There are endless options for measuring sizes, and we use different tools for different purposes. Rulers, meter sticks, tape measures? Check. Vernier calipers, both mechanical and digital? Check. Precision micrometers? Check.
Counting twelve-inch floor tiles? Check.
Precision matters, as does scale. A tape measure is helpful when moving furniture, even if it can’t determine the thickness of a sheet of paper like a micrometer can. Micrometers: really useless for determining if that new cabinet’s going to fit beside the CNC machine.
These Mitutoyo dial calipers – good for up to 12 inches in 0.001-inch increments – are kind of like a super-precise ruler. They’re in decimal inches, not metric, which makes them ideal for use with our lathe: also inch-only. (The calipers are more precise, so you know when you’re off by 0.003 inches.)
Not that we need that level of precision machining every day. But it’s good to know the option’s on the table.
For the most part, the light accumulation of dust, pollen, and other stuff on the objective lens of your telescope is a thing you live with and ignore. The damage you can do to the lens and its optical coatings is far more severe than the minor loss of image quality from tiny flecks. Known and accepted trade-off.
Here, however, we have a classic TeleVue Renaissance that’s still in good shape. Aside from the dust and dead spiders, anyway. Exact age is unclear, but we can roughly place it between TeleVue’s founding in 1977 and the construction of the “Halley’s Comet” models in 1985. Serial number 1100, for anyone keeping track at home. Even dust-covered, the optics appear good at a quick glance, and they have a reputation for remaining in good shape for a long time.
There’s a bit of chromatic aberration when you look closely, an issue which has been resolved in their current models. (Optics = hard.) The design type is called a Nagler-Petzval, which uses a pair of lens doublets to correct numerous distortions caused by refraction. Every design has its pros and cons; this one’s quite nice. Our version has – we think – an air-spaced doublet (two lenses utilizing different curvatures) as the objective, and a cemented doublet in the rear.
At least, that how the Halley’s Comet edition was made. The current optics update utilizes two air-spaced doublets – see the diagram for the NP101is – so it’s reassuring to see that the improvements are incremental. Good sign for the one we have.
Okay, the brass could’ve aged better, but it’s got character!
Needs polish.
Black on brass looks good.
Nice touch.
Even the knurled knobs on the focuser are brass. We don’t want to leave this for display, however. We want to see the stars!
Eesh.
That dust, though.
Speckly.
Yeah, definitely a problem. A cleaning is in order.
Can’t make it worse, right?
Not pictured: the dead spiders removed with air from a bulb blower. Dead spiders do not improve optical quality.
Red goo.
Here, we’re applying a coat of First Contact polymer cleaner, an expensive but effective treatment for safely removing gunk from precision optics. Comes in a wee bottle like it’s nail polish and smell like nail polish remover. Because it’s got acetone and other solvents in it.
Drying before removal.
Once it dries, that little tab lets us pull away the pink film with all of the dust and debris stuck in it. A good time to wander away from the stink of volatile solvents and get a cup of coffee.
Much improved.
And, well, that’s a substantial improvement.
Water spots. No dust.
It’s not perfect. The polymer is very good at removing particulates, but less so at water-soluble stuff. Once we evaluate this with a camera setup, we can see if a follow-up cleaning with deionized water is necessary.
Big improvement.
Problem there, of course, is that we run the risk of introducing tiny scratches in the process. Could be worthwhile if the effects are still visible, but we’re still erring on the “do a minimum of harm” side of things.
Despeckled.
Will it live up to its potential as an imaging ‘scope? Maybe. There’s a fair chance. If not, we’ll keep it around as a stylish yet usable throwback for visual observation. The best telescope, as they say, is the one you use.
Springs, of so many different sizes, spring rates, colors. Drawers upon drawers of them, some in good shape, others… not so much. Just because we don’t need them now doesn’t mean we should discard them, right?
Okay, it’s probably worthwhile to dig out the overextended ones and send them to the scrap heap.
