Polargraph Stockholm

Posted on October 28, 2018 by sandy

Patrick Wagner designed, organised and ran a workshop at the Royal Institute of Art Stockholm, using Polargraph machines to create beautiful marks on flat surfaces. Two brand new PolargraphSD v3.0 machines joined their lineup, and it was co-hosted by Christian Bazant-Hegemark.

You’ll know Chris from the Polargraph forum and also from his documentary series On Doubt. Patrick is a printmaker and has ran workshops with the Polargraph at the Royal Institute of Art Stockholm a couple of times already, but this was the most focussed so far. They are both creative visual artists in their own right.

Explaining the magic

This was a session for an international crowd of people who are practicing artists or also educators in the fine art field, to learn about what a drawing machine could bring to their process, and they had a great time making some wonderful marks. I was so pleased and excited to see the pictures coming out of that week long session, and glad to see that two fresh PolargraphSD v3.0s worked great, alongside a cast of existing machines. Seeing what happens when the tool is recognised for what it is, and put into the hands of people who value the act and the process as well as the outcome is absolutely thrilling!

Drawing with bleach onto fabric

Discussing the workshop with Chris and Patrick was also seriously enlightening, it collapsed a lot of waves and really clarifies my thinking. When I don’t talk to people much, my mind runs away into little cul-de-sacs where I’m making decisions without much information. I used to be the customer myself, after all, I built the machine for myself to do my own work as part of my own process. Now however, I don’t use the machine much for creative work, and so I’m easily disconnected from “the user”. Workshops like this, along with the advocacy from experts like Patrick and Chris are so useful. I had ideas for a bunch of features that I’m not going to take further, and learned ideas for a bunch I will. Unglamorous stuff like “longer power cables” or “a pause button that works”.

One of the things that often introduces a tension into my thought is imagining that buyers just want a plotter, or just want something quick, or just want something easy to understand. It’s easy to get into that thought pattern, but it does you all a disservice, and it runs quite counter to the ethos of the Polargraph. It’s a luxury to have an principled stance in commerce, but I think that’s really one of the things that makes Polargraph different to other kits. I’m simply not that interested in Polargraph being a general-purpose, high volume, fast and perfect machine that does repeatable, sharp, registered editions. It’s never going to be that. It is simply the wrong process if that’s your goal.

The lines in between are the interesting bit

While this sounds like making excuses for sloppy engineering, it isn’t. Entirely. The truth is that the quintessential Polargraph artwork is full of characteristic squiggles, blobs and patterns. It doesn’t need to be brilliantly engineered. Like Chris wonderfully summarised:

“… these artists are OK with a process taking time, with fine-tuning sometimes going wrong, with stuff not working right away. While it can be frustrating as well, artists also often benefit from such mistakes (a pen drying up during an overnight print; a badly-positioned gondola resulting in the drawing not being perfect on the paper, etc).
So I think that while every artist would always say “make the tool perfect!”, this isn’t actually what would benefit them.”

Getting news of this workshop was such a terrific validation and a glorious piece of news that really helped my bring my full enthusiasm to the launch of the new PolargraphSD v3, which I’m finally getting some reliable stock on (see here for that: https://polargraph.bigcartel.com/product/polargraphsd-v3-0-full-assembled-kit).

Patrick Wagner is blackheartpress on most social media sites:

Christian Bazant-Hegemark just has his own name across the internet:

Chris also creates the On Doubt series of interviews and vlogs, which I love, they look at the process and background for a load of really interesting and exciting creative people:

http://www.on-doubt.com/

Thank you very much to Patrick and Chris for running such a good event, and thank you extra very much for the folks who attended and helped inspire me to keep building the Polargraph.

Well that happened fast

Posted on October 4, 2018 by sandy

I posted a note out to the mailing list (http://eepurl.com/dhVafP to add yourself) announcing that the first eleven machines were in stock (https://polargraph.bigcartel.com/), and within two hours they had all been claimed!

