It’s the last week of the semester, projects are due in both the freshman and junior machine shop courses by the end of the week, and things are extra bonus crazy in the MTL as a result. I’ve had people I’ve never seen before coming in for night lab the last couple of weeks. This week night lab has been extended from 6-9 to 5-10, which made for a long night Monday and a longer one today, when I already was scheduled to work 2-5.
We were going to close from 5 to 6 so I could go get some dinner, but one of the guys asked what it would take to convince me to stay and keep the shop open through the dinner hour. I said I’d do it if someone brought me a pizza.
So he had one delivered.
Who am I to argue with that kind of dedication?
Unfortunately, the only thing to drink in this joint is the kinda-iffy-tasting city water from the fountain out in the shop, and half a pizza and some garlicky breadsticks later, I’m gasping for something better. I won’t be getting anything for another three-and-a-quarter hours, though, alas. The MTL needs a soda machine. One of those old-timey ones that do paper cups with ice in them. Does anyone even make that kind of vending machine any more? They were absolutely the best.
In the MTL tool crib, there is a window where the on-duty tool guy sits, and at that window is a stool. It’s an unremarkable object, as these things go, just a few bits of metal and a wooden disc manufactured, as the logo on the underside of the seat reveals, by Angle Steel, Inc., of Plainwell, Michigan. There is only one real problem with it:
It’s not very comfortable.
Last week, noting that I didn’t seem to be enjoying it much, Joel (my boss, the machine tool instructor, and the MTL building manager) asked if I’d prefer something a little more substantial and padded. I said I would, and he said it was OK with him if I got in touch with Disabled Student Services, since they handle special-furniture requests on campus, and made such a request in the department’s name. So I did.
Monday I came in for my night lab shift and found… a second, identical Angle Steel stool, with a tag on it saying “FOR BEN HUTCHINS, MTL CRIB”. Apart from the tag and a label with the international accessibility symbol on it (see above), it was exactly the same as the one we already had.
So I sent a note to the grad student in charge of furniture at DSS, apologizing for not being clear enough in my initial email and noting that we had one of those already, what we were hoping for was something a bit more upholstered. His response was very polite, but basically boiled down to, “That’s what we’ve got. Talk to your department’s purchasing person if you want something swankier.”
Today I got in for my afternoon shift, when, unlike in the evenings, Joel is here, and we got to talking about the Stool Situation. I said I’d found a couple of likely candidates online, but then I said, “It’s a little silly for us to pay $200 for a heavy-duty padded stool, I mean, this is a machine shop. Why don’t we build one?”
He went away to help a couple of the afternoon students cut some threads, I dispensed tools, and we both thought about it for an hour or so, and then he came back and said, “OK, let’s give it a shot.”
The first thing we decided was that we didn’t need to start from scratch. The Angle Steel stool’s metal structure is plenty adequate for our purposes; it just needs a better seating surface. So we dismantled one of the Angle Steel stools, which was a simple matter of unscrewing the wooden disc from the top of the frame.
Then Joel went and found a donor chair somewhere else in the building (he’s the MTL facility manager, remember, he can do that). This was a regular wooden chair, like you would find in a kitchen. We actually looked at a couple of them and decided that one would come apart more easily, and yield a part more suitable to the purpose, than the other. So Joel knocked out the stretchers, to make getting the drill in there easier, and we unscrewed the seat base from our donor chair. Then it was a relatively simple matter of marking out a radius (that’s what’s going on with the big metal ring and the square board in the photo above) and trimming the corners of the seat base a bit.
The result is not much different from the old version, but with a more substantial seating area, and provides a better platform for adding upholstery later, which Joel is rather keen to do once he has a chance to assemble the materials.
(You may notice that it’s turned so that what was the back of the seat when it was part of a chair is now facing toward the tool window workbench, at right. This is because it’s actually more comfortable that way; we didn’t radius the front corners enough. But we may not bother, since it works fine backward, the extra corner area provides more rear support, and once it’s padded the slight contour planed into the wood, from when it was a chair, won’t be relevant any more.)
