DIY Coupling for CNC made in POM

Below is my attempt at making a coupling between the threaded rod and stepper motor in my home-made CNC. The coupling is made in POM-plastic on my lathe and router, and was quite easy to make. It’s basically a 6mm hole in one end and 8mm in the other, with two holes drilled for screws and then a slot routed along the side. The idea was stolen from this commercial Delrin-coupling. It seems to work well, gripping both the stepper and rod tight.

2015-01-09 13.04.26

Upgrading the linear rails on my CNC

Here is a ‘before and after’ photo of the rails I’m planning to use. I’m not sure if these are the best rails, or if I should have gone for the type with a metal bar and a round linear bearing, which is common on 3d printers at least. I’m not quite happy with the ones I got here, as it seems they won’t cope with the load… They were quite expensive… bought them on AliExpress…

2014-12-16 22.22.24

Upgrading my CNC

I’m planning to upgrade my CNC. I’ve bought new sliders, new threaded rods and new electronics. I’m hoping in particular the speed will be improved.

Just to give an impression of the level of upgrade, here’s the new board next to the old. The new is a SOC-Robotics GenY32, and the old is a McWire Stepper board from Instructables-instructions. To be honest, the old board was working well, and it was a fun DIY build stepper board at quite a low cost. There are no big issues with it. I just felt like upgrading it I guess.

These days there are probably cheaper DIY alternatives than the McWire board. One reason I went for the GenY32 is that it can (soon) run the TinyG firmware, but it also allows for using the parallell port (with EMC2 or similar). It just felt more flexible.  Well, the setup is not up yet, but I’ll post more info as the build progresses (slowly).

NewBoardHere’s a picture of the old CNC. As you can see, the electronics board is on the left, the sliders are from drawers and the rods are normal threaded rods… The Dremel probably needs upgrading also.


The MSP430 FRAM and the Sharp Memory BoosterPack

A long time ago I wanted to make a watch, and I made some interesting builds. But I always wanted to use one of the Sharp memory displays for a build, and it seems TI has made things simple to test out. They’ve made a Launchpad using a FRAM-memory based MSP430, which uses very little power. And they’ve made a booster pack with a Sharp Memory display, which could be used for many booster packs of course, but they also sell them together. The demos look really cool, and although some of the demo projects needed a little tweak in the config to compile, it was quite simple to get up and running. These displays look so different from LCD that they could be used for some cool projects. The picture below is from one of the demos, and it’s actually running on a supercap that’s attached on the board. It doesn’t run very long, but part of the demo software uses less power and can apparently last a while.

Launchpad dev kitThe touch pad usage in the examples seem a bit … ehhh… touchy. It might be just a firmware issue. It senses touches sometimes without being touched, and the opposite. The touch pads are quite small, so that might be the reason also. In the user guide they excuse themselves by saying there’s no overlay and that the touch would be more accurate wth an overlay. On my own touch pad displays I have played with using silicon as overlays, and acrylic over that, which works quite well. It could be one could make a box for this display and have the touch accessible from the outside. That worked well with my displays. If one made a small breakout board to old the MSP430, the form factor could be quite small. The display user guide gives quite good info about the hardware.

BLE113 Breakout

I’ve designed this BLE113 module breakout. The intention is to work towards making a ‘BusPirate’ which is accessible over BLE from a smart phone. It breaks out SPI, I2C and a few IO (the I2C and SPI can also be IO). There’s also an attempt of a LIPO charger (that’s what the USB is for, not for accessing it from a computer).

I’ll send the board off for production now… The untested CC-BY-NC gerber files are here. This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

BLE Breakout Schematics
Breakout board

Climbing wall in the basement

I’ve been building a climbing wall for the kids in the basement. The next step could be to add an electronic game to it. Ideally something like this or this. I’d like to implement a game where a route has to be followed and each contestant is timed. The question is how to easily implement sensing the movements and reaching the points. I guess the simplest is a set of buttons rather than using the climbing holds.


Watch controlled biped

Here’s a video of the watch-controlled biped. Not the easiest thing to control, but it sort of works. Basically it’s a Chronos watch with an radio-chip in it which sends its accelerometer values to the MSP430 Launchpad with a RF Boosterpack radio receiver on it. The MSP430 controls the servos based on the accelerometer values. There is a small bug in the servo code so sometimes it goes bananas.