Category Archives: How To

Various how to’s with information about how to avoid, fix, and solve problems with your MakerBot

MakerBot Calibration

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After my design-print failure I thought it was about time I recalibrated my ‘bot:

  1. Starting from scratch, I’m using the 0.5mm test pieces from Spacexula’s calibration set.  Before starting I set Skeinforge->Carve->Layer Thickness (mm) to 0.4.  Thus, I came to test piece 815.1.  The piece came out well, but I noticed that where the Z axis raises there is some slight blobbing and just before the blobbing, some sparse areas I can see through.  Otherwise, great interlayer adhesion.  The height of the piece is 10.25, 10.31, 10.30, 10.55.  Throwing out the high and low, there’s an average of 10.305mm.  It is 22.29mm x 22.29mm.
  2. Skeinforge->Carve->Layer Thickness (mm) to 0.38.  Test piece 815.2.  Again, slight blobbing, very small sparse areas and great interlayer adhesion.  Piece height is 10.39, 10.40, 10.18, 10.19, we’ll call this 10.29mm.  It is 22.41mm x 22.13mm.
  3. Skeinforge->Carve->Layer Thickness (mm) to 0.36.  Test piece 815.3.  Slight blobbing, very small sparse areas and great interlayer adhesion.  Piece height is 10.25, 10.31, 10.14, 10.30, we’ll call this 10.275mm.  This one was 22.33mm x 22.29mm.

New 3x2x1 Rubik’s cube design – totally printable!

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X-Ray view of the 3x2x1 puzzle cube

X-Ray view of the 3x2x1 puzzle cube

This is easily my most intricate digital design for the MakerBot yet.  It’s a 3x2x1 variation on the Rubik’s cube puzzle I had posted earlier.

This version incorporates the prior improvements as well as designing a connector system inspired by R3bbeca‘s beco block connectors.

This has enabled a totally printable toy.  This just makes me happy. 1  The idea that I can crank out a set of these parts, clean them up a little, and just snap the toy together is just amazing.

TomZ‘s original 1x2x3 “friendlier” Rubik’s cube designs were also totally printable – but required a printed pin that was later glued in place.  I like the ideal of all printed parts – but strongly prefer a design that can later be disassembled easily.  And, as I mentioned above – the ability to hand assemble the toy is important to me.

I wasn’t able to recreate R3bbeca’s female connector designs2 so I made a simplified version that should suffice.

The simplified connection mechanism is essentially two plastic fingers that will (hopefully) pinch the barbell into place.  This was made by designing the outline of the gripping “fingers,” creating a horizontal cylindrical hole slightly larger than the intended end of the barbell, then creating a vertical cylindrical hole in the center for the barbell to be inserted through, then a bit of cleanup.

The biggest potential problem is that this design will require a carefully tuned ‘bot.  The center cube pieces have a lot of stuff packed in there – semi-circular slots for the semi-circular tabs, connectors for the barbell, and thin walls separating things.  With those thin walls and interior overhangs, this may be a difficult design to print.

I think Bender is up to the task, but we’ll see in a few hours.  :)  I can’t wait to print this!

For me, having a MakerBot is like waking up to Christmas every morning.

Oh, and before I forget, if you want one of these – leave a comment or send me an e-mail through the Contact page.  Make me an offer.

  1. Perhaps a little prematurely, since I haven’t actually printed this yet… [↩]
  2. I believe I’ve already sufficiently lamented my inability to understand women and their mysterious lady ways. [↩]

How do upgrade your extruder firmware

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Just as an FYI for anyone who’s having trouble upgrading your MakerBot Cupcake CNC plastruder firmware, the instructions built into ReplicatorG don’t tell you to unplug the TTL cable from the motherboard and plug it into the extruder board.

So, save yourself 5 minutes of frustration and googling for the answer…  and just plug the TTL cable into the extruder board.  :)

How to Raise Your MakerBot from the Dead

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Happy Zombie Day

Happy Zombie Day!!!

… or Happy Zombie Day!

My extruder is back online! Huzzah!  Since I had it disassembled I made a few minor modifications.

