Sunday, 26 April 2015

Maker Faire UK



This year I was lucky enough to take my family to the Maker Faire UK in Newcastle. My local hackerspace (Hacman) were exhibiting there.

There were many more exhibitors than my local mini maker faire. With some big name shows:

The Humane Machine by Johnny White was a definite crowd puller. I particularly liked the way he made gears out of ice:



I was assuming he had used a prime number of cogs to mininise wear when I realised that this was an art installation and had probably not considered longevity:



There was a stand with a vac forming machine that had a long queue of people assembling their messages from letters:



A jewellery making booth allowed visitors to twist copper wire into strands and add beads to make their own gear:



A barbot dished out (none alchoholic) drinks. I need to make myself a (modified) version of this.



Pretty much something for everyone. Sewing for the girls:



And Robot Wars for the boys:



Beauty by the geeks had a popular stand where the kids could mush stuff up and find out about DIY beauty products



I got to play 1D pong with my oldest which was much more fun than I expected:


A 3D printer with a chocolate extruder brought on excited questions about modifying my printer from the wife:



A remote controlled hexapod robot:



Which shot foam darts into the audience:



This stand had a digital zoetrope with individual LCD panels for each element of the animation. Of course they could be uploaded with different images to allow the animation to be changed:



This guy had made amazing bearing runs from hand soldered copper wire. I failed to get video of this, but goodness knows how long it took to perfect:



Much to the delight of my 7 year old there was a chap doing a bubble extravaganza...



This stand had some kind of analogue audio system that sounded quite good:



My local Hackerspace (Hacman) were exhibiting. An unrepeatable shot of my proton pack with a Dalek in the background,,,,,,

Bertha made a guest appearance on this stand..making me realise I need to dig out the DVD and show it to my youngest.



Most kudos go to 'Litre of Light' who showed that a simple soda bottle filled with water could be re-purposed into a practical interior light:



And inside....



Saturday, 4 April 2015

New Toy. 50W laser cutter.



Visit Tagbits to see the full range of tagger products described in this blog.

I've had one of these in my sights for a while now. And I came into enough cash to allow me to buy one. I ordered from AliExpress rather than ebay, as the price seemed better.

It arrived last week via DHL. Well packed but delivered by Mr. Grumpy himself:



It's slightly bigger than the cheapest that can be bought with a cutting area of 400x300mm. As a 2015 model, it comes with accessories that would previously have to be purchased separately:

An air assist laser head and air pump. This helps to extinguish flames and generally blow unwanted smoke away from the laser head:



A digital control panel, thoughtfully worded in Chinese and English:



A Z adjustable cutting bed.

A honeycomb bed. This reduces the amount of heat transferred away from the underside of the work piece during cutting, and also allows the extractor fan to draw down any smoke:



In typical cheapo Chinese fashion, the honeycomb was not flat, with about an 8mm delta from corner to corner. I solved this by drilling M4 holes in the corners that were raised, and drilled a 9mm holes on the upper side of the frame to allow screw heads to pass inside the frame. I then drilled and tapped the Z bed to M4. This allows me to screw the corners onto the Z bed, forcing it to be flat.



It's also supplied with a water pump to cool the laser tube. I got a 32L box from Wilkinsons and drilled two holes in the top and filled it up with 25L of distilled water from Halfords.



Distilled water is required to stop any impurities in tap water from depositing inside the laser tube. This could cause hot spots. I also added some propylene glycol to act as an anti bio/freeze agent.

Included with the package was a rotary axis to allow the engraving of cylindrical pieces:



Most impressive is the laser tube itself, glass with a helix! Covered in cautions written in Chinese. No doubt recommending not staring into beam with remaining eye.



The software was supplied on a DVDR with a USB dongle. Not entirely sure if this is legitimate or not. However, once installed, it works as expected. There is a plugin for CorelDraw included on the disk which seems to be the most useful of the bunch, providing direct access to the laser cutter from CorelDraw.

