posts tagged with the keyword ‘drawbot’

2014.11.18

FND v3.75

A few weeks ago I designed what I like to call “version 3.5″ of my main drawbot platform. The improvements were still mainly a two dimensional design, with horizontal plates sandwiching things together. I found two main faults with this design, so I started working on improvements.

The first improvement was in the tool holder. The one with rubber bands proved to not be strong enough to hold tools in place easily. The rubber bands were a pain to work with. (They did work well enough to hold clay carving tools though, and we ran the drawbot across some slabs of clay.)

I wanted to move to a new design where a screw could be used to hold the tool. I know that the Egg-Bot uses a screw, and for the unfamiliar, it looks like this.

Egg-Bot Pen Holder

This is a great design, but for various reasons I chose not to attempt to copy it. Instead I borrowed some ideas…

FND Pen Holder

The screw I’m using is a standard 8-32 screw with a wing-nut threaded on backwards to the head, and then a hex nut is added and tightened against the wing-nut. On the other end is another square nut to push against the tool, and again there’s a hex nut tightened against it.

In the above image showing the parts for the tool holder you’ll see the first and third pieces have holes for the screw to go through, while the second plate has a square hole to hold the square nut between them. So far it’s working quite well, and holds things without any slipping or wobbling.

Most of the rest of the plate is similar to the previous version, with the exception that now there is no bottom plate, as this mounts directly to the body.

The previous version relied on four screws and eight hex nuts to hold the motors between two plates. This was less than ideal for a number of reasons. First, there was no good way to align the motors and tighten things up. Alignment isn’t a crucial element of the drawbot, but it’s nice to have. The second issue was structural, as the 3mm wood was flexing quite a bit. I didn’t even try acrylic, but it probably would have been worse.

FND Servo Mount

The new version of the motor mount is much improved! I’m sure I’ll have an issue with some of the other servos I’m using, as they aren’t all the same size, but it should be as simple as printing two new parts with the properly sized and spaced holes. Again, there’s only three parts because this mounts to… the body!

FND Body

Here’s the new body platform. It’s got all sorts of mounting slots and such. The tool holder gets assembled and then attached to the body. (The “assembly” involves a lot of wood glue at this point.) The motor mounts are glued into place on the body as well. It’s nice finally having things rigid and not held together with hot glue and rubber bands. (Well, some things.)

At this point I’ve basically got a (semi-) generic platform with no specifics on electronics or components. You can fit any number of controllers and battery packs on it. That will probably change in the future as I choose the parts I plan to use.

FND 3.75 Plate

The whole plate fits in a 280mm x 100mm area. That’s just under 12″ x 4″, which means you could fit three of them on a 12″ x 12″ sheet of Baltic Birch.

On to the next revision!

2014.11.11

One of the issues I’ve had with the Friday Night Drawbot is the part that holds the tool has never been very solid. In early revisions I used corrugated plastic, and would just use an X-ACTO knife to cut a hole for a Sharpie, and it would work well enough, and when the plastic wore out, I’d replace it with a new piece. (The most recent body design failed miserably at producing a good pen holder.)

Since I’ve been using other things besides Sharpies, including pencils, charcoal, paintbrushes, clay tools, etc. I decided to design a proper tool holder.

Tool Holder Mockup

I typically use Inkscape to design laser-cut things, but often visualizing a 3D object, even if it will be made from flat pieces, can be difficult, so I decided to use OpenSCAD to model it in 3D. It definitely helped me picture how it would be assembled. I also had the idea of exporting the “plates” from OpenSCAD into DXF files I could then use for the final laser-cut design but that failed miserably.

Sizing

Here’s the start of my layout in Inkscape with the pieces laid flat. This let me get a good idea of the dimensions.

Tool Sizes

I wanted the tool holder to be adjustable, and handle tools from 8mm wide to 16mm wide. (In this top view, the blue circle represent the different sized tools, the yellow piece pushes the tool into a v-shaped piece to hold it tight.)

