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Posts Made By: James C Chandler Jr

April 15, 2009 06:32 PM Forum: Telescope Making

Slide Tube Focusing Design Ideas?

Posted By James C Chandler Jr

Have been thinking awhile of perhaps making a rugged little 'modular' spotter scope. Perhaps a 50mm F4 achro objective, or perhaps to a max of an 80mm objective later on.

I really like some of the Borg components, and would likely use a small borg helical focuser along with either the straight-thru erecting prism or alternately the 90 degree erecting prism, depending on needs. That is the crux of the idea-- A small OTA easily changed around for various purposes, and able to use the nicer eyepieces for low-power viewing.

The slide-tube gross focusing idea seems attractive. Slide tube for gross focus and then fine-focus with helical focuser.

Configure the length so that it reaches infinity focus with the slider almost all the way in, so that if I wanted to watch a small critter 10 feet away from the deck, there would be generous out-focus travel.

I don't have good mechanical imagination, and have been trying to think up a slide-tube mechanism that is smooth but with minimal 'wiggle'. Also a design fairly easy to fabricate, since I don't have fantastic fabrication skills either. But it is good practice.

Here is a crude photo of a crude sketch. Hope it is even readable. I suspect this design would not work good enough. Just an initial idea so maybe someone can tell me a design that would actually work.



All parts are aluminum except two plastic rings and stainless thumbscrews.

An eyepiece, straight thru erecting prism, or 90 degree erecting prism would fit in the turned aluminum attachment on the back of the aluminum slide tube.

The 'stiffener ring' is just a ring of aluminum on the outside of the Main Tube to give the focus-lock thumbscrew sufficient purchase, and keep the back of the Main Tube round. Alternately, the Main Tube could be turned down out of fairly thick aluminum tube to leave some thickness on the back.

The two plastic rings are 'linear bearings'.

Plastic Split Ring (A) might be Nylon, Delrin, or Teflon. It is affixed to the Main Tube so the the slide tube moves thru the Split ring. The ring would be machined to size and then cut a thin slice out of the ring, so the Focus Lock thumbscrew can get real tight when desired.

The Plastic Ring (B) is affixed to the front-end of the slide tube, and moves with the slide tube. The intended purpose of the front Plastic Ring would be to make dern sure that the slide tube has minimal 'wiggle'.

I suspect this design would not work because of tolerance issues-- That in some cases it might be too tight, and if I loosen it up a little more than too tight, in some cases it would be too wiggly. But MAYBE it would work as-is.

How about some better-simpler ideas? Thanks!

James Chandler Jr.



April 29, 2009 05:05 PM Forum: Politics

Re: Obama's spending

Posted By James C Chandler Jr

We need to buy a bunch of extra Money-Printing machines from China. Or perhaps failing newspapers' idle printer capacity could be repurposed for printing money. Got to print a whole lot of money. Hope the Sierra Club will allow all that tree cutting.

Ford didn't take bailout money yet, did they? I didn't like the only Ford I ever owned, but next time I need a truck, maybe Ford will still be an option. Just couldn't stand buying a govt-manufactured car. Unless GM gets private again, ain't gonna buy any more GM's, and never saw a Chrysler I liked good enough to buy.



May 5, 2009 12:21 PM Forum: Politics

Rebellious Youth

Posted By James C Chandler Jr

http://itsnotmydebt.com/



May 12, 2009 12:41 PM Forum: Politics

Denying Firearms and Explosives to Dangerous Terro

Posted By James C Chandler Jr

The text of H.R. 2159:

http://www.opencongress.org/bill/111-h2159/text

This would deny firearms to 'dangerous terrorists'.

Note near the bottom: "if the denial or revocation is based on a determination under subsection (b)(8) or (d)(2), then any information which the Attorney General relied on for the determination may be withheld from the petitioner if the Attorney General determines that disclosure of the information would likely compromise national security"

IOW, denials do not have to be explained or factually justified.

====

The Terrorist Watch List is now up to 1 million and growing--

http://www.usatoday.com/news/washington/2009-03-10-watchlist_N.htm

====

Apparently Homeland Security wants to watch anyone who might disagree politically with the current administration. Here is one of several recently-released documents:

http://www.fas.org/irp/eprint/rightwing.pdf

This is hardly new. During the prior administration, Homeland Security documents considered ecological activists and gay rights groups to be potentially dangerous terrorists.

If all the left-wingers are potentially dangerous, and all the right-wingers are potentially dangerous, then H.R. 2159 could potentially deny firearms to just about anybody, at the attorney general's discretion. The current AG has a long history of anti-gun views.

The homeland security laws are more dangerous to civil liberties than any security the laws may buy. They need repeal. Soon. While it remains legal to even PUBLICLY DISCUSS such laws.

May 14, 2009 02:06 PM Forum: Politics

Re: Obama as CEO

Posted By James C Chandler Jr

Something I've been wondering--

When health care is made more efficient and untold thousands of newly-redundant insurance company pencil-pushers are permanently riffed-- Will those folks be counted as jobs saved or jobs created?

May 14, 2009 10:05 PM Forum: Politics

Re: Obama Says U.S. Long-Term Debt Load ‘Unsustain

Posted By James C Chandler Jr

The solution is obvious, simple and painless. Print enough money to pay off the debt, and then print some more every year to cover the deficit, so we don't get in debt again!

Inflation would ordinarily occur, but we can prevent that with a permanent wage and price freeze.

Easy!

May 27, 2009 10:12 AM Forum: Politics

Re: Back to the 60's

Posted By James C Chandler Jr

Stay away from the brown acid, dude!

May 27, 2009 09:14 PM Forum: Global Warming - REAL or NOT

White Roofs

Posted By James C Chandler Jr

Though I don't know if libertarian principles would advocate a law that all roofs must be white.

Maybe it would help to radiate a little bit of heat back to space, my own tiny contribution to higher planetary albedo. Or maybe a silly drop in the bucket.

However, in the South I've been lobbying wifey about the next roof being white for a couple of years, and so far she ain't buying it.

My motivation has nothing to do with saving the planet. Am pretty sure a white roof would significantly reduce the air-conditioning bill. I already have dual layers of Reflectix in the attic plus a silly amount of insulation, and am pretty sure a white roof would make significant additional savings.

Wifey is aesthetically offended by a white roof. White just isn't a proper color for a roof. Wifey is not unusual in female style tastes. So perhaps a law to mandate white roofs, will get the biggest push-back from mostly every woman on the planet who happens to decide that white roofs are entirely the wrong color and would ruin the looks of the house. Maybe the white-roof proponents forgot to ask their wives about it .

Another thing I wonder about-- Northern folk with heavy winters-- Those poor souls pay the big bucks in the winter rather than the summer, and many don't even really need an air conditioner considering the pitiful excuse of a summer they get. I barely pay anything for heating, but get socked bad in the summer for cooling.

Those unfortunate yankees-- If they paint the roof white, will it INCREASE their heating bills and cause more greenhouse gasses and pollution than leaving the roof dark?

Another consideration-- My old southern house-- It can get down below freezing routinely in the winter, but just the winter solar heating plus heavy insulation and tight windows avoids running much heat. Low winter heat bill. If I paint the roof white, even down in the south I bet my winter heating bill would rise...

May 29, 2009 04:14 AM Forum: Politics

Re: Inventory

Posted By James C Chandler Jr

Hmm. Wonder how long an average person could drive a car on the same fuel that Nancy Pelosi the Queen of Green burns in private govt jet commutes?

http://www.snopes.com/politics/pelosi/jet.asp

Snopes says Queen Green did 20 Wash-California commutes in 2007-2008 in Air Force Gulfstream III and Gulfstream V. The following are estimates from quick googling. Any aircraft experts are welcome to correct mistakes. The references may be incorrect

The G III and G V were used when winds were expected to barely allow a nonstop trip, so we might assume about the entire fuel capacity is typically consumed one-way.

G III fuel capacity is listed 28,300 pounds, at 6.84 pounds per gallon that is 4137 gallons
G V fuel capacity was listed (wikipedia) 41,300 pounds, which if correct would be 6038 gallons.

Double it for a round trip. Assume for sake of laziness that 10 trips were taken in the GIII and 10 trips in the G V. An approximate average of perhaps 10,175 gallons fuel for each commute on the government dime.

OK, I use about 10 gallons per month or less. So ONE of Ms Environment's little jaunts burns more fuel than my old van would consume in 84 years!

Then there are Nancy's international jaunts. One of those would run my van for hundreds of years.

Hasn't the woman ever heard about telecommuting? I telecommute to western canada 5 or 10 hours per week, at a 'round trip distance' of 30,000 miles per week, for a few bucks a month. Couldn't she arrange to kiss the Pope's ring on a teleconference video monitor? What business is being transacted in China that couldn't be done via internet video?

http://www.cbsnews.com/track/rss/blogs/2009/04/22/politics/politicalhotsheet/entry4962384.shtml?

Here's a nice one-- Obama burns 9000 gallons of jet fuel on Earth Day. Me being a climate change skeptic, I would have to live to the age of 134 to use that much fuel in the old van. How many rich environmentalists can the planet survive?