The main issue with these budget laser cutters is the alignment of the mirrors. This image from LensDigital shows the laser beam path:


At assembly, they only seem to centre the laser tube on mirror 1. The user is expected to align everything else. I followed this video, and got everything aligned in about 40 minutes.



So with a day of tinkering behind me, I've managed to create a gear with the excellent, free Gear Generator and import a SVG file of a gear and cut it from 6mm acrylic. This has some random lines on it due to my inability to set the feed rate correctly, but still impressive:



A really nice feature of the cut is that it leaves no blemishes on the edges. A cut with a jigsaw would require treatment with a solvent to get this clean:

Wednesday, 11 March 2015

Fully 3D Printed Proton Pack Complete



Visit Tagbits to see the full range of tagger products described in this blog.

I finally finished my fully 3D printed proton pack the other week. I've spent the final days implementing the lighting system using a simple Microchip PIC and a charlieplexed array of LEDs.

The traditional circuit for lighting a pack consists of a 555 oscillator to produce a clock, which is then fed into a couple of shift registers, the output of which drive NPN transistors to drive the LEDs. This produces a column of lights that rises then resets.
A decade counter (with transistors) is used to illuminate the LEDs in the 'cyclotron', the 4 large circles at the bottom of the pack.



This seemed a bit over the top to me, as not only being complicated, with around 13 LEDs in the column, the wiring of some implementations is a bit challenging with a cable per LED.

So I designed some circuits to implement the same effects, but with far fewer wires. Not only does this simplify the wiring, fewer wires should also increase reliability.

I created a very simple circuit which brought out the I/O of a PIC (16F684) to a few connectors:



And a second circuit which gave me a charliepxed matrix:



I did this as two separate circuits as the pack has two LED columns, one on the pack and one on the thrower. A smaller PCB is used in the thrower with a second PIC board which means each LED column has a LED board and a PIC one. I chose a board pair solution as there is limited room in the thrower housing where the LEDs are mounted.

Charlieplexing works by utilising the tri-state ability of microprocessor I/O pins, in that only two pins are ever outputs at any one time. To implement this I used two look up tables: One to hold the port I/O register states (e.g. which pins were outputs, and which were not). One to hold the pin values (e.g. which pin high and which pin low).
I also included 16 levels of dimming per LED by implementing PWM in software. With the PIC running flat out at 2mips I can control each LED individually with dimming without flickering:



Here is the finished pack:




And here I am ready for Zuul with youngest as My. Stay Puft:


The proton pack parts can be downloaded from Thingiverse. And a few others worldwide have joined me in making this:

Iron Man of Maine.

and Jeffarazzi:

Monday, 2 February 2015

Raspberry Pi 2



Just got me a Raspberry Pi 2 from Farnell. I watched them go from 82 in stock to zero in 3 minutes.

Sunday, 1 February 2015

Proton pack thrower mount



tommyb345 suggested that I check out a pre-made mount to attach my proton pack thrower to the proton pack.

Trouble is these seem to start at $75 for decent ones, and the guy selling them on ebay doesn't export. So I decided to make my own.

The proton pack thrower mounts to a sloped fitting on the proton pack, this I made out of several layers of 3mm aluminium sheet:



A special fitting is required to mount the thrower to this. I designed one and bent it on the sheet metal bending machine we have at work:



This needs to be fitted to the proton pack thrower. The problem I had was that a screw solution would result in a raised profile on the inside of the mount. This would clash with the proton pack fitting, so I decided to weld the mount to a steel plate fitted to the base of the thrower.

I dragged out my trusty Clarke MIG welder with matching BOC Argoshield gas.



And my solar powered welding mask. This is great, you can see through the protective glass, but when the welding arc starts, the glass instantly darkens. Which means can can get set up for a weld without looking through very, very dark sunglasses.



I'm not a trained welder, but I managed to fasten the two pieces of metal together:



And after going over with the angle grinder, it wasn't too bad: