Mailing terrorist threats with ricin in the letters while complaining about gun control. Yeah, this could be a gun control advocate trying to make our side look bad. But there are tens of millions of people who passionately oppose gun control; it isn't much of a stretch to imagine that one of those tens of millions have the strategic planning capacity of a bagel.
I am actually pretty pleased with how seldom anyone on our side gets arrested for doing something this stupid. Here's a hint: making threats to overthrow the government if you actually plan to do that isn't exactly keeping the advantage of surprise, is it?
Kamis, 30 Mei 2013
Remember Trayvon Martin?
The case is getting more and more crooked. From the May 29, 2013 Miami Herald:
ORLANDO, Fla. -- A court employee who retrieved photos and deleted text messages from Trayvon Martin's cellphone has been placed on administrative leave after an attorney testified that prosecutors didn't properly turn over the evidence to the defense, an attorney said Wednesday.
Former prosecutor Wesley White said he was ethically obligated to reveal that Fourth Judicial Circuit Information Technology Director Ben Kruidbos retrieved the data that weren't turned over.And what were some of the pictures that came off the cell phone of the angelic Trayvon Martin?
The defense released photos of a gun, marijuana plant and Martin's text messages publicly, saying that if prosecutors planned to paint Zimmerman as the aggressor and Martin as the innocent bystander, they wanted the information to defend him. Attorneys won't be able to mention the teen's drug use, suspension from school and past fighting during opening statements at the trial, Nelson ruled Tuesday.I think I see why the defense wants that information -- and having that information hidden? Wow.
Sonoma County, California: The Newest Financial Disaster
I'm sure that Sonoma County boosters are overjoyed to see this beautiful place getting media attention -- although perhaps not this May 29, 2013 Financial Post story:
‘A disaster in slow motion’: Wine country latest California region to face fiscal crisisWow. A county of far left millionaires is now in serious financial trouble because of overly generous pensions for public employees. Who would have guessed?
Selasa, 28 Mei 2013
Dead Battery
I can't remember the last time that I replaced the battery on the Corvette, which, perhaps because I have not driven it since Thursday, is dead as a doornail this morning. The Chevrolet dealer tells me that they last replaced a battery on the Corvette in 2004, which is a pretty respectable lifespan for a car battery.
Imagine If A Republican Said This...
There's a bill before Congress to prohibited convicted murderers, rapists, and pedophiles from receiving Food Stamps. Mother Jones (well known left-wing publication) explains why this is a problem:
On Wednesday the Senate agriculture committee approved a GOP proposal that would amend the farm bill the Senate is considering to ban "convicted murderers, rapists, and pedophiles" from getting food stamps. On its surface, the idea sounds unobjectionable, but the measure would have "strongly racially discriminatory effects," according to the non-partisan Center on Budget and Policy Priorities (CBPP).So Mother Jones is saying that blacks are disproportionately convicted murderers, rapists, and pedophiles, and so such a law is unfair? Perhaps they meant that it was unfair to black murderers, rapists, and pedophiles? Well, no, it treats all murderers, rapists, and pedophiles badly, regardless of race. How can you parody the progressive mentality effectively when they do it to themselves so well?
Senin, 27 Mei 2013
Since The Weather Is Bad Anyway...
I mean, it snowed here on Wednesday! And the weekend has been nothing but clouds and rain. Once I successfully adjusted the spider legs to get the diagonal mirror centered in the telescope tube, I was able to collimate the telescope quite quickly. But when I changed the angle of the telescope so that it was no longer horizontal, the collimation was off again. I am pretty sure that the reason is that there are two parts of the diagonal holder that are too flexible:
1. The legs are made of .0325" aluminum -- and that is probably too flexible. I can replace them with 20 gauge steel, which would be the same thickness (and optical path interference) but three times as stiff. I may also go from 2" front to back to 3" front to back, which would improve stiffness even more. The steel will weigh more, but only an ounce or two.
2. The central body of the diagonal holder is made of acetal, which is easy to machine, but has about 1/20th the Young's modulus (flexural deflection) of aluminum. I think I will pick up 3" of .25" ID aluminum tubing, perhaps 1/8" wall, and use that as the new central body. That should improve stiffness substantially with no real difference in weight. (The existing acetal part is fairly thick, so probably about the same net weight.)
1. The legs are made of .0325" aluminum -- and that is probably too flexible. I can replace them with 20 gauge steel, which would be the same thickness (and optical path interference) but three times as stiff. I may also go from 2" front to back to 3" front to back, which would improve stiffness even more. The steel will weigh more, but only an ounce or two.
2. The central body of the diagonal holder is made of acetal, which is easy to machine, but has about 1/20th the Young's modulus (flexural deflection) of aluminum. I think I will pick up 3" of .25" ID aluminum tubing, perhaps 1/8" wall, and use that as the new central body. That should improve stiffness substantially with no real difference in weight. (The existing acetal part is fairly thick, so probably about the same net weight.)
What A Weekend
Most of Saturday and Sunday was spent providing close combat support to my son while he was out car shopping. Once this experience is complete, I am sorely tempted to write an article with the title, "How Car Sales Gives Free Market Capitalism a Black Eye."
