Polargraph Forum Feed

Re: Importing SVG > weird offsets

feeds@r.us — Wed, 25 Jul 2018 05:45:45 +0000

100% fix for me was to do two steps in inkscape: 1. ungroup the segments; select object and press ctl+sft+g 2. break apart segments; while still selected press ctl+sft+k save svg and load in controller. Let me know if that works for you! Brian

Re: Working on a new polarbot platform

feeds@r.us — Tue, 24 Jul 2018 21:14:20 +0000

Hey there! Looks like a great start - having the motors moving on the outer ring is a good call in my opinion. I'm putting all my energy into the next Polargraph... But I am strongly tempted to move everything to the gondola and simplify the wiring that way. Where's the best place to watch for progress? sn

Working on a new polarbot platform

feeds@r.us — Mon, 23 Jul 2018 19:21:24 +0000

Hi all, I've wanted to build a polarbot for a while. Then I saw the the Scribit Kickstarter and was dissapointed that it wasnt open source and didnt feel like paying for another kickstarter that I wasnt sure when it would arrive. I have a MaslowCNC that works pretty well and I borrowed a lot of ideas and experience from it. I also looked around at the other drawbots around. They all seem to get to about POC stage and die off. Except for this community So I thought this would be one to work with. Let me know if you;re interested in experimenting with new open source platform for this. trying to advance things a bit. I'm far enough along that I think it will happen. As interest grows I'll improve collaborative tools. Till then, this is what I have. I'll post a pic of what I have so far soon. https://github.com/SuddenDevelopment/WallPlottE thanks, -Anthong

Re: Repeatable Errors on Plots

feeds@r.us — Fri, 13 Jul 2018 09:27:36 +0000

Hi Sandy, I picked up a few boards to try my luck with the polargraph, That CNC Shield V3 in the photo had a dodgy cap when it arrived, so much for a $1.95 board, I really have to stop buying the cheapest of the cheap. I also got an adafruit motor shield v1 Clone but one of the L293D chips has gone dodgy after running too warm using 12V as the source. So i haven't got far! i'll keep here updated if i make any more progress Cheers Rob.

Re: Drawbots from around the web

feeds@r.us — Wed, 11 Jul 2018 23:32:47 +0000

Constructing A Building-Sized Draw Bot by Edwin Dertien and Janwillem te Voortwis https://makezine.com/2018/07/11/constructing-building-sized-draw-bot/ https://vimeo.com/278379059

Re: Home Point

feeds@r.us — Mon, 09 Jul 2018 22:51:07 +0000

Forgot to answer this - the home point location doesn't make any difference, it's arbitrary. The reason it's in the middle at the top is so that it's easy to measure where the middle is! And at the top because when you have no penlift you don't want it resting on your paper. When I've used really tall machines that I can't reach the top of, I've set the home point at the bottom instead. sn

Re: Repeatable Errors on Plots

feeds@r.us — Mon, 09 Jul 2018 22:01:36 +0000

A physical slipping error seems inconceivable to me, given the absolute step-perfect repeatability of the symptom. I should say that I've never tuned a stepper driver with a meter or with maths - only ever by ear and touch, so it's very possible I'm overcooking it. I don't really believe the 16x microstepping makes the difference, but you could always test it in 8x mode by snipping off the MS3 pin, or cutting the trace on the board. A bit irreversible. If you mean polargraph_server_a1 is EOL, then it isn't completely sunsetted. There's hardly been any functional change in the firmware in the last couple of years, so it might not make much difference. The next version of PolargraphSD v3.0 kits will be based on an ESP32, so the code is quite different to the firmware for the old MEGA-based machines, but it is functionally equivalent. I might add new features that use the hardware features of the ESP32 but I've got no plans for that yet. I see you've got another CNC board there though... Did you try drawing with that one? sn

Re: Repeatable Errors on Plots

feeds@r.us — Mon, 09 Jul 2018 06:34:19 +0000

Hi Sandy, That really is fantastic news! phew. I have still been playing, I expanded my machine width to 840, some printed mounting brackets and standoffs for guides. Installed my A4988 Stepper Drivers into a Shield and calibrated the Pots on the Stepper Drivers V x A = W 2.8V x 1.7amps = 4.76watts 4.76watts/12volts = 0.39Amps they were originally sent to double that from the factory. unfortunately my board has a design fault and is hardwired for 1/16 microstepping, I noticed now that A1 has gone EOL, i'm going to invest in some better hardware and revisit this. Cheers Rob.

