Tag Archives: maintenance

The Delrin Plunger

Fresh off my success clearing the left nozzle on my Replicator, the right nozzle stopped working.

So I cleaned it out with the aforementioned acetone and drilling process, and still no go. So the next thing to try is adjusting the fabled Delrin Plunger.

It sounds like Elvish plumbing equipment, but it’s just a little piece of plastic that lives inside the Replicator’s Stepstruder Mk. 8. The plunger’s job is to maintain pressure on the filament so that the stepper can feed it into the heated nozzle.

Over time the filament will wear a groove in the plunger’s head, which reduces contact between the plunger and the filament, which in turn makes it had for the drive wheel to push the filament through the nozzle.

This is what a plunger looks like after about eight months of more-or-less daily use. The blue arrow points to the wear on the head.

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If filament isn’t emerging from your nozzle, or it’s coming out really slowly, rotating your plunger may help.

With a couple of hex wrenches this is a ten-minute job. Be aware that the plunger is inside a two-piece plastic case held on to the stepper by two bolts.

This is a right extruder, so the plunger goes on the left side, pointing away from the Replicator’s midline.

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And then here it is with the second piece of the case attached. Note that I’ve rotated the plunger 90┬░ so the filament has maximum contact with the plunger’s head.

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When you disassemble this case be careful that the plunger and washers don’t go flying. The washers you could probably replace, but I have no idea where to get a new plunger. MakerBot’s fresh out of them.

Cleaning a Clogged Replicator Nozzle

Last week I came down with what must have been the flu, and all my creativity and motivation ebbed away like so much mucus.

So I haven’t updated the blog in a while. Thingiverse redesigned its website, which broke my /dev/random scraper script, and I’ve been so busy digging out from under a pile of flu-delayed work I haven’t had the opportunity to repair it yet.

I did manage to restore my dualstrusion Replicator to full operating condition, though. Here’s what it looks like when your nozzle gets clogged.

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A little bit of filament will still emerge from the nozzle, but it’s anemic and thin and bunches up around the tip. You won’t get any prints out of this.

MakerBot’s replacement nozzles have been out of stock for as long as I’ve been looking for them (about six weeks), so it’s up to you to solve this problem yourself.

They do have some maintenance tips that will help you get the nozzle off.

I skipped the “unbolt the stepstruder” step. The nozzle unscrews easily with a wrench or pair of pliers, but be careful, that little guy is hot if you’re following the instructions.

Here’s what eight months of melted PLA/ABS gunk on the inside of a nozzle looks like, as the late, great, Toshiro Mifune intimidates the nozzle into functionality.

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(I have a Yojimbo poster in my office. I think I’ve seen every Kurosawa movie at least once.)

The instructions say to leave the nozzle in acetone overnight, but I think that’s overkill and, in the case of a really clogged nozzle, probably ineffective. A combination of acetone baths and physical goop removal got mine working again.

So first, an hour in acetone. Find a container that the acetone won’t dissolve. A shot glass will work. Do not drink the acetone.

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I tried a few little tools before I found one that really scraped the gunk out well. Needles and bits of wire didn’t do the job, but this small drill bit did. I just stuck the bit in and twisted back and forth; no electricity involved.

Then back in the acetone bath for an hour, and then the drill bit again. Lather, rinse repeat two or three times.

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Replace the nozzle, load your filament, and before you can say Bob’s your uncle, you’re back in show-booty-bidness. I didn’t even have to recalibrate the build platform.

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I’m working on a couple of dualstrusion models now. Watch this space.