Sabtu, 25 Mei 2013
Spiders
The structure that holds the diagonal mirror in a Newtonian telescope is called a spider, because it typically has several legs.
Last night, I was finally ready to do collimation of the optical path, and I discovered that no matter what, I could not get the diagonal mirror centered in the tube! Why? Was it this far off in the old tube?
No. I had to cut down the mirror cell bottom plate because the inner diameter of the tube is 19.875" instead of 20.25"; I forgot that the spider required similar surgery. It was easy to forget, because the legs of the spider are made of .030" aluminum (in the interests of minimizing weight and diffraction of light), and they are flexible enough that they just bent to fit. But they did not bend symmetrically.
My first concern was that I was going to have to start from scratch on this, but it turns out that there was enough spare room where the legs attached to the center point that I was able to redrill the holes in the legs 3/16" over and solve the problem. The picture below was taken with my little HP PhotoSmart camera, and it isn't terribly sharp, but you can see where I moved the holes:
I may buy a ring roller at Harbor Freight today to make tube rings. One of the reviews indicated that one of the plastic parts broke almost immediately, which doesn't surprise me. I will be rolling 1/8" or 3/16" thick aluminum, so I doubt that I will be stressing it much, and it sounds like other than that one part (which I can probably machine a replacement for out of aluminum), it is an adequate tool.
UPDATE: After spending a bit of time, I discovered that because the spider legs are held in tension (rather than compression, as it more typical of spiders), it is very dependent on the order of tightening to keep the body centered. After a little experimentation, it seems to be well-centered, and collimation went very well. But I am a bit concerned that it might not hold collimation as it moves across the sky. Perhaps a more conventional (that is to say, commercial) spider would be a better choice for this.
Frustration: I bought the ring roller at Harbor Freight -- but it appears that some previous purchaser had tapped the taper pin that holds the handle to the roller before putting the handle in place. There seems to be no way to remove the taper pin now without drilling it out. So tomorrow I will go back and ask for one that has the taper pin not yet inserted.
Last night, I was finally ready to do collimation of the optical path, and I discovered that no matter what, I could not get the diagonal mirror centered in the tube! Why? Was it this far off in the old tube?
No. I had to cut down the mirror cell bottom plate because the inner diameter of the tube is 19.875" instead of 20.25"; I forgot that the spider required similar surgery. It was easy to forget, because the legs of the spider are made of .030" aluminum (in the interests of minimizing weight and diffraction of light), and they are flexible enough that they just bent to fit. But they did not bend symmetrically.
My first concern was that I was going to have to start from scratch on this, but it turns out that there was enough spare room where the legs attached to the center point that I was able to redrill the holes in the legs 3/16" over and solve the problem. The picture below was taken with my little HP PhotoSmart camera, and it isn't terribly sharp, but you can see where I moved the holes:
I may buy a ring roller at Harbor Freight today to make tube rings. One of the reviews indicated that one of the plastic parts broke almost immediately, which doesn't surprise me. I will be rolling 1/8" or 3/16" thick aluminum, so I doubt that I will be stressing it much, and it sounds like other than that one part (which I can probably machine a replacement for out of aluminum), it is an adequate tool.
UPDATE: After spending a bit of time, I discovered that because the spider legs are held in tension (rather than compression, as it more typical of spiders), it is very dependent on the order of tightening to keep the body centered. After a little experimentation, it seems to be well-centered, and collimation went very well. But I am a bit concerned that it might not hold collimation as it moves across the sky. Perhaps a more conventional (that is to say, commercial) spider would be a better choice for this.
Frustration: I bought the ring roller at Harbor Freight -- but it appears that some previous purchaser had tapped the taper pin that holds the handle to the roller before putting the handle in place. There seems to be no way to remove the taper pin now without drilling it out. So tomorrow I will go back and ask for one that has the taper pin not yet inserted.
Jumat, 24 Mei 2013
Advantages of Fiberglassing the Sonotube
I had mentioned that I was going to put the polyester resin on the edges of all the holes, big and small, that I made in the Sonotube, to reinforce the edges and prevent fraying. This worked like a charm. I discovered that it also made the holes just a little small -- which meant redrilling the holes for the small ones. I actually found the bolts that hold the mirror cell in place were threading into the holes! I would not count on threads in this stuff holding any real load, but at least the bolts weren't flopping about in there!
The eyepiece focuser hole, however, required some filing -- and unlike Sonotube, which doesn't file well, the composite material I produced actually filed very nicely indeed -- better than the paint, which chipped a bit. A very nice result.
The eyepiece focuser hole, however, required some filing -- and unlike Sonotube, which doesn't file well, the composite material I produced actually filed very nicely indeed -- better than the paint, which chipped a bit. A very nice result.
Kamis, 23 Mei 2013
Big Bertha, 3.0
I still need to do a bit of adjusting and collimation, and some touch-up paint, especially on the straps. I was hoping to get to that tonight, because we have a clear sky, but I had orders to fill, so....
But everything is back in the tube -- and it appears that it is slightly heavier than it was before. Oh well. At least it should be rigid.
