Archive | April, 2019

3D Printer meetup #3

09 Mar13

3D Printer meetup #3

Last weekend, I organized the third 3DP meetup in Oslo together with @kefir from reprap.no. Quite a good turnout of people and 14 different printers there. My two favorites were the Adapto printer that is using pretty much only parts that are avilable in normal hardware stores. How's that for RepRap? The other favorite were the two Rostock printers being built by two AHO-students. Very cool to see these in "real-life" and I could even help a tiny bit so that was fun as well.

The next meetup should be some time in May and I'm REALLY looking forward to see Johan's DuoHex machine! It has one of the smartest RepRap designs I've ever seen, using Hexagonal rods to drive a dual extruder design. Below is a short video showing the different machines at the event and here's some nice pictures that Kjetil took.

 

Makerbotting

24 Mar12

Makerbotting

When people ask me what I do these days I tell them that I still make games and apps, but that I play around with microcontrollers and 3D printing. Most people don't really know what 3D printing involves, but I usually have something in my backpack that I've printed. As soon as they get it they say "Ohhh I want one!". But do they really want it?

Lately I've spent quite a bit of time with the Makerbot Thing-o-matic (TOM) that VariousArchitects has in a back room of our office. It's been so much fun and so much to learn that I've spent most of my free time modeling, printing and testing various designs for my LED Cube project. What I've learned up until now is that Makerbots and 3D printers in general require quite a bit of fiddling to keep them in working order. It's a lot of moving parts that are held together with screws and bolts that constantly move. These come loose and the faster your printer moves, the more chance that things will come loose.

The thing that has caused me the most trouble on the TOM is that my models did not stick the the heated build surface (heated build platform or HBP for short). The model would stick for a couple layers and then one of the corners in the model would loose grip of the platform. The model would bend more and more and in the end it would bend so much that the print head knocked it off. I tried a coulple of the basic tricks like changing the Kapton foil on the build surface but it didn't help much.

My friend Jim at Various was the one that bought the TOM and he suggested that while I was working on the problem, I'd also upgrade and recalibrate it. Sure I thought. How hard could that be? With all my current Arduino experience, the upgrade itself was super easy. Getting the hardware to play nice was harder. After a lot of fiddling, I got everything to work tonight. Yep! I'm in my office in Oslo now at 23 hrs on a Saturday, printing and calibrating. That's how much fun a 3D printer is! Anyway - here's the list of things I did to get the 3mm white ABS filament to play nice:

  • The firmware was updated to the latest version for both extruder and main board (an Arduino Mega 2560)
  • The HBP was dismounted, every single screw beneath it was tightened and the platform was levelled completely
  • I went over every connection inside the bot and sure - the power to the extruder had come loose. It's way to short, so you'll pull it out unless careful
  • I also raised the HBP temperature from the recommended 110 to 115 degrees. This makes the builds stick MUCH better.
  • ReplicatorG was updated to latest (034) but I'm still using skeinforge 35. For some reason, start.gcode isn't included from the default position so I have to set the HBP temperature directly in the generated gcode. Haven't found a description of this being a bug, so I'll just keep looking tomorrow I guess.
  • I failed a lot when it came to the calibration because I didn't properly read the dialogue shown after calibrating: always regenerate your models (both gCode + s3g) completely after recalibrating.

Due to that last one, I had to change the Kapton foil quite a few times after the print head crashing into the platform after a little printing. Think I've spent almost two full workdays fiddling with this now but I finally got a successful print completed now, so time to head home…

But - this is so incredibly fun! So much fun in fact that after some careful consideration I ordered a Ultimaker last week! As opposed ot the Makerbot, this one moves the printer head and not the platform. This solves what I think is the biggest problem with the Makerbot design - if you print too fast, your model will simply fall off the platform. With the Ultimaker this is much less of an issue, just check this video out! That's not the "out-of-the-box" speed though and it comes as a kit.

But when will I get it? Not until 4-6 weeks :(

 

Making a good cube

19 Mar12

Making a good cube

It's fascinating how hard it is to make a good cube. It's such a simple task, but as soon as you introduce features it all gets more complicated:

  • Easy to open and close for changing batteries
  • Walls must have an even distribution of material so light from inside shines uniformly

For every iteration there is a process consisting of modeling in Rhino, generating toolpath with ReplicatorG, checking toolpath with Pleaseant3D, export a .s3g file from ReplicatorG, move to memory card and put into Jim's Makerbot Thing-o-matic, sit by the Makerbot while it's printing the first few layers, drop by to check that the printing goes well and then take the final product out of the machine. So - it takes a bit of time with each iteration but hey! I can think of something and have a working prototype in plastic less than 2 days later? That's just rad!

Here's a rundown of my experiences designing the cube and outputting it on a Makerbot Thing-o-matic. It's harder than it sounds and if you want to check out any of the images in very high resolution, check my flickr account.

Cube 1

I had been thinking a lot about how to make the first cube and everything worked like a charm! This cube only had one problem - the 5mm walls made the light really dim and that won't do. This cube is on Thingiverse as it really works. It's super solid and you could probably drive a huge truck over it without damaging the contents. You can see it in the pic above, or here to see it blinking away.

Cube 2

This was pretty much a complete failure. High on the success of the first cube, I didn't really think through the design of this one. The result was that the locking mechanism worked alright, but the lid could slide off sideways…. Bummer. However - this model showed that you could make really nice looking cubes with just 1.2mm walls. This is only two strands of plastic on the Makerbot and it'll actually print nicely, no matter the height of the object.

Cube 3

The biggest failure yet. It practically fell apart when I took it out of the printer… This cube used twice the thickness of the previous version (4 shells). I couldn't really see it when inspecting the model in Pleasant3D, but the outer two shells didn't connect to the inner two? I now inspect the toolpath much more carefully, but this really isn't an exact science.

Cube 4

In the previous version I had solved the lid nicely, but I didn't really like the look of it. It looked clumsy. I started thinking about how I would make such a cube from Plexiglass and it dawned on me - what if the lid has an inner square that fits into the main cube? That'll add rigidity as well as make the lid "snap" in place. I also started to get annoyed with the "slits" in the lid that this design required for opening. What if I ignored the slits and rather made the lid sort of "loose" so you could just rip it open without any tools?

The only thing that failed for me with this cube is that the things that hold the cube closed (the snaps?) are visible when you apply light inside the cube. Unless you do this, it can serve as a nice, little storage container so it's on Thingiverse for others to download.

Cube 5

This is the version I'm working on now, but I had some issues with the Makerbot. Will have to solve that, but the lid came out well and as you can see, I've sized up the design to 7x7 centimeters so I can fit batteries in the lid.

The initial idea was to use coin cell batteries, but there's actually three reasons for going with AAA batteries instead:

  • Battery life is much better
  • It's easier to get hold of and replace standard AAA batteries
  • I actually couldn't fit the required components onto the space available in a 5x5 cm cube…

The batteries slot in nicely and are held in place, but the holes/slits for the metal bits that'll be at the ends of the batteries didn't come out as intended. I know how to fix them though, so when I have some time I'll redesign that and print a new lid. Below you can see the sample fitting of the components for the 5x5 cube. It's tight so a little extra room will help.

Also used this post as a way to test my new light-box-thingie for taking high quality shots with diffuse lighting. Will use this for the upcoming hardware reference in my Arduino Companion app.