Home made automatic ping pong ball thrower

My kids and I are working on an automatic ping-pong ball thrower. We’ve come to the following design, which uses two rollers (paint rolls) being turned by separate motors. The laser-cut frame is supposed to also hold a servo which lifts the ball into the rolls, possibly controlled by sound-driven electronics. We’ll see where it ends up. wpid-20140114_222109.jpgThe files for lasercutting your own are here and here. They are licensed under Creative Commons Share Alike.

Creative Commons License
Laser cut ping pong ball thrower by Lars Kristian Roland is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
I’ve used InkScape to draw them.

Using a laser cutter when etching PCBs

No, I can’t use my laser cutter to actually remove the copper on the PCBs. Unfortunately. Well, I haven’t tried as I expect it won’t work. But I can use it to remove the photoresist, instead of using a transparency and UV box. I’m not sure it’s simpler, but I wanted to give it a go anyway.  Here is a picture of the board after I’ve ‘engraved’ it using the lasercutter.

And here is a picture after it’s been etched, the normal way, using FeCL. The FeCL solution was a bit old, so the quality of the etching is a bit uneven. It shows promise, though I must admit I’m increasingly using professionally produced boards. But for a quick prototype, this is quite simple and fast.

Case for MSP430, combining 3D-print and laser cutting

Here’s another attempt of making a case for the MSP43o Launchpad, with room for the LCD board I’ve made and touch sensors. The black side is 3d-printed, while the top and bottom is laser-cut. In this model I’ve used screws to fasten the top and bottom plate, but it may have been prettier to glue the top plate on. I could have chosen a less transparent plexiglass/acrylic, but I did it this way in the prototype to show the inside. It would probably be nicer with a less transparent one, but I would have had to cut a hole for the LCD display. I wonder if I could maybe cut a square hole for the lcd display and cut a similar square in transparent plexi, and glue it inside the whole. I might try that out.

There is a room in the side for the USB contact.

There is space between the capacitive sensors on the board and the top plate, and it turns out that air is a bad material to ‘conduct capacitive touch’, while silicone apparently is pretty good. So I filled the room with transparent flexible silicone glue from a tube. The type you use on the bathroom to waterproof stuff. I had to turn up the sensitivity in the firmware, from 1000 with nothing there to 50 (so the effect on capacitance is still pretty big). The acrylic is about 1.5 mm thick, so the total is about 3-4 mm of silicone plus 1.5 mm of acrylic.

A youtube video:

MSP430 Launchpad Laser cut enclosure

So every cool platform needs a laser cut acrylic box (apparently). I’ve now designed one for Launchpad, and here’s a picture.

The design is still a bit work-in-progress, but here are the files anyway. Expect some changes. The screws don’t quite fit for example, but I might change it so that the top is glued on, making the top slighly nicer looking with no screws.

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Launchpad Lasercut Box by Lars Roland is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Here’s a video of the laser-cutter cutting:

Testing laser cutter

Here’s a Raspberry Pi case I’ve made using the laser cutter. It’s still a bit rough around the edges, and I’ve got to tune it more to see exactly which power levels I need etc. For this cut, it didn’t cut through the acrylic on all the parts, so I had to break off some of it. Better next time. (The design is from Ladyada, and you can buy a version from there.)

And here’s a picture of the result of trying to make some solder stencils. The picture shows the result of different power settings, with the optimal being circled in black. The optimal seemed to be 10% speed, 20% power with a wet paper below. There are probably many other configurations that would work, like for example lower power and lower speed.