“The New Yorker claims that more than 1,300 students recently signed a petition calling for the college to eliminate any grade lower than a ‘C’.
The students complain that it is not fair to grade them on their performance in class because they are so distracted by their activism…
…Last December, for instance, Campus Reform reported that student protesters had submitted a list of demands to their school’s president, including one calling for hourly monetary compensation for activists.
Earlier this year, activist students at Brown University voiced similar complaints, saying their schoolwork was interfering with their activism efforts.”
May 31, 2016
May 30, 2016
I met with Keith at Techshop yesterday for a 2 hour TIG welding master class. The guy is a riot of old-school enthusiasm and energy and I learned a lot from him. At the starts of the session I showed him my practice welds (I have a plate of about 20 welds on it that I’m particularly proud of) and wanted to spend the time taking about the pieces I’d brought and how I would eventually weld them together. What does he see when he sees those pieces? How does an experienced welder view a part? What’s the best approach for clamping? What about cool down time?
He’d have none of this “planning” stuff.
Instead, he looked at my test piece with approval, said “you can weld”, then chucked the test piece aside, grabbed the horseshoe pieces, and said “you’re going to weld this…. right now”.
And so I did.
He did the first couple of tack welds to hold the part together, get things heated up (welding a part is much easier when it’s already hot), and generally give me a start, and then he handed me the torch and we went after it. If I made a slight mistake he jumped in and either corrected it or talked me through how to fix it, and then handed the torch back to me.
Over the next two hours we welded up the horse shoe and then aligned and welded up the center ankle. I feel really good about how things went, especially considering the fact that I didn’t think I’d be working on actual parts for a few weeks. Keith is a “get ‘er done” sort of guy that encourages students to jump in there and start even if they don’t know everything. I’m much more careful about parts that I’ve spent months and lots of money making, but Keith is kind of a whirlwind that you just get sucked up behind.
The hardest part of the process was the angles and orientation. I’d been planning on carefully laying out the parts so that the joint to be welded was flat and parallel to the ground. That way I could approach the weld exactly like I’ve done each weld in practice. Keith’s attitude was this is real welding! and he’d proceed to put the joint at some funky angle and then challenge me to do it. Sideways, angled, even upside-down at one point! Really awkward and tough stuff. And this was on my actual parts! It really freaked me out, but like I said, he was there to correct things when I got them wrong.
And boy,did I ugly up some of the welds. Black, splotchy, butt-ugly welds. They’re strong enough, sure, but I’ll be spending some real quality time with the grinder once I clean them up. Keith kept saying “don’t worry! You’ll improve!” and I kept saying “but I could do this if we could just lay it out flat!”. He’s respond with “no way! This is REAL welding!” and then make me bend myself into some impossible orientation to get ‘er done. It was stressful, but I learned a lot from the experience. The chief thing I learned was that, unless you completely destroy the metal with heat, you can fix just about any bad weld. Keith didn’t do much cleaning or anything and still managed some good welds. We talked pedal control, getting REALLY close to the puddle (he was probably 1/32nd from the weld with the tungsten!), using a different tungsten (I’d been using the red 2% thoriated and he recommended the purple 2% seriated because it holds a cleaner and more consistent arc), speed, power (150 amps!) and other stuff.
I got a couple of decent tingle/zaps from the setup when my left hand got soaked with sweat inside the glove. With 150 amps of 6v electricity, even with protective gear, getting a damp hand in the current can cause some discomfort. It didn’t hurt as much as it was just unpleasant. Some tingling like touching a 9 volt with your tongue. Lesson here is to take breaks and make sure you’re dry. But that’s hard to do when you’re in the Keith whirlwind.
So I’ve got both horse shoes welded and the center ankle. I’m going to mill up a special part for the center ankle to reinforce the mounting holes. I don’t think the 1/8″ of aluminum there is strong enough if R2 hits a good bump. It’s technically an “off spec” part but it’ll be hidden underneath R2 way up inside along the bottom of the frame so I don’t care. Better that than have the whole ankle shear away. An extra 1/4″ of aluminum there should work nicely.
No pics on these parts yet. I can’t have my expensive iPhone in my pocket when I weld lest I zap it. And usually I’m so tired and grubby after a 4 hour session that I just want to get home and take a shower. I’ll take pics later.
