Thursday, March 6, 2014

Object[printing]Lesson 2: Be careful when feeding filament for Mr. Jaws.

Duuun dun duuun dun dun dun dun dun dun dun BOM BOM dun dun dun dun dun dun doo dedoo doo dedoo dede doo dede doo dededoo

Yes, that's the theme song to Jaws (thanks to Textual Songs for helping me with the lyrics).  Wait, this is supposed to be about object printing, right? Why would I open with that?  Well, for some reason, once I received my printer, that song started going through my head.  I think it's the pressure of expectations - those made to myself and my family about just how awesome and useful this printer was going to be!  Well, there it was, sitting on the dining room table in all its laser cut wood and aluminum glory.  With everyone gathered around, it was time to show what it could do.

Ok, truth be told, I may have had a little anxiety.  This isn't your average purchase; it's basically a robot that melts plastic and forms objects.  I had only ever seen one in person at CES a couple years back.  Even then, just a glimpse through a glass/plexiglass case.  Now it's sitting there waiting for me to jump in the water.  Somehow, it's Jaws and I know it's about to consume me.

Duuun dun duuun dun dun dun

First things first.  With all 5 pairs of eyes on me, I just needed to set it up.  Let's see, I have a Mac and the last time I bought a printer, I just had to plug it in and, well, that's it.  Pretty much shows up on the system and can start printing.  Nice and easy.  Let's be clear, it's not that.  Maybe someday, but not now, not this one.

Firstly, there were no clear instructions included in the box.  There were, however, some instructions etched into the wood on the side of the printer - something about cutting zip ties and removing.  Woah!  Hold your horses.  I have to cut zip ties and remove something?

Duuun dun duuun dun dun dun

Yep, and that's just what I did.  The printer comes with some extra packing material (throw away laser cut wood) hooked together to keep pieces from moving about during shipping.  I was nervous and the etching wasn't super clear, but I seem to have done the right thing.  So, don't be surprised if you have to cut a couple of zip ties.  I wish I had done a full "unboxing video" to show this, but hindsight is 20/20.

Now, power it up.  That's straightforward (or not, more on this later), which is nice.  After, plug in the USB.  That mini USB port is a bit hard to find.  Look for the main control board of the Printrbot - it's the metal doohickey with the Printrbot logo on it.  The USB port is right on the edge on the left side when facing the logo.  It's up toward the topside.  Connect it to your computer as well.

From here, I needed help.  I located the Getting Started Guide Simple instructions on the website, downloaded and got started.  Have a look at the link, the basics are there including a workflow.  It's a pretty good guide.  Chapter 5, Connect your Printrbot only has 4 easy steps!  Wouldn't you know, I failed these 4 steps.  I had what appeared to be a physical connection, but proceeding to Chapter 6, Configure Software, I learned I had no connection.

Duuuun dun duuun dun dun dun

It's plugged into the power outlet, check.  It's plugged into the USB, check.  It's plugged into the computer, check.  Now what?  I was unable to see the USB device register on the list of devices in the printer software nor in the Mac system profiler.  Now, as to power, the printer itself didn't show any lights.  I figured there weren't any lights.  Turns out, though, that there is a light.  The main board has a green light that lights up when powered.  No light, means no power.  I had no power.  My power brick was defective.  When playing with the cords, suddenly the light turned on!  I carefully placed the brick into position without changing the angle of the cords, restarted the printer software and the printer appears for configuration!  The music was beginning to fade in my head - I had to be out of the water and into the boat by now.

This is a good time to mention Printrbot support. I contacted them about the defective part and within 3 days, I had a new power brick at my house, no questions asked.  Great customer service!  The new brick works without a hitch.

Now, let's drop back a second.  I had to have something to print.  As the theme for Jaws was running through my noggin, I decided on a shark.  Seemed appropriate.  There is this fantastic community called Thingiverse that allows people to post designs to be download and printed by others.  A quick search for "Jaws" and I found Mr. Jaws.

Mr. Jaws - a chip clip!
Mr. Jaws is a chip clip, which is basically a 2D extrusion.  Nothing complicated about this model - no overhangs, support material, or unusual curves.  This is just what was needed.  I downloaded the .stl file (this is the standard file format for 3D printers) and began to get excited.  The kids, by the way, had all but lost interest at this point - "wake us up when you get it figured out."  Thanks for the support, kids.

3D printers work by melting plastic filament and layering the melted plastic in the shape that is defined by a slicing program, which takes the full 3D shape and figures out how to "slice" it into layers.  Once I had the software all configured per the instructions and the imaged sliced, I was ready to print, but the filament needed to be loaded.  It's like ink for your inkjet printer, only much bigger and more difficult to deal with.

Aluminum extruder
The picture to the right is of the extruder.  This is a key component of the printer.  It holds the filament and pushes it down into the heating unit to be squirted onto the print bed.  You'll need to locate this - it's hard to miss.  On the top of it is a hole.  That's where the filament goes.  I pushed my filament into there and started printing.  Nothing came out.  I tried to manually extrude some material using the printer controls in the software, still nothing.  Didn't seem to matter what I did.  Nothing printed.

Looks like I'm going to need a bigger boat! Queue more Jaws music.

The getting started guide showed entirely different pictures than what I had physically in front of me.  This extruder, the aluminum one, was different than in the guide, which showed a wood extruder.  Turns out the 2014 Printrbot Simple model is upgraded and the docs are not.  I found a guide for assembling the aluminum extruder on the Printrbot site which helped.  This pic made the difference for me:

filament feeding in

Here's how you, too, can feed Mr. Jaws:

  1. Heat up your extruder to about 185C with the printer software.
  2. Loosen the screw on the left of the extruder.  This will drive that nut under the spring downward, reducing the tension on the spring. Don't remove the whole screw - it's hard to put back in. The whole top assembly acts as a kind of clamp to hold the filament against the rotating drum, which pushes the filament down during prints.  
  3. Squeeze the extruder to open the space for the filament to be pushed in.  I use my left hand placing my index finger on the top left and my thumb below the bottom right side of the extruder.  You should see a gap open in the middle.
  4. Push the filament with your right hand down into the top hole, past the drums, into the lower hole while squeezing still with the left hand.  Keep pushing.  If you have followed step 1, the hot end will be hot (so be a bit careful not to touch the area near the red tip) and some melted filament should push out of the nozzle onto the print bed.  You can stop pushing when you see some.
  5. Tighten that screw back up.  You will see the nut raise against the spring.  I stop when that nut is level with the metal at the top of the "U" shape (see the filament feeding in pic above).
  6. Use the printer control software and manually extrude some more filament.  This will test the extruder motor and tension in the unit from the screw you tightened.  More melted filament should come out and it should come out in a single strand.  If so, clear off the test plastic and you are ready to go.  If not, try running the manual extrude a couple more times.

Once I finally arrived to this point, I started Mr. Shark printing.  He printed quite well.  Here he is:

My Mr. Shark

Now we finally get to the main lesson: Filament feeding is critical to get a print!  Mr. Jaws didn't print at all without feeding the filament all the way in and preparing it properly.  With the extrusion temperature up to at least 185C, push the filament in until you see some melted material come out the "hot end" (that's what the nozzle is called).   Then, be sure to tighten the screw.  This is the first step to a good print!

Let me know how your first print went and come back for Lesson 3: Guard your power to prevent a Creeper from exploding (yes, that's a Minecraft reference - I have 4 kids, remember?)!

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