Woke up at 5am and couldn’t sleep so I took the Baylor sign I’m making and went to TechShop. I spent the next nine hours laser cutting all sorts of things. Then I spent four hours working on the sign. Then I took a two hour class on grinding your own tooling (I’ll use the lathe tool I ground myself to work on R2). A little over fifteen hours at the shop and I’m done. Off to an early bed….
April 25, 2015
April 24, 2015
Well, I just can’t stop myself. Today at TechShop after a class I checked out the key to the FlowJet (I just love saying that so casually: “I checked out the key to the quarter million dollar FlowJet”) and pathed the JAG20 file in FlowCut. I figured I’d take the file back to the WJ to see how long the cut would take. I’ve done this before and know how it usually ends.
I loaded the file and did a virtual cut. 30 minutes for both pieces. There are 2 JAG20 parts that look like this:
The part is the body-to-leg flange joint that connects the main frame to the leg assembly. It’s solid 6061 aluminum and 1 1/8″ thick. You can see it located here between the legs and the frame. It’s visible once Artoo is finished so it has to look right:
I bought a slab of aluminum from Metals4U a few days ago in preparation of this part. This is probably the biggest, most nerve-wracking part I’ll do. Partially because it took me weeks to figure out how to design in Inventor (I finally got help from an expert at TechShop… he solved the problem in 5 minutes), and partly because it is, by far, the thickest part I’ll have to WaterJet in the entire project. The single hunk of aluminum measured 1 1/4″ thick, 11″ wide, and 16″ long. Cost me over $80! So no, I did not want to screw this up.
So I put the hunk of aluminum on the FlowJet table and zeroed out the Z axis to get the mixing tube right down on the metal. At this point you don’t want to smack the tube into any clamps or weights holding the stock down. If you do, you’ll break the tube and owe TechShop $250 for a replacement. Fortunately, I know the guy who teaches WJ (I am the guy who teaches W.J.) and we have procedures to avoid that.
So, the file was loaded, the stock was weighted down, and I even did a dry run without the pump running (the part that costs money). It was a 30 minute cut. Well, why not? I verified that the machine had been working well and went for it.
Part on table weighted down. File loaded. All ready to go!
I hit ‘cut’ and watched with an eagle eye for the next 30 minutes as the water and abrasive jet slooooowly worked its way around the part. 4 holes, inside cut, outside cut, repeat.
The first part went off beautifully and I could tell that it cut through the material just fine once it was finished. The machine started in on the second part next. The 4 holes went fine (they’re first), but sometime during cutting out the center “shamrock” shape the pump started to lose power. Suddenly the cutting stream wasn’t making it all the way through all 1.25 inches of aluminum. You can tell this is happening because instead of the cutting stream passing through the material, the water starts spraying all. over. the. place. All over you. I got blasted with a muddy stream of grungy water (seriously, I looked like a motocross rider after a muddy ride). The normal procedure if this happens is to manually slow the cutting stream down. As I was already cutting at a pretty slow pace (which gives a better finish) I wasn’t too excited about slowing down further and making the cut even longer/more expensive. But it’s better than the cut being ruined.
So I slowed it down (which you can do mid-cut with a slider in the software) and managed to get the center cut done. On the last cut (the outside perimeter), the jet was still having issues. The solution was to slow it down even further. I think by the end I was cutting at somewhere less than 50% of the max speed and still unsure if it was making it all the way through.
Here you can see the layers of garnet that get blasted onto the parts during the cutting process. It’s an incredibly messy machine to operate.
Once the machine shut off I checked the parts and discovered that the first part to be cut (the one on the left in the photo above) came out brilliantly. Great finish, cut all the way through. Unfortunately, when I lifted out the part on the upper right I discovered that there were sections of the middle that didn’t get cut all the way through. Fortunately, though, it did lift all the way out so at least it got free. Unfortunately, the finish on the outside was terrible as a result of the gradual pressure loss.