I’m sitting on it right now for my night lab shift, and I have to confess it’s not that much better than the old version. I mean, it’s still hard and there’s still not much of anyplace to put my feet. Still, it does offer better support, and once it’s upholstered it should be very nice indeed. And besides – it’s an engineering project!
"We now take you to our correspondent in War-Torn Wherever, Benjamin Hutchins. Benjamin, what’s going on there?"
"Well, Bob, uh… not a lot, right now. But the locals tell me things were cuh-razy around here a month ago! Boy howdy!"
I think what makes me a lackluster blogger is the same thing that’s always made me a poor diarist and an indifferent correspondent: I don’t feel justified in posting or writing to someone unless I’ve got something interesting to report, and often I have a hard time feeling like I do. This is particularly true at the height of the semester, when it’s basically "Well, uh… went to class, did some homework, went to the next class and turned it in."
Still, the semester’s just about over now (there’s only finals week next week, and by an odd coincidence only one of my classes this semester even has a final),and there have been a few interesting developments to report.
Taking the most recent first, the final engine tests in MET 107 were conducted today. As you may recall, at the start of the semesters we were split up into teams of six and given a list of required parts (and the prints from which to make them), with the ultimate goal of building a single-cylinder pneumatic engine by the semester’s end. On the prints it’s called a steam engine, but since we didn’t actually have a boiler handy (for safety reasons), we drove ours with compressed air. We all got together in the machine shop this afternoon and ran our engines while Prof. Anderson timed them with a strobe. (An engine that didn’t run would have constituted a major grade deduction.)
The team I was on, Team 2, went into the competition pretty confident.
Fig. 1 Team 2. From left: author, Ben White, Bill Long, Clark McDermith, Cam Terry. Not present: Mike Peasley. Photo by Herb Crosby
We had all our parts done by the beginning of this week and were doing test runs by Tuesday evening. Bill, one of my teammates, had access to a deburring mill at his job and had spent a lot of time obsessively polishing all the parts as we finished them and turned them over to him, so ours was by far the shiniest engine…
Fig. 2 Engine No. 2. Photo by Herb Crosby
… and once we overcame the fact that I apparently can’t drill a concentric hole in a brass bushing even with the tailstock of a lathe (sigh – I must have scrapped eight of those damn things), it ran as beautifully as it looked. Bill could actually make it turn over just by blowing into the intake, and since the test pressure was 100 PSI (er, rather more than the average human output, I should think), we had high hopes.
The first run demonstrated that we might actually have done a little too well at the polishing and fettling, as, well, this happened:
We actually blew the valve rod bushing right out of the steam chest on the first run. (Amazingly, this was not the bushing I had so much trouble with. That one had the piston rod running through it and performed perfectly in the actual test. For the technically curious, I made the base plate, the columns, the piston rod bushing, and the piston.)
Fortunately, we had time to tear it down and fix the problem before our second run.
Fig. 3 Engine #2 down for repairs. Photo by the author
A couple of false starts, some hurried consultation, a helpful senior, and a few minutes’ work with the scissors in Bill’s Leatherman, some brass shim stock, and the arbor press, and Team 2 was back in business. By then the other teams had all had their runs, the fastest of which clocked a top speed of 2287 RPM, so Bill and Cam stepped up to the testing bench, and…
… 3266 RPM, baby. The fastest entry this semester, and only 480 RPM shy of the all-time record, 3746. (Bill’s sure we could get it going that fast if we had more time to futz with it.)
So hey! Victory. It’s what’s for dinner. (Apologies for the crap camera work. Bit excited.)
More news to come, and it’ll get steadily more out of date as the posts go on…
MET 107 lecture today was a bit stressful, but that was more my own psychological baggage than anything to do with the actual class. Heck, I pulled a 92 on last week’s exam (#1 of 3), and I know what I did wrong on the questions I missed, so things are, touch wood, going well.
But it’s a crowded lecture, 48 students in a room that could comfortably hold about 40, and some days there’s a lot of noise and chatter. There was today, so much so that Professor Anderson had to yell – literally, not figuratively – at everybody to quiet the hell down:
"OK, fellas, let’s get started. Got a lot of stuff to get through today. Settle down. … … HEY! THIS ISN’T A PAJAMA PARTY, IT’S COLLEGE, FOR CHRISSAKE!"
"In 15 years I’ve had to yell at a class three times, and now two of them have been you guys. Work a little harder on impressing me. You’re not paying thousands of dollars to listen to each other talk."
Now, I like Professor Anderson, and for the record I think he was entirely justified in taking this course of action. (Indeed, in his position I’d probably have used much stronger language in a couple of places, and possibly opened with a gunshot into the ceiling, which is why I am not and should never be allowed to be a teacher.) And his wrath had nothing to do with me – I wasn’t talking, because I’m 37 and frankly I got that shit out of my system in the ninth grade. And yet, when that happened, I spent the next minute or so grappling internally with a powerful instinctive flight reaction. I very, very much wanted, on some entirely anti-intellectual level, to just go home and lie down.
I guess that’s a scar from all those rancorous school board and town council meetings I had to cover. I just cringe at the thought of being in the presence of authority conflict, even when I’m not in any way involved. It was deeply – and surprisingly – uncomfortable, because so entirely irrational. I was just sitting there waiting for class to start, and suddenly my lizard brain was going Flee, flee from this place, the gods are angry! Very disconcerting.
Anyway, once we got into the lab, things got better. For one thing, there are only a dozen of us in the Monday afternoon lab session, and the room is much larger; for another, there was plenty to do, and Professor Anderson had regained his good humor, despite the absence of his tool crib guy and his regular TA (who had to go off to a doctor’s appointment, and did look like he felt truly dreadful).
So we went out and got to work, and after working on it for three weeks, I finished the last of my tool checkoffs, which means I’ve advanced to "novice machinist" and am no longer just some dude who wandered into the machine shop.
To be clear, they aren’t actually trying to make professional-grade machinists out of us in a single semester. As mechanical engineering tech majors, we’re expected to end up designing things that the real machinists then have to make, so the idea is to give us some exposure to the machine shop environment and the capabilities of machine tools, so we’ll hopefully have that in the backs of our minds as we design things that may or may not be a royal pain in the ass for some other person to make. So "novice machinist" is probably too generous; realistically, it’s more like "semicompetent dabbler". But it does mean I’m not as likely to burn the place down or cut my own fingers off as a random civilian would be. In theory.
In slightly more technical terms, I had to demonstrate a set of what marketing people would call "core competencies" on the four basic machine tools in what the University rather haughtily calls the laboratory: the pedestal grinder, the vertical mill, the engine lathe, and the band saw. Once, and only once, those tasks were accomplished was I cleared to work on the actual parts required for my semester project – which I believe I now have seven weeks to make and get working with the rest of my team’s parts. So no pressure there.
For those of you who are unfamiliar with machine tools, as indeed I was until recently, here is a quick rundown of what those four things are. If you’re not interested in that kind of thing, that’s cool – come back in a day or two, I’ll be talking about CAD.
The pedestal grinder – This is the machine tool people who’ve never been in a proper machine shop are most likely to have seen someplace, I suspect (with a couple of caveats I’ll get to below). It’s just what it sounds like – an abrasive wheel attached to a big ol’ electric motor on a stand. Actually, most pedestal grinders have two wheels, one on each side of the motor. Waste not, want not, after all. This apparatus can be useful for a number of things, but mainly what it’s used for is shaping smaller bits of metal into shapes suitably complex as to be hard to achieve on the other machines, and/or that don’t require a ton of really exacting precision. For example, it’s possible to sharpen up drill bits and correct worn-out flathead screwdriver blades with it. Or you can do what we did and actually make another tool, in our case a toolbit that is then used on the lathe.
All the animals in the machine shop are equal, but the pedestal grinder is a little more equal than the others in terms of how dangerous it is. It does have a great heavy abrasive wheel spinning at some ridiculous number of revolutions per minute, after all, and if that should happen to, say, come off, you could be in for an exciting time. In normal operation, though, it’s nothing to worry about as long as you don’t trip and fall face-first on it. Unless you do what my dad did when he was around 25 and use one without eye protection, in which case you will never be allowed to accompany your son into a room with an MRI machine in it later in life.