Next step is to do the outer ankles. I feel really good about my approach now that I’ve watched Keith do it. Then I’ll weld up the leg assemblies and then maybe the feet. I’ll leave the battery boxes for the end since they’re going to be a real challenge to align and tack up without them warping all over the place. Slowly, slowly.
May 23, 2016
That’s a great big old pile of aluminum:
What you’re seeing here are all the aluminum parts I’ve milled, water jetted, lathed, and otherwise mashed up since last September (really since about February).
Starting from the left are the leg boxes, horseshoes, ankles (bottom left), battery boxes, and ankle bracelets. Then on the right hand side are the feet (all spread out on the table).
I opted to let Big Blue Saw cut the water jet files for the feet since it wasn’t that much of a premium and since they would replace any pieces that were messed up. Overall I think this was the wiser course even if it wasn’t immediately cheaper. It was cheaper in the case of the water jet making a mistake (something that happens about 10% of the time at TechShop). Even so, there are 90+ pieces of the feet (center foot and two outer feet) that have to be welded.
And oh, the welding. Most of the above pieces except for the horseshoe at the upper left still need to be TIG welded. There are 174 remaining pieces that will need to be cleaned, aligned, clamped, and TIG welded. I’m not sure of the total length of welds but it’s a lot and I’m sure I’ll be at it for months. Fortunately, except for two pieces, all of the machining and cutting is pretty much done for this year. Once the feet are welded I have to cut some pipe to size and then lathe, cut, and mill out a weird piece. Then once all of what you see here is done I’ll begin designing and cutting/welding the foot motor mounts. I think I’m going to do those custom but I’m still thinking about it. That’s for later.
My goal is to finish all of this by September but I still don’t have a good handle on how long the welding will take. I’m going to put in a few more 4 hour sessions practicing before I try and tackle an expensive-to-replace part. I’m going to hopefully get a one-on-one lesson with Keith at TechShop this weekend. He’s the good welder from my previous posts (one of the best in Austin). Then I’ll go through the pile of parts and start welding up assemblies from easiest to hardest, thereby gaining experience as I go. I suspect the battery boxes are going to be the hardest so they’ll be last.
I’m thinking that I’ll end up missing my September deadline as things progress since I haven’t even included time to correct the leg boxes on the mill (long story for a future post), drill and tap holes for mounting the horseshoes, drill out the ankles and install bushings (no idea how to do that), and probably spend two or three long sessions making the funky curved parts for the outer feet. Oh, and I also need to research how to remove anodization with a lye bath. Got some industrial strength lye (and a pile ‘o protective gear) to remove that but I’ll need to do a practice session on some scrap to make sure I have the procedure down correctly.
Then it’s on to the foot motor assemblies, which I’m kind of looking forward to. I’ll need to commit to the motors (I’m thinking a pair of NPC2112 motors — they’re pricey but they represent “real” robotics motors instead of hacked up scooter motors). I’ll get those soon and then start designing the motor mounts. The feet need to be welded up first, though, so that I can make sure that I have enough clearance inside the shells.
Going to TechShop this morning for a 4 hour TIG practice session. I’m running out of scrap and will probably drop by Metals4U and get some .125” pieces (hopefully from their scrap pile) to continue practicing.
May 12, 2016
Harvard’s clueless illiberalism – The Washington Post: “Touring early America, Alexis de Tocqueville marveled at the people’s propensity to form associations for every purpose under the sun: ‘religious, moral, grave, futile, very general and very particular, immense and very small . . . to give fêtes, to found seminaries, to build inns, to raise churches, to distribute books, to send missionaries to the antipodes.’
Associational proliferation buttressed individual freedom, Tocqueville believed. As he explained, private groups are nimbler at orchestrating cultural and social life — ‘maintain[ing] and renew[ing] the circulation of sentiments and ideas’ — than government could ever be.
States ‘exercise an insupportable tyranny, even without wishing to, for a government knows only how to dictate precise rules; it imposes the sentiments and the ideas that it favors, and it is always hard to distinguish its counsels from its orders,’ he wrote.
Harvard University’s administrators should read Tocqueville’s book ‘Democracy in America.’ Their institution is not, strictly speaking, a state — it’s more of a state within a state, up there in Cambridge, Mass. In every other way, the school’s new crackdown on fraternities, sororities and a local variant, ‘final clubs,’ epitomizes the clueless illiberalism against which the French sociologist warned.