Pop rivets haven’t seen much use in the shop of late, but they always remain an option. You put one in the nosepiece of the tool, slide through a pre-drilled hole, and squeeze the handles. That action draws the rod and bead back to the tool, deforming the rivet to compress your materials together as the bead on the far side “pops” off. Can be handy, especially when you can’t access the other side of something easily.
This one was acquired at the tail end of the 1970s, for the not-insignificant sum of $25, or $100.54 today. You can pick up the equivalent tool from McMaster-Carr with delivery tomorrow for $31.25 plus shipping, whatever that tells you about the current state of the economy. Don’t read too much into it.
August, ’79. Nice vintage.
Note that the handle has also been etched with “Consumer Bargain,” which is cryptic and delightful. Clearly, this was a steal.
Stumbled across this little old gem while cleaning the Observatory. Age unknown, could use a little cleaning, but it still mostly works. We’re charmed by all manner of objects around here.
A great many jobs in the daily work of a shop consist of riffs on this: can you make item A connect to item B? It might be physical connections, electronic and/or digital signals, or even the relatively abstract interpretation of transitioning a lab space over from one experiment to the next without disruption. The simplest ones are when someone can’t locate the proper connector cable. (There are so many different kinds!) Less simple are those times when two things are supposed to fit, but don’t.
Just straight-up don’t.
At the Tressler lab, we have the luxury of permanently-installed piers which support our telescope mounts. For our purposes, this is an excellent improvement over the default, a very stable yet heavy tripod. Now in the process of upgrading our mounts, we find that the tapped mounting holes on the pier don’t match the drilled and counterbored corresponding holes on the custom-made mount adapters. By 1/8″ or more in some cases. Sounds small. Is actually huge. Is will-not-fit-even-with-brute-force huge.
Note: not made in-house. We could try to guess where the error might have arisen, but our job is to fix it.
Also note: the previous mounting plate was not precisely machined to the proper dimensions, either, but was close enough that it was fastened by brute force. Sensing a theme here, which is this: precise measurements are crazy hard.
Fix holes with more holes.
Getting to the adapter-for-the-adapter called for more than one CNC-milled plastic prototype. Measure, mill, test. Rinse, repeat. Polyethylene, as one might imagine, is cheap stuff.
A few test runs later, we have a custom-machined (in-house!) sheet of 1/2″ aluminum to connect to the 5/16″-18 tapped holes on the pier, which then sets up a new series of 1/4″-20 holes in this plate and the mount adapter to hold everything rock solid. Holes drilled and tapped, counterbored for a clean surface with all of those socket screws.
And all carefully measured and aligned on the milling machine to within 0.001″.
No one notices the unused holes in the dark.
You don’t appreciate the precision of reliable machinery and sharp tooling until the pieces slip together effortlessly. Whoa! Goosebumps!
Best part? The adapter is functionally invisible for anyone who doesn’t know to look for it. Few things feel as rewarding as solving a problem before (almost) anyone else realizes it’s there.
Ah, the printed circuit board. Svelte. Densely packed with teeny marvels of modern electronics. Those parts big enough to be labeled usually require magnification to read the text. The really little ones? It’s not really possible to replace those anyway, so just trust that they’re working as intended.
Until the whole gizmo isn’t working as intended, of course.
When that happens, it’s time to make an assessment of what can be fixed. Sometimes it’s a loose wire. Sometimes it’s a frayed cord, or a bad switch that’s not part of the circuit board itself. Not that these are likely, but it’s best to be thorough.
Assuming you can get the housing open to inspect it. These suckers aren’t built with repairs in mind, given that purchasing a whole new item is less expensive than the cost of labor plus the replacement value of what’s 98% of the whole item. So many tiny screws. So many snap-fit plastic parts. At some point you realize how much thought and effort went into designing this object for quick assembly, and how little went into ease of disassembly.
Pictured above, a faulty motion sensor, has no obvious loose connections or broken parts. It simply fails to collect consistent data, with erratic drop-outs punctuating the signal. Oh, well. Maybe it’s good for parts?