Layout

Here’s a top view of the layout with some guides to help align things. This is designed for 3mm Baltic Birch (though acrylic could be used.) The slots and tabs are all set for 3mm. There are no fasteners planned as I’ll be gluing it all together.

Layout

Another view from the top, this time with some pieces rotated 90 degrees to see how they will fit together.

Laser Ready

All of the pieces laid out flat and ready to be laser cut. I used 3mm Baltic Birch which worked well using the Epilog Zing 40 watt laser cutter at the DCRL. (I also ended up adding yet another laser cutting workflow to my list. I now have three different methods depending on which of the four lasers cutters I typically use.)

Tool Holder

Assembled with some wood glue, and using rubber bands to hold the tool in place. It works… sort of. I’m already planning improvements, so expect version 2 to arrive by next week. I may switch to a screw mechanism for tightening, which was my original idea, as the rubber bands aren’t working as well as I hoped.

2014.10.20

Friday Night Drawbot v1

There haven’t been a lot of updates to my Friday Night Drawbot project lately, but things are picking up again.

Pictured above is version 1, which was built back in 2011, on a Friday night, in my basement. It drew circles. (And that’s it.)

Friday Night Drawbot v3

The programming got much better, and I ended up rebuilding the chassis a few times. This is what I like to call “version 3″ of the Friday Night Drawbot, and is still in use today.

FND

Let’s call this version 3.5. We’ve shed the old corrugated plastic in favor of a replacement designed digitally, and created with laser-cut wood.

The front plate that holds the pen can now easily slide forward and back, and is held in place by a pair of screws and wing nuts.

FND Drawing

I started the redesign process by taking apart the drawbot and measuring things with the calipers. I then used Inkscape to create (on multiple layers) the parts needed, which consists of the main plate, bottom plate, and pen extender plate.

FND Laser Cut

Here are the pieces separated out and ready to be laser-cut, or, cut in some fashion, I should say…

Old Plastic Body

I tore apart the old chassis which was hot glued to the servo motors, and held together with rubber bands. I had to heat things up to release the glue, so it’s a bit destroyed. No loss!

FND Paper Prototype

This is a paper prototype I created with the Silhouette Cameo, which does a fine job of cutting thick paper. I often prototype cutting things with the Silhouette because, well, it’s in my basement, so I always have access to it (unlike a laser cutter.) I could easily print on paper as well, but I find that with the cutter close by and easy to use, I use it a lot. It helps to have physical things cut and in front of you sometimes.

FND Bottom

Here’s the bottom view of the laser-cut version. There’s a lot of 8/32″ hardware holding things together, mainly because SAE is cheaper than Metric around these parts. (Drat!)

You can see that the two wing nuts hold the pen extender plate in place, so it’s easy to loosen the nuts and slide things around. (The slot could probably be a little narrower next time.)

There’s also some regular nuts holding the bottom plate to the main plate to hold the servos in place. The 3mm Baltic Birch flexes a bit though, and may not be the best solution.

Pen Holder (Bottom)

There’s a captive t-nut to hold the pen in place. It’s a good idea, but poorly executed here.

Pen Holder (Bottom)

The screw does hold the pen, but again, the 3mm wood is a little thin for this to work well. It’s also difficult to tighten and loosen the screw without a screwdriver. I really need a screw that allows you to use your fingers, like the one on the Egg-Bot. I’ll probably make a 3D printed screw-thingy for this.

Detour! I often wonder/worry about mixing laser-cut stuff with 3D printed stuff, and I’m not sure why. Maybe it’s due to the recent kit design work I’ve been doing where we try to make everything laser cut, mainly due to speed and efficiency of production. In this case though, I’d see the 3D printed screw-thingy as an “enhanced” piece, so it should be totally fine. Or I could, you know, use a wing nut. (End Detour!)