Here’s a pic of the “good” part. You can see the smooth edges with just a hint of the typical jet “lag” on the bottom of the outside curve:
For the “bad” part, you can see not only where the stream didn’t cut all the way through, but also where the water jet “lag” on the outside is much more pronounced, resulting in a much more ragged and bad looking surface:
And here’s a side-by-side of the good part and the messed up one (zoom your screen or click for a closer image):
So, while I’m really happy to get these parts behind me, I am somewhat disappointed in the results, considering that for about the same amount of money I could buy an aluminum part that’s shiny and perfect.
I’m still cogitating on how I’m going to fix this. The good news is that the final piece needs to be 1.125″ thick (1 1/8″). The rough piece in the pictures is 1.25″ thick. So I should be able to reduce the thickness of the piece and “face off” the thin little bridges of aluminum that keep the inside section attached. This will also have the effect of making the faces of the part nice and shiny. I think I can do this on the lathe at TechShop but I’ll have to ask the pros about the best way to go about this.
As far as the outside of the donut shape, I need to see if the part can be a smaller diameter than the 6.375 listed in the drawings. I think it can. If I can safely shave off a few thousands I think I can get rid of those marks on the outside and make the part shiny.
Sorry to be so wordy. This experience was a relief in that the part is somewhat workable but frustrating in that I just don’t feel like I can completely trust that machine. I need to improve my skills on the manual mill and lathe but that takes decades. The WaterJet, while expensive, can let a newbie machinist cut any part they can design in the computer. That’s huge.
The final major part for the frame is the pair of side panels where JAG20 mounts. They’re .5″ thick aluminum (thank goodness) but also contain a lot of little holes that’ll make the water jet turn on and off quite frequently. I may wait a few weeks until the pump is rebuilt to attempt those. They’re only 20 or so minutes each but I really don’t want to mess those up. At least not the small little precision holes.
April 23, 2015
April 20, 2015
Exciting news on the R2 front. JAG 01 is cut! JAG01 is the part number for the topmost ring in R2’s aluminum body. It’s by far the most complex part of the main body (along with the leg support panels).
Each of those holes (accurate to within +/-.005) mean that the FlowJet has to cycle on/off each time. In my experience teaching the tool, there is most likely to be a problem during a start/stop cycle. Yikes!
I’ve been putting off JAG01 for a few months now since it’s such a tough part and I didn’t want anything to go wrong. I laser cut the file in thin plywood using my Inventor .dxf file and it seemed right, but there’s nothing like actually water jetting a part to show you your errors. The FlowJet has been down for a few weeks at TechShop and they finally got it working again. I happened to be there when they did and the employee said they needed a test file. Would I like to run JAG01 in some scrap (too-thin) aluminum? YOU BET!
So we took about 12 minutes to run the file in some 18ga aluminum and I took the part and laid it out against my plywood version. Perfect fit! So I know the file worked fine. Now all I had to do was clamp the 1/4″ slab of 6061-T6 aluminum onto the table, take a deep breath, and go for it. I did that tonight and kept an eagle eye on the tool as it cut (not that I could salvage the part if anything went wrong). Fortunately, it worked! 18 minutes later I had a beautiful part resting on the FlowJet water surface and I could breathe again.
Below is a picture of all the pieces I have milled up in the past 6 months when I started this crazy project. Each part is accurate to within a few thousands of an inch. JAG01 is in the upper right.
And here’s the frame so far balanced precariously together.
Year 1 is the frame and I’m more or less on track to have it done in 4-5 months. I have to do two copies of JAG04 (the shoulder mounting plate), and then two copies of JAG20 (the shoulder flange). For JAG04 I’ll use the WaterJet again in combination with the manual mill. Then I need to go back in to a bunch of the holes that were WaterJet and either tap them with threads, or countersink a chamfer on the edge so the screws sit flush. For JAG20 I’ll be learning a whole new tool: the Tormek CNC Mill. That’ll take a month or two. I could buy the part online for about what it’s going to cost me to make it, but this project is about testing my boundaries and learning to do new things. I will have to buy some parts for R2 (the skin and dome), but I’m trying to do as much as I possibly can myself, and use the most difficult material (aluminum as opposed to wood). If I hose JAG20 I’ll consider buying the part, but I want to try first.
Once all the parts are done, drilled, tapped, countersunk, and fit together correctly, I’ll sandblast everything to remove milling scratches, then sandblast again using baking soda. Then it’s off to the anodizing step to give the frame a beautiful coat of anodized metal. Then I’ll laser etch a pattern into the frame.
