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Category Archives: Safety

Birds and City Lighting: a Toxic Mix

21 Thursday Apr 2022

Posted by gfbrandenburg in astronomy, education, History, nature, Safety, science, Uncategorized

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birds, dark, environment, insects, light, light pollution, migration, navigation, night sky

An alarming article about studies of bird deaths due to bright city lighting. A couple of quotes:

Every 11 September at dusk, in memory of the 2001 attacks, New York City mounts the Tribute in Light, an art installation in lower Manhattan. And every year, as twin towers of light bloom skyward, they attract thousands of migrating birds, sucking in warblers, seabirds, and thrushes—along with predators such as peregrine falcons eager to take advantage of the confusion. On each anniversary, bird conservationists wait below, counting and listening to disoriented chirps. If the observers report too many birds circling aimlessly in the beams, organizers flip off the lights.

In recent years, on-site observers have also used a complementary tool to quantify the orbiting birds: weather radar, which bounces off birds as well as raindrops. In 2017, a group led by Cornell University ornithologist Andrew Farnsworth found that during seven previous anniversaries, the once-a-year installation had attracted a total of about 1.1 million birds. Within 20 minutes of lighting up, up to 16,000 birds crammed themselves into a half-kilometer radius. But when the lights flicked off, the dense clouds of birds on the radar screen dissipated just as fast, a finding later confirmed by on-site thermal cameras.’

Later, discussing a single building, the author found that a

‘key factor was how many of the convention center’s windows had been illuminated. Each individual bright window left more dead birds for volunteers to find the next day. The correlation suggests halving the number of lit window bays would halve the number of bird strikes, the team estimated, saving thousands of birds at this one three-story building. “It really does seem that each window makes a difference,” van Doren says.’

Correct weight of the mystery glass

13 Wednesday Oct 2021

Posted by gfbrandenburg in Hopewell Observatorry, optical flat, Optics, Safety, Telescope Making

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mystery glass

More progress with the 22-inch wide, 4-inch thick mystery glass.

It took four of us old farts- Jim Kaiser, Alan Tarica, Tom Crone, and me – to extract the mirror from its case (which was located under a very heavy Draper-style grinding and polishing machine) roll it onto a little stand we fabricated on a decent gym scale I borrowed from my gym ( http://www.True180.fitness ) and weigh it.

We were very careful when moving that heavy mirror. Nobody got hurt in any way. When putting the mirror back into its sturdy wood carrying box, we used ancient Egyptian technology of little rollers, and it worked like a charm.

The bathroom scale we had used earlier, up at Hopewell was very, very wrong. We found that the weight of the glass was really 212 pounds (about 96 kilograms, or 96,000 grams), not 130 pounds. Its volume was 20,722 cc, so its density is roughly 4.6. Will have to see what types of glass have roughly that density and an index of refraction of about 1.72 to 1.76.

I heard from one veteran telescope maker:

“I’ve been in the Tucson astronomy club for many decades and also in the optics industry there. Most all institutions that had connections to astronomy or optics in the 60s got portions of several semi loads of “glass bank glass”, glasses that at one point in the past were considered strategic materials for certain optical designs/systems. There was a wide variety of materials, but almost all was identified in some way. We’re there any markings ar data scribed in the glass? The largest I saw was about 15”, so yours might be a different source.

“A co-worker of mine has identified several mystery glasses from an accurate determination of density. Seems like you should be able to get better results w/a more accurate scale. Also many glass types made decades ago are obsolete – my friend has some older glass catalogs that might help you determine what it might be with more accurate numbers.”

So these were cast-offs from the Military Industrial Complex, basically: pieces of glass that the military decided it no longer needed for projects that had either been completed or abandoned, and that they didn’t feel like storing any more. So they gave them away to groups like National Capital Astronomers and Hopewell Observatory.

The only markings on the glass are the following: a heavily inscribed (by hand) apparent date of 2-8-56, which probably means either February 8 of 1956 or the 2nd of August 1956. Judging by the handwriting style of the numerals, it was probably Feb. 8 of 1956 (US style). Under that are the numerals 0225, which we have no idea about. In pencil, someone with US-style handwriting wrote what looks like “Low #” in cursive. Again, we have no idea what that means.