I was amazed and encouraged and excited, because I was rather expecting that most of you would have given up waiting after getting almost a year’s-worth of “maybe next month” from me… So I’ve got a few left of that first batch still to pack up and post out, and then I need a bit of a pause to wait for some more lasercut parts to come in (congratulations to my lasercutting lady for her new baby – I can’t really complain too much about that delay!).

I got a big shipment of power supplies earlier this week and have half a dozen machines-worth of parts absolutely ready to go, bar acrylic cases. I’ll list those as soon as I can, and send a note out on the mailing list to those who have ticked the “tell me when you have stock” box.

Subscribe to the mailing list to be notified. If you’ve missed out this time around, please be patient. I feel very confident in this new design.

Software updates

The machines are shipping with firmware v2.0.1 onboard. This is more-or-less feature complete, matching what the old MEGA-based PolargraphSD could do. The main thing missing is the Norwegian Pixel style.

I’ve since worked up firmware v2.1.0 which reinstates the Norwegian Pixel style and also adds menus and buttons to the onboard touch interface to change machine size directly. It can also change the page size and position. This doesn’t really do anything yet, but I’m going to put a bit more thought into how the machine gets used in practice, hopefully helped by my beta testers Patrick (Wagner – Blackheart Press) and Chris (Bazant-Hegemark http://www.bazant-hegemark.com/) who will be testing this out in a workshop for The Royal Institute of Art Stockholm soon.

Problems

Since starting shipping I’ve already discovered an irritating issue where a 160 second pause randomly appears while drawing. It seems to be limited to USB traffic (I mean it doesn’t happen when drawing from SD card), and it doesn’t actually crash, it just stops to think for a couple of minutes. I’m sure this is a timer overflow or something like that, but these microcontrollers are hard to debug. That’s my number 1 priority because It Is A Stinker.

The future

Current roadmap:

Able to set up and specify a machine fully using the touch UI
Use millimetres to describe all dimensions (uses an odd mixture of mm and steps at the moment, which makes it very dependent on the physical motor setup)
Integrity checking: Emit warnings when the machine that’s specified in the controller doesn’t match the machine that is connected (this mismatch is the source of a lot of problems)
Specify and start drawings from raw image format rather than using the controller to build a queue first
- Bitmap format drawn using norwegian style (for instance)
- Vector drawing from raw SVG (but how to deal with shading/fill?)
Endstops for self-calibration and encoders for reliable long-term drawing

Subscribe for updates: http://eepurl.com/dhVafP

Polarshield v3.0

Posted on May 13, 2018 by sandy

The new Polarshield v3.0 is a refreshed version of the core Polargraph hardware. It has been re-designed from scratch and snips out a few of the snaggles that the old machine had.

It allows integration of:

Espressif ESP-32 based microcontroller
2x A3988 stepper drivers
LCD and touchscreen
SD card for stored command queues
Servo for a pen lift

So the only real difference is the controller, which is a fast, 32-bit, dual-core device, with a real-time operating system (RTOS), oodles of memory AND built in bluetooth and wifi features. There is a working Arduino-based toolchain for this ESP-32 device, but it also has the horsepower and memory to run micropython.

I’ve ported the standard polargraph_server_polarshield code to target this platform (in a branch – https://github.com/euphy/polargraph_server_polarshield/tree/esp32) and it works great … in principle. There’s a couple of bits don’t work yet, and I haven’t done any long drawings with it.

On the Polarshield itself, the hardware design is simplified because the ESP-32 is a 3.3v device and so are the stepper drivers, touchscreen and SD card, so there’s no need for level shifting. The LCDs are of a more modern and widely supported design too, so I expect to have fewer problems with them.

There are spare pins I’ve broken out for:

2x motor shaft encoders for close-loop positioning
End stops for automatic calibration

I haven’t yet implemented any features around the encoders, endstops, wifi or bluetooth, and might never do that.

Why the change?

The Polarshield v2 has never been a reliable build. The straw that broke the camel’s back was earlier this year when I was building a batch and I ordered 20 boards, built them and only got six working Polargraph machines out of them. The LCD that it uses is growing to be somewhat esoteric in that configuration, and so it’s hard to debug. It uses a kind of simulated SPI which just isn’t reliable enough, or has too many odd interactions with other parts of the circuit.

