Monthly Archives: June 2013

Slime Counter Fail

Slime Counter Fail

I had an Etsy store order come in and I just couldn’t get one of my slime counters to print properly. Tried everything; adjusting layer height, slower print speed, re-leveled the print bed.

Turns out one of my Z-axis shafts had worked its way loose, which made the platform wobble during the print. A little bolt tightening and I was good to go, but not until I’d already made a dozen or so failed slime counters.

The original slime counter is here, free to download.

A Little Counter Intelligence

So I’m printing out a couple sets of Magic: The Gathering +1/-1 counters for an Etsy customer and I run into a problem. The red ABS +1/+1 counters are printing fine, but the -1/-1 black PLA counters are getting all feshnicket about midway up the print.

feshnicket couner

Good enough for a pickup game at Casa de Zheng, but one of these might show up at a tournament somewhere and we can’t have our customers looking anything less than their best.

If you don’t have your own 3D printer, you can get these counters on Shapeways, and if you do have your own printer head over to The Forge and print them at home. They’re in the Miniatures section.

These fellas are pretty small, so the newly-extruded PLA isn’t cooling off before the extruder head comes around to the same X-Y position on the next layer. Gooey plastic gets smudged a little bit and the edge of the counter becomes irregular. Fugly.

The solution is a little bit of custom gCode. A brief pause between layers gives the PLA time to stiffen before the extruder drags itself over the same spot.

The gCode needed for this is G4, or “dwell,” with a parameter measured in milliseconds. You’ll also want to move the extruder head out of the way while it dwells so that it doesn’t continue pumping heat into the print.

Here’s the gCode that needs to be added after each layer. Everything in parentheses is a comment and might make your interpreter go to la-la land.

G91 (set to RELATIVE positioning)
G1 Y10 F3900.0 (move 10mm in Y)
G4 P5000 (wait for 5 seconds)
G1 Y-10 F3900.0 (move -10mm in Y)
G90 (reset ABSOLUTE positioning)

You could add this with a Find/Replace in a text editor; just search for (</layer>) and append the gCode above to the end.

OSX’s TextEdit will actually let you add carriage returns to your find/replace fields if you hit CTRL-Q and then hit the return key. But saving that output gave me some weird text encoding errors, demanding that I switch from UTF-8 and it’s not 1994 anymore so WTF Apple.

It’d take me longer to figure out that text-encoding problem than it would to write a short Python script to do the job. Assuming you’re on a Mac and have in_file.gcode on your Desktop:

import os

# read the input file
f=open(‘/Users/zheng3/Desktop/in_file.gcode’, ‘r’)
#Windows and Linux paths are left as an exercise for the reader.
content=f.readlines()
f.close

gCode=’G91\nG1 Y10 F3900.0\nG4 P5000\nG1 Y-10 F3900.0\nG90\n’
# the \n puts a carriage return after each line.

for i in range(len(content)):

if ‘()’ in content[i]:
content[i]=content[i]+gCode

#write the output file
f=open(‘/Users/zheng3/Desktop/out_file.gcode’,’w’)
f.write(“”.join(content))
f.close

Then fire up out_file.gcode in ReplicatorG and a few minutes later, you’ve got yourself a decent print. Nice print on the left, yeechy print on the right.

fixed

Zheng3 Amazing Nose Ring, Now in Stainless Steel!

Nose Ring, Stainless

Now you can purchase the Amazing Nose Ring on Shapeways, in plastic (inexpensive) or stainless steel (awesome!)

I’m astonished at how durable the stainless steel version is, and can’t wait for stainless steel printing technology to reach the hobbyist market. Five years, maybe? Who nose.

Please check out the Handy-Dandy Amazing Zheng3 Nose Ring Sizing Chart to ensure that you’re purchasing a ring that is comfortable for you.

The ring is available in these common sizes: 5 6 7 8 9 10 11 12 13

As always, you can download the model for this ring for free at The Forge.

Using Slic3r with the Printrbot Simple and Repetier-Host

Seej Bloxen Flag, Basic

I’ll be using a basic Seej bloxen for my slicing demo. It’s more exciting than a test cube and potentially useful should a vigorous Seej match break out at your makerspace. You can never have enough bloxen sitting around. Grab the model here if you want to follow along.