Thanks so much, Jim, Alan, and Tom!

More about spray-coating astronomical mirrors with silver!

30 Monday Dec 2019

Posted by gfbrandenburg in astronomy, Optics, Safety, science, Telescope Making, Uncategorized

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Here is a batch of articles and links concerning the spray-on process for making astronomical mirrors reflective using protected silver solutions.

Long ago, I translated Foucault’s monograph on making paraboloidal, silvered astronomical mirrors. Part of his article described the process that he and Steinheil developed for silvering, which involved using silver nitrate solutions and various other reagents. It looked quite tricky, and also required further polishing! Plus, our telescope making workshop here in Washington DC had a Navy surplus vacuum chamber that was (and still is) quite effective at putting on good-quality, inexpensive aluminum coatings for any mirror up to 12.5″ diameter.

However, I and a couple of other ATMers (Bill R and Oscar O) are working on mirrors in the 16 to 18 inch range, and they simply won’t fit. So I was quite intrigued to watch how Peter Pekurar and some other folks coated a couple of rather large mirrors right in front of a small crowd of onlookers in a tent at this summer’s Stellafane.

I have a few videos on my webpage (here).

There is also an article on the process in the January 2020 Sky and Telescope, and a webpage (here) on the topic run by Pekurar and Howard Banich and others.

Not to mention a bunch of posts on Cloudy Nights (here) and a nice PDF explaining it all, (here).

What is really, really amazing is that the webpage by Pekurar and Banich also has interferograms showing that the overcoating has absolutely no effect on the sub-microscopic, geometrical figure of the mirror! Unfortunately, it’s only effective against chemical attack, not against dirty fingers or scratches. They also did some careful experiments on reflectivity at various wavelengths with various treatments of the surface.

A couple of local ATMers and at least one professional at Goddard Space Flight Center have told me about their experiments with the process; they found that it is easy to mess up if you aren’t stringently clean and also easy to waste materials.

Some Progress – AT LAST! – With Figuring the 16.5″ f/4.5 Thin Mirror That Headlines This Blog

10 Saturday Nov 2018

Posted by gfbrandenburg in astronomy, Hopewell Observatorry, Optics, Safety, Telescope Making

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Bob Bolster, George Ritchey, Grinding, Hopewell Observatory, matching Ronchi, Mel Bartels, Polishing, Ronchi, ronchigram, Telescope Making, testing

I have been wrestling with this mirror for YEARS. It’s not been easy at all. The blank is only about twice the diameter of an 8″ mirror, but the project is easily 10 times as hard as doing an 8-incher. (Yes, it’s the one in the photo heading this blog!)

Recently I’ve been trying to figure it using a polishing/grinding machine fabricated by the late Bob Bolster (who modeled his after the machine that George Ritchey invented for the celebrated 60″ mirror at Mount Wilson over a century ago). That’s been a learning exercise, as I had to learn by trial and error what the machine can and cannot do, and what strokes produce what effects. The texts and videos I have seen on figuring such a large mirror with a machine have not really been very helpful, so it’s mostly been trial and error.

My best results right now seem to come from using an 8″ pitch tool on a metal backing, with a 15 pound lead weight, employing long, somewhat-oval strokes approximately tangential to the 50% zone. The edge of the tool goes about 5 cm over the edge of the blank.

This little movie shows the best ronchigrams I have ever produced with this mirror, after nearly 6 hours of near-continuous work and testing. Take a look:

And compare that to how it used to look back in September:

 

Also compare that to the theoretically perfect computed ronchigrams from Mel Bartels’ website:

perfect theoretical ronchigrams for guy's 42 cm mirror

Part of the reason this mirror has taken so long is that after grinding and polishing by hand some years ago, I finally did a proper check for strain, and discovered that it had some pretty serious strain. I ended up shipping it out to someone in Taos, New Mexico who annealed it – but that changed the figure of the mirror so much that I had to go back to fine grinding (all the way back to 120 or 220 grit, I think), and then re-polishing, all by hand. I tried to do all of that, and figuring of the mirror, at one of the Delmarva Mirror Making Marathons. It was just too much for my back — along with digging drainage ditches at Hopewell Observatory, I ended up in a serious amount of pain and required serious physical therapy (but fortunately, no crutches), so this project went back into storage for a long, long time.