The following two pictures show what happens when you use a flash, and don't use a flash. From the first picture, you would never know the inside of the tube is black.
But everything is back in the tube -- and it appears that it is slightly heavier than it was before. Oh well. At least it should be rigid.
The following two pictures show what happens when you use a flash, and don't use a flash. From the first picture, you would never know the inside of the tube is black.
Individual End Mill Prices...
I was looking online to order up a replacement for the 1/8" end mill that I broke yesterday, and I am startled to see how expensive individual end mills are. Just the 1/8" end mill at Grainger costs almost as much as this entire collection that I bought several years ago from Little Machine Shop. Admittedly, the end mill from Grainger is U.S. made, and might well last forever with the amount of milling I do.
Rabu, 22 Mei 2013
Lack of Blogging...
My wife had a shoulder repair operation yesterday at St. Luke's, and pretty much the whole day was spent with getting her checked in, surgery, post-op. I probably should have brought my laptop, but I wasn't expecting the entire day to get consumed. I will say that I am always very impressed with the medical and support staff at St. Luke's (and every other hospital here in the Boise area). Friendly; courteous; concerned.
She is doing okay, but considering that they went in and removed bone spurs inside her shoulder, she is in a bit of pain. I stayed home yesterday and today to take care of her; I just can't imagine what single people do in these situations.
The evenings have been lost in the great telescope rebuild. I discovered that all the work I put into trimming the C-channel pieces down was a mistake; there was not enough clearance for attaching the steel straps without a lot more precision in cutting than I could easily do with a bandsaw, so I started over, and it was much faster. When drilling the attachment holes in the steel straps, the straps are thin enough that they briefly went red-hot as I drilled them! (More oil next time.)
The new versions were faster to make, in spite of breaking the 1/8" end mill that I was using to cut the slot. I finished with a 1/4" end mill, which looks less elegant for an .030" thick piece of steel strap, but it isn't like you can find a 1/8" end mill in Horseshoe Bend.
The upper picture shows the static end of the strap; the lower picture shows the screw that tightens it down. Unfortunately, the thumb screws I bought at Grainger just weren't long enough. A 1" long screw thread sounds good enough, but once the captive nuts were on it, that was not enough travel to be useful, so it now has a conventional hex head bolt. I may replace those when I can order a thumb screw with a longer thread. They work well -- although it takes a while to crank them down enough. Of course, that also makes it less likely that I will overcompress the tube with the straps, so I guess that's a positive.
The mirror cell has turned out to be a "I was too clever for my good" moment (as have several in the project). It turns out that having the mounting brackets separate from the bottom plate was a great idea -- except that the bolts holding the brackets to the bottom plate can't get past the mirror once the brackets are mounted inside the tube. So I guess I will do what I was trying to avoid -- tap the mounting brackets so that I can screw the threads in from the outside of the tube. This is a blind operation, but at least I can see the brackets from the rear. Some other mirror cells have you trying to find the threaded holes in a circular casting where there are no real clues as to location. The slots in the mounting brackets were for 1/4"-20 bolts, so it is easy enough to tap these for 5/16"-18 bolts -- which, fortunately, I have some in black oxide finish that I can use for this.
But that will be tomorrow night, or maybe the night after. I actually have ScopeRoller orders rolling in, and I need to get some of these filled.
She is doing okay, but considering that they went in and removed bone spurs inside her shoulder, she is in a bit of pain. I stayed home yesterday and today to take care of her; I just can't imagine what single people do in these situations.
The evenings have been lost in the great telescope rebuild. I discovered that all the work I put into trimming the C-channel pieces down was a mistake; there was not enough clearance for attaching the steel straps without a lot more precision in cutting than I could easily do with a bandsaw, so I started over, and it was much faster. When drilling the attachment holes in the steel straps, the straps are thin enough that they briefly went red-hot as I drilled them! (More oil next time.)
The new versions were faster to make, in spite of breaking the 1/8" end mill that I was using to cut the slot. I finished with a 1/4" end mill, which looks less elegant for an .030" thick piece of steel strap, but it isn't like you can find a 1/8" end mill in Horseshoe Bend.
The upper picture shows the static end of the strap; the lower picture shows the screw that tightens it down. Unfortunately, the thumb screws I bought at Grainger just weren't long enough. A 1" long screw thread sounds good enough, but once the captive nuts were on it, that was not enough travel to be useful, so it now has a conventional hex head bolt. I may replace those when I can order a thumb screw with a longer thread. They work well -- although it takes a while to crank them down enough. Of course, that also makes it less likely that I will overcompress the tube with the straps, so I guess that's a positive.
The mirror cell has turned out to be a "I was too clever for my good" moment (as have several in the project). It turns out that having the mounting brackets separate from the bottom plate was a great idea -- except that the bolts holding the brackets to the bottom plate can't get past the mirror once the brackets are mounted inside the tube. So I guess I will do what I was trying to avoid -- tap the mounting brackets so that I can screw the threads in from the outside of the tube. This is a blind operation, but at least I can see the brackets from the rear. Some other mirror cells have you trying to find the threaded holes in a circular casting where there are no real clues as to location. The slots in the mounting brackets were for 1/4"-20 bolts, so it is easy enough to tap these for 5/16"-18 bolts -- which, fortunately, I have some in black oxide finish that I can use for this.