  1. I’ve added binder clips to the front and back edges of the build platform.  I found that my acrylic build base is slightly deformed and probably getting more so with each build.  This is a temporary fix while I get around to picking up a new build base.
  2. You’ll notice I’ve also added pieces of rubber band.  I cut a long rubber band into two pieces about an inch long, tied them off to make small loops, and put them around the handles to the binder clips.  I don’t want to take the handles out of the binder clips because then they’ll be difficult to move/remove/replace.  But, as I printed they tended to vibrate creating unnecessary noise.
  3. When ABS oozed down my PTFE threads and around the barrel, I sliced off about 1mm to use as a washer between the nut and large washer.  The reason I’ve heard suggested for the PTFE washer is that it keeps the large metal washer from acting as a heat sink.  The nut is right on the barrel and is able to heat right up along with the rest of the barrel.  When the large washer is pressed on the nut (as it is supposed to) it is able to absorb heat through the nut as well as it’s contacts to the barrel.  The thin surface area contact between interior hole in the large washer and the barrel probably doesn’t allow for much heat to be transferred to the large washer.
  4. I’ve read it mentioned that wrapping an extruder with nichrome is a two person or three handed job.  I’ve found it to be fairly easy with just my two hands.
    1. I use a small piece of kapton to tape the nichrome to the extruder head/nozzle oriented so that it is lined up parallel to the barrel. 1
    2. From the point where I can see the nozzle touch the barrel I leave about 2-3cm of nichrome hanging off the edge, with the rest of the nichrome pointed up towards the barrel.
    3. Then I wrap the nichrome up the barrel in a single layer keeping a tight contact with the threads until there’s about 2cm or so left.
    4. Then I tape down all of the nichrome on the barrel, except the last 2cm.
    5. I untape the part of the nichrome on the nozzle.
    6. As I was out of those little metal connectors provided by MakerBot, I had to improvise a little.
      1. I stripped the leads on the nichrome so that about 3mm was exposed and used needle nose pliers to put it into a hook shape.
      2. Then I stripped the leads to the insulated wires so that about 15mm was exposed, used my fingers to twist the leads, doubled it back along itself, twisted it again so that there was a little loop.
      3. I hooked the nichrome into the loops of braided copper leads and crimped it down using the needle nosed pliers.
      4. Solder and done.
    7. I then liberally applied kapton to wrap the barrel and nichrome so that it would be unlikely the wire or leads would ever have to bear any of the stress should I move the extruder around.
  5. With my last two extruder assemblies I’ve taken a slightly different approach to attaching the thermistor.  This method makes it easier to pull the thermistor out, but slightly more difficult to install it in the first place.  Here’s what I do:
    1. I laminate the thermistor between two layers of kapton tape just past where it meets the insulated wires.  Only the very tip of the thermistor is exposed.
    2. I wrap the barrel in nichrome as above, then ceramic tape, then wrap that in kapton – without the thermistor inside.
    3. Once the entire barrel is wrapped up just as I want it, I use a utility knife to make a vertical slice up the ceramic tape starting at the edge of the nozzle until I reach the point where the nozzle meets the barrel.
    4. I then peel back the ceramic tape and kapton, exposing a V shaped portion of the nozzle.
    5. I put the tip of the thermistor down into the V, replace the ceramic tape and kapton over it, and tape it down.
    6. I then re-wrap the barrel in kapton again.
    7. The first time I disassembled my extruder I screwed up my thermistor when unwrapping the barrel.  While this makes it more difficult to get the thermistor into the assembly, it also makes it so much easier to pull it out and reuse it.
  6. At the top left of the above photo you can see a small black box with green and white wires coming out of it.  That’s where I added an ethernet jack connector to the extruder assembly to make it easier to connect/disconnect the extruder.
    1. When I assembled my MakerBot I used insulated wire out of an ethernet cable.  Since I only needed a few sets of insulated wire, I ended up with one piece of ethernet cable that still had the ethernet jack on it with four wires sticking out.  I also had two ethernet ports left over from my opto-endstop kits.
    2. I plugged the ethernet jack into the ethernet port and tested the leads on the wires against the leads on the port.  Once isolated I soldered wires to the four leads that lead to the four wires from the jack.
    3. I then soldered the four wires from the ethernet jack to the thermistor and nichrome.
    4. I took the wires I soldered to the ethernet port and ran them through the hole on the right side of the MakerBot in the back on the top.  Then connected those leads to the appropriate ports on the extruder board.
    5. Once the wires were soldered up and extruder assembled I plugged the ethernet jack into the ethernet port and checked ReplicatorG to see if I could get a thermistor reading (yes) and heat the barrel (yes).

