Tag Archives: extruder

Hareware isn’t everything

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With Charles Pax’s recent proof-of-concept of a motorized conveyor belt print platform, we’re going to need some software/firmware changes to make full use of these improvements:

  1. Queuing print tasks
  2. Removal/auto-wiping of the test extrusion
  3. Moving the print platform to the front/back/side of the MakerBot for ejecting the finished print
  4. Ejecting the printed part
  5. Returning the platform to 0,0,0 / center

From the video posted on Charles’ site, it looks like he’s managed #3 and #4 already.  The extrusion path around the print that we see in Nophead’s prints probably would work at #2.  I also seem to recall some (such as Zaggo?) have mounted a toothbrush head on the build platform for auto-wiping of the extruder head.

Returning the platform to 0,0,0 is an interesting proposition.  This would seem to work best once the opto-endstops are installed.  I’ve got my set of six fully assembled opto-endstops sitting in a box next to my MakerBot because I haven’t really needed them and they tend to get in the way of printing.  Although the opto-endstops have been removed from the standard MakerBot kits, I think we may now start to see them returning.

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.  :)

A totally imaginary interview

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It’s been an interesting year for RepRap/MakerBot.  We’ve seen demand for parts and electronics increase.  The MakerBot crew reported that for certain components they’ve actually cleaned out every source in the world.  I’m not sure which component they’re referring to, but I suspect it’s the toothed extruder pulley.  I love the idea that MakerBot has created a product garnering such high demand the entire freaking planet ran out of parts.

Can you imagine giving an interview after such an announcement?

  • Reporter: Guys, this has been a great year for MakerBot.  What are your plans for next quarter?
  • MBI: Gosh, we’ve got so many ideas!  The community has been hugely supportive and their rate of contribution and development has helped us so much.  Right now we’re splitting our time between production and development.  Batch 12, consisting of  about 147 robots, is out the door.  Batch 13 has already started to ship as the parts come in.  We’ve come a long way since the 22 robots of Batch 1.
  • Reporter: Fantastic!  What are your plans for Batch 14?
  • MBI: Dang, we were hoping you wouldn’t ask that.  Zero.
  • Reporter: I’m sorry – zero robots?  Why did demand drop off so suddenly?
  • MBI: Quite the opposite – we’ve completely exhausted the entire world’s supply of aluminum toothed pulleys.  We’re hoping to have some custom made, but at this point we’re competing with the Japanese for aluminum.  Some people suggested we start melting down soda cans for the metal.
  • Reporter: <incredulous> You’re competing with the Japanese?
  • MBI: Not every Japanese person, but the automotive industry, sure.  For a while India looked to be a competitor, but with the strength of the rupee I’m just not expecting that much competition.  We’re far more concerned about the ability of Chinese to scale their production to meet demand.  Fortunately, we think we’ve found a toner cartridge factory willing to switch over to aluminum toothed pulleys.
  • Reporter: <even more incredulous> Wait, wait, wait…  You’re concerned about the ability of an economy of one billion people to scale production to meet the needs of a DIY robot kit start up???
  • MBI: Concerned is a strong word.  The Chinese ambassador has been leaving us messages about this issue.  When we finally got around to returning his calls he assured us they’re up to the task.  I’d say we’re cautiously optimistic.

Backing out the filament

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I’ve found that backing out the filament after each print, while a pain, has been helpful in avoiding extruder jams.  Or, rather, I have found fewer extruder jams while doing this. 1

I suspect the reason this has helped is that it removes from the PTFE insulator any of the remaining plastic that might have been about to ooze near the barrel top.  Have you found that this helps you?

  1. Not to confuse coincidence, correlation and causation, but I have also found fewer extruder jams when wearing my underwear inside out… [↩]

Have we reached the bottom already?

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Having reached the bottom of a market can actually be a very good thing.  It means anyone who wants a set of RepRap parts can have them for as little as the market will bear.  Right now there are lots of options for someone who wants to get involved in building a RepRap/RepStrap.  You can get a MakerBot, RapMan, ShaperCube, Profound Devices, Isaac Mendel, or pick up a large selection of parts on eBay.

As an owner of a MakerBot, I’m far more likely to want to print up my own RepRap parts than buy them.  However, each of Spacexula‘s Mendel print sets would probably take me 2-3 hours of print time plus about 15 minutes of human intervention/monitoring.1  I would of course also print up parts for any friends/family who wanted parts. 2  I’d be willing to do this to create my own Mendel, but the idea of spending three weeks3 , say $30 in plastic4 , and about six broken up over that three weeks fiddling with stuff5 makes me wonder if there’s a better way to make $300.00.

Setting that aside, I wonder where the bottom of the RepRap parts market is heading?  Spacexula has suggested around $250 or so based upon the price for lasercut parts.  I suspect the price of printed parts will always be higher than the price for lasercut or molded parts – because of the time involved.  Lasercut parts can be cranked out as quickly  as a lasercan cut. 6  Molded parts can be churned out as quickly as the poured material can be dried.  Plus, no matter how nice lasercut/molded parts are – you still have a RepStrap, not a true RepRap.  Assuming identical quality, I’m probably always going to be more interested in printed parts over alternatives.