The new 5v step-down power supply is an economic choice. I’m using a little off-the-shelf mini-assembly with a MP2307 and an inductor on it, rather than building the supply right onto the board itself. Amazingly, the little assembly is available to buy (ready-made) for less money than it costs me to buy a single MP2307 chip on it’s own.

The ESP-32 is a little cheaper than a good Arduino Mega-2560 clone. The current Arduino toolchain is a bit of a dog to set up, but dedicated developers has done an amazing job porting libraries to it. It’s dead fast and has a good small footprint. Mega-2560s are huge. Natively running at 3.3v is a bonus and performance with SPI-based touchscreens is phenomenal.

What’s next

This is a platform that could easily take us into PolargraphPro territory, with encoders and endstops to make for a safe and reliable continuous drawing experience. The MCU is powerful and the wireless features are very tempting.

However, I have no immediate plans to implement any new features and will focus on getting old ones ported and re-worked where necessary. I’ll probably take this opportunity to dump a few lesser-used features too.

Mailing list

If you want to be alerted when these reach stock, or you’re interested in email updates about the project, you can sign up to my mailing list and choose what kind of things you want to hear about:

Polargraph mailing list (http://eepurl.com/dhVafP)

Polargraph, back in action

Posted on April 9, 2017 by sandy

Without much fanfare, I reopened for business last month! I had a waiting list, so gave those people first dibs before announcing it widely.

But the first dozen machines are delivered now, and I’ve just listed the next ten in the usual place:

http://polargraph.bigcartel.com/product/polargraph-sd-assembled-tested

In an embarrassing twist, I accepted the challenge of making some videos to show what the machine is, and how it goes together.

Oh, er, there’s more of my gurning fizzgog:

And just when you’d had enough … more:

Sorry about that.

Polarshield v2.4 compared

Posted on April 15, 2016 by sandy

I got a pile of boards back from the maker recently: Polarshield v2.4 (https://github.com/euphy/polarshield_hardware). Here it is alongside the 2.2 version (on the left) to show the progress.

Not much right? There’s no revolution, indeed, but a couple of minor changes that makes it easier to build.

More surface mount parts. The tactile switch in the top-left is now surface mount. SMT parts are just quicker to work with.
Moved the microstepping jumper solder pads to the back of the board, and freed up a load of space.
Squished four of the 1k resistors into another 4-row resistor network. This is the smallest part I’ve ever used, 2x1mm, you can barely see them on the picture. There’s one between the two motor driver sockets, and there’s another below the stack of LEDs on the top-left. This makes pick-and-place much faster. I’m not convinced the super-high density was a good idea though – it is far less tolerant of sloppy placing / solder paste application. We’ll see.
Better designed for soldering with hot air, and iron. Some of the traces on the board were sometimes difficult to heat effectively, without also over-heating the component. The electrolytic capacitors were particularly problematic. I’ve routed the traces less efficiently in some cases, so that they have more copper that I can heat with the hot air pencil.
LEDs are all orientated in the same direction. The old board has them pointing everywhere, so I was always spinning the board around. v2.4 has the anode to the right-hand side in every case. It’s to reduce the chance for placing errors.
The holes for the DC power jack are placed off-centre, so the solder tabs are a friction fit. It makes the part self-aligning. Nice work sparkfun!

And the great thing is, it works, ha!

I’ve been taking some time off the Polargraph shop lately, because of work pressures and a couple of other things. It’s been really nice not to have to rush to the workshop every hour of the day to keep on top of things, and I’ve been able to do a little development here and there.

I think I’ll be back eventually, but maybe in a couple of weeks, and I might try a different manufacturing pattern.

Labelling evolution

Posted on April 5, 2016 by sandy

My manufacturing process is ~~always~~ sometimes evolving. It’s not a complicated one, but there’s enough steps and nuance that I benefit from reminding myself what I’m supposed to be doing.