But that will be tomorrow night, or maybe the night after. I actually have ScopeRoller orders rolling in, and I need to get some of these filled.
Selasa, 21 Mei 2013
I Have A Philosophical Problem With Seat Belt Laws
But here's a warning that if you really prefer bouncing around the inside of your car in the event of an accident, be prepared for increased enforcement of the law. From May 20, 2013 KIVI channel 6:
The Caldwell Police Department and other Idaho law enforcement agencies will be stepping up seatbelt enforcement starting May 20th through June 2nd.
Over 70 Idaho law enforcement agencies will begin dedicating extra hours and patrols to educate and enforce the state’s safety restraint law during a 14-day period including Memorial Day.
Senin, 20 Mei 2013
No Wonder Ken Dauzat's Rings Didn't Respond...
Ken's Rings is now closed as of April 15, 2012 and is no longer taking orders.Unfortunate. He made a nice product.
Minggu, 19 Mei 2013
How To Attach The Tube (Cont.)
Here's a diagram of a simple to build tensioner for nylon webbing, stainless steel strap, or even belts.
The fixed side attachment doesn't move; I tap this side of the C-channel for a 1/4"-20 bolt. Depending on the strapping material, I may need a large washer to distribute load across more surface area. For nylon webbing, I would triple the layers for this attachment point.
The adjustment side attachment consists of a 1/4"-20 tapped hole and a bolt (probably a thumbscrew) with two nuts locked in position at the end of the bolt. The way that I have found works most easily for this is to drill through a hex head nut into the bolt, tap the hole for 6-32 threads, and use a 6-32 set screw to lock bolt and nut together. The strap goes through the slot in the side of the C-channel, and is held by two washers inside the captive nuts. The strap can rotate between the washers, so it isn't a tight fit there. You have to the get the length of the strapping pretty precisely correct for a snug fit, and then you turn the thumbscrew to clamp everything down. This also gives some room for strap stretch over time. If you reach the limits of the bolt, you can redrill the holes on the fixed side attachment, but I am considering this a short-term solution to the problem.
Limiting yourself to a thumbscrew not only simplifies tool-free adjustment, but also reduces the change of putting so much force on the tube that it damages it.
UPDATE: Good news: I asked my pastor this morning where I would steel strapping material on a weekend. He just happened to have a 50 foot roll of .030" thick, 1 inch wide steel strapping material. I started work on the device above to use some of this. I discovered that the vertical mill definitely works better with the longer screw holding everything together; I also discovered that once again, the single most important factor in milling is getting the workpiece really well clamped in position. Anything that lets it jostle in the vise is a problem. I also discovered that the 1/4"-20 thumbscrews I had...were something metric, not 1/4"-20. I guess I will buy two of those tomorrow.
The adjustment side attachment consists of a 1/4"-20 tapped hole and a bolt (probably a thumbscrew) with two nuts locked in position at the end of the bolt. The way that I have found works most easily for this is to drill through a hex head nut into the bolt, tap the hole for 6-32 threads, and use a 6-32 set screw to lock bolt and nut together. The strap goes through the slot in the side of the C-channel, and is held by two washers inside the captive nuts. The strap can rotate between the washers, so it isn't a tight fit there. You have to the get the length of the strapping pretty precisely correct for a snug fit, and then you turn the thumbscrew to clamp everything down. This also gives some room for strap stretch over time. If you reach the limits of the bolt, you can redrill the holes on the fixed side attachment, but I am considering this a short-term solution to the problem.
Limiting yourself to a thumbscrew not only simplifies tool-free adjustment, but also reduces the change of putting so much force on the tube that it damages it.
UPDATE: Good news: I asked my pastor this morning where I would steel strapping material on a weekend. He just happened to have a 50 foot roll of .030" thick, 1 inch wide steel strapping material. I started work on the device above to use some of this. I discovered that the vertical mill definitely works better with the longer screw holding everything together; I also discovered that once again, the single most important factor in milling is getting the workpiece really well clamped in position. Anything that lets it jostle in the vise is a problem. I also discovered that the 1/4"-20 thumbscrews I had...were something metric, not 1/4"-20. I guess I will buy two of those tomorrow.
Sabtu, 18 Mei 2013
Telescope Project Marches On
There was some pooling of paint at the bottom of the tube when I painted the first coat with the tube on end, so for the second coat, I went back to the suspension approach that I used when applying the fiberglass resin.
The method of holding the tube in the air at that stage wasn't very good, because sometimes the tube started rocking, and then the aluminum tube holding it would go flying off the chairs. So I came up with a way to prevent the aluminum tube from getting too far afield:
Unlike the first coat, which did not stick spectacularly well to the fiberglassed Sonotube, the second coat stuck quite well. It still wasn't very even, so I sanded it after the second coat as well, which again evened out the surfaces a bit (although taking off a bit of paint in the process). There were still some pretty big depressions caused by air pockets in the area where I had used fiberglass cloth, so I mixed a bit more resin, and tried to fill in the holes.
