Monthly Archives: May 2013

Rat Week, Day 5: Stretch!

#ratweek concludes with Stretch, who’s reaching, reaching! for the weekend.

Just a few more hours, kid! You can make it! Then go join buddies Biggie, Skritch, Hambone, and Cody under the barstools for chestnuts and mead.

MTG Rat Token, Stretch

download

I’ll put all these guys into a pack and make them available for download in The Forge sometime this weekend. So many projects, so little time. #staytuned

Printrbot Simple: First Impressions


Lao Zheng's Printrbot Simple

In mid-May I got all hopped up on endorphins from 6AM yoga and BAM! right there in my Twitter feed was an offer. The first N users who bought a Printrbot Simple would save $50 off the already low, low price of $300. My impulse control weakened by the flush of healthy qi, I had one in my shopping cart within two minutes, or roughly the time it takes me to huff and puff four sun salutations.

Two-fiddy plus shipping isn’t a budget breaker for a 3d printed squirrel magnate, and the gnomes at Interdimensional Bank of Zheng say we haven’t skimmed anything off the upgrades fund in a while, so why not, indeed.

A quick note for anyone thinking they might purchase this printer once it’s out of beta in June and available to folks other than the lucky N.

if (eval(‘yourTime’)>=eval(‘yourMoney’)):
     buyADifferent3DPrinter()
else:
     thisIsThePrinterForYou()


If you’re a high school student with a few hundred bucks and a weekend to burn, grabbing the Printrbot Simple is a no-brainer. If you own a complete set of matching stemware, look elsewhere for your first 3D printer. Especially if your only exposure to 3D printing so far has been the SkyMall catalog.

Make no mistake, even more so than the Replicator1, this is a hacker’s 3D printer. You’re like two steps up from a homebrew RepRap when you get into the Printrbot Simple. If tweaking and calibration and watching prints fail while you dial in gCode ain’t your thing, purchase a different printer.

On the other hand: right after I made my first successful print on the Simple I was mobbed by Brazilian bikini models. Your mileage may vary.

On the gripping hand: as an instructional tool, the impact of the Printrbot Simple can’t be overstated. Anyone who assembles, calibrates, and prints with this bot is going to learn buckets about the ins and outs of 3D printing at a granular level.

Best of all, at $299, it’s relatively inexpensive. I’d be disappointed if hundreds of these bots don’t find their way into high school STEM clubs.

Well-to-do techie parents looking to build a 3D printer with their tweens might be the sweet spot for this bot, but Mom or Dad should be prepared to sneak back to the basement after bedtime to put in an hour or two of extra build time.

The Build

warning The Simple is a beta, so there are guaranteed to be some bumps along the road. It ships as a kit, so you’ve got to put it together yourself. You’re also paying someone else for the privilege of beta testing their hardware, which is a genius business model if ever there was one. Fortunately Printrbot is up front about that fact; “BETA” is laser-etched onto the build platform. You buys your ticket, you takes your chances.

Printrbot describes the build difficulty as “moderate.”

I am reminded of the time I went to the Thai place across town that isn’t my usual Thai place and I ordered the larb with a 7 on the 1 to 10 spicy scale which is where I like it but they use a different hotness scale and hoo doggies that’ll burn tomorrow on the way out but I could still mostly finish it. Ach, mein ass.

So maybe Printrbot’s definition of moderate is different than mine.

I’m not a complete idiot. I can read English and make logical deductions, I’ve got a well-stocked toolbox, I have an amateur’s burgeoning knowledge of electronics, and I’m not afraid to jimmy-jim-jim a part to get it to work. Surprisingly, given my pyrotechnic proclivities as a pup, I still have all ten fingers. I have a SparkFun wish list, for the love of Pete.

Even with my bona fides, I still find Printrbot’s estimate of one to two hours for assembly of the Printrbot Simple wildly optimistic. I’m sure there are wizards from the Printrbot community who can wham-bam-thank-you-ma’am this printer into a finished state in that time, but coming at this build cold I’ve probably got 8 hours put in over the course of three days. Keep build time in mind while you’re salivating over that $300 price tag.

Printrbot’s marketing claims that you can put this together with only a screwdriver. Maybe, if you’re the Last Son of Krypton or you have vise grips for hands. There are a few tools that will make this process much easier:

  • you’ll need super glue.
  • it amazes me that my kit didn’t include an Allen wrench. Maybe Printrbot figures that IKEA has acheived such market penetration that the probability of an Allen wrench being within reach is approaching 1.0 for a given location in the Western hemisphere.
  • a cordless drill with an Allen bit will speed up the assembly considerably.
  • a metric/Imperial ruler so you can tell the different bolts and screws apart
  • scissors or a hobby knife– you’ll be cutting fishing line.
  • an adjustable wrench, and maybe an M3 socket.
  • needlenose pliers
  • zip ties. You’re going to need a lot more zip ties than are included with the beta to manage all those cables.
  • painters’ tape for the print bed. No sense in marring that nice birch any more than you have to.

