The Big Think

July 2, 2015

More Skirt

Filed under: The R2 Project — jasony @ 5:57 pm

Went back to TechShop today for about four hours and recut the skirt parts. Fortunately the design work was done and I already had the free metal so all it took was about 30 minutes to set up the machine and cut (the cutting time itself was exactly 5 minutes). So at a cost of $15 I remade the surround parts.

Next, I turned to the slip roller and carefully rolled them out so that they’d match the curve of the thick piece (in the photo below). It took figuring out a little jig but I’d already done that, so even that part went fast. Unfortunately, the machine grabbed one of the curved pieces and chewed it up pretty badly. Sure, I could have made it work, but did I mention I’m redoing the skirt? I was going to just use it but didn’t want a rehash of the first time through when I kept plowing forward despite errors, only to have to start again so… more waterjet! I got the key, set up the blank, zeroed the machine, and had the part cut inside of five minutes. It took 1:18. Such a short cut, in fact, that the desk staff just let me have it free! Between the free metal and this free waterjet part, all it cost me to redo that specific part was my time: about ten minues.

I… very carefully… slipped rolled this part until it was perfect. And I mean perfect. It’s by far the best made part on the skirt surround. In fact, I was so happy with it that I grabbed the other curved part (the one that was almost perfect) and decided to run it through the machine so that it would match. I’d have two perfect pieces!

Big mistake.

Did you know that aluminum, when subjected to multiple rolling forces, slowly gets harder? Yes it does. And now I know it, too. Because when I sent the formerly-almost-perfect piece through the slip roller it got stalled and bent out of shape. Not a lot out of shape, but just enough to throw the alignment of the entire surround off. AARGH!! In a panic, I tried to correct the mistake by slip rolling it again but only made the problem worse (and the aluminum even harder). So… I stopped, took a breath, and manually re-bent the piece. I got it back to aaaalmost as good as it was before and then called it done. It’s close enough that I will (hopefully) be able to put some pressure/clamps on it when it JB Welds and then repair any small gaps with Lab Metal. If not, there’s always Skirt 3.0!

The surrounds are drying at TechShop right now. I’ll go back in at 10 or so tonight and move them to my locker after the JB sets. Then tomorrow I’ll go and spend some quality time on the mill fixing the gap issues. Here’s a pic:


Overall it took about 30 hours to design, cut, and assemble my horrible looking first version of the skirt. The second version took about 4 hours (though it’s not quite done yet). I’m glad I redid it but I’m sure ready to have this part behind me. Lots to do on it, though. Stay tuned.

R2 Skirt Redux, Redux

Filed under: The R2 Project — jasony @ 8:46 am

I used the wrong plans. The skirt is wrong. Yes, after all that work – 30 hours of work over a month or so of days – it turns out that R2’s skirt just isn’t going to work. There are clearance issues when I put the skirt on the frame that I just can’t kludge together and make work. Here’s a pic:


There shouldn’t be that gap between the skirt and the frame (keep in mind the whole assembly is upside down in this photo).

It turns out that I was using a slightly modified version of the skirt made to fit a different frame. The external dimensions are correct but the thick piece on the top of that photo above causes alignment issues. I should have used bent sheet metal that would have created a pocket where the posts rest on the skirt, thereby getting rid of that clearance.

So I’m going to have to start completely over on the skirt and remake it. Fortunately I have the waterjet files and the side pieces are correct. I also scored a free piece of metal from Metals4You that was the right size and shape from their cutoff bin. They told me to just take it (guess they appreciate all the metal I’ve already bought from them). The waterjet time will cost about $12 so that’s not a huge loss. More JB Weld cost less than ten bucks.

I will have to go back in and spend some time milling up the thick bottom plate to create pockets for the posts to remove that gap. I’ll also have to shorten the posts slightly (about .2″) to tighten the gap up. Those posts aren’t Canonical since they’re inside supports so I still have a screen-accurate droid. The important part is the shape and size of the visible parts of the skirt.

To be honest I’ve suspected I was going to have to remake the thing for a couple of weeks now. The old skirt was progressively looking worse and worse as I made mistakes and kludged together fixes that caused more errors. Now that I’ve been through the process once I’m confident that I can quickly cut, bend, and assemble the new skirt with minimal fuss. And I still have the old skirt to practice powder coating on so that’s good.

I keep telling myself that I have plenty of time and no real deadline on this (though I would like R2 to be mostly finished by my 50th birthday in Sept. 2019). This is supposed to be fun and a learning experience. I guess that means that I’ll occasionally have to go remake something as I learn my way around mistakes the first time through.


Filed under: Politics — jasony @ 8:05 am

Investigators find proof IRS destroyed evidence in targeting scandal:

“‘We’ve confirmed the backup tapes no longer exist,’ Koskinen said. He maintained Lerner destroyed the hard drive on the computer and no additional information could be retrieved.

Despite a subpoena order to provide documents, IRS employees working night shifts demagnetized the contents of Lerner’s’ computers, according to the inspectors general.”

The Justice Department has refused to press charges. This will be minimally covered by the media, and nobody will go to prison.

Nixon was a schmuck.

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