I still won't call the result, after the third coat, "beautiful," but I think it will do, at least until I can talk myself into believing that the big money for a carbon fiber composite tube that weighs 13 pounds less makes sense:
I mentioned a few days back that I was going to epoxy some steel rod on either side of the center line of the tube where it attaches to the dovetail plate to prevent rocking, which would eventually damage the tube. Then, yesterday, I mentioned that it would be better to have tube rings that lock onto the outside of the tube and screw directly to the dovetail plate.
I am still waiting on a price quote on those rings, and I started thinking. I noticed that at the edges of the dovetail plate there are a bunch of 1/4" holes. Hmmm. Could I mount supports in those holes to prevent rocking? My first thought was to machine some 1/4" (or perhaps slightly longer) plugs that would provide the support? I could even just use 1/4" hex head bolts; the heads would provide just the right elevation to prevent rocking (although at the risk of marring the surface of the tube).
But the more I thought about it (and was glad that enamel dries so slowly), it occurred to me there was an even better solution that gives me the flexibility to rotate the tube, not drill permanent mounting holes, solve the rocking problem, and involves minimal use of materials.
1. I take the C-channel which was used to mount the old scope to the dovetail plate, and cut off two 2" sections (preferably the ones that have 1/4" through holes already).
2. Shorten the legs of the C-channel down to 1/16" inch (since I no longer need long legs for stiffness of the section). Now I have a round tube to flat base adapter.
3. Drill and tap 1/4"-20 holes in each side of the two sections.
4. Buy four leather belts at the thrift store. (I need about 60 inches total length, and preferably 1 3/4" wide belts.)
5. Use a 1/4"-20 bolt and a washer to hold one end of each belt to each side of the C-channel.
6. Use the belt buckles to secure the tube to the C-channel sections. (This means that I will need to get roughly similar belt buckles when picking out belts.)
7. Perhaps drill some holes in these belts to get them in a position where I can tighten down the tube without crushing it marring the surface much.
Now I have the 60 pound or so telescope load held by two belts, which is, I think, sufficient to prevent anything from moving or working loose.
An alternative would be to look for some flexible 2" wide stainless steel straps, and apply felt to the inside to protect the tube. But then I have to figure out a way to secure the steel straps so that they can be loosened without having falling completely off. The Cave Optical mount that I had long ago used this approach, with a screw brazed into one end of the strap, so that you could loosen the straps at one end, rotate the tube, then retighten. If I could find something like this (with roughly 60" long straps) that had some way to tighten and loosen tension, this would be preferable. But the belts might be a quick way to get the telescope operational, and then worry about rings at a later time.
UPDATE: Or Velcro? This claims that the closure shear strength is 11.0 pounds per square inch. I can buy a 15 foot by 2" wide piece of Velcro at Home Depot for $28.97, what they call industrial strength Velcro. If I had ten inches of overlap of hook and loop (and if I understand what they are claiming for the closure shear strength), that would be 220 pounds per strap. That seems more than enough. It would not be as elegant as aluminum rings, but it would be light, I could pick up the Velcro tomorrow, and put the telescope together tomorrow afternoon.
UPDATE 2: Or perhaps use nylon webbing with buckles. The webbing has a tensile strength of 5500 pounds (probably more than the buckles that come with it or where I would attach it).
UPDATE 3: The more I think about it, nylon webbing and Velcro are likely to stretch under load, and that sounds a bit dangerous. If I can find some steel straps at Home Depot, I could put a bolt through the adjustment end, and use a wing nut to tension it.
The method of holding the tube in the air at that stage wasn't very good, because sometimes the tube started rocking, and then the aluminum tube holding it would go flying off the chairs. So I came up with a way to prevent the aluminum tube from getting too far afield:
Unlike the first coat, which did not stick spectacularly well to the fiberglassed Sonotube, the second coat stuck quite well. It still wasn't very even, so I sanded it after the second coat as well, which again evened out the surfaces a bit (although taking off a bit of paint in the process). There were still some pretty big depressions caused by air pockets in the area where I had used fiberglass cloth, so I mixed a bit more resin, and tried to fill in the holes.
I still won't call the result, after the third coat, "beautiful," but I think it will do, at least until I can talk myself into believing that the big money for a carbon fiber composite tube that weighs 13 pounds less makes sense:
I mentioned a few days back that I was going to epoxy some steel rod on either side of the center line of the tube where it attaches to the dovetail plate to prevent rocking, which would eventually damage the tube. Then, yesterday, I mentioned that it would be better to have tube rings that lock onto the outside of the tube and screw directly to the dovetail plate.
I am still waiting on a price quote on those rings, and I started thinking. I noticed that at the edges of the dovetail plate there are a bunch of 1/4" holes. Hmmm. Could I mount supports in those holes to prevent rocking? My first thought was to machine some 1/4" (or perhaps slightly longer) plugs that would provide the support? I could even just use 1/4" hex head bolts; the heads would provide just the right elevation to prevent rocking (although at the risk of marring the surface of the tube).
