Chris (http://www.artoo-detoo.net) has added my blog to the builders’ blog RSS feed. I guess that means I’m officially a club member now. I feel honored.

I’m done with the skirt. For me, this has been a very hard part — all this chamfering and curving parts. And I can’t say I’m too happy with the results; see below.

 

I learned a new word: Chamfering. It’s ancient Enochian for “to voluntarily put oneself through the most tedious torture possible”. Chamfering with a file, like I did at the beginning, takes ages and no matter how much you file, you never get it right. Took me a while to figure out a method to do it with a little less work. Basically, I use my Dremel with a routing bit to do a very rough chamfering and then only file/sand away the remaining irregularities. The above image shows the basic idea, only normally I’d hold the piece down with my hand, which was needed here to take the photo.

The photo to the right shows the skirt at about 60% completeness. The paper sheets I’ve put underneath are to keep the glue from gluing the skirt to the base of the body frame, since I want to be able to separate them later on.

  

The completed skirt, separated from the body. Getting those curves properly was a pain! And it didn’t work out very cleanly.

  

The skirt screwed to the body. There are 10 M4 screws, and the body plate has been reinforced to 6mm thickness and tapped for M4. I didn’t really trust M3 for this part, as it’s going to carry a lot of weight later on.

You can’t really tell on these bad photos, but the whole thing hasn’t turned out very clean. There are protruding edges and corners, parts that aren’t really glued together but have gaps, etc. It’s not pretty. It’s also not very clean, as you can see from the center image above. One more thing I learned: The glue on the underside of duct tape, when brought in contact with styrene glue, will dissolve and bond with the styrene. I used duct tape to hold parts together while the glue set, since I had no other way to hold these rounded parts together with clamps. Result: Brownish stains left by the duct tape.

Oh well. The stains and some of the unclean work will probably be hidden by the painting process later on. Anyway, this is kind of a temporary part. When I’m modifying my droid with the 2-3-2 mechanism, I’ll redo the skirt.

Another thing: I’m planning to mount ultrasound sensors on the skirt, 3 to the front and 3 to the rear, between the pairs of ribs that are close together. Let’s see how that works out.

The body frame sitting on the screwed-on skirt.

Next up: The legs!

Some progress:

My “Workshop”

1mm Styrene with skin template glued to it

Test fitting the skins — looks good, but botched vent cutouts

I cut the inner skins and learned a couple of things. First of all, cutting 1mm styrene is very very easy. I love this material! Second, at least for styrene this thin, you can cut everything with the knife, even circles! I botched up the inner front skin around the front vents, clearly visible from the image above, because I used a circle cutter mounted to my drill, which promptly slipped. The circles around the shoulders were cut by hand, without any guide except the printed outline of the plans, and came out great. Maybe I’ll do the inner skin again. Then again, the front vent cutouts are duplicated in the outer skins, so the botched ones I have now won’t be visible, so maybe I’ll just keep them.

I won’t glue the skins on until I have the legs done, so I have time to decide.

The skirt. Not for the squeamish!

I screwed up.

I also started work on the skirt. This is not for the squeamish! Gluing a half circle out of 3mm styrene is pretty hard. Again, I learned a couple things. First of all, don’t use circle cutters on drills if you don’t have a drill press. The image on the right above shows a corner that I drilled. I couldn’t hold the drill and the styrene properly at the same time, so I ended up drilling out much more than I wanted. Oh well, I won’t glue the skirt on but screw it on, so I can change it later. Second, the next skirt will be done with the aid of a hair dryer.

I’ll finish the skirt over the course of the week. Then it’s on to the legs.

I’m still trying to decide what I’m going to do with all the details (octagon port, power couplers, booster covers, …): Buy them or make them all myself.

Since Arislan asked, here’s a picture of the router setup I use to cut circles:

I just took my Dremel and its router attachment and screwed it onto a wooden plate from the hardware store. Those marked holes you see in the second picture are the centers of the circular body plates. Just put a nail through a sheet of styrene and through one of those holes and start routing

The nice thing is that I can move the router just a tiny little bit with my hand underneath the plate while cutting, which gives very fine control over the resulting diameter.

I don’t have space for a proper workshop in my apartment (as the basement is full of keyboards and Ilka’s drum kit), so the wooden plate you see is the entirety of my Astromech factory. Anyone can do it, indeed!

What do you do if you have no free time and too many projects? Why, you start a new one, of course.

I’ve always wanted to own an R2-D2. In a way, the fascination with that little droid is what brought me to robotics, so it’s probably R2s fault that I am where I am today. Thing is, you can’t buy one, and until very recently you needed a pretty large workshop, CNC router, bandsaw and all, not to mention some mechanical building talent, to build one. As a software guy, I lack all of this, but things have changed recently through the genius of the R2 builder’s club and Dave Everett, who designed a set of plans from which anyone who can wield a Dremel can build an R2 out of styrene.

I’ve put in about 10 hours so far, I would guess, and it’s been a blast! This weekend, I completed the body frame. Here it is in all its glory:

The first two images show the frame halfway completed, the next two are the completed frame. The last image shows a slight modification to Dave’s plans I’ve done: The center foot is originally fixed, but I want my R2 to eventually have a retractable center foot and do the infamous 2-3-2 transition. Since I don’t want to build a new body at that time, I’ve cut out the hole for the retractable center foot and will build a removable assembly of skirt, bottom plates and fixed center foot. Then I can swap between retractable and fixed at will.

I had a hard time finding some of the stuff required for droid building in Germany; some of the recommended building material has different names or is not available. The main stuff, “styrene” in English, is “Polystyrol schlagfest” or “Styrolbutadien” in German. You can get transparent Polystyrol under the name of “Bastlerglas” at hardware stores; don’t use it, it’s hard (not in a good way) and brittle. The right stuff is white and very pleasant to work with. You can get it online here, here or at many other places. To glue it, I use Ruderer L530TF, cheap and awesome and available at your local model builder’s store.

I’ll be posting my progress here now and then. Feel free to comment!