Most people willing to tackle this process are going to have this stuff in the toolbox anyway, I just include the list because I’m a huge fan of deflating marketing hype by emptoring my caveats.

There’s a point during assembly where one must gently fit two steel rods through laser cut plywood holes; these are the rods that stabilize the extruder arm as it traverses the lead screw. The holes are cut to very fine tolerances, so much so that it can be difficult to push the rods through.

I recommend that you put your steel rods in the freezer maybe an hour before you get started on the build. Thermal contraction will temporarily shrink them just enough to get them through the plywood. Once they warm up again they’ll be nice and snug.


rods in the freezer

Be prepared to slightly modify some of the parts that came with the kit to get them to fit. The laser cut plywood all fit together perfectly, but I had to file down the plastic edges of my hot end so that it fit into the extruder assembly. I accidentally stripped the wood around an M3 nut and had to super glue the nut in.

Not a big deal for your average maker geek, but someone expecting a snap-together 3D printer is going to be sorely disappointed around hour three. You can see where my file chewed up the top of the hot end in the closeup below.


hot end

Suggestions for Printrbot

I’d like Printrbot to etch more directions onto the wooden parts of the printer. Etched labels like “this side faces out” would be very helpful in determining orientation during the build. I got turned around a few times and ended up dismantling and reassembling the previous two steps of my build.

At the end of each step, a photo of the entire printer from multiple angles could help a lot. I kept getting disoriented and had to backtrack or skip ahead to find out what part went where.

Once you get the bot together the first print is very satisfying, but along the way there is likely to be some gnashing of teeth and rending of garments. Here’s a test print of a small cylinder that I did, just to make sure everything was put together properly.


first print

Calibrating the Printrbot Simple so that your prints are the right scale is a whole other can of worms. I’ll get into that in a subsequent post sometime in the next few days. Watch this space.

Rat Week, Day 3: Biggie!

The latest installment of #ratweek introduces Biggie! Biggie is what happens when Hambone (Day 2) finishes eating.

MTG Rat Token, Biggie

downloadBiggie’s belly is a direct result of the limitations of FDM printing. I needed some kind of support to keep his abdomen from turning into a big pile of ABS ramen, so I just extended his belly further down until it touched the base.

#staytuned! Two more rats will finish out the pack by Friday.

Rat Week, Day 2: Enter Hambone

#ratweek continues here at zheng3.com! I’ll be posting one Magic: The Gathering Rat Token model every day through Friday.

MTG Rat Token, Hambone

downloadCreative Commons Attribution notice: Hambone is gnawing on a human metatarsal from DrGlassDPM’s Anatomic Human Foot and Lower Extremity 2.0, available on Thingiverse.

Three more rats to go this week! #staytuned

Rat Week, Day 1: Meet Skritch

It’s #ratweek here at zheng3.com!

MTG Rat Token, Skritch

Last week I took a break from the Drake and cranked out my first Magic: The Gathering rat token.

It worked out so well that I posed him five different ways and printed myself a pack of rats. I’ll be releasing one a day for the rest of the week.

downloadHere’s Skritch with a d20 for scale. There’s not a lot special about him, but if you’re going to print a pack of twenty rats you might like to drop some Skritches among them for variability.

So. #staytuned for four more rats this week. One a day, every day.

Leaping Rat Fail

I’m working on a pack of rats, five or six different poses all based off my Magic: The Gathering Rat Token. There’s only so many ways you can pose a rodent before they start looking the same, so I thought I’d try something more epic in my latest rat.


rat fail

This little fella hasn’t gotten past the low-resolution test print stage on my Replicator yet. His only points of attachment to his base are the tip of his tail and his feet, which form fulcrums for the rest of his body. Invariably around 40% of the way through the print, right at the hips, the stress of being wiggled by the extruder head detaches part of the model.

I’ve tried all kinds of wily 3d printing tricks, slowing down the extruders, increasing the number of shells, etc.

I have a gallery of Lovecraftian rats-but-not-rats in the scrap bucket. Here’s what he should look like.


leaping rat

I might give it one more go with slightly thicker legs that are less likely to break off. Stay tuned.

You can download the model here and give it a shot yourself. It’s not Forge-worthy until it can be verifiably printed. This looks like a job for a non-FDM machine like the mUVE 1, Form1, or b9Creator. Have at it, bots.