The vertical mill – Also known as a "Bridgeport" after the most commonly known manufacturer. Someone not familiar with machine tools, but knowing someone with a reasonably well-equipped garage, would see a Bridgeport and think, Damn, yo, that’s one big drill press. And, in fact, that’s pretty much what a vertical mill is – a drill press with a college degree. It can do a hell of a lot more than just drill holes, but the basic principle is the same. What makes a vertical mill different is its adaptability. It can be set up to run at a wide range of different speeds and equipped with a variety of different tools, and the table can be moved around in all three axes, often with power feed in at least two of them. With that capability and the right tool mounted, you can trim a piece of metal to a precise size, put a nice finish on a part, put a chamfer on something – you can even drill a hole if you’re feeling really audacious. Or cut threads into one you’ve already drilled.
The surprising thing about operating a vertical mill, from the standpoint of someone who had worked with drill presses before but never seen their bigger cousins, is how much stuff there is to keep track of. For instance, what speed you run the machine at matters – a lot. A home garage drill press is usually either on or off, but the RPM setting on a vertical mill is something that requires some foreknowledge and thought. You need to know what the material you’re cutting is, what your cutting tool is made of, and the maximum cutting diameter you’re dealing with, at the very least. Once you have all those things, if you have the appropriate tables handy or have memorized them, you can calculate the best speed, and then you look at the plate on the front of the machine to see how close you can get – and then you have to open it up and fool with the belts to set it up. It’s all very old-school, and somehow strangely satisfying.
The engine lathe – This is another tool that looks something like something people with reasonably-well-equipped wood shops will be familiar with. With a wood lathe you can make fancy table legs and whatnot. A metalworking engine lathe works on the same principle, and looks similar, but – as with the metalworking equivalents of many woodworking tools – is a lot beefier and more complicated. The basic principle is similar to the vertical mill’s, except sort of reversed and standing on its head – the workpiece rotates but is otherwise stationary, instead of the toolbit as in the mill, and the toolbit can move around relative to it on a complicated carriage mechanism. You can face stock to a desired length, turn bits of it to different radii, drill a hole in the end of it – you could even make a fancy table leg if you wanted, though it would be pretty heavy.
The lathe is my favorite machine tool. It’s also the one with the most complicated set of dials, levers, and buttons. These two facts may not be entirely unconnected. Once you’ve worked out the RPM setting (which is the same sort of thing as you have to do with a vertical mill), there’s also the feed setting to consider. Again, there’s a reasonably complex little formula that involves looking stuff up on a table, particularly if you’re cutting outside threads, and then there’s another chart on the machine itself which tells you how to set the levers and dials for the feed gearbox to achieve the desired result. This is a little like cracking a safe and invariably makes me feel like I’m starring in my own very short little caper movie. Very satisfying.
The band saw – This is, well, a band saw. Not really that exciting, except for the size of it: The horizontal band saw in our shop is about five feet long. Cutting stock with it is a fairly straightforward procedure. It doesn’t have speed settings or any futzing around with feeds; you just put the piece you’re trying to cut in it, make sure it’s properly supported if it’s too long to fit on the table, make sure you’ve put something in the other end of the vise to balance it if it’s too short to go all the way across, start it up and let gravity do the work. Cleaning it up afterward is the hardest part, because it makes tiny little chips and they get all covered in cutting fluid. Nasty.
So yeah, I’m enjoying MET 107, for the most part. As previously noted it trips my hate-being-bad-at-stuff response quite often, but the instructor and his TA are patient and my checkoffs went well. I got my first piece of for-real stock cut today, too, but ran out of time before I could do anything more to it than file off the burrs.
Now that I have my credentials on the tools, so to speak, I (slightly annoyingly) get to not use them for three weeks, because that was our last meeting before spring break. I could go in for one of the evening sessions this week (probably Thursday) and try to get some stuff done; we’ll see.