Thursday, December 13, 2012

Belts!

It's been a while, but I've been busy! This blog is starting to fall on the wayside... My printer is already up and running, and has been for a while. Hopefully that will mean that this is blog will get a steady stream of content for a while.

Anyways, belts. Belts belts belts. It doesn't really matter what kind you get, as long as they are "high quality". I recommend Ultimachine's GT2 timing belt, as it works well. I also sprung for machined pulleys. The plastic pulleys I got were a bit wonky, and I figured "Better safe than sorry".

Now onto why belts suck. Belts suck because they need to be tensioned. They need to be tensioned juuuust so. Too much tension, and your motors will skip steps. Too little tension and your motors will skip steps. Once you get the perfect amount of tension... It loosens up and your motors skip steps. I should count myself lucky, since constantly having to tighten belts is the biggest issue I have with my printer. After much pulling and swearing, I finally bit the bullet and installed this belt tensioner. Right now it's only on my X-axis, as the Y-axis seems much better about keeping its tension. This has solved all my problems. It's pretty nice! I'm looking to improve, though.

I want to have a tensioner much like the ones in modern 2D printers. The idler pulley is on a spring, and can slide further away from the motor if needed. It probably hasn't been done before because of patents, but who knows. That's not on the priority list, though. Right now the priority list is printing things.

More to come!

Tuesday, October 9, 2012

The hot end

This is just going to be a quick post on what hot end I used on my Prusa. I wasn't very good about keeping track of its progress, and didn't take a single picture during assembly, unfortunately. What follows is just some basic info about the hotend I chose, and what I would do differently next time.

I used the MakerGear Hot End Kit for 3mm filament from UltiMachine.com. I chose to have the nichrome pre-wrapped and covered for a bit extra because it was my first hot end, and I wasn't very confident in my ability to construct it well. The hot end arrived, and the pre-cover of the ceramic was absolutely beautiful.

The instructions on MakerGear's website were a little less beautiful. I ended up watching a series of YouTube videos of the hot end assembly, the first of which you can find here.

The hot end went together pretty easily, and worked (and still works) great! I did have some hiccups, though. My crimping skills are pretty bad, and I unknowingly ruined the connectors of the heating element. This made them not fit into the provided plastic housing, and so I would sometimes have my heating element become unplugged mid-print! I was getting pretty frustrated with it, so I just soldered the connections. It works just fine, but now it will be very difficult to remove the extruder if I ever want to (which I do...).

But I digress. This post is about the extruder from MakerGear. It really is a good extruder. With a nozzle of only .35mm, I can get some awesome resolution, even without rigorous calibration.

Would I buy it again? Unfortunately, the answer is no. There are other designs that use ceramic resistors and alumuninum blocks, and they go together quite easily. The MakerGear hot end is very reliable, but pretty difficult to build if you didn't buy a kit.

Next post will probably be about belts, why they suck, and what I'm trying to make them suck less.

Friday, September 28, 2012

Using a cooling fan on a RAMPS 1.4

Putting a cooling fan onto a 3D printer is pretty necessary. If you don't, then the layers on small objects will not have time to cool, and the print head will mush them around and ruin your crisp lines. You can avoid this in Slic3r by telling the tool head to go off and draw random circles if the time it takes to do a layer is under a set amount of seconds. This can add a lot of time to your print, especially if you've got a tall, thing tower.

Fans fix all of that. I got a small (1.5" x 1.5") fan from Makergear when I purchased my hot end from them, which was a nice little surprise. The wires were only 3" long, but a quick and dirty soldering job fixed that. After that, it's just plug and play, right?

Wrong.

First I had to figure out what to plug the fan into! A quick Google revealed the connection should be at D9 on the RAMPS 1.4 board. Plug the wires into the screw terminals, and we were off!

Not really. I wanted to test the fan to make sure it would work while printing. I typed M106 S100 (M106 activates the fan, S### controls the speed, from 0-255) into Pronterface.

Nothing.

I read on the Reprap forums that sometimes the fan had to be all on, or it wouldn't work. M106 S255.

Nothing.

