Polargraph Pro Preview

Hello, I’m getting excited about the new Polargraph installation that’s been eating up all my time recently. IMG_20140327_160058025_HDR This is part an exhibition called Making It, itself a feature of the Edinburgh International Science Festival, and it’ll be running in the Grand Hall of the National Museum of Scotland, here in Edinburgh, for most of next month (April 2014).

IMG_20140330_112312329_HDR

I’m just putting some finishing touches to the machine and the control software.

There’ll be more of an update when it’s up and running.

Pre-order PolargraphSD v1.8

I’ve just made a listing for the PolargraphSD v1.8, over at the Polargraph Shop.

The price of it is likely to be the same as the last round, but if you want to pre-order at a decent discount, you can put a 25% deposit down to hold your place in the queue as well as make cash flow a little more predictable. It’s a kind of micro kickstarter. I hope to have this ready for shipping in May, but it’s more likely to be June.

I hope to enlist an extra pair of hands to help me assemble this time around, and am having this semi-formal fund-raising period so that I can buy a few critical parts in a full-sized batch (ie 50), rather than buy them piecemeal over the run of the batch. That ended awkwardly last time, with delays and malfunctions a-go-go.

Edinburgh Science Festival Project

I’ve been asked to make an installation as part of the Edinburgh Science Festival in April, so that’s the project that’s eating up my time at the moment, and the reason for the halt to PolargraphSD manufacturing.

This thing is going to be great though: Two large portrait machines, continuously drawing faces from a kinect / webcam on rolls of paper.

I’m using a Teensy rather than an Arduino for this project, EasyDrivers and optical encoders to close the loop and keep track of position. This will make for a more robust, semi-automatic machine. I hope to have endstops too, and a good presentable gondola that can take a range of fat pens.

I also hope to be taking one of my machines along to the Mini Maker Faire that closes the festival at the end of April.

 

Pause for thought. And breath.

I’ve got half a dozen Polarshield PCBs left, but I’ve marked them as “sold out” in the shop.

I’m tired. I’ve had a few technical set-backs recently, that would be merely irritating if I was only make two machines a month like this time last year, but it immediately escalates into a full car-crash when I’m making a dozen a month – there’s just no room for mistakes, all the stakes are higher, and things move faster, sell out faster, need more careful management and delays cause more people at a time to be annoyed.

Not a bad problem to have? Well that’s true, poor me, boo hoo, there are worse problems, and I genuinely thank all my customers profusely, and everyone who has joined in on the forum and by email – actually by far the best bit of the project.

But I’m going to work to get this last problem sorted out (accursed SD cards and power management, I do bite my thumb at thee), and then pause my sales and manufacturing department (that’s what I’m calling my hands this week) for a bit to review the project as a whole.

I have an installation to work on in February, which will hopefully be presented as part of the Edinburgh Science Festival in April, and should be jolly exciting, and result in some neat new pieces of tech and software – encoders and a proper library at last! Right now I would not be at all disappointed if that was the last Polargraph machine to roll off the production line – the last of the V8 Interceptors, as it were.

However, let’s be realistic, I suspect the lure of the humming motors, the clattering of beaded cord and the pleasure of visiting my favourite post office lady will soon bring me back in, and … with upgrades.

External power input on Polarshield

Polarshields have always had a space for an external power input. This is so that you can have a high voltage supply to drive the motors, while letting your arduino, and all the logic chips run on a standard 5v, or USB supply.

External power jack on polarshield

I got this idea of running two power supplies from the Adafruit motorshield. In their case, the reason was that when the motors started sucking down the power, the voltage supplied to the arduino would drop below 5v for long enough to cause a reset.

I’ve never had that exact problem, but I don’t like running an arduino on a high voltage, when there’s also a high current (like when running motors). The voltage regulators get hot, and while they are within tolerances, it’s not right, and always makes me worry when I put my fingers on them.