But the more I thought about it (and was glad that enamel dries so slowly), it occurred to me there was an even better solution that gives me the flexibility to rotate the tube, not drill permanent mounting holes, solve the rocking problem, and involves minimal use of materials.
1. I take the C-channel which was used to mount the old scope to the dovetail plate, and cut off two 2" sections (preferably the ones that have 1/4" through holes already).
2. Shorten the legs of the C-channel down to 1/16" inch (since I no longer need long legs for stiffness of the section). Now I have a round tube to flat base adapter.
3. Drill and tap 1/4"-20 holes in each side of the two sections.
4. Buy four leather belts at the thrift store. (I need about 60 inches total length, and preferably 1 3/4" wide belts.)
5. Use a 1/4"-20 bolt and a washer to hold one end of each belt to each side of the C-channel.
6. Use the belt buckles to secure the tube to the C-channel sections. (This means that I will need to get roughly similar belt buckles when picking out belts.)
7. Perhaps drill some holes in these belts to get them in a position where I can tighten down the tube without crushing it marring the surface much.
Now I have the 60 pound or so telescope load held by two belts, which is, I think, sufficient to prevent anything from moving or working loose.
An alternative would be to look for some flexible 2" wide stainless steel straps, and apply felt to the inside to protect the tube. But then I have to figure out a way to secure the steel straps so that they can be loosened without having falling completely off. The Cave Optical mount that I had long ago used this approach, with a screw brazed into one end of the strap, so that you could loosen the straps at one end, rotate the tube, then retighten. If I could find something like this (with roughly 60" long straps) that had some way to tighten and loosen tension, this would be preferable. But the belts might be a quick way to get the telescope operational, and then worry about rings at a later time.
UPDATE: Or Velcro? This claims that the closure shear strength is 11.0 pounds per square inch. I can buy a 15 foot by 2" wide piece of Velcro at Home Depot for $28.97, what they call industrial strength Velcro. If I had ten inches of overlap of hook and loop (and if I understand what they are claiming for the closure shear strength), that would be 220 pounds per strap. That seems more than enough. It would not be as elegant as aluminum rings, but it would be light, I could pick up the Velcro tomorrow, and put the telescope together tomorrow afternoon.
UPDATE 2: Or perhaps use nylon webbing with buckles. The webbing has a tensile strength of 5500 pounds (probably more than the buckles that come with it or where I would attach it).
UPDATE 3: The more I think about it, nylon webbing and Velcro are likely to stretch under load, and that sounds a bit dangerous. If I can find some steel straps at Home Depot, I could put a bolt through the adjustment end, and use a wing nut to tension it.
Jumat, 17 Mei 2013
Roll Your Own (Rings, That Is)
The quick but inflexible solution for attaching a telescope to the dovetail plate is to drill holes in the tube and turn bolts through the tube into the threaded holes on the dovetail plate. The more elegant solution (because it lets you rotate the tube into more useful viewing positions, with a little bit of effort) is to use rings like these. I have bought Ken Dauzat's rings before for another telescope, and I was very pleased with them. I have asked for a quote for the monster tube, and I am shuddering a little at the likely price.
But I saw this device for rolling your own rings from either tubing or flat. It's $169, but that doesn't seem like a particularly high price if it comes out the same price as buying one pair of rings. Does anyone have experience using such a tool?
But I saw this device for rolling your own rings from either tubing or flat. It's $169, but that doesn't seem like a particularly high price if it comes out the same price as buying one pair of rings. Does anyone have experience using such a tool?
Kamis, 16 Mei 2013
To Parody The Dojo Owner in Napoleon Dynamite
"I developed this while spending two hours in the hexagon!"
It actually came out rather well. I started with the 20.125" diameter aluminum ring, used a protractor to measure 60o angles, drew lines, then cut them using both the table saw and the bandsaw. The first try with the bandsaw was disappointing -- it produced a very ragged edge, until the blade broke. Then I switched to the table saw, which produced a straighter but very rough edge -- and then I went back to the bandsaw, using a wider blade, which produced a much straighter line. Then I used the belt sander to even out the roughness and get straighter edges. The points were still out at the old diameter, but I trimmed those to the right diameter with the bandsaw and sanded them smooth and straight.
The holes where the brackets attached were in the wrong place, so I just moved the brackets from positions 1, 3, and 5 to 2, 4, 6 (for those who immediately see benzene molecules when you see a hexagon). I also used my stamping dies to mark 1 on the corresponding bracket and hexagon locations.
I rolled the interior with flat black paint Wednesday night, and the exterior with the first coat of white gloss paint this evening.
It doesn't look good yet. After it dries tomorrow, I will sand it with some 400# paper, and apply a second coat. Depending on how it comes out, I may sand again and apply a third coat, but at that point, if it isn't beautiful, it doesn't matter. It will be dark most of the time.
All the holes (except for mounting) are drilled; once the final coat dries, it is ready for assembly. Once assembled, I will determine the balance point, drill four holes for attaching it to the dovetail plate, epoxy in place two pieces of steel rod to prevent rocking on the saddle, and be ready to put it on the mount.