At this point I was a little worried, since people were talking about possibly having shorts and replacing MOSFETs and all that. That was way too much trouble for a little fan. But I saw that my D9 LED was lighting up when I activated M106, so I figured the board must be fine. But what about my connections? Remember when I said that the wires were too short, and that the soldering was quick and dirty? Well, I wasn't exaggerating! I thought that maybe my solder joint was so bad that no signal could get through.

I took the fan off the RAMPS and hooked up each wire to the terminals of a battery. Lo and behold, the fan spins! So the problem, obviously, must be on the board.

I went to plug it back in when I noticed something obvious. There was a small "+" next to one of the screw terminals. And, wouldn't you know it, it was next to the screw terminal that I had connected the ground wire to.

I plugged the red wire into the "+" terminal, and the black to the other, then loaded up Pronterface. M106 S255. A small whirr greets me! I tested it with other values, before finally typing M106 S0 to turn off the fan.


So, to make a long story short:
To use a 2 wire cooling fan on a RAMPS 1.4 board, plug the fan into D9, making sure to plug the positive wire into the positive socket. If M106 doesn't do anything, try switching the wires.

Good luck!

Soldering the electronics

When I was building my Clonedel, the Printrboard had just come out onto the market, and I was rather torn between that 160$ all in one board, or the 200$ RAMPS 1.4 board. I decided to go with RAMPS for a few reasons.
  • I had very little soldering skills, and soldering an entire board was a great way for me to practice.
  • If any of the Polulu stepper drivers burn out, I can simply pop them out and replace them.
  • I wanted dual extrusion capabilities in the future.
  • Lastly, RAMPS has been around longer, and is more "tried and true"
I ordered my RAMPS board from Ultimachine, and got the DIY kit (with SMT pieces already assembled). Then Tyler (who also ordered the same board) and I sat down for a few hours and knocked out the entire assembly.

A short timelapse of assembling the RAMPS 1.4 board

The assembled RAMPS 1.4 board (Taken from the RepRap wiki)

I am pleased to say that both Tyler and I were successful in soldering our boards. No magic smoke genies, thankfully.

I would highly recommend soldering your own board to anyone who is considering purchasing a RAMPS 1.4. The through hole soldering is very simple to do, especially if you have a friend with experience walking you through it. It also gives you the confidence to tweak the electronics if something isn't working. One of my Polulus was not talking to my motor correctly, and this resulted in jagged motion rather than smooth. I quickly found that one of the pins had become loose because I didn't put enough solder on. What could have been a disaster was a two minute fix.

That's it for the electronics! Next step was the hot end.

More to come.

Thursday, September 27, 2012

Just starting out.

In spring of 2012, I joined WOOF, the 3D Printing Club at the University of Washington. The club caters to both newcomers and veterans. They help people build their own printers, brainstorm new advancements, and just have a good time. You can learn more about WOOF at their website:

woof3d.org

Anyway, back to my project. I joined to learn more about printers in general, but the main selling point for me was being able to get help building my own.

UW professor Mark Ganter designed a fork of the Reprap Prusa Mendel called the Clonedel. The parts are designed to be able to be cast in polyurethane out of silicon molds. You can cast an entire set of printer parts in only 30 minutes! Our club was fortunate enough to use Ganter's molds and only pay for materials, so my vertices, carriages and mounts came out to only 15 dollars! It was a great deal.
Casting the Clonedels in Solheim Lab at UW 

About 6 Clonedels!

A cool feature of casting is the ability to use dyes and transparent resin. Many of our club printers were cast in dark purple, but there was definitely a printer or two cast in pink with sparkles. My printer ended up being mostly translucent red, with a couple of purple parts thrown in.

We also did a bulk order of the threaded and smooth rods, as well as all the nuts and bolts. Big thanks to the club president, Matt Rogge, for dealing with all that. That was another 60 dollars. I had the entire frame put together for less than 100 bucks! I love 3D Printing, but there is definitely a time when casting parts is a better process.

A short timelapse of the frame build.

Still have got a ways to go...

At this point, my build really slowed down. Getting bulk orders on heavy items like rods was nice, but having to wait for every person to lay down the cash for the next parts got a little tiresome. Tyler Habowski and I surged ahead and ordered our motors, electronics, belts, and all that on our own. We got most of it from Ultimachine.com, and they were awesome. But that's for another time.

Next up, soldering the electronics!