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.

Who will rid me of this troublesome SD card reader

Happy New Years Polargraphers!

So I got a recent report from a soul who was impeded by an SD card not reading in his new PolargraphSD machine… And these are cards that I’d supplied along with the kit mind, so you’d expect them to work right?

Well, I did too. I could replicate his issue perfectly – New 4GB Kingston SDHC card (from this giant batch I’d patted myself on the back for getting such a good price on, and so many!…), that shows up during the Polargraph boot sequence as having no usable partition. Oh. Yet try the same card in an older machine kit and it shows up fine. Huh. What’s that, ah the touchscreen (which incorporates the SD reader, and I buy as a discrete unit) is now v1.3 rather than v1.2. Hm. I hadn’t noticed that.

Yet the 4GB cards work fine in everything else I put them in, they read and write and format fine on a computer. So that’s a problem. Luckily for me (and the next couple of orders) I _do_ have some spare 2Gb cards that work fine, so it’ll not slow delivery, and of course I’ll be sending a replacement out to anybody who has got one of these 4Gb cards late in December. That was obviously a goof.

Furthermore, the 4GB card works ok when powered over USB, but not if a higher-voltage supply is connected as well (or instead of). It’s a power supply or signal level issue.

In software, this kind of regression testing is second nature, in hardware, I suppose it should be an even higher priority because the stakes are even higher. In software, unit tests can be rattled out in an afternoon, and can be messed up a hundred times with only a time penalty. In hardware mistakes are expensive, and making up test jigs is another venue for mistakes to occur in.

None of that is an excuse, it’s just a convenient explanation that I’d give to the pointy-haired boss (which in this case .. is myself …  that’s frightening). It sounds comically like the same excuses I’d give to bosses in bygone times about why it wasn’t worth doing unit testing in software, ha. Embarrassing.

The devil here, if we must have one, is in the detail lost during the commoditisation, homogenisation of resources and products – On paper, v1.2 and v1.3 of the reader are identical, and the SD cards also are identical. No reason to think they wouldn’t work together.

So, the takeaway is that if you ordered a PolargraphSD and got an SD card that isn’t working in it, and I haven’t already been in touch with you, drop me a line, or buy a replacement 2GB SD card and bill me!

The reason I’m dwelling on these issues of delays and problems so much, is not [just] because I’m a masochist, it’s because I think it might be useful for other folks who are venturing down this same kind of path as I am. Not helpful directly, but I admit I always found the war stories inspiring.

Happy Holidays

So the building that my workshop is in closes down over the holidays, from now until the 2nd of January, and like Bagpuss, when the studio goes to sleep, the Polargraph Company goes to sleep too. Of course I NEVER sleep, and will hopefully get a bit of time to finish the polargraph processing library over Christmas and New Year. That and Battlefield 4.


There’s a couple of new professional developments that might bear some fruit next year too, including a project with the Science Festival to make a big, show-and-tellable version. I’m hoping that will be a springboard to get auto-homing working properly, and do a bit more work on large scale machines.

Thanks to all the folks who have supported me this year, I hope you think it’s been worth it.

See you all in 2014!

Sorry I’m slow again, but on the other hand, you are fast (like Dreamcast), and you make my day

I got a good portion of the backlog moved when I got the batch of PCBs in, and PCB production is going fine.  I’m waiting on LCDs though. More about that in a minute.

I noticed we silently broke through the 200th Polargraph mark last month: Since September 2011 you’ve helped me move parts for over 200 drawing machines.  I think that’s remarkable, and for that, I salute you, drawing warriors!

In particular I would like to thank all the folks who have contributed to the forum, or written elsewhere and brought more people to the community. You know who you are.  

This is probably the first time I’ve been involved with something that wasn’t already happening anyway, and it’s very gratifying indeed. (Also mildly terrifying.)

So, now, back to our scheduled apology:

I know it’s pathetic to be waiting on parts (it’s not like it’s a surprise requirement), but I was surprised to find that the last handful of LCDs I had in stock were all cracked.  Still work, but not really usable for paying customers, what.

I’ve got a mega big batch of LCDs arriving soon, and they have been arriving soon, since I ordered them a fortnight ago.  I’m just going to have a whinge, so I apologise in advance – everybody else I know has already heard this whinge more than once, so it comes to you, kind, gentle, compassionate reader.  Long lead times is fine, and short lead times is great. Reliable lead times is best. The previous batch of LCDs I ordered astonished me by arriving 5 days later, from the other side of the world. Amazing! So, after ordering this next batch two weeks ago, I was expecting it to be here by now, but in fact I only got a tracking message about it yesterday, saying it was in Hong Kong.  Oh: less amazing.  The good news is that it means it’ll be here some time next week, the actual delivery is air freight, so super fast.

I’m only really exposing this whinge to indicate that I share your pain and to wave a pathetic little white flag. It’s dead frustrating to have ordered something, and then not to have it a month later, when you were quoted a month as lead-time.  I’m sorry about that. What I would like to impress on you is that I take this very personally, and take the necessity to provide a good service for your hard cash very personally, and in cases like this, I really feel I’m _not_ giving good service. It’s disappointing, and disheartening, and makes me sad and anxious.

I’m not blaming my suppliers of course, I’m sure they have their reasons for the delay, and assume they are just as invested in keeping me happy as I am in keeping you happy. The solution for me is unsurprising, and more frustrating because of that – just add a healthy margin of error onto expected shipping dates. That’s what I’ll do in future, again.

I’ve discovered that achieving consistency in a service is a much harder thing than achieving consistency with a pen, on a page. That’s something that I have a much clearer understanding of now, but it is surprising to me that having an understanding of the problems is only a very small part of providing solutions to those problems.

In other news, I have a big pile of _everything else_ sitting around, looking forlorn.  That is what passes for good news at this juncture.

Polargraphs, finally go again!

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


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, and hack circus

Ha, so the good news is that I got the fixed v1.5 Polarshields back, and so far they are looking good.



Not properly tested the motors yet, but so far, so good.

I’m going to be away for a week though so I am not going to have much time to work on this.  One of the things I’ll being doing next Sunday is showing a different project at a Hack Circus event in London.

Linear Clock is like a circular clock, but unrolled.  It’s a project from a while ago that I recently revived, and I’ll be doing a show and tell.



That’s Sunday, 6th of October, between 2 in the afternoon and 6 o’clock in the evening. It’s in the back bar of the Star of Kings pub, Kings Cross, London.  Tickets can only be bought ahead of time at this site, and I think it’ll be a lot of funny, as well as jolly interesting.

Please come along and see what happens, if you like technology, speculation, funny things, theremins, the phenomenal Sarah Angliss, or chat with brainy folks.  It will be lovely to meet you.