Open the Object Placement tab and click on Add STL File. Navigate to the bloxen model and Slic3r drops it into your build area. The bloxen should be centered, but if it isn’t, you can fiddle with the translation and rotation values, or just hit Center Object. When you’re done it should look like this:

Added Bloxen

Click the Slicer tab (not the Slice with Slic3r button) and then click the Configure button. We have a few settings to adjust.

This is the point in the tutorial where normally I’d walk you through changing a half dozen parameters. Teach a man to fish, Lao Tzu says, and he’ll eat for a lifetime. Screw Lao Tzu. You want your fish now. You can learn to fish in an hour after your belly’s full.

So I’ve zipped up the settings that have been working for me and put them up for download. You can just swap out whatever default settings showed up with Slic3r with the contents of this archive right here.

On OSX, Slic3r stores its settings in three subdirectories within

~YourUserName/Library/Application Support/Slic3r/

You can copy the archive contents into that directory and you should be good to go.

I have no idea where these settings will be saved in Windows. If you’re on Linux, you’ve already written a shell script to slice models using spare cycles from your video card and can stop reading now.

warningWARNING: The usual warnings about destroying your printer by using the code I’ve provided apply. Use these settings at your own risk. You might think about backing up your old settings in a safe place, just in case.

Once you’ve got the settings installed, click the Slice With Slic3r button. You should have a pile of G-Code in your G-Code panel. I’ve been consistently deleting/commenting out a couple of lines from my code and have gotten good results by really babysitting the first layer of my prints.

Delete this Code

If you comment out the code by putting a semicolon in front of it, the printer won’t use it but it’ll still be there for reference porpoises:

;G28 ; home all axes
;G1 Z5 F5000 ; lift nozzle

This assumes that I’ve manually homed my printer by moving the print bed all the way to the right and the extruder arm as far forward as it will go. The hot end should be over the bottom left of the print bed.

If you’ve manually homed the printer, make sure you hit the Set Home button the the Print panel before you print.

I watch the extrusion carefully on the first layer and adjust the Z-axis manually (physically turning the leadscrew with my fancy new Z-Axis Knob) to make sure I get a good adhesion on the painters’ tape. Once I’m satisfied that the first layer is OK I’ll go wash dishes or something while the printer burbles away.
First Layer

Let’s assume everything turned out more or less OK for you and you’ve got a mostly-perfect bloxen sitting on your print bed. Now would be an appropriate time to learn to fish.

Layers and Perimeters

Layer height: I’ve been getting OK results with .35 mm. This is fairly coarse for a machine that claims .1mm resolution on the spec sheet, but for something as plain-jane as a bloxen it’s probably OK. If you get a .35mm layer bloxen to work, try a higher resolution on a more complicated model. This Magic: The Gathering Beast Token is a great detail test.

Infill

I leave this density at .25 when printing with PLA unless the object’s going to undergo physical stress. If I go much lower I find that the top layer of PLA tends to sag too much for my tastes.

Skirt and Brim

I’ve set my skirt layer height to 0 layers, which effectively turns it off. If you’re not 100% confident in the levelness of your bed, using a skirt can give you a few seconds to nudge your Z-axis before the main body of the print begins. A brim will apparently help your print stick, but I haven’t had to use one yet. Hot PLA and a level platform goes a long way towards sticking to painters’ tape.

Support Material

I try hard to design models that print without support, so I’m not a good source for information on this setting. Keep it off unless you’re printing something that needs it. I keep the raft layers set to 0 as well; no sense in printing more than we have to if things are sticking to the platform anyways.

Filament Settings

Even though your Simple ships with 1.75mm filament, somewhere in a Printrbot setup guide I recall reading that you should set this to 1.70mm. Sure, whatevs.

I’m printing with PLA at 200° for the first layer and 190° for subsequent layers. Go much hotter than 210° and the PLA that printrbot shipped with the Simple starts getting liquid. This seems to work for loading the hot end, but I wouldn’t want to try and print with liquefied PLA.

Printer Settings

I’ve set my Simple to have a 100x100mm build platform, since most of what I’m trying to print is tiny and I usually end up manually homing the printer anyway.

