Nerds in Berlin (again)

We've been here in Berlin for a few days - in the salubrious district of Kreuzberg - and slowly getting to understand (some) of the appeal. It has many similarities to Brighton: only a grubby, dirtier, graffiti-strewn version - and no seaside. The last time I came, I hated it. This time, the weather is better, there are more people about, and we've met some really cool characters. Kreuzberg is still a dirty, rotten area of Berlin, but - as with so many places - it's the people that make the city, and we've met some pretty cool ones!

One of the more exciting things about our short visit was visiting the drop-in print making workshop. There are places like this all over Berlin: places that hackerspaces should be aspiring to. It's basically a shop where you turn up, explain what you need to do and they supply the parts, materials, equipment and (where it's needed) expertise to help you get the job done.

The shop is open an manned by staff five days a week; there's a massive indie/punk subculture in Berlin where people make their own t-shirts, fliers and cd/album covers, mostly using screen printing. Everyone seems to know someone who knows screen-printing! So we took ourselves along to see how it all works.

Andrea made up a simple screen by hand-stretching some medium-grade silk over an A4 sized picture frame and stapled it along each edge. Although you can get machine-stretched frames, this hand-made one seemed pretty taught, so we thought we'd just give it a go. At the print-shop they provided the photo-sensitive emulsion. It's ready mixed, so you just need to put a thin film on your screen and leave it to dry.

the photo-emulsion is a bright lime-green colour. When it's "baked" it goes a dark, leafy-green colour.

A thin film of paint is dropped into a trough (it's expensive stuff and is difficult to re-use, so only the smallest amount needed is taken out of the pot) and the trough is swiped quickly up both sides of the silk - working vertically, from bottom to top

The aim is not to place a film on the surface of the screen (although this may happen) - it should be as thin as possible and we're just trying to get the emulsion to fill the gaps in the silk. Sometimes the paint doesn't get quite into the corners, which is why the screen needs to be oversized: our frame is for an A4 picture so is actually a little larger than A4, all the way around

While the screen was drying, in a dark, warm room, we set about preparing the artwork. Some PCB circuits were laser-printed onto 100gsm paper (not acetate as we were expecting). The paper was then coated with cooking oil (rapeseed I think) and it magically turned translucent: a handy tip to remember for future screen printing - much cheaper than expensive acetate sheets!

we weren't sure, so coated both sides of our sheet with oil

About half an hour later (or however long it takes to drink a coffee in the sunshine, at the cafe opposite) and the screen was ready for exposing. We placed the image onto the exposure bed, then the screen on top and turned on the vacuum to help remove any air bubbles trapped between the image, screen and glass bed. It took a good ten minutes - but only because the exposure box was absolutely massive!

Matt at BuildBrighton always wanted to make a large exposure bed - but this one may be outside even what he was dreaming of!

A4 on medium-guage silk takes about ten minutes to expose, apparently. So after ten minutes, we took the screen out and blasted it with a high-pressure hose. The screen wasn't as dark as we'd expected (but apparently the emulsion continues reacting in sunlight, so is yet to get a bit darker) but after a minute or so of washing, the magic started to happen. All the "unbaked" emulsion washed away and we were left with a perfect copy of our PCB design on the silk:

(our pcb design was only eurocard sized, so we put a solder mask on the bottom half of the screen)

All in all, an amazing success.

The whole thing cost less than five euros and we got help and learned a lot about the how and why of screen printing. Why the screens need to be larger than the image, why different meshes are needed for printing onto different surfaces and so on.

It was a really interesting few hours and has given us a lot of confidence with our own homebrew screen printing rig. Of course, you can use professionally manufactured screens (there were some machine-stretched screens at the workshop which were tighter than a snare drum skin!) and spend a lot of money getting everything "just so". But you can also fudge it with some cobbled-together gear and a bit of know-how. And that's what got us excited.

All we need to do now is go back and see if we can actually print an image with the screen!

Updated Fridge Calendar Project Completed

Another great project was completed this afternoon at the Tinker's Workshop.  If you have not been following along you can catch up now with this post of the Fridge Calendar project that I just put the finishing touches on.

The design looks great with the new look of the rectangular pieces shown here. 

Here is a good shot of the original design along with the new improved design.  The new version has almost the same number size, smaller over all size, and three times less weight. Plus the months can be displayed not too.

Here's a good shot of all the pieces that are needed for the perpetual fridge calendar. 100 pieces in all were needed to be printed and put together for the project. 

There are 162 total pieces to make the calendar which includes the printed parts and the magnets that are mounted on the back of each piece. These pieces were Super Glued on to the back of each piece from a magnetic roll after cutting them to size with a scissors.  There were 100 pieces to print on my 3D printer in the project which took 36.5 hours to do.  Then add at least another 25-30 hours design time and the project got to be a lot bigger than it looks.  I think the effort was worth it in the end.  Not that I would begin to duplicate this project to start selling them any time soon.  I would think a mold would be the order of the day as it would be a lot cheaper and faster to produce. No matter what this will make a nice addition to my kitchen that my visitors can enjoy as much as I do now. 

The Sphero Peackeeper, a $10,000 Robotic Ball!

Do you have $10,000 laying around. If so, you could be able to purchase the Sphero Peacekeeper from Orbotix! Seriously though, how awesome would it be to have and iPad-controlled 150 pound robotic ball. You could drive it around your yard, chase cars, and torment your pets. Just kidding, this Sphero was just an April Fool's prank!

The New Fridge Calendar Is Slowly Taking Shape

Today has been another long session of printing 3D parts for the Fridge Calendar project. Twelve hours to be exact.  A total of 100 parts will be needed to complete this project and at this point I am only up to part number forty-three.  This is what it looks like so far.

 It looks great already but printing the same parts over and over gets old very quickly.  Each of the smaller blue and red rectangular pieces  are the same and take 22 minutes each to print using my 3D printer.  The larger rectangular red pieces will display the months for the calender once I have the white inserts made.  These larger pieces take 34 minutes each to print so I am more than happy that I only have eight more to go.  Then on to the inserts for all the pieces.  Luckily each of these are different and will make this portion of the project a bit more interesting.  

The upper photo shows what the new calendar will look like once it is completed and the lower photo is what I have on my fridge right now. The new design looks a lot more up to date with the rectangular design and is a third of the weight of the original design.  Another thing that will be good with the new design is that the numbers and letters are all the same size as the original design but because of the new shape the amount of space that is need to display the calendar is reduced in size.  Hopefully I will complete this project by the weekend and I can get it put up on my fridge at that point.  I'll also keep a running tally of the hours I have on this project and be able to tell you the total cost to make this unusual calendar then too. Check back here to see the finished project.