There’s a long, long way to go.
April 18, 2015
More R2! Now that the show is over I’ve been busy teaching at TechShop and building a project for Baylor’s StuPro (a really cool CNC’ed progress board for the Sing groups). So I’ve been spending a lot of time at TechShop. The other day I got a few hours free while up there and decided to jump back on the mill to keep my meager milling skills sharp.
When you cut something on the Water Jet, you have to leave tiny tabs of metal connecting the part to the larger piece of stock. This is so parts don’t shift around while cutting or, worse, break free and sink in the tank. After the cut is done you have to break these tabs and remove the part. However, little sharp bits of these tabs are left behind on the part that must be dealt with. If you design the part right, the leftover tabs aren’t too big (maybe the size of a rice grain or slightly larger) and you can work them away with a file. But since I hadn’t been on the mill for a while I decided to take some time and remove them with that tool. Overkill? Sure, but logging time on the mill was worth it.
So I took 3 hours or so and sent about 10 parts– some large structural pieces, some support pieces– through the mill and removed the sharp little tabs. You can tell where my mill marks are because what is milled is freshly shiny and smooth aluminum (as opposed to the oxidized and rough cut from the Water Jet). But since these frame parts are going to be inside the frame and invisible I’m not too concerned. I’ll see if there’s anything I can do to clean things up later but my guess is that it won’t be an issue, and my plan to anodize the frame in the future will cover up a lot of issues anyway.
Next up: water jetting the main top “A” ring. It’s one of the biggest and most complex parts of the frame. I’ve been putting off doing this part because the water jet has been down and because it’s a rather long and expensive cut in a big (expensive) piece of aluminum. Fingers crossed.
“Takings-clause jurisprudence is quite recondite. The government, however, says two contradictory things. It says the Hornes ‘acquired’ raisins and hence must either surrender a large portion of them — in some years, 47 percent — or pay huge fines. But it also says the Hornes do not have sufficient ownership of the raisins to raise constitutional objections.
The government says the Hornes voluntarily entered their raisins into the stream of commerce, so they must comply with the RAC’s raisin reserve requirement. But the Supreme Court has hitherto rejected the idea that a person must give a portion of his property to the government in order to purchase the government’s permission to engage in a lawful business transaction, such as selling a commodity. The government says its required contributions to the raisin reserve merely regulates raisin sales. The Hornes say it is not a mere regulation but an expropriation.
The government says it owes the Hornes nothing in exchange for the raisins they supposedly owe it, because they somehow benefit from the government’s manipulation of the raisin market. The Hornes say it would be unconstitutional for the government to come on their land to confiscate their raisins or the proceeds from their raisin sales, so it is unconstitutional to fine them for not complying with an unconstitutional requirement.”
Outdated laws should be deleted. Those who slavishly adhere to them in the interest of maintaining their bureaucratic organizations should be forced to look for another line of work. Eating out our substance indeed.
“District 12 shall continue to produce their quota of raisins”
April 16, 2015
Instapundit: “General Atomics Introduces a Weapons-Grade Self-Contained Laser Cannon That Can Be Mounted On the Roof Of Your Car. ‘What we were able to find out about this thing is that it’s a laser weapon with output energies (that’s output, not total power in the system) ranging from 75 kilowatts all the way up to 300 kilowatts. To put that in perspective, about a year ago we wrote about how Lockheed was using a portable fiber laser to shoot down rockets at a range of 1.5 kilometers using just 10 kilowatts of power. Suffice it to say, 300 kilowatts is rather a lot.’”
April 9, 2015
April 7, 2015
Utility scale electricity storage and generation from a train and a box of rocks. What a great idea. Engineers are pretty clever.