I may even be able to reuse the black flocked material from the existing upper cage for this. I have gone out of my way to buy as many black oxide bolts and screws where something will be exposed on the inside of the tube. Even then, I flat black them; the black oxide just means that if paint does scrape off, it is still pretty much black.
It actually came out rather well. I started with the 20.125" diameter aluminum ring, used a protractor to measure 60o angles, drew lines, then cut them using both the table saw and the bandsaw. The first try with the bandsaw was disappointing -- it produced a very ragged edge, until the blade broke. Then I switched to the table saw, which produced a straighter but very rough edge -- and then I went back to the bandsaw, using a wider blade, which produced a much straighter line. Then I used the belt sander to even out the roughness and get straighter edges. The points were still out at the old diameter, but I trimmed those to the right diameter with the bandsaw and sanded them smooth and straight.
The holes where the brackets attached were in the wrong place, so I just moved the brackets from positions 1, 3, and 5 to 2, 4, 6 (for those who immediately see benzene molecules when you see a hexagon). I also used my stamping dies to mark 1 on the corresponding bracket and hexagon locations.
I rolled the interior with flat black paint Wednesday night, and the exterior with the first coat of white gloss paint this evening.
It doesn't look good yet. After it dries tomorrow, I will sand it with some 400# paper, and apply a second coat. Depending on how it comes out, I may sand again and apply a third coat, but at that point, if it isn't beautiful, it doesn't matter. It will be dark most of the time.
All the holes (except for mounting) are drilled; once the final coat dries, it is ready for assembly. Once assembled, I will determine the balance point, drill four holes for attaching it to the dovetail plate, epoxy in place two pieces of steel rod to prevent rocking on the saddle, and be ready to put it on the mount.
I may even be able to reuse the black flocked material from the existing upper cage for this. I have gone out of my way to buy as many black oxide bolts and screws where something will be exposed on the inside of the tube. Even then, I flat black them; the black oxide just means that if paint does scrape off, it is still pretty much black.
Terrorism Charges Filed in Boise
From May 16, 2013 Boise channel 6:
Fazliddin Kurbanov, 30, was arrested Thursday morning in Boise after a federal terrorism investigation.And in case you notice the byline on the report--yup, that's my son.
Charges were filed Thursday afternoon in Boise and Salt Lake City against Kurbanov who was a United States citizen living in Boise currently.
The charges filed came after a federal grand jury in Boise returned a three-count indictment charging Kurbanov with one count of conspiracy to provide material support to a designated foreign terrorist organization. In addition, one count of conspiracy to provide material support to terrorists and one count of possessing a destructive device.
There Are Descriptions For Which No Comment Is Printable
I know not to trust everything that appears in Wikipedia, but a reader brought this to my attention, and it is rather like a contest to identify the number of despicable, wrong, horrible, evil things that can be done to a person, describing Brenda Spencer, who was one of the first mass murderers at a school in the modern era:
Spencer excelled in photography, winning first prize in a Humane Society competition.[6] After her parents had separated, she lived with her father in virtual poverty; they slept on a single mattress on the living room floor. Police later found half empty alcohol bottles throughout the house. In 2001 she accused her father, Wallace Spencer, of having drunkenly subjected her to beatings and sexual abuse.[7] He said the allegations were not true.[8] Spencer is said to have self-identified herself as "having been gay from birth."[9]
In early 1978, staff at a facility for problem pupils which Spencer had been referred to due to truancy, informed her parents that she was suicidal. In the summer Spencer was arrested for shooting out the windows of the Cleveland Elementary with a BB gun, and burglary. In December a psychiatric evaluation arranged by her probation officer recommended Spencer be admitted to a mental hospital due to her depressed state, but her father refused to give permission. For Christmas 1978 he gave her a Ruger 10/22 semi-automatic .22 caliber rifle with a telescopic sight and 500 rounds of ammunition.[8][10] Spencer later said: "I asked for a radio and he bought me a gun." To the question as to why he might have done that, she answered: "I felt like he wanted me to kill myself."
Not All Cultures Are Equal
Someone mailed me a gruesome picture purportedly of a Syrian pilot's head being grilled by one of the resistance fighters. Fake atrocities are a fundamental part of warfare, but I see this May 14, 2013 Telegraph article refers to a variety of acts of cannibalism by the Syrian resistance, and the leaders of that resistance defending such acts:
A Syrian rebel militia leader filmed cutting the heart and organs out of a regime soldier's corpse and putting it in his mouth has defended his actions as legitimate vengeance.
The actions of Khaled al-Hamad, known by the nom de guerre Abu Sakkar, handed an instant propaganda victory to the Syrian govenrment, which accused the West of ignoring rebel atrocities.
The video purported to show the leader of a breakaway rebel faction cutting the lungs out of a soldier’s corpse before apparently eating a small piece of the organ...As much as I find the Assad government worthy of destruction, I am reminded that in much of the Middle East, this is not a conflict between barbarism and civilization, and between different branches of barbarism. As much as it hurts to see innocent bystanders suffer from such wars, it is rather like what happened when Iraq and Iran went to war against each other in the early 1980s: both were enemies of not only the U.S., but of all civilized notions of proper behavior. You do not want to applaud, but it is hard to justify spilling even one ounce of American blood or spending one penny of tax dollars to "help" either side. The more time that various forms of barbarism kill each other, the less time they have to hurt us.