Pen Holder (Side)

As mentioned, I find the 3mm wood a bit thin. This whole design is really just 2 dimensional, or maybe 2.5 dimensional if you want to stretch things a bit. I want to have the next iteration be much more 3 dimensional. I may stay with laser-cut wood for most of it, but there is a lot to explore in the design for assembly aspect of things.

FND

I may play more with this version, introducing minor improvements, or just move on to the next revision, which will be much more box-like, and move away from the flat plates.

Since I like to build things really fast, it’s hard to know what will happen next.

2012.04.22

Arc-O-Matic

Once again Gallery Night was a blast… This time myself and the Milwaukee Makerspace guys joined forces with Bucketworks and showed the art-lovers of Milwaukee what we do. (Make things!)

Since both Drawbots were busy at the Art Milwaukee Wedding event, I needed something new to show. (And yes, I did say “both” because there are now two rolling drawbots.)

Anyway, I saw this blog post over a year ago, and made a mental note to explore the idea more, and I did, and the result is the Arc-O-Matic: a robotic drawing arm that makes arcs. Well, that’s basically what it does at this point. See the Arc-O-Matic project page for all the details.

People seem to really like seeing machines that draw, which means I’ll probably keep on exploring the world of art robots.

File Under: FUN.

(Also, if anyone knows who I can talk to at Sharpie about a sponsorship, I’d appreciate it!)

2012.04.04

DamCamp

DamCamp (aka BarCamp Beaver Dam) happened on Saturday, March 24th, 2012 and this is my review…

First off, I will shout out a big thanks to Jason Gullickson, his wife, Wayland Academy, the Beaver Dam Makerspace Project, and anyone else who helped organize the event and made it happen.

Wayland

The Venue
DamCamp was held at Wayland Academy, which is a coeducational college preparatory boarding and day school in Beaver Dam. The main room was an auditorium, which was full of seats, a stage, large screen, and projector. There were two other rooms we were going to use, but we really ended up just using one other room, the lab, where the 3D printers were set up. The venue was easy to get to, and there was plenty of free parking! :)

The People
This was the smallest BarCamp I had ever been to… and that isn’t a bad thing. I remember times in BarCampMilwaukee history when some people were very focused on the numbers, and personally, I prefer quality over quantity. If the right people are there, that’s better than more people being there.

I saw people I knew who I haven’t seen in a while, met some new people, and met people IRL that I’d only met online before. What more could you ask for?

Time Lapse Bot 3

My Junk
If you’ve been to a BarCamp with me, you know I tend to bring a lot of stuff. I’ve been known to bring a photo booth, cameras, tripods, audio recording gear, tables, 200 feet of extension cords, power strips, and on and on. This time I brought Time Lapse Bot, the Egg-Bot, Friday Night Drawbot, my still camera, and not much else. It only took me about 3 trips to load in! (And I found it quite refreshing.)

Friday Night Drawbot

The Sessions
After the opening and introductions we launched into the first session… which happened to be my session. I gave a quick talk about some art robots that I like, and my take on what an art robot is (and isn’t) and then did a demo of the Friday Night Drawbot and the Egg-Bot. (Slides are here.)

I did not keep track of all the sessions, but we did one on 3D printing (there were 3 RepRaps there) and one on creating hackerspaces/makerspaces, and one on making noise with electronics. I ended up getting a lot of good info from the 3D printing session, and I’m a bit more motivated to find the time to finish my RepRap build. (Less sleep is the obvious answer!)

In conclusion, I had a good time, and I learned things. It was a small event, but I don’t think that detracted from it at all. In fact, I wouldn’t mind seeing more smaller events. BarCampMilwaukee is big, and it’s awesome, but it’s also a lot of work, involving a lot of people. Perhaps both ends of the spectrum can co-exist.

If you haven’t been to a BarCamp event yet… why not!? Maybe you’re more into food than technology. Well, you should consider attending Madison Food Camp which is coming up April 7th, 2012! (Yes, I said “Food” not “FOO”, just to be clear.)

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