Re: Repeatable Errors on Plots

feeds@r.us — Sun, 08 Jul 2018 18:28:31 +0000

Ok, good news and bad news: Good news is I got a chance to draw out the hilbert curve svg that you were trying. Bad news is that it drew out fine - no distortion. I used the current version of the Polargraph controller, with the SVG at the same scale as yours, on the same sized page. My machine is not the same size as yours, but not far off. The hardware is different though: I'm using a Polarshield, which sits on an Arduino MEGA 2560 and wires up two A3988 motor drivers, hardwired to microstep at 8x. Usually this uses the polargraph_server_polarshield firmware, but I also tried with the polargraph_server_a1 firmware, with serial steppers configured - same result. The rest of the hardware is a 9v, 2.66A PSU and two NEMA 17HS13-0404S steppers, motor speed and acceleration were around 2500 (that includes microsteps, so it'd be 5000 on yours to move at an equivalent speed on the page). Hypothesis: This hilbert curve is a bit of a "torture test", cramming in as much back-and-forth as possible to try and prompt tiny errors, then magnify the consequences of it. I'd be amazed that physical errors (overshooting or dropping steps) would be so consistent between runs, and that there was no sign of them during other drawings (the crown)... But I've been amazed before. Perhaps if you drew hundreds of tiny crowns you'd find that they lost integrity too. On my stepper drivers I can tune the current to give more or less torque/grip. If yours can also, look at bumping them up a little and see if that makes any difference. This is a fascinating exploration! You could try to replicate my settings more exactly by changing to step multiplier of 8 (will still work fine, but will lose half of it's internal resolution) if that's appealing. I don't imagine it will make any difference though.

Re: Repeatable Errors on Plots

feeds@r.us — Thu, 05 Jul 2018 08:31:35 +0000

Aha ok that's that theory out the window then. Can you email me the SVG so I can have a go? sn@polargraph.co.uk or point me at whatever generates the patterns. I'd be curious to see if the problem occurs at every scaling level - if you double the size of the vector in the controller do you still get the issue, OR if you crop the drawable section down to just the area with the most obvious distortion using 'select area' then 'set frame to area's, does the distort still happen. I think that experiment would tell you firmly whether the problem is in the controller (specifically the part that converts vector points to native coordinates) or some weird firmware edge case. Very exciting! Sn

Re: Repeatable Errors on Plots

feeds@r.us — Thu, 05 Jul 2018 07:58:58 +0000

Hi Sandy, Thanks for the words, I'm just using an Arduino Uno with a couple of A4988 Stepper Drivers plugged into Nema 17 Motors. It's hardwired for 1/16th Stepping. I had a look at the configuration but serial stepper drivers don't seem to have the same option as AF boards. i.e. const int stepType = INTERLEAVE; I have another stepper board available which I can set to Full Step and try that. Cheers Rob. Cheers Rob.

Re: Style Overview

feeds@r.us — Wed, 04 Jul 2018 22:32:30 +0000

Hey krummrey this is a really good job! congratulations !! I'm sorry for the basic question, but I'm new here. How can I include these styles in the polargraph? Tks