March 28, 2015
“Forging new habits has become an obsession among technology companies. In an age when commercial competition is only a click away, the new mandate is to make products and services that generate compulsive behavior: in essence, to get users hooked on a squirt of dopamine to the brain’s reward center to ensure that they’ll come back…
It starts with a trigger, a prod that propels users into a four-step loop. Think of the e-mail notification you get when a friend tags you in a photo on Facebook. The trigger prompts you to take an action—say, to log in to Facebook. That leads to a reward: viewing the photo and reading the comments left by others. In the fourth step, you inject a personal stake by making an investment: say, leaving your own comment in the thread. This pattern, Eyal says, kicks off a cycle that lodges behaviors in the basal ganglia, the part of the brain where automatic behaviors are stored and where, according to neuroscientists, they last a lifetime….
“I’m not an advocate for creating addiction,” he says. “Addiction has a specific definition: it always hurts the user. I talk about the pathways for addiction because the same things that occur in the brain help us do something that can be good.”””
I guess that depends on who gets to define “good”.
March 23, 2015
Infants in College: “Safe spaces are an expression of the conviction, increasingly prevalent among college students, that their schools should keep them from being ‘bombarded’ by discomfiting or distressing viewpoints. Think of the safe space as the live-action version of the better-known trigger warning, a notice put on top of a syllabus or an assigned reading to alert students to the presence of potentially disturbing material. . . .
the notion that ticklish conversations must be scrubbed clean of controversy has a way of leaking out and spreading. Once you designate some spaces as safe, you imply that the rest are unsafe. It follows that they should be made safer. . . .
while keeping college-level discussions ‘safe’ may feel good to the hypersensitive, it’s bad for them and for everyone else. People ought to go to college to sharpen their wits and broaden their field of vision. Shield them from unfamiliar ideas, and they’ll never learn the discipline of seeing the world as other people see it. They’ll be unprepared for the social and intellectual headwinds that will hit them as soon as they step off the campuses whose climates they have so carefully controlled. What will they do when they hear opinions they’ve learned to shrink from? If they want to change the world, how will they learn to persuade people to join them?
Or, put another way, how will they grow up?”
When this gets written in the New York Times, of all places, you know there’s truly a problem.
February 18, 2015
A great summation of positive and negative externalities as they pertain to the ACA. Yes, it’s actually rather more interesting than that stunning sentence would indicate.
February 12, 2015
“Jon Stewart’s genius — ‘and for once that overused word is appropriate,’ Aucoin of the Globe insists — is that he provides intellectually lazy people with an excuse for forgoing the hard work of informing themselves at anything but the most superficial level about political events. Human beings being what they are, there will always be an acute need for humor in our political discourse; Stewart’s contribution has been to substitute humor — and an easy, vapid, shallow species of humor at that — for the discourse itself, through what Jim Treacher deftly described as his ‘clown nose on, clown nose off’ approach to commentary: When it comes to Obamacare, the minimum wage, or the national debt, you don’t have to get the economics as long as you get the joke.”
Stewart has always had an uncanny behavioral resemblance to a certain class clown during my high school days. Able to be sincere and intelligent when the circumstances called for it, he nonetheless opted to play the buffoon and go for the easy laugh. Smart guy who ended up looking pathetic and adolescent at my 10th reunion. He was still reliving the high school glory days while the rest of us had moved on.
If Stewart truly represents the Genius that his admirers are lauding, if his leaving the daily show is “akin to the Beatles breaking up”, then that says quite a bit about his average viewer, and what it says shouldn’t make them feel too comfortable.
February 6, 2015
“I may not speak for many other upper-middle-class types, but I’ll tell you what: I’m happy to have the government spend less on me if I know it’s spending less altogether and is directing what money it does spend to people who need it more than I do. But if you’re simply talking about raising taxes in order to maintain the bloated status quo plus a bunch of new programs, count me out. That’s not because I’m selfish. It’s because I’m not stupid.”
Exactly. Let’s take care of those who need it. Let’s not waste money on programs designed to harvest votes and perpetuate bureaucracies. But for some reason stating it just that clearly still gets you labeled as a Poor Hater.
February 5, 2015
Brian Williams: Big, Fat Liar | Ricochet: “NBC Nightly News anchor Brian Williams admitted Wednesday he was not aboard a helicopter hit and forced down by RPG fire during the invasion of Iraq in 2003, a false claim that has been repeated by the network for years…
The admission came after crew members on the 159th Aviation Regiment’s Chinook that was hit by two rockets and small arms fire told Stars and Stripes that the NBC anchor was nowhere near that aircraft or two other Chinooks flying in the formation that took fire. Williams arrived in the area about an hour later on another helicopter after the other three had made an emergency landing, the crew members said.