Harvard has concluded that, in response to sexual assault and other manifestations of gender inequity, it must reform campus culture. Single-gender social organizations are unavoidably discriminatory, President Drew Gilpin Faust noted, ‘in many cases enacting forms of privilege and exclusion,’ contrary to what Harvard stands for.
Being private, self-funded and, technically, off-campus, the groups can’t be banned; but they can, and will, be discouraged and stigmatized. Starting with the class admitted in 2017, no student members of single-gender fraternities, sororities or final clubs may hold ‘leadership positions’ in Harvard’s hundreds of officially ‘recognized’ undergraduate organizations. Nor may they apply for fellowships, such as the Rhodes and Marshall scholarships, that require an official college endorsement.”
Read the whole thing.
It’s interesting to me that suddenly the various groups who have been in favor of limiting freedoms they don’t agree with have suddenly become outraged when their own particular ox is up for goring. This has been the (sadly missed) point of the voices who have spoken out against Social Justice Warriors and anti-free speech people lately. What’s become of “I don’t agree with what you say but will defend to the death your right to say it?”. It’s been flushed down the PC toilet. And now the next step is to deny under penalty of economic sanction the freedom of association that we take for granted in America.
And just so I preempt the people would would say “but Harvard is private! They can do whatever they want! Freedom of association is only a government thing!”: you don’t really get the bigger point here? But don’t worry, your ox is up for goring next.
May 11, 2016
I did a drop test on the dummy part and determined that I need to grind the channels between the layers a little deeper to get better holding between the layers. But otherwise I’m actually ahead of where I thought I’d be after only 12 hours of practice! Very encouraged.
I spent 10 hours at TechShop today. 4 doing welding practice and the rest grinding and prepping the parts for welding. Really successful day.
May 10, 2016
I’ve spent the last few days (post concussion) designing and tweaking the design for Artoo’s Outer Ankles. The water jetted layered .25″ aluminum trick is working nicely. I still have to TIG weld everything but Keith was able to TIG the .125″ horse shoes a few weeks ago and it worked well.
Today I checked out the water jet and spent four hours cutting 21 parts for the outer ankles. I had to remake one part since I didn’t clamp down the metal well enough and the edges were really jagged and messed up. I could have maybe dealt with it while welding but I decided to spend the extra three bucks and just cut another one. Total price for the outer ankles was just over $50 for the water jet time. The reason it took so long (4 hours!) was because I cobbled together a bunch of scrap aluminum that I’d used on other parts. I got all the parts in on scrap! This saved me probably $50 extra dollars in aluminum and let me clear some cruft out of my locker. Keep in mind that I’ve now done all three ankles (one center and two outer) for about $120. If I bought these over the internet from one of the suppliers they’d have cost me over $900!
In fact, I just looked at my master budget sheet and if I just look at Year 2: Legs I can get a sense of just how much I’m saving making the parts myself. Here’s the going price on the internet if I just bought the aluminum leg parts that I’ve made so far:
Leg boxes: $900
Ankle Bracelets: $30
So if I’d have just laid down the dough I’d be looking at almost $2500. I’ve spent less than a fifth on the legs. From here I still have to do the feet and the drive mechanisms, which would add another $1800 if I bought them…. and which I’ll get for an even better fraction.
So yeah… building it yourself is definitely the way to go, and the skills you pick up can’t be beat.
Speaking of which, I’m into my TIG welding practice. I’ve spent 8 hours at the TIG and can just now barely succeed (sometimes) at not embarrassing myself. But if I can just break through to reliably making two or three inches of halfway decent welds then I’m home free. I’m saving a bunch of offcuts and scraps of aluminum in various thicknesses to practice on. My plan is to make all the parts for the legs– horseshoes, ankles, leg boxes, feet, etc– but not weld any of them. Once the parts are made I’ll then dig in for several weeks of slow and methodical welding on each part. All I have to do is one or two inches at a time, let things cool, then repeat. I figure I probably have 200 feet of welds to do. It’s gonna take a while.
But slow and steady wins this race.
I may not be the most talented guy at any particular thing, but what I lack in ability I make up for in sheer stamina. I figure if I can stay with this R2 build for a half decade then really nothing is outside of my grasp.
