Just Another RepRap

Well, it’s been three and a half weeks since my last real description of any progress. In that two-posts-ago post I’d described the “crisis” of potentially losing the Makerbot before I was done printing pieces. As the circumstances of my last post pointed out to me rather harshly, that doesn’t really qualify as a crisis. Still, that issue was averted, as I was able to bring the Makerbot into work for the 3D printing class, then get it back out of the building.

Since that time, I’ve gone from having 20 pieces left to having 6 pieces left, but once again I’ve run out of time, as we received the expected request to return the Makerbot. I feel bad because it’s been in my possession almost 100% of the time, and Chris barely was able to use it (though he assures me he feels bad because he was able to enjoy actually having free time over the past few months while I did all of the hard learning for us, but I don’t know if I believe him. 🙂 ). Being completely frustrated with constant extruder stall failures, I called Chris on Saturday and asked if he wanted to take the Makerbot for the few days that we have left, which he did.

Our hope had been to finish the parts for my Mendel, start printing parts for his Mendel with the Makerbot, then when my Mendel was assembled print half of his Mendel pieces with my Mendel to halve the print time. Instead it looks like we’ll be printing his entirely with my Mendel, once we find a way to get that done. As I said, we’re 6 pieces down (we still need the y-motor-bracket, z-motor-bracket, two z-leadscrew-base pieces, and two belt-split-jig-bracket-universal pieces). Maybe Chris will figure out something I’m missing on how to reduce friction enough to keep the extruder motor from stalling and he can actually print them out, but he’s dealing with the same machine I was, so I’m keeping my hopes in check.

Anyway, let me document more of the success I’d actually had during that time. As usual, pictures and video…

When I had twenty parts left, I tried printing one of the z-leadscrew-base parts out of PLA, but it failed. Here I was, 18 minutes into the destined-to-fail print:

..and here is a description of the failure:

So here let me take a second and describe what I’ve now learned about how to somewhat recover from a stalled extruder motor (at least temporarily). If you’re printing and the extruder motor stalls (meaning you’ve probably got some sort of jam beneath the extruder in the heater barrel or insulator), and you know it was supposed to be printing rather than just traveling (because the head is moving slower, or you’re on the perimeter where it’s supposed to be printing, etc), press the pause (||) button in replicatorg (DURING A TIME WHEN IT WAS SUPPOSED TO BE EXTRUDING, NOT JUST TRAVELING). I used to think the pause button was almost useless because it kept the extruder motor on, so you’d end up with some huge blob of plastic ruining your piece. However, in this case it works to your advantage. Now that the bed is paused, you can grab some pliers, grip the filament as hard as you can, and push it hard into the extruder (I used to attempt to do this while the bed was moving, which sometimes worked but more than often would push the nozzle into the piece itself, causing it to catch, miss steps, become misaligned, etc). If you push hard enough, eventually you’ll hear the stepper motor “catch”, as you added just enough pressure to move the motor past the threshold where it couldn’t push any more, and the motor will start up again. Plastic will start extruding, and you can click the pause button again to resume printing. Unfortunately this is a temporary fix, since whatever caused the jam is still probably there and it’ll jam up again soon. This can help though if you just spent 1 hour and 45 minutes of a 2 hour build watching it print fine, just to see it almost fail at the end.

Ok. So here’s a piece that printed extremely well – y-bearing-180-inner_2off:

By the way, every time I see that piece I think of this building in Boston:

I was about to bring the Makerbot in for the 3D printing class I mentioned two posts ago, and wanted to do a few ABS prints to remind myself what it was like (I’d been printing with PLA for so long that I’d forgotten what it was like). While PLA is excellent and wins in many categories, ABS does have its advantages too – one of which being that it extrudes in a closer-to-solid state that seems to allow you to print insanely fast with it. (However, don’t take my account as a source of any real information on this! I wouldn’t be surprised if some people have PLA printing super fast on their RepRaps, perhaps with modified extruders (or even the regular Mendel extruder).. or maybe speed doesn’t even enter into it).

Here is video of me printing the x-360-z-bearing-plate_2off piece in ABS, which I’d also attempted in PLA but I’m going with the ABS piece:

So I packed up the Makerbot (weeks ago), and brought it into work for the 3D printing class that I’d actually been looking forward to since around October. The talk was by Dr. Zoz Brooks, who you can see on the TV show “Prototype This!” on the Discovery channel. It was a great talk, and after in the hands on section we saw all of the hardware at work and I was able to show the Makerbot to everyone (along with all of the parts I’ve made for Mendel so far).

As I said above, I was able to take the Makerbot back home after that. Then Laurie threw me a surprise party for my 40th birthday. Two of the RepRap-related gifts that I got are visible in this picture: the PLA in the front from Cheryl, and the Terminator bobblehead on top from ChrisR. Chris’s public statement with the joke was something along the lines of “So Jeff talks to everyone about the RepRap, but he sometimes leaves out the best part of the whole thing – it’s a self replicating robot. The inevitable conclusion, of course, is that this will eventually lead to Skynet and the destruction of mankind. So this is to keep him honest and remind him of what he’s making.” 🙂 (I disagree that I’ve ever left that part out, but why ruin a good joke).

Part creation continued.. Making two x-360-z-bearing-plate-mirror_2off pieces at once:

I made a much better z-axis-opto-spring than I had a month or so ago:

Comparing the two versions I made of the z-axis-opto-spring:

Again, as I said before, the default Makerbot ABS settings I’d grabbed from somewhere have the motors move extremely fast (maybe I’d slowed things down for PLA – I don’t remember). Here’s video of extremely fast printing of the y-bearing-360-outer-left_1off piece:

Here is a piece that might be unnecessary but I printed anyway, bed_height_spacer_31m:

And here’s another piece that might be unnecessary, but it was easy enough to print – x-cable-clamp_1off:

That’s it for successful parts. 🙁

Here’s video showing how incredibly beneficial it is to mount the extruder controller board above the plastruder, so you can see the idler wheel actually turn:

Here was a failed attempt to print a z-motor-bracket_1off out of ABS:

I’d gone through enough motor stalls that I was curious about what exactly the geared DC motor looked like inside, and before returning the Makerbot I figured it was worth taking a look. For anyone who’s interested, here’s what the inside of the motor looks like so you don’t have to open your own:

When taking the bearing off the shaft of the gearmotor, I realized that one side of the gear had actually broken off. In case it was adding resistance to the turning of the motor, I left it off.

Last two things.. First, the M6 nut on the heater barrel allows failure cases like this to live longer and remain undetected – here’s the heater barrel completely covered by plastic:

And finally, here’s the plastruder rebuilt by me (possibly for the last time, assuming I’m able to move onto my Mendel by somehow getting the last six parts I need):

The next thing I’ll do when I have free time is assemble more of the pieces I have (I should be able to complete the X axis, at the very least).

Six parts. So close, and yet so far.

This entry was posted on Monday, February 15th, 2010 at 8:13 pm and is filed under MyRepRap. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.