Clearing a Jammed Filament

printrbot calibration fails

In the beginning, One does not know that which One does not know. The Dark Art of 3D printing is shrouded in a miasma of confusion and rage and smug forum posts, and One despairs.

With time, kobolds and goblins and glitches and bugs fall beneath one’s blade as vermin are wont to do, and One’s place at the tavern edges ever closer towards the dim corner where the new Ones timidly approach to receive their quests.

And when One’s troubleshooting reflexes are honed vorpal-sharp, One is a scythe to trouble, or a rapier, or a headsman’s axe, and no issue endures the coming of dusk.


As troubleshooting goes, this is an easy one, but the trick to it is recognizing when it’s happening. This happens on my Replicator, too, it’s just a thing with FDM printing.

The Symptom: The extruder motor pulls the filament in for a few centimeters, and then stops. You can’t feel the motion of the filament between your fingers any more. The extruder motor continues to chug to no effect.

The Problem: A small piece of filament has snapped off inside the extruder, past the drive gear’s ability to move it further. This filament scrap is blocking the new filament from entering the hot end.

The Solution: Remove the hot end from the extruder assembly by backing out the screws that hold it in. Place the hot end on a non-flammable surface and heat it up to 200°C or so. Remove the offending filament with pliers. Let the hot end cool down and then replace it.

Pro tip: an animal-print workspace brings the boys to the yard. Gridded workspaces are sooooooo 2012.

Planting a Flag, Redux

Seej Battle Flag, Basic

About a year ago I designed the Seej Battle Flag, Basic to be printed on my Replicator1. A user on the Printrbot forums was having trouble getting it to print, so I decided to see if I could get it to work myself. Good news! It can be printed on a Simple without any voodoo involved.

It helps if one doesn’t try to print the model all at once, so I’ve broken it into three parts and updated the entries in The Forge and on Thingiverse accordingly.

I find leveling the Simple’s bed along the Y-axis to be a little difficult, especially as the weight of the extruder arm at maximum extension pulls it down in Z. I understand there’s a fix for this, I just haven’t had the chance to apply it yet.

I’ve aligned the parts of the battle flag along the X-axis, which should make them a little bit easier to print individually.

If you’ve never heard of Seej before, check out the rules and give it a go. It’s an Open-Source tabletop wargame based around 3d printing. Have at thee!

Printrbot Z-Axis Knob, Refined

I find myself adjusting the height of the Z-Axis on my Printrbot Simple with every print, sometimes during the print itself. Handling the leadscrew directly can get a little uncomfortable, so having a knob attached to the top of the axis helps a great deal.

Printrbot Z-Axis Knob

downloadThis knob is based off Bill Owens’ Printrbot Simple Z-Axis Knob which is in turn based on jridley’s Parametric hex head screw or nut knob. Circle of LIIIIIIIIFE

This version has some rounded edges for comfort because I’m a delicate desert flower that only blooms once a year and I must preserve my girly hands for stroking my Shih Tzu.

Did you hear about the new zoo that opened in Chicago? It’s only got one animal: a dog. It’s a Shih Tzu.

This knob also has some transitional elements between the two major volumes, and a graceful inverted flare on the shaft. These are completely unnecessary aesthetic changes to the perfectly-usable model made by Bill Owens, but since complexity is free in 3D printing, why not.

Here’s a perfect demonstration of how the Creative Commons license fosters creativity. First, in need of a knob, jridley throws together a parametric design and shares it on Thingiverse. Now anyone can adjust a few numbers and get a printable knob.

Standing on the shoulders of that giant, Owens refined the basic design until he got a knob he could use in his particular situation. He puts it up on Thingiverse where dozens of Printrbot Simple owners download and start using it.

I don’t know much about OpenSCAD, the software jridley used to design the original knob. But I can take the output into software I’m familiar with and edit the geometry to fit my needs.

All legal, all free, no ethical quandaries or patent fights. All we have to do is give each other credit where credit is due.

I found Owens’ knob to be a little loose given the crop of nuts grown in my part of the world, so this model might be a little tighter or looser for you.

You will need a pair of 5/16″ nuts to use this knob properly. Put one nut on your z-axis leadscrew, attach the knob, and then tighten the second nut.

The model is also available in The Forge along with assorted other baubles.