Making moulds using CNC, with urethane foam, wax, silicone and epoxy

I’ve been doing a bit of work on making moulds for the injection moulder. I’ve been making the base moulds with urethane foam and machineable wax. The was is definitely better since the foam is too grainy. I’ve ordered some urethane boards that will probably be really good for this, but they haven’t arrived yet. If you’re interested in some pictures of the process, read on. I’ll be posting some videos later on.

Continue reading Making moulds using CNC, with urethane foam, wax, silicone and epoxy

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.

Plastic injection moulder – finished!

I’ve just tested making my first plastic thingys using the plastic injection moulder. The design needs some final touches, but it works! I’m extremely happy right now. This project has been something I’ve wanted to do for years, it has been one of those projects that I had as a goal, but was put to the side as other shorter-term ideas came up.

The crazy thing is that while I’ve had this dream of making a plastic injection moulding device, I’ve had no plan of what actually to make with it. Making the device has been the goal, not what I can make with it.  Hmmm… more on that later, but first some pictures. The mould was pictured in an earlier post, and it’s basically a (gold) coin with the letter M on it, signifying the ‘Maker’. The mould is in aluminium, machined with my DIY CNC.  I will try to come up with something more useful to make…

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injection-moulding

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I bought the heating PID controller from dx.com, the heater from here and the plastic from this guy. I asked for a mix of different colours and plastics, and he delivered as requested (but unfortunately he didn’t mark the bags, so I’ve got some detective work to do to find out which ones are which). The coin in the picture is made from Gold Polyethylene (I think) and I used a temperature of about 200C, though I’m not quite sure I’m getting exactly the right temperature of the internal part of the cylinder. Anyway, it works!!!

The PE plastic I’m using doesn’t require much pressure to be squirted into the mould. One of the other plastics requires a lot more pressure (so much that I’m finding this difficult to use).

But why am I doing this? What is this Maker-dreams thing? I think it’s a reaction to how we are less used to making our own things now and just get things handed to us, ready-designed and ready-made. In research we call it ‘interpretive flexibility’… we have some of it, but not fully.

Interpretive flexibility is flexibility in what an object is (perceived to be), but also says something about the flexibility in how an object is designed. It says something about the room of possibility an inventor sees when inventing something, and the room for different uses the user sees when using it. In most cases, most people who have a hammer will only use it as a hammer. Few people will use it for other things than hammering, and even fewer will modify it or make their own hammer if they have some specific task they’d like to do.

I’m keen to understand and shorten the gap between the physical objects we have around us and the understanding of how they are made. I want to enhance our common understanding of how things are made and how they can be improved. Because the greatest obstruction to creativity is a thought that “x is not possible”. Maybe that’s what this Maker-dream thing is about. Narrowing that maker-user gap.

BLE Cordova Plugin

Evothings have made a BLE Android plugin for Cordova, which lets you access the Android BLE functions from the Cordova framework.

Cordova is a framework for using web-technology to make (almost) native apps for Android, iOS etc. In theory you can use the same web-app for all mobile platforms, and the plugins connect your Javascript/HTML-based application to the native calls such as accelerometer, camera, location etc. This is really useful and a nice way of making apps on Smart phones.

Not sure who Evothings are, but I’ve tested their plugin on Android and it does work, which is really cool. There is a separate plugin for iOS made by someone else, but this is probably not compatible so you’d have to change your Javascript code.

Here are some links:

Bluetooth Low Energy heart rate monitor app

I’ve made a quick attempt at a heart rate logger Android app, using the Polar H7 heart rate chest belt.

Yes, you guessed correctly: I got a H7 Polar for Christmas and the apps on Google Play are rather limited. Well, there are several better than mine, but that’s why I’m open sourcing it. You can find the source on my Github account. Feel free to contribute and improve it. It is pretty basic. It gets data from the chest belt, shows them on a graph and allows you to upload the data to dropbox.

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My first aluminium mould

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Made a test mould on my home made CNC today. I broke two end mills before I found one that sort of did what it was supposed to. It is a bit rough, but seems like an ok start. The picture doesn’t really do it justice, as it looks worse in the picture than it really is. Honestly 🙂

The aluminium is from a round bar, cut with a saw and flattened using my lathe. Next step is to try this mould on the plastic injection tool.

Plastic injection moulding press – progress

I’ve been making slow progress on the plastic injection molder. Since I don’t have a spare drill press with enough travel, and I want to practice my welding, I have been building a press using square tubing. Here’s the picture of the progress so far:

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And here are some other pictures of the process, for example showing my poor welding…

Continue reading Plastic injection moulding press – progress