Justin Dunham

It’s been a busy couple of months on this project, and I have lots more to say, but here’s a quick summary of what ended up happening with the bot:

Where I last left off, I had physically assembled the Makerbot as well as the extruder. I ended up trying it the next day…

And it just didn’t work. I tried lots of different experiments – different software on my computer and the various hardware boards on the bot, disassembling things and reassembling them, testing circuits, etc. etc. Nothing. The platform moved, but I couldn’t communicate with the machine via my computer.

One thing that quickly became apparent was that the extruder board (which controls the part that actually melts the plastic) was defective or otherwise busted. This was sort of a shame, but I was eventually able to get a replacement board from the sellers, Makerbot (more on that later).

I ended up shipping it back to myself in Philadelphia to keep working on it. Right away, I replaced my defective extruder board with the new one. Should work, right? Well… sort of. The extruder wouldn’t extrude for more than a minute or so, if that. When it did, it was globby and slow. The build platform would also skip steps, meaning that it would not move as far as it should one at least one of the axes as it was building.

(What does this mean? Since the motor has no idea whether it was successful in moving the platform, this meant that you’d get something built a little bit, and then the next step up would be shifted a little bit – imagine if you were constructing a building, and the second floor started ten feet over to the right of the first, you’d have an overhang, the building wouldn’t look right, or be stable, etc.)

Fortunately, I’m a member of Hive76, which is a local Philly community of makers and 3D printer people. Several people there spent literally hours with me troubleshooting these problems. Here’s what we found:

• I made a mistake in putting the extruder together – the toothed wheel that grips the filament as it comes into the extruder wasn’t put on tightly enough, so it was slipping. The rod that Makerbot ships (shipped) with each machine to help you get this distance right is actually not helpful for fixing this problem! It just needs to be quite close, so it gets a strong grip on the filament.
• Applying lubricant to all of the axes – particularly the z-axis – basically fixed the skipping problems.
• As for simply getting the machine connected to my laptop so I could control it – the key was to keep trying different versions of the extruder firmware and motherboard firmware. I wonder if the fluorescent lights in my fiancee’s Dad’s workshop also may have caused some interference with the electronics.

And that was pretty much it… Oh, except for the very, very long process of calibrating the machine. There are dozens and dozens of settings with completely inscrutable names (“feed rate” controls the movement of the build platform, the setting for the ratio of filament length to width is on the “Carve” menu, etc.). This took me another few weeks of detailed work to get right.

So I got the bot working pretty well, as you can see in the video. The bot is printing a small plastic part that can be used to build another, different, 3D printer. The printer isn’t at all perfect, but it’s also not bad for this level of technology and for my level of skill. I’ve also been thinking a lot about whether it’s possible to build a more reliable kit, and how this could be done, and working on that. I’ll probably have some more posts about that later.

Soldering.

A properly soldered joint.

Everything's completed... technically. Extruder is on the right.

Alright, today I thought I was going to be able to finish this whole project off, but I didn’t quite get there. Got close, though.

The first thing I had to do was finish building the extruder, which took quite a while. I had a fair amount more soldering to do, including hooking up the thermistor, which measures temperature and allows the information to be transmitted electronically.

I ran into lots of problems today, including wires breaking (and therefore needing to be re-stripped and re-soldered), tight fits, and various other random issues. At one point, I needed to use a small steel rod to determine the appropriate spacing between two components. But everything seemed to come together in the end. Until I started hooking the Makerbot up to my computer to start doing some calibration and testing of the extruder.

Makerbot has great software called ReplicatorG that helps you interact with your Makerbot. Specifically, you can send it things to print, and you can also manually move the build platform around and do other things as well. Unfortunately, when I went to use ReplicatorG, I was unable to get it to communicate with my extruder. Therefore, no printing. I took a pretty careful look around some help forums, and while I found some good ideas that I will try tomorrow, I’m not optimistic about getting this to work soon.

The good news, however, is that everything else seems to work well – the platforms move just as they should, which proves that that’s all built correctly. More as it develops on the extruder issue.

The setup for building the extruder.

The multimeter. The dial on the top measures current flow, the knob allows adjusting the range that the dial shows. The red and black leads connect to an electrical source.

• Note 1: This entry is the fourth in a series.
• Note 2: I am looking for likeminded people who want to work together on building some kind of desktop fabricator business. If you read this and agree with what I have to say, will you drop me a note? For more about me, check out my LinkedIn profile.

When I left off yesterday, I was about to start building the extruder for my Makerbot. The extruder is the part that heats up, and then lays down, the plastic used as printing material – it’s the 3D printer equivalent of a printer head.

Building the extruder, for an electronics novice like me, is intimidating. This would be first time I’ve ever really soldered, used a multimeter, etc. (A multimeter, by the way, is a device that allows you to measure how much electricity is flowing across a circuit.)