May 9, 2016
Former Facebook Workers: We Routinely Suppressed Conservative News: “Several former Facebook ‘news curators,’ as they were known internally, also told Gizmodo that they were instructed to artificially ‘inject’ selected stories into the trending news module, even if they weren’t popular enough to warrant inclusion—or in some cases weren’t trending at all. The former curators, all of whom worked as contractors, also said they were directed not to include news about Facebook itself in the trending module.
‘I believe it had a chilling effect on conservative news..I’d come on shift and I’d discover that CPAC or Mitt Romney or Glenn Beck or popular conservative topics wouldn’t be trending because either the curator didn’t recognize the news topic or it was like they had a bias against Ted Cruz.’
The former curator was so troubled by the omissions that they kept a running log of them at the time; this individual provided the notes to Gizmodo. Among the deep-sixed or suppressed topics on the list: former IRS official Lois Lerner, who was accused by Republicans of inappropriately scrutinizing conservative groups; Wisconsin Gov. Scott Walker; popular conservative news aggregator the Drudge Report; Chris Kyle, the former Navy SEAL who was murdered in 2013; and former Fox News contributor Steven Crowder. ‘I believe it had a chilling effect on conservative news,’ the former curator said.
Other former curators interviewed by Gizmodo denied consciously suppressing conservative news, and we were unable to determine if left-wing news topics or sources were similarly suppressed.
Managers on the trending news team did, however, explicitly instruct curators to artificially manipulate the trending module in a different way: When users weren’t reading stories that management viewed as important, several former workers said, curators were told to put them in the trending news feed anyway.
…When stories about Facebook itself would trend organically on the network, news curators used less discretion—they were told not to include these stories at all. ‘When it was a story about the company, we were told not to touch it,’ said one former curator. ‘It had to be cleared through several channels, even if it was being shared quite a bit. We were told that we should not be putting it on the trending tool.’
‘We were always cautious about covering Facebook,’ said another former curator. ‘We would always wait to get second level approval before trending something to Facebook. Usually we had the authority to trend anything on our own [but] if it was something involving Facebook, the copy editor would call their manager, and that manager might even call their manager before approving a topic involving Facebook.’
I’m waiting for the online counterargument to go from “this couldn’t possibly have happened” to “well, all news is biased so this isn’t really a big deal”.
What’s a big deal is getting a filtered view of reality when you think you’re getting the straight information, and trying to make decisions based on that assumption.
All the people in favor of this sort of corruption are only in favor of it because it helps their side. Give it to me straight and let me make up my own mind.
April 25, 2016
After sitting and pondering and sitting and thinking and sitting and staring off into the distance for far too long I think I have finally cracked the center ankle problem. This whole time I’ve been trying to figure out how to make this shape:
from either a solid billet of aluminum (expensive and hard with many chances to break bits), or by forming/welding a rectangular bit of channel and then welding onto a solid hunk of aluminum for the curvy bits. The problem with the second approach is that aluminum is such a good conductor of heat that the thin walled channel will overheat and melt before the solid hunk even gets up to melting temp. A true welding pro can do it, but me? Not even close.
So what to do, what to do? More sitting and staring off into the distance, and then a long, slow walk around Techshop. I do my best 3D thinking while moving.
Then I looked at the layered horseshoe assembly I’ve been working on and thought OF COURSE! Could I adapt that idea to the center ankle?
So I used Fusion 360 to design the two different layer shapes, exported them as .dxf files into Illustrator, checked the geometries, did a little bit of redesign on the interior of the foot, and then dropped them onto the laser cutter with some 1/4″ plywood for a proof of concept. The plywood was being stubborn and didn’t cut too well (and there was a guy waiting to use the laser anyway), so unfortunately I had to finish the cut on the bandsaw. It turned out very rough but I was more worried about seeing it prototyped than seeing it neat.
Here’s the Illustrator file of the layers:
With the layers (badly) cut, I quickly glued them together, trying my best to keep the layers aligned. For the aluminum version I might cut a couple of alignment holes and then tap threads so that I can run some permanent alignment screws. That way they’ll be nice and tight and aligned before welding.
Once the stack dried I took them into the wood shop and hit them with the big stationary belt sander to clean up the edges and sides.