In Damascus, Ali Haider, the minister for reconciliation, said this was only one of many atrocities carried out by the regime’s enemies. “If the international media has just discovered this now, then they are coming to it very late. These type of atrocities have been happening in Syria since the beginning of the crisis,” he said. “The international community just didn’t want to admit it.”
Mr Haider added: “We have documented hundreds of acts that are equally as horrific as the one documented in this video. We have seen one of our pilot’s heads cut off and cooked on a grill. We have seen rebels toasting their success by drinking the blood of their victims.”
Rabu, 15 Mei 2013
Just More Islamophobia, I'm Sure
From May 14, 2013 CBS Boston:
BELCHERTOWN (CBS) – Shortly after midnight Tuesday, seven people were caught trespassing at the Quabbin Reservoir.Note the time: "shortly after midnight." Isn't that when college students usually make unauthorized visits to public water supplies?
State Police say the five men and two women are from Pakistan, Saudi Arabia, and Singapore, and “cited their education and career interests” for being in the area. The men told police they were chemical engineers and recent college graduates.
The Quabbin, in Belchertown, is one of the country’s largest man-made public water supplies. Boston’s drinking water comes from the Quabbin and the Wachusett Reservoirs.
So Busy Being Sick...
I didn't notice this new PJMedia article by me:
Sen. Chris Murphy (D-CT): Credentialed, Not Educated
Robert Sherrill's Saturday Night Special
My friend Nicholas Johnson writes about a book that is now largely forgotten: Robert Sherill's Saturday Night Special (1973);
I just dusted off an entertaining screed from 1973 written by former Washington Post reporter Robert Sherrill. Although you can gather it from his credential as a Posty, the prodigious title of the book better signals his views on the “so-called” right to keep and bear arms. To wit: The Saturday Night Special: And Other Guns With Which Americans Won The West, Protected Bootleg Franchises, Slew Wildlife, Robbed Countless Banks, Shot Husbands Purposely And By Mistake And Killed Presidents – Together With The Debate Over Continuing Same. Absent from Sherrill’s list is any suggestion of the utility of firearms for legitimate self-defense.I agree with Professor Johnson's take on Sherrill's book: it is profoundly hostile to gun ownership and gun culture, but honest enough to recognize that gun control is fundamentally impossible in a free society. Sherrill is also honest enough to admit that the Gun Control Act of 1968 wasn't passed to disarm criminals, but to disarm poor black people -- and as a result, managed to accomplish neither.
The book is a vivid reflection of the times, urging confidently the states’ rights view of the Second Amendment that today not a single member of the United States Supreme Court attempts to prop up. But enough nostalgia.
Concentrated Misery
As bad as Monday night was, at least all the vomiting was concentrated in a very short period of time: from about 8:00 PM to about 5:30 AM Tuesday morning. I have vomited that much before, but over a period of several days. Now I am just sore, partly from strain on muscles causing by the vomiting, and partly because I am still fighting a slight fever. I am not going to work until I am pretty confident that I am not contagious. I wouldn't even meet with President Obama, this stuff is so bad.
Senin, 13 Mei 2013
Hexagon Time
The machine shop that said that they could turn it down to 19.875" diameter? I showed up, they looked at it, and said, "We can't turn something that big." And then, "We have a five week backlog." Wow. I could have been trimming this down to a hexagon over the weekend instead of waiting for them.
Minggu, 12 Mei 2013
More Weight Reduction
It turns out that I have a total of six bolts holding the bottom plate of the mirror cell to the attachment brackets -- and the bolt, lock washer, and nut combo weighs 0.4 ounces. Strictly speaking, six bolts are not required. Each one has the tensile strength to easily hold this, and I am not worried about any of them working loose. In addition, I can also remove the extra material on the attachment bracket where the second hole was located, perhaps saving two ounces total.
UPDATE: When I was looking for an alternative to turning down the bottom plate of the mirror cell, I did a little thinking about alternative strategies. One is to cut the circle to a hexagon, which can be done by drawing a circle of the required diameter, measuring 60 degree angles, then drawing lines connecting the points, and running these through a bandsaw. In addition, the area of a hexagon that fills radius r is 3r2, instead of pi * r2, so slightly less weight. A triangle is another possible strategy, where the area of radius r is 2r2, so even more weight reduction.
UPDATE: When I was looking for an alternative to turning down the bottom plate of the mirror cell, I did a little thinking about alternative strategies. One is to cut the circle to a hexagon, which can be done by drawing a circle of the required diameter, measuring 60 degree angles, then drawing lines connecting the points, and running these through a bandsaw. In addition, the area of a hexagon that fills radius r is 3r2, instead of pi * r2, so slightly less weight. A triangle is another possible strategy, where the area of radius r is 2r2, so even more weight reduction.
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