Recently I’ve tried more work by hand and by machine. Unfortunately, when I do work by hand, it seems that almost no matter how carefully I polish, I cause astigmatism (which I am defining as the mirror simply not being a figure of rotation) which I can see at the testing stand as Ronchi lines that are not symmetrical around a horizontal line of reflection. (If a Ronchi grating produces lines that look a bit line the capital letters N, S, o Z, you have astigmatism quite badly. If astigmatism is there, those dreaded curves show up best when your grating is very close to the center of curvature (or center of confusion) of the central zone.

Using this machine means controlling or guessing at a LOT of variables:

  1. length of the first crank;
  2. length (positive or negative) of the second crank;
  3. position of the slide;
  4. diameter of the pitch lap;
  5. composition of the pitch;
  6. shape into which the pitch lap has been carved;
  7. amount of time that the lap was pressed against the lap;
  8. whether that was a hot press or a warm press or a cold press;
  9. amount of weight pushing down on the lap;
  10. type of polishing agent being used;
  11. thickness or dilution of polishing agent;
  12. temperature and humidity of the room;
  13. whether the settings are all kept the same or are allowed to blend into one another (eg by moving the slide);
  14. time spent on any one setup with the previous eleven or more variables;

Here is a sketch of how this works

bolster's ritchey-like machine

What a Great Night!

05 Monday Mar 2018

Posted by gfbrandenburg in astronomy, astrophysics, Hopewell Observatorry, monochromatic, Optics, Safety, science, Telescope Making, Uncategorized

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Just got back from an exciting astro expedition to Hopewell Observatory with one of the other members. Great fun!

Anybody living on the East Coast in March 2018 has just lived through a very strong, multi-day gale. The same weather system brought snow and flooding to the northeast, and here in the DC-Mar-Va area, it was cut off power to many (including my mother-in law) and caused almost all local school districts to close — even the Federal Government! Two of my immediate neighbors in DC had serious roof damage.

Today, Sunday, Paul M and I decided the wind had calmed enough, and the sky was clear enough, for an expedition to go up and observe. We both figured there was a good chance the road up to the observatory would be blocked by trees, and it turns out that we were right. My chainsaw was getting repaired – long story, something I couldn’t fix on my own – so I brought along work gloves, a nice sharp axe, loppers, and a 3-foot bowsaw. We used all of them. There were two fairly large dead trees that had fallen across the road, and we were able to cut them up and push them out of the way.

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However, there was a large and very dangerous ‘widow-maker’ tree (two images above) that had fallen across the road, but it was NOT on the ground. Instead, was solidly hung up on the thick telecommunications line at about a thirty-degree angle to the ground. The power lines above it didn’t seem to be touched. You could easily walk under the trunk, if you dared (and we did), and you probably could drive under it, but of course the motion of the car just might be enough to make it crack in half and crush some unlucky car and its driver. Or maybe it might make the phone line shake a bit …

No thanks.

So, we didn’t drive under.

I called the emergency phone for the cell phone tower (whose access road we share) to alert them that the road was blocked and could only be cleared by a professional. I also attempted to call a phone company via 611, without much success — after a long wait, the person at the other end eventually asked me for the code to my account before they would forward me to somebody who could take care of it. Very weird and confusing. What account? What code? My bank account? No way. We will both call tomorrow. Paul says he knows some lawyers at Verizon, whose line he thinks it is.

But then: how were we going to turn the cars around? It’s a very narrow road, with rocks and trees on one side. The other side has sort of a ravine and yet more trees. Paul realized before I did that we had to help each other and give directions in the darkness to the other person, or else we would have to back up all the way to the gate! Turning around took about four maneuvers, per car, in the dark, with the other person (armed with astronomer’s headlamp, of course) yelling directions on when to turn, how much to go forward, when to stop backing up, and so on. Success – no injuries! We both got our cars turned around, closed them up, got our cutting tools, gloves and hats, and then hiked the rest of the way up, south and along the ridge and past the big cell phone tower, to the Observatory buildings themselves, moving and cutting trees as we went.

As we were clearing the roadway and walking up the ridge, we peered to the west to try to find Venus and Mercury, which had heard were now evening planets again. It wasn’t easy, because we were looking through LOTS of trees, in the direction of a beautiful multi-color, clear-sky sunset featuring a bright orange line above the ridge to our west. Winter trees might not have any leaves, but they still make the search for sunset planets rather tough. Even if you hold perfectly still, one instant you see a flash that’s maybe a planet, or maybe an airplane, and then the branches (which are moving in the breeze, naturally) hide it again. So what was it? Paul’s planetarium smartphone app confirmed he saw Venus. If the trees weren’t there, I think we also would have seen Mercury, judging by Geoff Chester’s photo put out on the NOVAC email list. I think I saw one planet.

In any case, everything at the observatory was just fine – no tree damage on anything, thanks to our prior pruning efforts. The Ealing mount and its three main telescopes all worked well, and the sky and stars were gorgeous both to the naked eye and through the scopes. Orion the Hunter, along with the Big Dog and the Rabbit were right in front of us (to the south) and Auriga the Charioteer was right above us. Pleiades (or the Subaru) was off high in the west. Definitely the clearest night I’ve had since my visit to Wyoming for the solar eclipse last August, or to Spruce Knob WV for the Almost Heaven Star Party the month after that.

Paul said that he and his daughter had been learning the proper names of all the stars in the constellation Orion, such as Mintaka, Alnilam, and Alnitak. As with many other star names, all those names are Arabic, a language that I’ve been studying for a while now [but am not good at. So complicated!] Mintaka and Alnitak are essentially the same Arabic word.

After we got the scopes working, Paul suggested checking out Rigel, the bright ‘leg’ of Orion, because it supposedly had a companion star. {Rajul means “leg”} We looked, and after changing the various eyepieces and magnifications, we both agreed that Rigel definitely does have a little buddy.

I had just read in Sky & Telescope that Aristotle (from ancient Greece) may have given the first written account of what we now call an “open cluster” in the constellation Canis Major (Big Dog – that’s Latin, which I studied in grades 7 – 12) called Messier-41, only a couple of degrees south of Sirius, the brightest star in the sky. A passage in a book allegedly written by Aristotle (roughly 230 BC) seems to indicate that he could see this object with averted vision. (He was trying to establish that it was a fuzzy patch in the sky that was most definitely NOT a comet, just like Charles Messier was doing almost exactly two thousand years later!)

M41 was quite attractive. But no, we didn’t then look at M42. Been there, done that many times before. And no, what you see with a telescope does not have all those pretty colors that you see in a photograph.

Instead, we looked on a multi-sheet star atlas (that stays in the observatory) near M41 and found three other open clusters, all really beautiful. We first found M38 and thought that in the C-14 and 6″ Jaegers, it looked very anthropoid or like an angry insect, if you allowed your mind to connect the beautiful dots of light on the black background. In the shorter 5″ refractor made by Jerry Short, it looked like a sprinkling of diamond dust. This cluster must have been formed rather recently. We then found M36, which was much less rich, but still quite pretty. Lastly, we found M37, another open cluster, which has a very bright yellow star near the center, against background of much fainter stars. It seemed to me that those other stars might be partly obscured by a large and somewhat translucent cloud of dust. We saw a web of very opaque dust lanes, which we confirmed by readings on the Web. Really, really beautiful. But I’m glad we don’t live there: too dangerous. Some of the stars are in fact red giants, we read.

Then we looked straight overhead, in the constellation Auriga. We decided to bypass the electronics and have Paul aim the telescope, using the Telrad 1-power finderscope, at one of the fuzzy patches that he saw there. He did, and my notes indicate that we eventually figured out that he found Messier-46 (yet another open cluster) with his naked eye! Very rich cluster, I think, and we even found the fan-shaped planetary nebula inside!

At this point we were getting seriously cold so we moved over just a little, using the instruments, to find M47, again, a very pretty open cluster.

Realizing that the cold and fatigue makes you do really stupid things, and that we were out in the woods with no way to drive up here in case of a problem, we were very careful about making sure we were doing the closing up procedures properly and read the checklist at the door to each other, to make sure we didn’t forget anything.

On the walk back, we saw the Moon coming up all yellowish-orange, with the top of its ‘head’ seemingly cut off. When it got a bit higher, it became more silver-colored and less distorted, but still beautiful.

I really thought all of those open clusters were gorgeous in their own right, and I think it would be an excellent idea to make photographs of them, but perhaps black dots on white paper, and give them to young folks, and ask them to connect the dots, in whatever way they feel like doing. What sorts of interesting drawings would twenty-five students come up with?

I am not sure which of our various telescopes would do the best job at making astro images. I have a CCD camera (SBIG ST-2000XM), with a filter wheel. What about just making it a one-shot monochromatic black and white image? I also have a Canon EOS Revel XSI (aka 450D, I think). Compare and contrast… The CCD is really heavy, the Canon quite light. I also have a telephoto lens for the Canon, which means that I have essentially four telescopes to choose from (but not a big budget!). One problem with the C-14 and my cameras is that the field of view is tiny: you can only take images of very small bits of what you can see in the eyepiece with your naked eye. This means you would need to make a mosaic of numerous pictures.

In any case, no imaging last night! Not only did I not feel like hauling all that equipment for a quarter of a mile, after all that chopping, sawing, and shoving trees, it turns out I had left my laptop home in the first place. D’oh!

I had previously found every single one of these open clusters when I made my way through the entire Messier list of over 100 objects, with my various home-made telescopes, which had apertures up to 12.5 inches. However, I don’t think I had ever seen them look so beautiful before! Was it the amazing clarity of the night, or the adventure, or the company? I don’t know!

But this was a very fun adventure, and this photography project – attempting to make decent images of these six open clusters – promises to be quite interesting!

 

 

 

 

 

Make your own telescope!

18 Thursday Jan 2018

Posted by gfbrandenburg in astronomy, education, Optics, Safety, Telescope Making, Uncategorized

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achromatic, doublet, Gaithersburg, lens, make your own telescope, PVC

This weekend, I’m hosting a small workshop at the Community Museum in Gaithersburg, MD, where interested persons from 8 to 88 years of age can make their own telescope in an hour or two. We will be using surplus but high-quality achromatic primary doublet lenses as well as inexpensive eyepieces, along with PVC tubing and some really cool tripods to hold it steady.  We will some basic optics experiments to help explain how these gizmos work, and will have spray paint and colored tape to decorate the tubes.

If you are interested, here is the necessary information:

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Gaithersburg Community Museum's photo.
JAN21

Make Your Own Telescope

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    Sunday at 1 PM – 4 PM
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    Gaithersburg Community Museum

    9 S Summit Ave, Gaithersburg, Maryland 20877
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Make your own refracting telescope in just an afternoon! This workshop will be led by veteran DC amateur telescope-maker Guy Brandenburg. He will show you how to make a small functioning telescope that can either be held in your hands or mounted on almost any camera tripod. All of the materials needed will be provided, and no experience is necessary. This workshop is open to anyone from the ages of 9 through 99, but a parent would need to accompany any child from 9 – 11. You might get a little dirty, so don’t wear your best clothing!

You will also see how various types of telescopes such as reflectors, refractors, and catadioptrics are put together and operate, using actual examples, including the type made and used by Galileo around 1609.

$30 City of Gaithersburg residents/$35 non-residents. Space is limited to 15 so pre-registration is required. To register go to RecXpress at https://online.activenetwork.com/gaithersburg/Start/Start.asp. It’s activity #49690.

For more information or if you have trouble registering call the museum at 301-258-6160 or museum@gaithersburgmd.gov

 

Australian TV Bit on Me and the DC ATM Workshop

27 Monday Nov 2017

Posted by gfbrandenburg in astronomy, astrophysics, nature, Safety, science, Telescope Making

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2017, ATM, Australia, eclipse, Stephanie March, Telescope

Some very nice folks from the Australian Broadcasting Corporation came and interviewed me on film for a bit on folks who make their own telescopes to see the great August 2017 eclipse. Here is the link:

( https://www.facebook.com/abcnews.au/videos/10157157152414988/ )

Safer Table Saws Should Be Mandatory

14 Monday Aug 2017

Posted by gfbrandenburg in History, Safety, science, Telescope Making

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finger, Safety, SawStop, table saw

Three parts to this little essay:

  • What happened to me about a month into my retirement, with an old, nearly-free table saw that lacked SawStop safety features (and which I was using totally improperly, because I didn’t know better)
  • Table saws are one of the most commonly-used power tools both commercially and at home, and are responsible for an AMAZING number of injuries and amputations every DAY.
  • A fix for this exists — the technology included in every single SawStop table saw. The inventor tried, but failed to convince table saw manufacturers to incorporate this essential, and not-terribly-expensive feature, and they ALL turned it down, essentially saying that ‘safety doesn’t sell’. Congress has the power to make this feature mandatory and to save many a hand, finger, or eye.

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Part One

These are not trick shots. It’s just my left hand, imaged poorly just now with my smart phone. I was really ashamed, embarrassed, and sad when this injury occurred, roughly a month after I retired from teaching, for several reasons:

(1) It turned out that I was using the table saw totally improperly, holding a very small piece of wood as I fed it into the blade

(2) I literally did not know that was an improper way of feeding wood into a table saw; I was treating it like a band saw

(3) I should have read up on safety rules for table saws, even though I had used them without incident quite a few times earlier, and thought that I was safe enough (and I wasn’t)

(4) While I am right-handed, losing part of one’s left-hand index finger and having the adjacent finger be mauled so that it lacks feeling on one side, and doesn’t bend properly, and is crooked, means that there are many things one can never do again – for example typing quickly and efficiently. The letters e, r, t, d, f, g, c, v, and b (look at your keyboard and if you ever learned touch typing, you’ll see why) are all now much harder for me to type. And unfortunately for me, E and T are the two most common letters in the alphabet. (I’m not asking for sympathy! Just don’t do this to yourself!! Wear safety equipment and read the fri&&14& manuals!)

 

On the good side, I am extremely grateful and amazed at the skill of Dr. Reisin, my hand surgeon. Without any warning that I could see, my hand got dragged into the blade by the tiny piece of wood. My two fingers looked like very fresh hamburger, and I thought I had lost them down to stumps. I was amazed that when I got my first view of the damage, I still had most of them! Yay Dr. Reisin! Really, amazing job!

In addition, we have Kaiser Permanente family high option insurance. It’s not cheap, something like $400 a month that I pay, plus I have a wonderful subsidy from the DC government, which pays something like $1000 a month. All of that adds up to just about 1/3 of my gross retirement pay, but at least I was never asked to liquidate my retirement savings or sell our house to pay for the astronomically huge bills for all of the doctors’ fees (think anaesthesiologist, primary care physician, ER physicians, surgeon, just to name a few) and the hospital stay and the several months of careful and skillful rehabilitation. It was tens of thousands of dollars, though I certainly don’t know the exact total. If we did not have medical insurance, it would have been very, very tough, but we had minimal co-pays for each visit and for the various antibiotics and painkillers. EVERYBODY SHOULD HAVE THAT!

Again, I was really embarrassed at my own stupidity. For the first few months, I labored under the misapprehension that the wood had been thrown INTO my hand by kickback. But a more knowledgeable friend (WHR) convinced me otherwise; plus I looked at the sawblade scars on the underside of the other pieces that I had fed through – in each case, the saw had started grabbing the wood and had left its marks on the pieces of plywood — and I was too stupid and ignorant to notice. This video shows how dangerous table saws can be – it’s pretty similar to what happened to me: the blade catches the wood, AND the author’s pushing block, AND just barely misses taking off his finger(s).