So if you’re keeping track, I had a brainstorm and was able to use the following process to go from idea to physical prototype:
Fusion360 CAD software
Trotec Laser Cutter
All in the course of about two hours (a little more if you count drying time). The end result?
You can see the inside lip that the corresponding mounting block will rest against. This means that the weight isn’t being borne by the screws (as in the blueprints), but by the structure itself. That was my little idea. Yay me.
And here it is on the upside-down frame. It works! It works GREAT! I’ll double check the measurements tomorrow but it looks great! I’ll just have to make sure that the layers are perfectly aligned before I weld them together since there is literally maybe .001 of slop in that inside joint. If I mess up the alignment it’ll be a whole lot of filing to get it to fit together. Lining up the screw holes isn’t going to be fun either. But hey, if there’s one thing I can do, it’s the slow and steady thing. I might not be the most talented guy around, but I’m stubborner and mule-headeder than anybody.
My prototype isn’t pretty, but it does the job and I think it’s exactly the right way to go about this. I’ll make the curved outer part out of 16ga (.063″) 5052 and bend it on the slip roller, then cut and weld the curved part with the slot in it last (and probably file and sand for hours).
I’ll still have to TIG weld the edges of the aluminum once they’re cut on the Water Jet and ground down to make the little “V” shaped edges. But since I’m working in consistent 1/4″ layers, uneven heat build up shouldn’t be a problem. That’s the beauty of this design and I’m actually rather proud of my solution. I’m fairly certain that I’ll be able to use the same procedure to make the outer feet with just a few alterations for a slightly different geometry. The best news? If I bought these feet online from a builder they’d run around $900 (!!!!).
Doing them this way will be about a quarter of that.
I feel really good about my progress lately. I had been feeling stuck lately what with the horseshoes. But all the thinking and staring off into space finally got things unjammed. I feel like I have some momentum now.
After the ankles will come the feet (a huge multi-month job) and then the motor mounts but those are both on the far side of 40 hours of TIG welding practice. But that’s basically Year 2: Legs in a nutshell. I can’t see the end of this particular tunnel but I feel like I finally have a map that makes sense.
This morning (really early… insomnia) I also bought some aluminum prep cleaner (called, naturally enough, “Alumiprep 33”) that should make the TIG learning a lot less painful. Dirty aluminum is a pain to weld and this stuff cleans it right up. Wasn’t too expensive either.
So yeah…. Center ankle!
An interesting article about a potential space drive breakthrough that nobody can explain. This story is cropping up in the more respectable tech press and has been around a while so I’m intrigued. It looks like there might actually be something to it.
April 24, 2016
When even a (very left-leaning) Vox writer notices it, you know something has gone badly wrong in political discourse. My hope is that the people who need this the most will read it with consideration. My fear is that they will and not see themselves therein.
April 23, 2016
It’s been a busy R2 week! Feels good to get some serious time in on the build. Tonight, after spending 8 hours at Techshop (four of which were teaching a water jet class), Erin and I went out to dinner. While leaving dinner I said “I kinda feel like going to Techshop”. It’s nice that the place has such a good hold on me and I don’t get tired of it.
Now that it looks like I have a handle on the horseshoe I went ahead and cut the rest of the layers (six of them) for the other side. Then I filed off the tabs and ground down the v-grooves on the edges of each. So now I have a second stack of horseshoes all ready to weld! I might hit up Keith again to walk me through it, but this time maybe he’ll let me weld while he advises from the sidelines. I’m about ready to get started TIG welding parts.
Side story: tonight my water jet class had two people in it. Normally it has four. I really like two person classes since I can help the students more and I don’t feel as rushed. One of the men in the class was about 70 years old with a great sense of humor. Funny stories (he was a pilot as well so we could talk endlessly about planes and flying), great sense of humor, and — unusual for someone of that generation — was heavily involved in programming and microcontroller technology. We hit if off immediately and I had a great time teaching him. The only issue was that it was sometimes rather difficult to understand him on account of the fact that half of his face was missing. And one whole eye.