June 7, 2009 11:58 AM Forum: Guns and Hunting Optics

Teeny Tiny Reflex Red Dots

Posted By James C Chandler Jr

Have had an inexpensive BSA red dot on the Mark II target pistol a very long time. Has been rugged and can't complain for the price. Then recently put a not-inexpensive EOTECH Holosight on a rifle. Can't say enough good things about the EOTECH.

Being a reflex type of sight, if you can see the dot in the EOTECH, the bullet will go there. The old $40 BSA is not a reflex sight, and unless the dot is in the middle of the sight, the bullet ain't gonna go where the dot is. I'll never be a really accurate shooter, but there was a certain limit to basic accuracy with the Mark II that had to do with improperly getting the dot exactly centered in the sight frame.

Recently the battery went down on the BSA and I didn't have a spare onhand, so used the Mark II iron sights. The iron sights shot somewhat more accurate than the BSA red dot, but my eyes are old and the iron sights are very difficult to see, especially against certain target colors. Black sights against a black bullseye, no fun. OTOH, paint a white rim on the sights, that would suck against a white bullseye. Since I was having so much trouble even SEEING the ruger iron sights, and still shot (a little bit) better than the BSA red dot, then the parallax issue on the BSA must be pretty significant in the 25 foot ballpark, unless the dot is precisely centered in the frame.

I like iron sights on the higher-caliber pistols because accuracy expectations are lower. If the majority of 9mm or .357 shots can hit a paper plate at 25 feet, hey wish it was better but that is not too bad for an old guy. With the .22 pistol, the acceptable grouping is much smaller than the size of the iron sights against the target.

As an experiment, I drew a black Sharpie Marks-on-Anything dot precisely in the center of the front glass of the BSA red dot sight. Test-shooting, the accuracy was very good if I superimpose the black dot and red dot on the bullseye. So precisely centering the red dot helps a great deal. However, the sharpie-drawn black dot is difficult to see against dark target backgrounds. Maybe some kind of tiny red ring could be inscribed on a disk of plastic or glass, and mounted on the front of the BSA. Maybe that would be more easily visible than an opaque black dot. Superimpose the red dot on the red ring on the bullseye.

On a rifle, it might be easier to reliably center the red dot in a non-reflex sight, and at rifle distances perhaps the parallax would not be so bad. Dunno.

However, instant gratification would be to replace the BSA with a reflex sight. Another EOTECH for the Mark II would be nice, except the EOTECH costs about the same as the pistol, and it is a little on the heavy side. Supposedly the model 511 is discontinued but still available around $380.



Bushnell sells a Gen II holosight you can get around $300 some places, which is essentially identical (made by the same USA company) except lacking the metal protective hood. $80 is a lot of money to pay for an extra piece of aluminum but OTOH one would wish for the metal hood the first time inevitably whacking the sight against something hard.



Many reflex sights have a separate 'screen' sticking up that appears begging to break off if you unfortunately catch that obstruction against something:



A well-reviewed sight that looks similar to my BSA is the Nikon Monarch. But I can't find any reference claiming the Monarch is a reflex sight, so maybe its great on rifles/shotguns and not so great on pistols.



A small light 'Pistol Sized' reflex sight that doesn't get horrible reviews looks like this:



And then here is obviously 'about the same thing' less expensive:



That style uses 'auto brightness', and the biggest user review complaints have to do with the auto brightness circuitry automatically setting the wrong brightness, so that doesn't sound great. The ultra-cheap units that 'look like the big boys' get bad reviews for breaking easily or not holding aim point.

Looking for small pistol-size but not pinching pennies, nobody seriously complains about the Aimpoint Micro, which doesn't have any parts to snag and break off and has a manual brightness knob:



Aha, but then there is a Sig asian clone (OTOH, maybe the Aimpoint is imported too, dunno):



Poking around, it has been alleged that the ITac Defense company is owned by Sig and was created to handle imported items like this. Dunno, that is just what has been claimed. The ITac branded looks an awful lot like the Sig, dunno if it is in every way identical. Costs less:



And then it gets very inexpensive (compared to the above) with the Konus Sight-Pro Atomic Electronic Red Dot Sight. Same published specs, $82. And ya gotta love that product name.



One would expect that the more expensive versions somehow work better or are more reliable. Or would one? Maybe the Konus rotary switch is less reliable than the ITac, Sig or Aimpoint? Maybe the Konus will fall apart from recoil or not hold aimpoint or eats batteries in 10 minutes or has a dot that looks like a comet?