Lasercutter

After having used the Bitlair laser cutter, I was convinced of it’s use. When the dutch company FabCreator launched it’s affordable kit on kickstarter, I decided to join their campaign. Unfortunately their kickstarter did not get enough funding, but they decided to continue on their own. I recently received my kit and managed to assemble it with the help of Dimitri. After some tweaking I ended up with the following result:

Some pictures of the build process, which took me two full days and a couple of evenings to complete:

Dome rotation

After the body rotation, dome rotation was next. Goal was to determine the start position using a hall sensor, and count the steps using a optical rotary encoder. This way it would be possible to return the dome to it’s center position when desired. Turns out, it works rather well:

Testing rotation

Since I want to make my R2-D2 switch from 2 to 3 leg mode and back, I needed to figure out a way to handle the rotation of the body versus the legs. Two guys at the R2D2 builders club use window power regulators and then use some clever electronics and microswitches to make it switch. As I want to be able to rotate the body also in smaller increments (so that I can make him look up/down a little), this min/max approach would not work. Most of the rotation sensors are either incremental (so I would need a start location), or not made for this (potmeter’s), but luckely I found the AS5048 magnetic rotation sensor, which does absolute positioning.

To test if this would work, I build a small test rig in Fusion 360, then cut it out on Bitlair’s laser cutter and assembled it.

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I still need to work out how to handle PID control properly, but the initial results are promissing.

More body parts

I’ve continued working on the body parts for R2D2. I made a few more adjustments to the Powercouplers, by splitting the insert into 4 separate pieces., which made putting them in a lot easier. I also found out that the majority of the scenes in A New Hope have the top of the center cone painted blue, so I made that a removable ring so that it can be painted separately from the silver parts.

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Next up were the coin returns, which weren’t so much a design to model, but more so to print. I ended up printing them upside down, which gave the best surface finish with all the slopes and reduced the amount of support material (which was still a lot).

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Initial painting tests were quite promising, but does show the importance of sanding everything completely smooth, as every imperfection shows through the silver paint.

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I’m currently working on the octagon ports. The initial model is ready for it’s test print. I might need to do a few adjustments based on that.

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Due to the small indents in the inner part, I had to split them into separate pieces so they could be printed without support. Eventually they would just be glued together and sprayed silver.

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Light sabers, painting and power couplers

It’s been a while since my last post, but I’ve been quite busy researching various parts of my R2-D2 build. Ofcourse I got a bit distracted by my new BigBox printer, and ended up printing a light saber, which is going to be my airbrushing test object.

Speaking of airbrushing, I’ve been trying various possibilities for the metal / aluminium parts of the build. I’ve painted some sample pieces with Vallejo metal paints (aluminium, duraluminium and chrome), but have not yet been really impressed.

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I do think I want to go for the not-so-shiny look of the dome from A New Hope, but won’t know for sure until I’ve also tried the solvent based Alcad II paints. I have 3 colors (aluminium, polished aluminium and chrome) to try before I can decide, but given that I need to paint that stuff outside, the gloss black primer is going to have to sit there till the weekend:

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I did manage to get a bit of work done on the power coupler model, which was needed as the parts didn’t really fit together the way I had imagined they would. The fit is still a bit too tight, and I’m a bit worried that applying XTC-3D will make that even worse, so I might add a little bit more spacing.

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All in all a lot of research, but all slowly taking me closer to actually building R2-D2.

Learning onshape

Appearantly creating a more complex shape consisting of multiple separate parts in OpenSCAD is testing the limits. After adding a couple of connectors between parts, the preview slowed to a crawl and exporting parts took ages. So I set out to test various CAD tools to find one that was affordable and easy to work with. For the moment I’ve settled on OnShape while I attempt to make the models for the rear door.

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My biggest problem with OnShape so far is that you can only have a couple of private documents, and more importantly they cannot be more than 100Mb. Now you would figure that would be enough for some basic stuff, but with the whole version history even a simple frame as the one above takes up about 30Mb of space. I might end up having to make the design public just to get around the 100Mb limit.

Cutting complete

After lots of cutting, I finally removed the last bit of styrene from the skins. Being the perfectionist that I am, I see lots of flaws in my work, mostly near round edges. At some points I hope to build a (Mostly Printed) CNC machine to redo the skins, but for now these will do to give an idea of the size of things. I measured the rear door and it came out the size the blueprints specify, so that can be a good first test for my 3D printed frame.