As I tinker and modify my MakerBot it seems I’m moving towards a system where I try to make the extruder assembly as modular as possible.  I didn’t have this as a conscious thought when I started, but that’s where these modifications have been headed.  While it is very convenient to have a totally modular extruder only connected to the robot by four bolts and an ethernet cable, that system is most useful if you are using drastically different print heads (such as a frostruder, Paxtruder, Bowden extruder, etc).

If you’re just swapping between PLA, ABS, or other plastic filament or color variations thereof, you can reuse the vast majority of the extruder assembly – the board, the motor, and the entire acrylic plastruder.  If you had a different heater assembly you could just undo the two screws that attach the heater to the extruder, disconnect the thermistor, disconnect the nichrome, and swap in a new set.  Although I don’t have a fully assembled second heater section yet, this set up makes a lot of sense to me just for ease of maintenance and repair.

  1. While I sing Christmas carols with my friends Meryl and Cheryl. [↩]

Things I learned while trying to unclog my extruder barrel

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I learned a lot this morning!  And now you don’t have to learn, as they say, the hard way.

  1. Never ever ever use tiles. I thought I was being very clever with the tile idea.  Apparently leftover kitchen tiles can shatter and fly apart when you heat them.  Who knew?
  2. Instead, use a big piece of metal to hold the barrel. I ended up using a piece of metal I had laying around to hold the extruder barrel and weight it down with a rock.  This worked perfectly.
  3. Don’t tilt your blow torch too much. Probably an elementary thing for most people.  My torch kept going out when I tilted it too far – probably a safety feature.  This meant I had to change the set up so that the barrel was somewhat elevated so I could keep the torch mostly vertical.
  4. Keep a friend handy. This was one of my few ideas/preconceptions that actually worked out.  Thankfully I didn’t need him to use the fire extinguisher or garden hose, but I very well could have.
  5. Don’t leave a nut on the extruder barrel. At the last minute I decided to screw a nut part way on the barrel.  I figured I could prop the extruder barrel up in the washer, heat it, and not discolor the nut or washer.  This didn’t work out because I needed to apply more heat to the barrel to get the clog out.

MakerBot extruder clog experiment

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DO NOT USE THIS extruder unclogger setup

DO NOT USE THIS extruder unclogger setup

UPDATE: DO NOT USE TILES!!!  THEY WILL SHATTER!  READ LATEST POST!

The bad news is this is my first clogged extruder.  The good news is I have all the spare parts to whip up a new extruder, no problem.  That means I can experiment with wild abandon!  My backup plan is to slice and dice the PTFE insulator into washers.

Having drilled out most of the plastic clog from the barrel, it’s mostly empty.  The PTFE is in pretty good shape with the threads intact, if a little worse for wear.  My plan to get the remaining plastic out of the nozzle is to put the nozzle/barrel assembly into the large washer upside down and prop it up on some ceramic tiles.

My hope is that by applying a heat source to the nozzle the plastic will just drip/fall out.  The suggestion for using a blow torch to clear out the barrel and nozzle comes from Rick Pollack / MakerGear.  Thanks again Rick!

By the way, wicked Google Sketchup skillz, no?

How to diagnose and fix a burned out thermistor

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Unfortunately, Bender just stopped working.  As I was keeping the nozzle warm while I was working on a new model, I looked up to see a flash of fire/spark shoot out from the nozzle area, ricochet off the build platform, and disappear.  Looking at the RepG control panel I discovered that I wasn’t getting any readings from the thermistor.  Not good.

The RepG control panel showed 0.0 as the temperature, so I shut the plastruder down, not wanting the heater to burn out of control.  I restarted Bender and RepG – but I discovered that while I could control all three axes very slugishly, I could not move the extruder motor or detect temperature.  I’m guess I couldn’t have increased the temperature either, but I didn’t want to try it since I couldn’t monitor the temperature.  That about covers the symptoms.