Re: Repeatable Errors on Plots

feeds@r.us — Wed, 04 Jul 2018 09:09:11 +0000

It's quite fascinating! I'm sorry not to be more helpful, I'm away at the moment so not able to dig I to it... But this is a really interesting study. It looks like each block of the drawing has integrity, but there's something going on between the blocks. The controller does do rounding (so the .5 might be significant), but it isn't relative, or compounding. The inaccuracies shouldn't build up. There are also natural distortions in how the machine draws, but these would be evenly distributed. The repeatable nature tells me it's not a physical problem (belt or motor slippage). I can think of some experiments to do in order to debug, but an obvious answer isn't springing out. It looks like your configuration is for a Adafruit Motorshield V2, running in microstepping mode. So you've got squealy motors, and step style in the firmware config section set to MICROSTEP. Microstepping, when it's not working right _does_ lead to compounding errors, so that's the only thing I can think to try. Changed the step style in the firmware to INTERLEAVED and re-flash your arduino with it. Then change step multiplier to 0 and stepsperrev to 400 (easiest to do that by editing the default.properties.txt file), and re-upload the machine spec. That would by next step... But I admit I never liked the microstepping on the adafruit shield so I'll take any excuse to be it as the villain! Sn

Re: Repeatable Errors on Plots

feeds@r.us — Tue, 03 Jul 2018 14:51:06 +0000

Nope that wasn't it! I really thought I was onto something. I feel like I have turned over every stone at this stage

Re: Repeatable Errors on Plots

feeds@r.us — Mon, 02 Jul 2018 13:03:29 +0000

I just noticed this

machine.motors.stepsPerRev=200.5

Where as it should be 200, it seemed to get skewed between importing and exporting. I have changed and it adjusted my canvas, Could this be the error that is building up? Cheers Rob.

Home Point

feeds@r.us — Mon, 02 Jul 2018 13:02:01 +0000

Hey Guys, Is it Ok to have my home point bottom left of canvas? as pictured here or is it better to use centre top as is the dafault? Thanks Rob.

Re: Repeatable Errors on Plots

feeds@r.us — Mon, 02 Jul 2018 09:21:36 +0000

I tired another "Crown" just to make sure I havent broken anything and it plots fine

Re: Repeatable Errors on Plots

feeds@r.us — Mon, 02 Jul 2018 08:45:18 +0000

This is Hilbert #2 error is always in the same spot with this one

Re: Repeatable Errors on Plots

feeds@r.us — Mon, 02 Jul 2018 08:35:34 +0000

This is my Polargraph Properties file, if that helps:

# *** Polargraph properties file *** #Mon Jul 02 15:32:52 WST 2018 controller.pixel.samplearea=10 controller.pictureframe.position.y=244 controller.pictureframe.position.x=64 controller.testPenWidth.startSize=0.3 controller.machine.colour=969696 machine.motors.mmPerRev=32.0 controller.vector.filename=C\:\\Users\\Rob\\Desktop\\hilbert curve.svg controller.window.width=1920 controller.frame.colour=C80000 controller.image.position.y=218 controller.image.position.x=156 machine.motors.accel=400 controller.image.height=567 controller.machine.serialport=1 controller.window.height=1018 controller.maxSegmentLength=2 controller.geomerative.polygonizerLength=1 machine.penlift.up=180 machine.penlift.down=120 controller.page.position.y=243 controller.vector.scaling=61.6 controller.page.position.x=58 machine.step.multiplier=16 controller.pictureframe.width=421 controller.grid.size=18.0 controller.testPenWidth.endSize=0.61 controller.pictureframe.height=298 controller.page.colour=DCDCDC controller.testPenWidth.incrementSize=0.05 controller.image.width=453 machine.motors.stepsPerRev=200.5 machine.pen.size=0.4 controller.page.width=420 controller.pixel.mask.color=00FF00 controller.machine.baudrate=57600 controller.vector.minLineLength=0 machine.width=537 controller.geomerative.polygonizer=0 controller.page.height=297 controller.vector.position.y=206.96 controller.vector.position.x=148.64 controller.image.filename= controller.background.colour=646464 controller.homepoint.y=539.93 controller.homepoint.x=56.98 machine.motors.maxSpeed=800 controller.guide.colour=FFFFFF controller.density.preview.style=2 controller.pixel.scaling=1 controller.densitypreview.colour=000000 machine.height=740

Re: Repeatable Errors on Plots

feeds@r.us — Mon, 02 Jul 2018 08:18:54 +0000

Another couple of Gosper Tried a Hilbert Curve