A run of bad Polarshields last year prompted me to start being a lot more careful about how I assembled and recorded the assembly of them. I started putting little journals on each one, which were just a strip of sticky tape with any story on them. Anybody who bought a Polarshield will have found such a thing.

I recently kicked myself a couple of times in a row when I thought I’d forgotten to test a certain aspect of the board, and had to open up a pile of sealed parcels to find out. Fortunately in that case, there was no problem, but I made up some new labels to help me not make a mess in the future.

The evolution is in the pic. The QR takes you to Building a Polargraph from a vitamin kit on the wiki. The final version is less handsome, but more useful, and there’s a beauty in that trade-off.

I like seeing these kinds of “work in progress” pics on other makers’ blogs.

Polargraph at the Edinburgh Science Festival 2015

Posted on April 11, 2015 by sandy

Once again, the Polargraph Pro is featured as part of the Edinburgh Science Festival’s Making It touring exhibit, stationed until the 19th of April 2015 in Ocean Terminal Shopping Centre down the road in Leith.

Tricking the machine with smartphones

I was a bit nervous about having the machine presented in such a uncontrolled environment (it was in the National Museum last year), but it’s been remarkably low-maintenance during it’s first week.

Some better than others

For this year’s outing, there were a very small number of changes to the firmware, mainly to add a feature to support a button and an indicator LED on the circuitboard that is controllable via commands, and used to signal to the Science Communicators that it needs it’s paper changed.

The changes to the Polarweb controller software are a little deeper, and there’s now a visualisation video stream published to a browser so you can see what the machine sees, and what processing it’s doing. Worked pretty well, but taxed the original laptop a bit much (it was an Atom), so the machine has been upgraded.

Other upgrades:

Minimum face size, so only people close-up get recognised and drawn
Path sorting to make for more efficient drawing (I hope to pull this work into the general Polargraph Controller some time soon)
Except for changing the paper, there is no manual intervention required during operation
Tracing controls are available in the interface to change posterisation levels, minimum path length, maximum path count and smoothing
The pen lift servo wire is routed more neatly, and uses spring-loaded retractable cable spools rather than the coiled cable that got stuck all the time
Drawing sequence can now fixed bottom-to-top so that pictures can be cut out and taken home as soon as they are drawn

How to make a PolargraphSD

Posted on January 27, 2015 by sandy

Just thought it might be interesting to see the steps that go into making a PolargraphSD. I’m curious about this kind of stuff, and I love work-in-progress pictures. So I assume you do too.

Apply solder paste.

Starting with the PCB mounted in a jig made of other PCBs, I use a plastic stencil, and a card to squeegee on the solder paste. This can be messy, but it’s very fast, takes less than a minute for each one. I have taken to making up batches of 10 polarshields at a time, it takes a reasonable weekend, or a long day from beginning to end.

Sometimes bits get missing, or I accidentally rub off the paste during placing, and I use a little syringe to do touch-up stuff. Afterwards, there’s these nice little pillows of paste on all the pads.

Pick and place

I’ve got all the parts I need in little boxes, and empty out about the right amount of parts, sort through the pile and turn them over and line them up with a pair of tweezers. I used to use tweezers to place them too, but have recently got a cheap vacuum pickup tool that makes it a bit quicker.

Using magnifiers and good lighting, dealing with these tiny parts is much easier than I thought it would be.

I place most of the ICs with tweezers, because I get a bit more control over their orientation – they have a tendency to swing around a bit on the tip of the vacuum. The really big parts (electrolytic caps and the inductor) are just placed with fingers.

Soldering / reflow

I’ve got a hot air gun (Atten 858D+) that I used to take 8 minutes to melt all the solder paste on each board, and I still use that for touch-up and fixing. The last couple of batches of Polarshields have been soldered with a little home-made reflow oven though. This is a mini oven, retrofitted with a Zallus temperature controller. The temperature controller was a Kickstarter I backed at the end of last year, and it seems to work really well. Though the whole contraption looks like junk – but that’s my fault.