Signs! They’re all around, some not-so-subtle hints to remind you that you’re in a working machine shop full of dangerous things. There’s an informal ranking of which tools qualify as the most dangerous, but improper use can make anything a hazard. So it’s safety goggles required, watch your fingers, and don’t touch anything you haven’t been trained to operate safely.
Can we assume you understand that open-toed shoes are a no-go?
Hazard signs have a hierarchy, beginning with CAUTION, often in yellow. Caution tells you that you’re in a potentially hazardous place, and failure to take appropriate precautions could result in injury. Safety goggles around the machines, please. Don’t press any switches unless you know what they do.
Warning. Seriously, don’t touch anything if you don’t know what it is.
Next step up: WARNING. The situation here is moderately hazardous. Failure to take appropriate precautions could result in death or serious injury. Maybe not likely, but please don’t lose a finger to the bandsaw. Keep those knuckles well away from the business end of the belt grinder.
Danger. These machines will bite.
And at the top, DANGER. Oh, danger. You get the quality of imagery that belongs on packs of cigarettes. Danger tells you that certain situations will result in death or serious injury. Not might, but will. Do not mess around with the table saw. Do not allow loose clothing or hair anywhere near the lathe. We like gallows humor for some very good reasons.
Nothing quite like the worst-case outcome for Charlie Chaplin in Modern Times laid out for you in stark silhouette.
Tools undergo a great deal of stress in doing their job. They wear down, dulling their edges. There are impacts, intended and not. There’s a lot of force, and heat, and effort in shaping raw materials into something more useful. Tools are generally made from hard materials, intentionally harder than the material they’re working. Harder materials, broadly speaking, are more brittle.
So they’re good, they’re good, they’re good… oops. Broken.
A lot of the shop’s milling and milling-adjacent tools are made of high-speed steel (HSS), a group of steel alloys which perform well at high temperatures without losing their temper. Tungsten carbide (often called carbide) is even harder, and we save those for jobs that need it. Carbide’s brittle enough that it can’t be used in hand tools, instead requiring a sturdier, rigid setup like a milling machine, a drill press, or even better, a CNC machine.
They’re awfully expensive to replace.
Some tools, though, require human hands and a deft touch. Taps are one such example. The action of cutting threads takes firm yet gentle pressure, with frequent pauses and reversals. The tap gets hot; the material gets hot. The corresponding thermal expansion makes the tap more and more difficult to turn, increasing the risk of fracture. Best be patient.
And sometimes, despite all that effort? The high-pitched *tink* that tells you the tap snapped. It’s subtly different from the similar sound that a curled, not-yet-removed burr of metal makes when the tap runs up against it. Sigh.
Reverse the tap, slowly, carefully. See if you can remove the broken piece without damaging the hole. Remember that it’s harder than the material it’s in, and probably as hard as the drill bit you’d like to use to dislodge it. If need be, drill a new hole and try again. This particular tap met its end putting threads into cast iron, a less-than-ideal material for most of our machining jobs.
Most impressive is that the yellow paint has lasted this long.
It seems the university has drifted away from this, but if you look around at old equipment, a great deal of it is marked with the date it was acquired and – if it’s old enough – the cost. They’re fascinating glimpses into the past.
Here, an optics bench made by the Central Scientific Co. of Chicago, Illinois. Or, as they’d prefer, Cenco of Chicago, U.S.A. This particular 132cm chunk of cast iron and steel joined the department in late September of 1943, for the low, low price of $40. According to the U.S. Bureau of Labor Statistics’ CPI Inflation Calculator, that’s an excessively specific $681.17 in today’s dollars. (Significant digits!)
Surely there’s a reason for the cities listed in that order.
Up until now, it’s been in more or less continuous lab use, only recently replaced by brand-new extruded aluminum optics benches. Almost 80 years, and they’re not entirely kaput just yet.
After all, if an apparatus continues to be useful, we’ll keep it around. This one is getting repurposed for future labs, so we’ll see how many more decades it has in it…
