (or use Slic3r), you may notice small, fine threads hanging within your parts.

For KISSlicer, the suck is the amount of filament which is reversed out to reduce ooze (and therefore strings), while wipe will cause the hotend to backtrack over a set distance to wipe off plastic before it moves again. Lastly, prime is the amount of plastic which is pushed out once an extrusion begins to counteract the action of the suck command we saw earlier.

Now, if you look back to this print:

If you look at that arrow, you can see some of the inconsistent extrusion. When I went back and looked at the gcode, I noticed this part was where the suck was happening. It was also a reproducible issue and I noticed this with all models.

What I didn't know about suck was suck isn't instantaneous. It will occur well before the print head gets to the end of its path. In fact, my suck setting was so high, it meant the ends of all paths didn't have enough plastic so they all failed.

When I returned the settings to default, the problem vanished. Clearly the suck setting is something to be weary of.

In summary:

• Sucking at setting suck, sucks.
• Wipe gives most of results for destring. Suck helps, but I prefer to keep it low now

Z wobble and Z couplers

I have a confession to make. I had no idea what 'Z wobble' meant. I know what its effects are (regular horizontal banding patterns), but I had no idea why people called it Z wobble.

The reason why is due to the movement of the Z threaded rods when the assembly moves up and down. If you watch your printer's threaded rods moving from side to side (as if it was wobbling), then you are likely to see banding patterns similar to what I'm getting:

NOTE: the top layers being off is due to the print head hitting the plastic and misaligning. Seems to do that a lot with low layer heights.

Initially, my left threaded rod was wobbling all over the place. This was because the nut was much too loose in the nut trap. I added a bit of bulk to the nut using a bit of tape, and now that rod is completely solid.

Problem is, now the right rod has been getting a few issues. The reason for this is I had to cut the tubing which were being used as my Z couplers. Despite my best efforts, the Z coupler wouldn't let go of the rod, so I had to cut it.

To replace the couplers, I printed off a set using this: http://www.thingiverse.com/thing:81002, except I printed a much shorter version since the original size is simply too long for it to fit. Long story short, the new couplers aren't working. The right rod continues to wobble around. I suspect it might be due to the slant in prints I've been experiencing, most likely due to a poorly constructed frame. This led to a poorly printed Z coupler which could be responsible...

That's all I got for now, till next time. (hopefully with a fix to the slanting issues)