Live data from Hacker News

BrachioGraph – a cheap, simple pen plotter

brachiograph.readthedocs.io

71–80 of 109 posts

Re: BrachioGraph – a cheap, simple pen plotter

#71
post #70

I like the layout of this site, what is being used to present the documentation on this site? Or is it a fully custom built site?

I think it's the standard https://readthedocs.org/ standard. It's definitely not custom. I've seen many projects with it.

Edit: Seems to be linked to the doc tool called Sphinx.

Re: BrachioGraph – a cheap, simple pen plotter

#72
post #18

If you’re in to this kind of stuff, you might want to check out the hashtag #plotterwitter. Some really good stuff there. https://twitter.com/hashtag/plottertwitter

Nice! I've been enjoying the work from skullcat recently: https://twitter.com/mrmrs_/status/1159339640459059200

Re: BrachioGraph – a cheap, simple pen plotter

#77
post #7

It's my understanding that higher quality plotters/3d printers/mills' accuracy and precision come from higher quality motors (e.g. stepper motors instead of servos). Will it be possible to someday just put cameras on the plotter which watch the current print and self-correct as needed? That's basically what our eyes do when we write/sculpt/carve. Will cheap motors + cameras + software eventually meet or exceed the qu…

That's in interesting thought but instead of a camera what if it used an optical mouse sensor? Even cheap ones in $5 mice can do hiDPI now and track on most surfaces. Maybe it could slide on the paper next to the pen with a fixed offset telling the software exactly how far the pen has moved.

Optical sensors will drift over short timescales so you will never have a repeatable "zero" point. it would probably work for small organic shapes but anything more geometric would not turn out well.

Re: BrachioGraph – a cheap, simple pen plotter

#78

This looks like great fun, but I'd prefer to make something where the output is a little more precise. Does anyone know of a DIY plotter that's a step up quality wise from this one? Or maybe a site or community that lists similar projects?

I haven't looked to far into this project, you might be able to gain a decent amount of stability with better materials like 3d printed plates instead of cardboard. (This is a place where CF filament actually makes sense, it's one of the most rigid printable plastics)

Or you could just laminate that cardboard with some fiberglass and epoxy, on both sides. A roll of 5cm x 3000 cm fiberglass woven cloth is $9 incl shipping on ebay. Buy some two component epoxy at the local hardware store, like 10 fl. oz. for $15.

Cut your cardboard and fiberglass to whatever size and shape you like. You're going to make a sandwich: fiberglass, cardboard, fiberglass. Wear disposable gloves. Cover your benchtop in two layers of cling film. Put your sandwich down, carefully rub epoxy into the top fiberglass, two layers shrink wrap on top, flip the thing over, rub epoxy into the second fiberglass, more cling film. Put it in press with some weight, leave overnight. If your cardboard has some thickness and good compressive strength, the strength of the resulting sandwich is probably such that you won't be able to break a 10 cm long stick with your bare hands.

3D printing is cool. But for random repairs around the house, or building strong flat things like this, epoxy and fiberglass is the bee's knees. We've built stand up paddle boards with this technique, just replacing the cardboard with XPS plates. No vacuum bagging required, really. (Of course it would give further strength and much improved aesthetics.)

Re: BrachioGraph – a cheap, simple pen plotter

#79

Earlier quoted context omitted.

I haven't looked to far into this project, you might be able to gain a decent amount of stability with better materials like 3d printed plates instead of cardboard. (This is a place where CF filament actually makes sense, it's one of the most rigid printable plastics)

Or you could just laminate that cardboard with some fiberglass and epoxy, on both sides. A roll of 5cm x 3000 cm fiberglass woven cloth is $9 incl shipping on ebay. Buy some two component epoxy at the local hardware store, like 10 fl. oz. for $15. Cut your cardboard and fiberglass to whatever size and shape you like. You're going to make a sandwich: fiberglass, cardboard, fiberglass. Wear disposable gloves. Cover you…

Regarding the solidity of this technique, these days a lot of indoor climbing holds are made of fiberglass held together by epoxy, with a thin layer of textured plastic on the outside. These are generally called fiberglass volumes.

The material is so solid that a meter-wide hold is actually just an empty shell with a thickness of a few mm. This easily withstands a heavy dude jumping onto it sideways (in fact, that's what it's there for!)

Re: BrachioGraph – a cheap, simple pen plotter

#80

I love pen plotters. When I worked with CAD we still had them. It was so much fun seeing it slowly working on a technical drawing. Laser printers are obviously much better and faster but much less fun to watch.

Oh yeah. When it would change colors it would run over to the pen holder and pick up a new color. That was fun to watch.

That reminds me of the create-a-card machine that was in Hallmark stores in the 90's!

I had forgotten about that. I remember watching in awe as it drew a Simpsons-themed card.

Post reply on HN