You see, this funny, lighthearted, intelligent septuagenarian is fighting a long battle with cancer. 8 years ago he had a tooth that wouldn’t heal and here, eight years later, he’s had one eye removed, he’s missing the teeth on one side of his head, the entire left side of his face is nearly gone from the cancer, he’s wearing two hearing aids, jokes about his lack of depth perception, and says the hardest part of his life comes every four months when he goes in for his MRI to see if the cancer has returned yet again (it keeps coming back). The hardest wait is between the MRI and waiting to see the doorknob turn and see if his doctor’s face is smiling or ashen. He calls it “getting his ticket punched for another four months”.
And now this guy chooses to spend four hours of his remaining time in my classroom learning how to use the water jet because he wants to be a Techshop member and he wants to use the tools to build cool stuff. He’s not sure if he’ll be here next year, or even six months from now. But with the time he has left he’s going to make stuff, and try to make it well. And I can’t tell you how much I enjoyed getting to know him.
Some good success today. I coated the horseshoes in JB Weld and LabMetal to fill in the little V-grooves that I ground in each side layer. It was ugly once it dried:
Next I clamped the part in the vice with some wooden shims:
Then I ground the welds and filler down with an aluminum grinding disk that Keith gave me the other night (thanks, Keith!) They looked really good after I was done. Nice and smooth and flush with the surface. Since I was using a disk and not a belt, though, it was easy to make little divots and gouges in the soft aluminum. There’s a bit of waviness on the edge of the part in this photo:
So I’m ordering some Rage Gold body filler from Amazon (the same stuff I used to make the Tri Delt clamshell prop about five years ago). I’ll do a few layers of filler on the outside so I can cover up the metal edges. But before that I still need to drill out that broken screw (you can see it in that top photo).
So in spite of the expected (and unexpected) little snags it appears that I have a clear way forward on the shoes! Really happy with the way it’s turning out.
I spent about 3 hours at TechShop this afternoon and in addition to the grinding I also did some thinking about the center leg ankle. The finished part should look like this:
with this inside (I’ve already made the rectangular part):
I had what I thought was a shoe-in idea for this and spent some time at TechShop designing a file in Fusion 360 (what a great program), but now that I look at it in the first picture above I’m not so sure it’ll work. More thought needed.
A lot of this thinking is due to the fact that I can’t TIG weld (yet). I really should get off my butt and just do it. I’ll probably ask some advice and start that process next week. So much would be easier about this project if I could just TIG. Even badly. Grinding down that aluminum results in an amazingly clean joint (see the post-ground horseshoe pics above). But the process kind of scares me.
April 20, 2016
In the great-news, slightly annoying news department, I went to Techshop today and bumped into the welding instructor (a super guy named Keith Wojcik who is one of the best welders in Austin). Great guy, great teacher, great welder.
I showed him the part and asked him if it was even possible to weld it and he said “come here” and wandered back to the welding room. Back there he set up the TIG welder, described what needed to happen, and then just welded it for me right there. I couldn’t believe it. The aluminum was pretty dirty so the welds ended up a little messy (absolutely not Keith’s fault), but at the end all seven layers were securely welded together. Success (so far).
It’s a tack weld job and will be ground down and cleaned up, but the layers are connected. I’ll also put a coating of Lab Metal between the welds to cover the layers and then grind/sand it down until it’s smooth.
Unfortunately (you knew this was coming), I think the screws were overheated when the aluminum got hot — and it got stupendously hot. It took more than 45 minutes for the aluminum to even be movable, and even then I had to wear leather gloves. Anyway, the screws got bound in the holes. I also think that the act of clamping the parts together compressed the threads in the holes and made the screws bind even tighter.
Sooooo… when I went to take the screws out they were extremely difficult to turn. Two of them came out with a little bit of effort. But that third one? The screw head just snapped right off. Nooooo!!!! Luckily there was still a little bit of thread showing so I got some Vice Grips after the little threaded leftover…… and promptly snapped that off as well, completely flush with the surface.
So I have to figure out how to remove that bloody screw. That stinking #$@#@^ screw. It’s so completely stuck in there that a normal screw remover probably won’t do the trick (though I have nothing to lose by trying). What I think I’ll end up having to do is slowly destroy the screw by drilling it out with progressively larger bits. I might have to enlarge the hole and put a #10 screw in there instead of the #8 that’s stuck, but that means enlarging the mating keyhole, which introduces alignment issues (which I’ll have to figure out a solution for). There’s also the risk of breaking the welds when I clamp it on the mill to remove the screw. UGH
But hey! One of the horseshoes is welded. Better yet, Keith told me that he’d weld whatever I need. He’s also going to teach me TIG. I took his MIG class again tonight and had fun. TIG is a whole different story. I get to learn from the master.