The machines I sell are protected by the case, and I was overjoyed when I got a new batch of Freaduino Mega2560s through to use in them, because they are the only arduino compatible boards I have seen to use a high-current, switching voltage regulator rather than the hot’n’cheap linear regs used everywhere else (including the genuine Arduino). These little chips are efficient and stay cool under lots of current.

However, when you buy a Polarshield on it’s own, or in a vitamin kit, you can plug it into any old board. Because they are exposed, it is so much more obvious that something is getting hot. Again, it isn’t dangerous with the motors I use in the vitamin kits, and at low voltages, but if you want to use bigger motors or run at higher voltages, it will not do. The heat makes it clear that there is no headroom.

 

So the solution is to separate the two power circuits by removing the small blue jumper on the polarshield (just beside the power jack), and plugging your motor power supply into the polarshield power jack. The arduino should have it’s own power supply.

Historically, I’ve not soldered the external power jack in, but I have a bag of them and if anybody wants one, I’ll post one over. From now, all polarshields will include this jack, soldered in – unless you drop me a line to say otherwise.

Polargraphs, finally go again!

After a long wait, Polargraph machine are finally available for sale again!

P1040815_c

http://polargraph.bigcartel.com/

I am pleased with the last batch of Polarshields I had made, so I’m waiting for a Big Batch coming in the next week or so, and I already have all the other stuff I think.  But in the meantime, I am taking orders – I find having the anxiety of holding onto peoples cash focusses the mind wonderfully.

 

New boards No.

So I was excited to get the sample for the “final” version of the polarshield v1.5 through today, very nice… Except I noticed it only had traces on one side of the board!  No traces on the bottom!

Hm.

To have a board made, I produce a bunch of files, each one containing information about one layer of the board – silkscreen printing, soldermask, copper traces, cutting outline, drill holes etc – and zip them up (they’re also on github).   I raced to check the files I had sent, and – crestfallen – spotted that I’d somehow managed to miss the bottom copper files.

Infuriating! The wasted money stings a bit, but the main penalty is that production is knocked back another two weeks, and it’s already been too long.  I’m getting anxious, and making stupid mistakes like that really doesn’t help.

 

New boards ho

Well that’s a nice surprise – the new v1.4 boards work!  I shouldn’t be surprised I guess, since they are just the 1.3 boards with less stuff on, but it’s always nice when something just works.

Untitled

I had a thought when soldering this up though: Because the pins for motor A protrude through the board, they need to be filed down and insulated so that they don’t short against the housing of the USB-B connector on the arduino underneath (a blog about it).  This is a pain, and in principle (if not in practice), makes for a weaker connection.  This has never been a problem for building the full kit, because the arduino mega I use has a mini-USB connector, but for everyone else (and all the vitamin kit parts), it’s a glaring issue.

So I think I will swap motor A with motor C, so that by default, for polargraph, that filing doesn’t need to be done.  Will still be wise to put a bit of electrical tape on it because it could still contact, given the right pressure.

Motor C was added because I had the space, and also because I have a few plans for things that might like to have a third axis of control.  The parts for motor C will be unpopulated by default, for Polargraph products anyway.

So, I think I’m immediately going to revise this to swap A and C, but also I might try to move the servo and endstop pins, and add some more lights.  I’ve got all these LEDs to use up!

Another fortnight for v1.5.

Studio tenants show on this month

The building where I have my studio has a exhibition of work on all through August, so I’m in it too.  I’ve got a cabinet of jewellery and a polargraph drawing!  Why don’t you come and see it?

WP_000620

My photograph is dismal, the reality is better.  I might have some live drawing at some point, but I failed to move fast enough (and ran out of parts) to get it sorted out for the launch.

I’ll be at the preview tonight, Friday 2nd of August at Arts Complex, St Margaret’s House, 151 London Road Edinburgh EH7 6AE, but the show runs all month, and there’s three massive galleries of stuff across a range of budgets, so call in. My stuff is in Gallery 3.

If you want to come down, drop me a line and I can come and meet you! And show you some other stuff if you want to see it.  Or not, if you don’t want to, that’s fine too.