‘I would not have chosen to make this mistake,’ Williams said. ‘I don’t know what screwed up in my mind that caused me to conflate one aircraft with another.’”
No sir. It’s not a “mistake”. A mistake is getting the tail number of the aircraft wrong. A lie is saying you were onboard it an hour earlier when it crashed as a restult of rocket fire, then repeating that same statement for over a decade.
Kind of makes you wonder what else he’s “mistaking” about.
February 4, 2015
Over 300 businesses now whitelisted on AdBlock Plus, 10% pay to play | Ars Technica: “Since 2011, AdBlock Plus, a popular browser plugin that blocks online ads, has kept a ‘whitelist’ of websites that are allowed to serve ads despite the presence of the AdBlock Plus plugin. In an e-mail to Ars, AdBlock Plus Communications Manager Ben Williams wrote that currently, the browser extension has granted a pass to ‘over 300 sites/entities’ out of ‘over 1,500 applicants’ to the company’s whitelist. That’s up from October 2013, when AdBlock Plus allowed the ads of 78 sites or entities out of 777 applicants.”
If I had the resource I would introduce a $5/year “real” adblock that nuked ALL ads. Then retire a rich man.
Students with autism learn social skills with R2-D2: “AUSTIN — Fifth-grade students at Blazier Elementary School in Southeast Austin are learning social skills through technology.
The students are part of the school’s SCORES program, which stands for Social Communication and Resource services, for children with autism. Over the past few months, they created a fully operational R2-D2 replica robot thanks to their teacher, Caleb Zammit.
‘The main focus was just learning to work as a group, and how to get along and use their manners when working on a big project all together,’ said Zammit.
They are also learning about motors, batteries, measurements, power tools and metal.
‘The best part of my day is having fun with my friends and building R2-D2,’ said Mathew Fan, a student at Blazier Elementary.”
That’s pretty fantastic. One of the things I’m looking forward to the most about finishing R2 is being able to take him to a local children’s hospital (or the like). That’ll be really rewarding.
“To the casual observer it appears that Virginia is run by violent psychopaths. That’s the takeaway from the recent report of an anti-poker SWAT team raid in Fairfax County, in which eight assault rifle-sporting police officers moved against ten card-playing civilians. The police possibly seized more than $200,000 from the game, of which 40 percent they eventually kept.
There was no indication that any of the players was armed. As a matter of fact, it appears that a gambler is more likely to be shot without provocation by the Fairfax Police than the other way around. The heavy firepower at the Fairfax raid was apparently motivated by the fact that ‘at times, illegal weapons are present’ at such poker games, and that ‘Asian gangs’ have allegedly targeted such events in the past. This is, then, a novel approach to law enforcement: as a matter of policy, Fairfax police now attempt to rob and steal from people before street gangs get around to doing it.
It is a mystery why we put up with this obscene police behavior. Gambling itself is not illegal in Virginia; it is simply controlled by the state. So the Fairfax police department did not bust these hapless poker players with guns drawn for doing something truly immoral and fully outlawed, merely for doing something in a way not approved by the state legislature. Were gambling actually forbidden in Virginia, then a crackdown could at least be understood, if not condoned in so paramilitary a fashion. Yet Virginia’s stance on the matter is not to treat gambling as malum in se, but rather as an instrumentum regni: our government prefers to funnel gambling money into its own coffers for its own ends, outlaw the same thing when it’s done outside of the state’s jurisdiction, and then steal the money of the poor fellows who happen to get caught….
…Governments control gambling not to legitimize and sanitize the practice, but to extract as much money from the citizenry as they possibly can. In the state’s eyes, the fault of the poker players in Fairfax lay not in betting money on a card game, but in not pouring money into the state’s bank account while they were doing so.”
Because Public Safety.
January 30, 2015
The dome arrived! It’s actually 2 domes (the inner dome is still in the box). Little R2 is still a long, long, long way from completion but he’s graduated from feeling like a box of random aluminum scraps and circuit boards to something more like a robot. Really enjoying this process.