The first step was actually to go shopping! I needed a bunch of stuff that wasn’t included in the kit, such as the multimeter, wire strippers and cutters, and some other odds and ends. I also thought I would need kapton tape, which is a special type of insulating tape that turned out to be included in the kit. Thank goodness for that, since it wasn’t available at any of several electronics stores I tried in Portland. Neither was a certain type of wire that’s called for, which also turned out to be included in the kit… I think.

These slight oversights bring me to one thing that bothered me generally about this part of the build process: it’s a level up in difficulty from the rest of the build, and the instructions provide lower quality, and often less, guidance than before. I think this is one thing that will definitely need to be addressed if the Makerbot is to have wider appeal (or perhaps, as I said yesterday, the extruder should just be pre-built for you). As an example, to quote from the instructions:

The nichrome wire should have a resistance of approximately 6 Ohm. Usually this amounts to about 300 mm of wire, but use a multimeter to be on the safe side. Cut the nichrome wire to a length which amounts to about 6 Ohm of resistance (+/- 1 Ohm).
NOTE: It’s difficult to measure the resistance of the nichrome until you strip the ends, so cut it long, then trim it down until you reach 6 Ohms.
NOTE: Make the wire too long, and your heater takes longer to heat up. Make it too short, and you burn out the MOSFET on the extruder board.

So, what does this mean? You have to cut a certain type of wire to a certain length. In order to get the right length, you have to measure the resistance with a multimeter. If you haven’t used a multimeter before, you have to learn how to do so. And then if you get it wrong, you may end up destroying a critical component of the machine when you start to use it.

Fortunately, learning to use a multimeter isn’t that hard, and I was able to figure it out. So what am I complaining about? I guess I don’t really mean to complain – this kit is clearly targeted at hobbyists, and as I’ve said many times, it’s an ingenious machine and up to now extremely thoughtfully documented. But I think it would be a good idea to simplify build process steps such as this one, and that will be necessary to broaden the appeal of these fabs beyond hobbyists.

There are some other really touchy steps, too – for example, when building the idler wheel, you have to put a circular bearing within a larger plastic ring. But the bearing must be glued to the outer wheel at a very precise depth – i.e. it shouldn’t be flush with either the top or the bottom of the wheel. Moreover, it has to be superglued in place, so, no second chances. Lastly, there is some kind of problem with the instructions here, where someone has inserted a note to update the instructions, without actually doing this. I had to tread carefully, and I’m not 100% sure that I did it right.

A soldered (and then taped) wire connection.

Things like this aside, construction actually went pretty well. I did my first real soldering – hooray! – and you can see the results of that in the pictures accompanying this post. Tomorrow, I’ll try to get a picture of me actually performing the soldering operation, so anyone unfamiliar can see what that actually looks like. This was a pretty forgiving situation, but I was happy that that went well, and I was able to confirm that everything was OK, using the multimeter (which is a very cool tool).

I also built the supports for the extruder, which are called “Weird Dinosaur” and “Big Dinosaur” on account of their shapes. I’m not sure if this is helpful nomenclature or not…

Tomorrow I am hoping to complete the build of the Makerbot, though there’s a lot to do between now and then.

Parts for the Z Stage Assembly.

The completed X and Y Stage Assemblies, together with parts to install them in the body

Mechanically complete Makerbot!

For tomorrow...

Today I tackled 3 separate stages of the Makerbot build sequence: The Z Stage Assembly, the XY Stage Installation, and the Z Stage Installation. The end result is an (almost)  mechanically complete desktop fabricator.

First, let me explain briefly what each of these stages means. The Z Stage is the part of the machine that controls the movement of the extruder up and down. So today I basically built and then installed the parts of the machine that enable that to happen. The X and Y Stages are the parts of the machine that allow moving the extruder (actually the build platform) left and right and back and forth. I built these parts yesterday, and installed them today.

The way that the Makerbot extruder moves up and down is actually pretty ingenious. (Much of the machine is, but this was a particularly interesting piece). Basically, there is a platform on which the extruder will sit. The goal is to get it to move up and down, for reasons similar to the reasons why you lift a pen from the paper when you’re done writing.

The way you do this with a Makerbot, is that a very long bolt runs through each corner of the platform. Bearings and nuts are put onto the bolts also, in such a way that you essentially move the platform by screwing and unscrewing the bolt. So think of the way the head of a screw goes down when you drill it into wood. The Z-stage motion of the Makerbot takes advantage of this principle, with the result that you end up with an easy-to-build and elegant mechanism for this motion.

Anyway, other than that finishing up the mechanics of the Makerbot pretty uneventful – a lot of the same old nuts and bolts (literally) that I’ve been doing for the past two days. One minor problem was that the tolerance between the pulleys and the shafts of the motors is way too tight, which means that you have to do a fair amount of sanding to get everything to fit together. The worst part about this is when you put one of the pulleys on a driveshaft to test the fit, and then it won’t go into position, but you can’t remove it anymore, either.

However, we then move on to hooking up the electronics and software. This is an area where I had significantly more trouble, and I was actually surprised at how much the quality of the documentation seemed to rather suddenly deteriorate. “Now you’ll just need to hook up the electronics and Plastruder”, indeed!

My major issue was with the instructions for assembling ribbon cables. Makerbot doesn’t provide any of their own, though they do point you to the instructions that come along with the RepRap, which is the design on which the Makerbot is based. The main problem is that these are somewhat difficult to follow – it was hard to get a good sense from the pictures of what goes where, how everything should be aligned, and how much force should be used.

The most annoying part about this was that preassembled ribbon cables aren’t that expensive – does it really make sense to build these from scratch? (This must be a fundamental decision that has to be made with all the parts Makerbot provides, and it’s one I recognize from lots of other projects – build or buy, or this case, supply parts or supply part?). Anyway, it seemed like there wasn’t as much support on this step for people who don’t already know their way around this stuff.

After hooking that up, I went on to check out the instructions for building the plastic extruder. For some reason, I thought these would be relatively easy to complete. They… are not. I think it will go OK, but this is the first time I’ve felt somewhat intimidated by this project.

The kit for X Stage Assembly

Completed X Stage Assembly. The build platform will slide along those rods.

The kit for body assembly.

Completed body!

Today I completed two more steps in the building of my desktop fabricator – the building of the X Stage Assembly, which will allow the build platform to move along the X axis, and the building of the Makerbot body.

This was a pretty major couple of build steps; I’d say I’m about halfway done now. Overall, the build was successful, but I ran into a couple of problems. The first was that I managed to put in the aluminum drive pulley in upside-down. The aluminum drive pulley will pull the belt that allows the Makerbot build platform to move along the x-axis – so, it allows movement from left to right. I’m not sure exactly how this happened, but I think I was confused by the instruction to put the pulley onto the motor shaft “set screw end first”.

This was definitely my mistake, but I guess I thought that meant “set screw end up“, and for some reason I ignored the picture. I only managed to fix this when my fiancee’s dad pointed it out to me – otherwise I would happily have allowed the belt to sit slanted, which would have happened because it wouldn’t have been vertically aligned with the idler pulley on the other end of the belt.

The idler pulley was my second mistake, and I don’t just mean the vertical alignment. Instead, it was simply mounted in a wobbly fashion. The reason for this is as follows: the instructions say to “set aside the small idler pulley”, but it wasn’t until I tried explaining this to someone else that I realize there were actually different pulley sizes. As a result, I spent a fair amount of time using a pulley that was unstable because it was far too big for the screw that was anchoring it.

Finally, it also turns out that during yesterday’s build, I had actually used the wrong drive belt for a certain task. The instructions specify e.g. “the 196-tooth belt”; I just guessed at which belt was which, as I didn’t realize the tooth numbers are actually printed on the sides. I realized this when today’s instructions called for the “second-shortest drive belt” (the one I had used), so I was able to fix the error. I wish the previous day’s instructions had been as specific!

I ran into a few manufacturing defects as well. As usual, some of the parts don’t fit together perfectly as they aren’t machined exactly enough; this is totally understandable. Also, one of the bolts, which happens to occupy a critical position, is a little bit too long. This means that the Makerbot is unable to move the build platform in a particular direction. I had to go through a fairly long process of trial and error to figure out how to shorten this bolt with the equipment on hand (I ended up using a hacksaw to shave off the extra length). I was slightly surprised at this oversight, though it is explicitly mentioned in the instructions.

Other than that, the build was pretty uneventful. I built the body as well, which basically meant a long process of tediously bolting together the sides, back and front.

This is the sort of thing I would pay money to have done for me – it takes about an hour to get all 60-odd bolts and nuts in the right place, but there is no real thinking involved. I also thought it might be interesting to paint and otherwise decorate Makerbots. Since most of the structural pieces are just wood, this would be pretty easy, and the instructions even explicitly mention that you should do any decorating before you do the assembly. Anyway, at the end of the day I had a complete Makerbot body.

In the course of the built, I was also asked the very interesting question of what the “killer app” is for the Makerbot. That is, what is the application that results in millions of people buying a desktop fabricator and putting it in their homes, the way they bought the telephone, dishwasher, refrigerator, television, etc. – all the standard equipment that had to be introduced and marketed at some point in the past.

I answered that I don’t know. Right now, the Makerbot is really targeted at hobbyists and other people who are curious about the technology. It’s not yet particularly usable “for” anything. As far as what it could be sold as today, I think it’s mainly useful for artists who want to incorporate printed objects into their work, whether that’s individual sculptures, or mass-market pieces as might have been created with Bakelite ninety years ago. There are some other random applications as well, such as certain technical tasks in e.g. jewelry making. But no killer app yet, until the technology can be dramatically improved.

The next key step is to figure out a way to generate cash flow so that more can be invested into R&D on desktop fabricators – specifically, improving their ease of use and capabilities. This will require lots of market research, and identifying at least the interim “killer app” for certain niche markets.