When I left the shop tonight one of the Techshop employees said “that’s why they call it a Herculean effort”. Every step has something go wrong.
Every. Single. Step.
It’s been a while since an R2 update. I probably need to write a lot more but I don’t have time right now (I’m actually building instead of writing about it).
About two weeks ago I decided to mill up the little leg “cups” that hold the leg hubs. It’s an easy part to overlook. Fortunately, I was able to find some aluminum tubing with an inside diameter (I.D.) that was close. I got a 12″ piece, chopped off a 5″ piece, and proceeded to very slowly mill out the I.D. on the lathe.
That wall is less than .125″ thick. It’s really delicate and I was worried about milling through it so this cut took me about 2 hours. I’m slow on the lathe but the tool scares me so I play it as safely as I can.
Once I got the I.D. correct I just cut off a piece that was the right length (two, actually). The part separated early before the cutting tool had cut completely through, which I was initially upset about (oh no! sanding a delicate part!)
but it turns out that the little edge you can see on the left was pushed in a few thousandths of an inch and so it fits perfectly inside the mating hole and acts as a guide! I’ll have to chamfer off a tiny amount on the inside of the hub when the time comes so the hub will clear it, but since it’s inside the leg you’ll never see it. And besides, the little guide ring makes alignment and gluing MUCH easier. So an unintended mistake turns into a win! Happy accident.
In the past week I’ve worked about 20 hours at Techshop on the Horseshoe parts. Well, one horseshoe. I water jet cut out the 8 layers (out of .125″ aluminum 6061) and test fit them together.
Here’s a pic of the sheet of 6061 before and after water jetting
And here are the layers stacked up on the leg (which is itself just stacked precariously and not welded yet):
Great fit. I had to file the tab from the water jet off of each layer (2 tabs actually)
I bought a set of files from Lowes since so many of the TechShop files are corrupted with steel or not in good shape. Add it to the budget.
Once I’d filed away the tabs I sandblasted each part to give each layer a bit of “bite”. My idea here was to lay down a coating of aluminum epoxy to bond the layers together. However, once I got the epoxy and did a test run on some scrap, the scrap debonded (it broke) with very little pressure. So instead I VERY carefully aligned the eight layers and clamped them together, then spent the next three hours in the machine shop drilling and tapping some holes so the layers could be held together with screws. Somewhere during this process (power washing after the sandblasting, I think) some of the layers got very slightly bent. So now my perfectly flat horseshoe ends are flayed out. Ugh. I’m going to TechShop tonight to talk to a professional welder to see if it’s possible to clamp the layers together and tack weld them. In preparation for that I spent a few hours grinding a bevel on each layer so that when they’re stacked up there’s a little “V” shaped groove on the edges between layers. Hopefully if the layers can be welded this will give the aluminum rod enough “bite” to hold the layers together after grinding off the excess material.
Keep in mind that I’ve worked about 40 hours on just this one horseshoe. I haven’t even cut the parts for the second one yet. I’ll give the welding thing a try and if it works I’ll go ahead and commit to the second one. If, however, the welding is a total bomb then I’ll step back and rethink how I’m doing the horseshoes. I really really want aluminum shoes but if it’ll delay me too much I’ll do MDF now so that I can move on. Those parts are easy to replace in the future if/when I choose to revisit them. It’s been so long since I’ve seen forward momentum that it’s easy to get discouraged. So I’m considering making some temp parts and replacing them in the future if I get stuck at a certain point. Droid building is the Everest of Nerddom, as I’ve said. So there will be some parts of the journey that feel like you’re stuck. But I don’t want to get so mired up in one part that I get discouraged and wash out.
I’m frankly terrified to weld these things. I’ve spent a lot of time (and not inconsiderable money) getting the horseshoes to this point and if they warp under the heat (something I’ve been warned about) then it’s back to square one. But if I’m so nervous about messing them up that I don’t move forward then I’ll be stuck here forever. So I guess I have to do something. Hope I don’t screw it up. I might hire a pro to do these particular parts, or at least to just tack them in five or six places so that I can come back and Lab Metal them and sand them down.