The boards go in two at a time, and cook for 6 minutes, releasing all kinds of (probably deadly) fumes. I only use lead-free solder in all my stuff, so it’s not the nice smell you get out of rosin-fluxed lead solder. I miss that. My old tutor told me that eating plenty of jam would help ward off the poisoning that we would all get off the solder fumes. I like the story.

Now comes the really boring bit.

Through-hole soldering

There doesn’t seem to be any way to short-cut this one, just got to cut lots of parts to length and solder them all in. Using the kind of small iron tip that is useful for touching up SMT work makes this an absolute misery, so use a big clumsy chisel tip instead to whizz through.

There are 156 points of through-holes to solder. During soldering, I sometimes spot things like this:

There’s a solder bridge between the first three pins of the IC. This is irritating, but out of 10 shields, there’s normally four or five bridges like this that need a touch-up. Fix it with some solder braid. In this case, I noticed the IC was a bit skew-whiff on it’s pads too. I am not sure if it is something about the heating profile, but it seems like the parts don’t always get “pulled” onto their pads by the solder tension during flowing. At least, not as straight as I saw when I was using the heat gun. So with this IC, I reflowed it using the heat gun, and just nudged it to straighten it up. Afterwards, I wash the board with Techspray Flux remover to clean it up. Add stepper drivers and LCD, and it’s ready to test.

Testing

Upload the latest version of polargraph_server_polarshield and see what happens. Well, I just got a white screen. So I took another look at the board and spotted another solder bridge. Fixed it.

Testing involves plugging in a couple of steppers, a servo and an SD card and running a test script from the card. If the motors move smoothly and quietly, and the servo wiggles, and the LCD responds to touch, then it’s cooked.

For full PolargraphSD kits (with the motors and cables), I do another test of the same routine before I pack everything up, to make sure the particular motors and the cables are correctly constructed, and they all work together.

Case

The case is made up of 16 laser cut parts, and is fastened together with six M3 nuts and bolts, tab and slot style. I try to leave as much of the protective film on as possible during assembly.I enjoy peeling that stuff off when I buy a new product, so I assume other people like it too. It stops my grubby fingerprints spoiling it too. I’ve got white gloves and everything, for this bit.

So now you know. Tune in next week and I’ll show you something equally as thrilling, how I clean my oven or do the hoovering or something.

Slow going

Posted on July 3, 2014 by sandy

Slow going, but … going!

The hardware is working fine now, working with all kinds of SD cards, all servo motors and all power supplies, but I’m waiting for the full set of the new cases to be cut and sent.

The case is funny. Probably the ugliest thing I’ve ever made, but I quite like it.

Choice between clear acrylic and MDF – any thoughts? The clear looks shows fingerprints but looks pretty snazzy.

PolargraphSD progress

Posted on June 9, 2014 by sandy

The PCB v2 testing is still ongoing, the end is closer and I’m expecting the final boards late next week. This extra round of board testing was always accounted for in the schedule, but what I didn’t account for is the last set of PCBs taking three weeks instead of one week to arrive. So although I feel this is disastrous, and the project is crashing down around me, actually it’s only literally two weeks behind, and I just need to get a grip.

I know that’s not much consolation to those of you who have been waiting since February, and I am really sorry about that, and that’s the bad news.

Why

I’ll do a proper introduction when it’s done, but in short, the Polarshield v2 has an integrated switch-mode step-down power supply so that the arduino can be run safely from a single higher-voltage power supply, without overworking the arduino’s on-board voltage regulator. That’s all gone fairly smoothly. This makes the system much more tolerant of working with cheap, basic arduino clones.

The second feature is fixing the circuit that converts the arduino’s 5v signals to the 3.3v signals that the screen and SD card expect. Previously this used resistor networks, but I’m using logic buffer chips now. This should make SD cards from different manufacturers much more reliable. BUT, it is new to me, and that’s why I’m determined to make a mess of it.

For those who are interested, the PCB files, and the gerbers that go to the PCB house are in the repo at https://github.com/euphy/polarshield_hardware.

Polargraph

drawing by robot

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