Hi, I just wanted to drop by and say thanks to everyone and Sandy in particular for the inspiration to build a robot. In my living room.

She goes under the working title Pol Plot, and she's not quite finished yet, however, tonight we are drawing our first picture.

I thought I'd share some thoughts, if anyone is interested.

Most of the setup is "standard", as much as it can be. The bead chain is from ebay:
http://www.ebay.com/itm/Ball-Curb-Cable-Rollo-DIY-Unfinished-link-Chains-Fit-bracelet-necklace-Free-ship-/180943244903

Electronics are an Arduino Uno with the Adafruit motor shield and Sandy's software. Thanks alot for this work Sandy.

The motor brackets, bead chain sprocket and pretty much everything else is hacked together in Inventor and printed on a Makerbot here.

The gondola then. I didn't have any of the nice huge-ID ball bearings, but I had a bunch of cheap 3x10x4mm bearings (623), so I came up with a linkage to make the wires converge to the center pen point. It is a bit overkill, of course, but it works and looks great 😉

I also tried several designs with the wire point separate from the pen point, but I find them all to be extremely difficult to balance..

The weight and support are 3 aluminium platters (95mm outer, 25mm inner diameter) from a scrapped hard drive. While not transparent, they are robust and make for a pretty nice look with the mirror polish.

As for the pen holder, the gondola has a 17mm hole. I then make "adapters" for the pens I want to use. Right now I just use an old "Stabilo" 0.4mm felt tip thing which nicely enough is hexagonal. The pen is dressed in the adapter which the fits snugly into the 17mm hole. The pen/adapter is held into place by a quick-release spring thingie (work in progress..)

The idea was to have the gondola so heavy so that it would always rest properly against the drawing surface. The pen would then be lightly spring-loaded against the surface. Right now the spring is way to stiff so actually the gondola only rests on the pen and the rest hovers 0.5mm over the surface.. It works anyway, with some wobbling, as you can imagine. I need more HDD platters and a weaker spring.

But before technical development, next up is some aesthetics. Dressing the board in cloth and sorting out all the cabling. We have a party coming up next week, and by then it must be pretty.

I attach a few images, and here's a google link for some more:
https://plus.google.com/photos/112438695711543203451/albums/5949955968061232385
Sorry for the quality. I have neither proper camera, nor lighting at the moment..

The masonite board is from the largest IKEA frame I could find. The plan is to cover it in thin cloth.

Close-up of Gondola with four-bar linkage and HDD platters. I attach the pieces with fishing line which is then tied to the bead chain further away.

Coins in a cage as counter weight

Hi Jonas, welcome, and thanks for posting! This is a really cool setup. I love that gondola. The big bearings on my gondola really are more of a bug than a feature - this seems a daringly elegant solution. The real problem with the bearings is that the pen size is so drastically limited - this system opens that central area right up. I don't immediately see a downside. I drew a bunch of sketches back in the day, that looked a bit like this, but never actually built anything like it. Insectoid too, definitely, I like that.

Have you been following (Kongorilla's experiments without a stabiliser? I think, if you went with a vertical drawing surface, you might be able to balance the gondola and dispense with the stabiliser. Some weight would still be good, but the visibility is improved.

Your lines will improve once you're drawing on something with a bit of cushioning too (paper - or I use one of those translucent rubber desk-pads that IKEA sell, smooth-side up).

sn

I can't seem to get the image rotations right today.. but here you go, and image album is at
https://picasaweb.google.com/jonas.einarsson/PolPlot?authuser=0&feat=directlink