SECOND PART:

It took me a while to realize that I was far from the only person who had suffered this sort of injury. I was quite aware that the workers at my college (Dartmouth) were almost ALL missing a finger or two or five – but that was from industrial accidents in the textile mills that used to exist all over New England, but had moved on to other places, probably because the owners could get labor for even less and spend even less on safety than before… I wish now I had asked them more about those injuries… But I’m pretty sure that they were not operating table saws.

I did not know that anywhere from SCORES to HUNDREDS of Americans have some sort of an injury with a table saw not per year, not per month, not per week, but EVERY SINGLE DAY.

Let that sink in. Somewhere between 40 and 400 people in the USA have an accident with a table saw, EVERY SINGLE DAY. Some of these accidents were worse than mine, some were less so (two sources on numbers: here,  here and here, each with links pointing elsewhere. It seems to me reprehensible that Robert Lang, the author of the Popular Woodworking magazine (the second link), belittles the number of injuries, comparing them to the number of kids who are hurt by doors everyday.

‘Back in January 2005, the Consumer Product Safety Commission (CPSC) required that new tablesaw models include a riving knife and modular guard to prevent these injuries. Since that time injury rates have remained virtually unchanged, which begs the question: “Why are so many people hurt while using tablesaws, despite improvements in guards and splitters?”’ (source)

As soon as I could use my arm again, I supervised getting rid of that old table saw. I think we sold it for scrap iron. (It had been sold to us for a pittance by a friend — who passed away from a heart attack at a very early age, as it happened. I never had the chance to mention to him what happened to me.)

Fortunately, after this event, the same friend (WHB) got wind of someone who wanted to donate funds so that we at the NCA Amateur Telescope Making workshop could actually get a decent, SAFE table saw. We also used the monies to purchase a very nice H-Alpha solar telescope for the astronomy club under whose auspices we operate, as well as a nearly-unused Grizzly milling machine… And while it doesn’t have lots of fancy features, that SawStop table saw will immediately (in 0.003 seconds) if it senses anything like your finger touching the blade while in operation; if it does, it slams the blade down into an aluminum chunk and stops it immediately and OUT OF THE WAY. (Have you seen any of those hot-dog table-saw videos? or ) Sure, it kills the blade and the chunk of aluminum (roughly $60)  but that’s way better than cutting off your finger!

In fact, the inventor agrees to put HIS OWN finger into a SawStop table saw, under a high-speed camera and very bright lighting, here. He does so, and the sawblade stops instantly, you can see that no damage to his finger at all: no blood, no bruising, no nothing. The inventor says it felt a little like a buzzing insect or a tickle. Absolutely amazing!

Plus, the saws are really, really well made and easy to put together, and have a very good manual that comes with a spiral-bound notebook with laminated pages and very clear instuctions in English, that you can lay flat at any page you want.  In other words, not the incomprehensible hieroglyphics, printed on flimsy paper, that is so common with manuals today. (Think IKEA…) And the prices are well within range of the prices of other table saws with comparable features.

The original inventor has recently testified at the Consumer Product Safety Commission, and was interviewed by NPR. He could not get manufacturers to agree to put his device (or one just like it) into their saws, EVEN AS AN OPTION. So he set up his own company to make them.

It’s also reprehensible that something like the Power Tool Institute wants to prevent the government from making this electronic safety feature mandatory, as you can see here. 

It’s the usual crapload of hysterical propaganda: higher unemployment, making companies go bankrupt — the same lies that the Big Three carmakers said when they resisted putting in seat belts, antilock brakes, turn signals, doors that have hinges at the front and not the back, unleaded gas, airbags, and so on. But those inventions (and others) have saved untold millions of lives, despite the resistance of the rich and powerful. It’s disgraceful.

Yes, we ordinary humans do make mistakes, each and every single day. People are going to lose focus, or get distracted, or make stupid errors of judgement, like me. It doesn’t matter if you drive (or use a table saw) correctly 99.9% of the time: that still leaves that one time in a thousand where you don’t, AND IT CAN KILL YOU OR MAIM YOU FOR LIFE.

If the fix for that is simple — and even if it costs something — it should be done.

We are only human.

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