  1. Such as setting up, warming up, untangling plastic, checking, peeling off, etc. [↩]
  2. At this point, this is purely theoretical/hypothetical since none of my family/friends are interested in their own RepRap.  Hmm…  Maybe I should talk about RepRap MORE??? [↩]
  3. A little over one sheet a day [↩]
  4. I haven’t weighed a sheet of Mendel parts, so this is pure conjecture. [↩]
  5. Assuming no extruder clogs, blocks, PTFE bulging, oozing down the threads, and problem free printing… [↩]
  6. How many phasers could a laser slice if a laser could slice phasers? [↩]

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. [↩]

PTFE versus PEEK thermal insulating barrier

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How do you choose whether to use a PEEK or PTFE barrier?  Well, I asked the benefits of using PEEK over PTFE thermal insulating barriers in an extruder assembly and Nate True gave a fantastic summary:

PEEK is more rigid and won’t bow out and leak everywhere with ABS. It would be better for PLA except that PLA likes to stick to everything. So PTFE (being not sticky) is preferable for PLA. ABS is very slippery by comparison so PEEK is more than adequate for it.

…BBQ

I’m still rockin’ my black ABS coil, so I’ll probably have to add a PEEK barrier to my MakerBot wish list.1

ttp://cre.ations.net/blog
  1. The bit about BBQ is a joke about the over-use of acronyms. [↩]

Well, there’s your problem

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I’ve been fiddling with settings on my MakerBot for the last week or so trying to improve print quality.  Skeinforge setting this, Skeinforge setting that.  Up, down, left, right, set it to pi, increase the print temperature, decrease the raft radius, adjust the feedrate speed.  Unfortunately, all I managed to do was decrease print quality.  Over the last two days I noticed the filament was coming out fairly slowly and today I noticed I kept stripping the filament.

Well, it’s because ABS oozed down the barrel threads and around the nut.  Yay.  Time to break out the blow torch, eh?

In disassembling (mostly) the extruder I found:

  1. Plastic down the threads of the barrel
  2. Plastic that had oozed onto the nut below the barrier
  3. Plastic still stuck inside the barrel itself
  4. A plastic plug inside the PTFE barrier and a slight bulge to the barrier

Plastic on the threads is not a huge deal, but not trial either – it mostly peeled off in spirals.  Plastic on the nut is not a big deal – I pulled that off with some needle nose pliers.  Plastic inside the barrel can be drilled out using my drill bit and rubber band trick.1

Plastic inside the PTFE barrier…  well, now, that’s a different animal.  I’ve succeeded once in rescuing my PTFE barrier from PLA oozing down the threads, but in that case there wasn’t a plastic plug inside the PTFE.  The problem with a plastic plug inside the barrel is that I can’t really drill it out.  If I try to drill it out from the top, I’ll probably still leave a bit of plastic where the barrier meets the barrel.  If I try to drill from up from the bottom, I stand a good chance of ruining the part where the PTFE meets the barrel – creating a small gap where plastic can get stuck.

Thus, I think I will drill out the barrel and slap in a new PTFE barrier.  Since I have this old (ruined?) one lying around, I have sliced off about a 2mm wafer to use as a washer on my next heater assembly. Using a small hacksaw blade did the trick – even if it left me with a relatively uneven slice.

While I’ve been putting off buying additional parts for my MakerBot, I think it’s time to invest in some new bits.  I’m liking the MakerGear modular thermistor kit ($5), MakerGear modular heater core ($15), MakerBot heated build platform ($42), MakerBot SMT Soldering Toolkit ($50), and a hotplate.2

  1. Think of it as a poor man’s precision vise. [↩]
  2. Cue George Plimpton: “And a hotplate!” [↩]

Beco Block Connections

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I really like the connection mechanism behind the Beco Blocks. 1  It appears to allow a wide range of movement and rotation in the joint.  There’s a lot of applications that come to mind:

  • Beco Block Voltron. ‘Cause, you know, I really really want a printable Voltron.
  • Beco Block Leonardo Robot. ‘Cause my robot’s hips keep breaking! 2
  • Beco connector Z axis crank. There’s a crank for everything, why not a Beco Block?
  • Beco connected printruder. Why not just snap the extruder together and hold it in place with fewer bolts?  Or, if that’s too fragile, why not a printruder that snaps into the printed dinos?
  • Beco connector dalek hinges. All that is stopping my dalek from ruling the universe (and time!) is some freedom of movement.

In furtherance of these possibilities, I’ve taken the smallest male/female Beco Block and sliced it between the male/female connector parts.  My idea is to start grafting these connector parts into other designs.  I need to fix up the files a little – but when I get them usable I’ll post them up to Thingiverse.

  1. Having only printed one block, I suppose I can’t really speak about it intelligently.  Then again, ignorance has never really been an impediment to me talking/typing before… [↩]
  2. I’m not kidding.  It’s pretty sad.  First his left shoulder, then his right hand, then a hip, then both hips. [↩]