Posts Made By: Sam Greenlaw

The web site at 1800Destiny and his eBay postings sell tubes for telescopes. The material in these tubes is very heavy, but there is no warning on site or on the eBay ads.

I bought a 12.5" OD tube for a 10" f/5 mirror scope. 56" length. $ 45.00 on eBay plus $ 47 S&H. This tube is .4" thick.

Weight of the tube is 50#. That's more than most modern design 10" mirror OTA's including the mirrors and the hardware. My Meade GEM is SOL, unusable with this tube. Email to seller brought no response. No change to either web site or ads.

Caveat emptor....

New Group at Yahoo:

http://groups.yahoo.com/group/obsidian_optics_mirrors/

This thread got way out of hand. Couple feet out to the right.... ;^)

The Yahoo Group is at 13 members. Free at Yahoo. Several members have the mid-size 8" and 10" high-quality mirrors from Mark Cowan at Obsidian Optics.

We're waiting for delivery of 14" and 16" mirrors from Newport blanks shipped to Mark last week.

Dedicated do-it-yourselfer *******

I have a couple of heads from microscopes that look to be usable for do-it-yourself binoviewer projects. These are dual-prism systems built to be used with standard light microscopes. Nikon and Tiyoda.

The older compound mikes were built to German industry standards. They're wonderful for first-rate optics.

There are also the 30mm stereo mikes, but that would require an exotic secondary, if it would be possible at all ?????? I've got a 20x Nikon and an SZ6 Leica stereozoom.

I'm doing a 16" f/4.7 Dobson and have a 10" f/5 for prototyping. The 16" is a thin-mirror (1.25" blank) system, so it's going to get a PLOP-designed state-of-the-art mirror cell.

Giving this 16" a binoviewer sounds good. Then making it modular, so's if I get hooked on doing a Schiefspiegler...;^)

About a year ago I bought one of those wonderful white telescope tubes on eBay. 12" diameter. 56" long.

What the seller didn't say -- ooppss$$$$$ -- was that the $%^&*%#^*& tube weighs 50 pounds ! So, how's to salvage something useful ?

Looks like the tube will yield several bottom ends to go with 10" mirrors for simple, beginner level truss scopes.

Question: how can I cut 1/2" thick PVC tubing to get clean, smooth surfaces ?

Jig saw didn't like the task. Very rough. Don't have a band saw, just a hand saw and a circular saw. Plainly there's a good way to do this..... ;^)

Home Depot guys didn't know either.

Mark Cowan's had his problems with glass, pyrex and getting grinder tuned just right. Now he's going as he'd wanted.

Dave McNally has two mirrors done, now. SN0316A and SN0316B.

http://www.obsidianoptics.com/specs/SN0316A.htm

http://www.obsidianoptics.com/specs/SN0316B.htm

Show me a 14" better than that 1/22.1 SN0316A.... ;^)

My 16" is in polishing now. Looking forward to the spec's on this one. SN0319.

If God is simply all the Good of the Universe, what does this matter ? Willy's way cool -- 2 - 3 movies and a mini franchise.

Science can be equally Good or Evil; it is a tool.

Free WillY: The Predestination arguments are gross expansions of a type of logical fallacy "Post Hoc, Ergo Propter Hoc." Their "Post Hoc" singular event is a creationist Will of the Hairy Thunderer moment, from which everything is predestined.

God is Good, literally and as a noun. How's not to believe ? Thanks for the tweak, Glenn.

Modell's is selling double sets of ball-bearing scooter wheels. San Diego Speed'ds the importer. They're about 4" diameter. $ 2.50 a pair.

The stores also have the matching axle sets. The axle setup has a machined center piece and a two-part center screw. The center screw has flanges, so's you can make supports with 1/8th inch steel.

Perfect for Dobson altitude, azimuth, or the more complex ~15-degree/hour counter-rotion base systems.

If you want to try something different from teflon....

These wheel packs include a pair of scooter hand grips. Foam. Got a recycle use for them ???

The grinding machine thread got to be interesting. 1-phase vs. 3-phase, converters, etc. Big help for John Ziegler. So maybe a pass on woodworking and general shop tools will get similar results.

What do you guys like for woodworking tools ?

Is it all power tools ? What's a middle-of-the-road setup list for a do-it-yourself ATM ? Neat workarounds ?

Anything to avoid ? (Sears Flex Shaft table saw, Central Machinery everything....) Sites that support amateur woodworking ?

The Equipment forum ran a thread on carry-along scopes. Pretty amazing stuff.... ;^) Same for tools ???

Anybody tried this: using a worn-out vertical mill to build a mount system ???

Vertical mills go into surplus by the thousands. The heads wear out and tables are expensive to replace. This equipment is very high quality machinery, running $4,000-100,000 new for cast iron turret v-mills.

The turret-casting type vertical mills are massive. One-ton is a minimum weight, even with the quill machinery and table removed. The very smallest column turret types have everything for ATM mecdhanical use.

Gearing for "RA" and "DEC" is integral for several of the larger types. The column-turret types have the integral "RA" capability.

Driving the positioning gears smoothly on a v-mill would be a challenge. Similar to the recent DIY GEM threads for technology.

Despite problems, seems to me that modern computer controls could be adapted to positioning a vertical mill for astronomy. A manual-positioned v-mill should be reasonably economical as a used, stripped item.

One mad idea: tilt the one-ton v-mill to make it polar. A one-ton or more cast iron GEM. The column axis does the RA, the head-tilt handles DEC. GEM grande !

Anybody done it ? Tried it ? Thought about it and rejected it for simple, obvious reasons ?

Yes, there's a "knee" at the front of v-mill machines that kills off 15-degrees of rotation. It's in the way. An inconvenience unless that's the bottom of a tilted GEM.

Also, this idea would be best for a permanent home. It needs a well-sunk reinforced concrete floor.

If this works out, an old $500 v-mill could provide a great home for a big refractor or a one-meter Newt.

"You have to have at least graduated high school to believe in the "Big Bang" Theory, because in high school three things happen:

First, you’re persuaded the impossible is possible,
Then you become persuaded the possible is probable,
Finally you become persuaded the probable is certain.

It takes at least 3 years for this.
Children will never buy everything came from nothing."

http://www.johndobson.org/articles/by/bigbang.html
>>>>>>

Big Bang now also involves an orthodox insistence that the universe is expanding, endlessly. J.D. isn't quite having all of it.

It's also not clear why light doesn't just age in some ugly, red-shifting way. It has billions of years to confound us. Losing energy by any means whatsoever would cause red-shift.

Why 16 billion ? Why not 16 billion billion ? Why would light age in a straight, linear, well-behaved way ?

Why would "time" run the same anywhere near a Big Bang event ? It doesn't make sense, that "time" would have any meaning.

16,000,000,000 isn't much.

16,000,000,000,000,000,000,000,000,000,000. The whole known universe gets to be a grain of sand, fast.