Looking forward, there are so many aluminum parts that need to be welded that I’m almost certain I’ll have to learn to TIG weld. This project is about learning new skills but TIG is extremely difficult to master and represents a major detour while I develop the skill. Probably about 40-60 hours running a mile of bead to get good. In the meantime nothing will get planned, designed, or built. But there are so many parts to weld that hiring someone to do it doesn’t make much sense. My Techshop friend Bill May gave me a pep talk the other night that helped a lot. I was getting a bit discouraged thinking about the ridiculous challenge this project represents. Bill had some really kind and encouraging words for me and encouraged me to learn to TIG and keep moving forward. Frankly, I kind of needed it and appreciated it more than I think he realized.
It seems like at every single point in this project, from major design decisions down to where to clamp a part on the mill, there is some sort of little issue that crops up. For example, while tapping the holes in the horseshoe stack I discovered that my tap was about 1/16th too short. But since the stack was already clamped and the hole drilled I had to solve the problem right then. No coming back to it later since I couldn’t take it off the mill until the holes were drilled and tapped. I managed to figure out a solution but it took a lot of seat-of-the-pants thinking. The entire project is like that: nothing easy, everything fights you. So Bill’s words were really helpful. Keep pushing ahead. Eat the elephant one bite at a time. Don’t look at the summit– just look at the next step to be taken. This will take another three or four years (if I’m lucky!) and if I think of the whole project at once I’ll just get discouraged.
April 18, 2016
“It shouldn’t be hard to tell a 5’9” white guy that he’s not a 6’5” tall Chinese woman, but clearly it is. Why?
And what does that say about our culture?
And what does that say about our ability to answer the questions that actually are difficult?”
Watch the video (sorry if the link is small. Working on an issue with MarsEdit).
April 12, 2016
I was referring to the following chart for R2D2 aluminum fit tolerances. I was just looking at one of the engineering drawings that I have to reproduce in a year or so and inadvertently started giggling like a crazy person. What am I doing? I’m insane. I’m insane. Not until one of the other members at Techshop looked at me funny did I realize that I had just said everything out loud at full voice.
Oh, R2. You’re going to be the end of me.
April 9, 2016
Here is a carefully thought-through argument I have spent years forming.
But I don’t hate anybody. I just have this calm, cogent argument that addressing the issues in what I view as a proper historical and cultural context.
WHY ARE YOU SO FULL OF HATE!?!? IT IS MY DUTY TO SHAME YOU PUBLICLY TO SHUT YOU UP.
Wait, wait, wait, wait… you haven’t even heard me out. I think if people just stop for a minute and…
YOU MAKE ME SICK. HATEFUL HATER.
True story: our old pastor, one of the most caring and compassionate people you’ll ever meet, who has decades of service and pastoral experience, was told that he was “full of hate” because of his (equally compassionate and nuanced) political opinions (which he, significantly, went to great pains to avoid expressing). The exact comment was “I can’t believe someone like you could have so much hate in his heart”.
Hate has become the new weapon, to be wielded by the emotional to shut down arguments they disagree with. This is what passes for argument among a significant portion of our society (both on and off of Facebook). We’ve become such a bumper-sticker culture that the feeling seems to be if you can’t zing your opponent or get your argument out in five seconds then the other side doesn’t have to make an effort to understand you and has a right to shut you up. And if they shout louder, they win.
It’s going to be a long year.
March 29, 2016
Just upgraded my MarsEdit software so I’m taking it for a spin. Testing testing.
And here’s a picture of us on our recent trip for testing
February 9, 2016
“I learned how to think by reading the great books, boldly. It has led to financial success for me. And I’m not alone.
In a videotaped interview in 2012, billionaire inventor Elon Musk, founder of PayPal, Tesla Motors and SpaceX, said a passion for original ideas was a secret to his success. Musk argued that it is essential to base one’s thoughts not on what he called ‘analogy’ — trying to invent something new by borrowing somebody else’s ideas — but rather on ‘first principles.’ ‘Boil things down to the most fundamental truths and say, ‘OK, what are we sure is true?’’ he explained. Doing so, he said, provides far greater opportunity for true innovation, even if it ‘takes a lot more mental energy.’”