In order to diagnose the problem I tried to isolate the various parts.  I pulled all of the wires out of the extruder board.  Then, while the wires were still out I tested the nichrome for resistance – still around 6ohms.  Then I tested the thermistor – no connectivity.  Again, not good.  I tested the  motor for continuity, and it was fine.  Since the nichrome and motor seemed fine, that left the thermistor and extruder board.  I popped a random resistor into the thermistor ports, but still couldn’t get a reading on it.  Unfortunately, after several resets of the motherboard and extruder board, I still couldn’t get the motor to move or a reading from the thermistor.  Also, I was getting an error message that the Payload was not big enough.

Rick Pollack of MakerGear suggested on the MakerBot Operators group that I reflash the extruder firmware.  After several failed attempts, I finally figured out how to flash my extruder firmware from the Arduino environment by holding down the extruder reset button.  This got rid of the payload error message as well as the avrdude errors and let me reflash the extruder.

I pulled the entire extruder apart and did a little maintenance.  I flossed the extruder pulley teeth, pulled all the stray bits of plastic out of the idler pulley wheel area, removed the old thermistor, unwrapped the nichrome (which was wound down and then doubled over itself as the original pictures in the wiki suggested) and rewrapped the nichrome (a single layer from the nozzle up the barrel following closely in the threads to make good contact everywhere) as suggested by several people in the MakerBot operators group.  I then tested the nichrome again once it had been taped down for the proper resistance, check.

Once I pulled the thermistor out of the heater assembly, I tested the thermistor at its own leads, rather than at the wires soldered to it (in case the thermistor had come apart from the wires).  Still nothing.  I plugged a random resistor into the thermistor ports and was now able to get a reading off the extruder (as well as move the extruder motor). Concluding my problem was the thermistor, I forged ahead with a plan to replace it.

Luckily, I had placed an order for some PLA and nearly every single part needed for a secondary extruder (or what would be needed to fix a broken extruder) including a new thermistor.  If you haven’t picked up backup parts, I highly recommend it.

I clipped the old thermistor off the wires, pulled out the new thermistor and taped it to a white piece of paper immediately, putting the tape across the leads just below the bead.  I then bent the leads upwards, tinned them, soldered them to the wires, taped down the wires, pulled up the original piece of tape, and then sandwiched the thermistor in tape as per the instructions.  I then plugged the heater, the motor, and the thermistor back into the extruder board – and was able to get a temperature reading, apply a little heat to the barrel, and move the extruder motor.  I also noticed that this removed the sluggishness from the 3 axes stepper motors.

With the heater, motor, and thermistor working separately I put everything back together and reassembled the plastruder, plugged it back into the board and tested it again – readings, heat, and extruder motor working.  I then popped it back into the dinos, did a test extrusion, and starting printing again.

“Rock on completely with some brand new components”

Christmas robot shopping

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I went to the hardware store after work today to pick up the items on my shopping list.  Walking to their register I fell victim to their bargain basement aisle.  In the process I dropped the $3 superglue I had found and picked up four times as much for $2.  Sure, its a no-name house brand…  but as long as its reasonably sticky there shouldn’t be any problems.

I also picked up some 3-in-1 oil for the various rods.  I installed the Z-axis rods without cleaning them properly (too enthusiastic to get building).  I also bought a large flexible magnet in sheet form (the kind used for fridge magnets – only in an 8.5″ x 11″ size), work gloves, and another utility knife.

Adding the circuit boards

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Once I had the opto-endstops all soldered up, I really wanted to keep going.  I made the Y-endstop cables, bolted the opto-endstops on, and bolted the motherboard and stepper motor boards to the MakerBot.  Clipped in the cables and it looks like a robot after all!  I’m going to need to organize those cables, but that will have to wait until all the other parts are in place.

An interesting side note – as I was moving the various axes someone noticed that little lights started flashing on the stepper motor boards!  Cool!  I presume moving the platform caused the motors to act like generators and pushing power to the boards, lighting up the LED’s.

Once the opto-endstops were done, I couldn’t resist bolting them on.  Once I started doing that, I wanted to make the Y-endstop cables, then the ribbon cables, and wire it all up.

If nothing else, it looks like a robot now!