Posts Made By: Sam Greenlaw

For those of us who really want to get away cheap. You know. The White Castle end of the ATM community....

What's to choose between a cheap little bench bandsaw and a decent bench scroll saw ?

A 9"/10" bandsaw or a decent 18"/22" scroll saw will both cost under $200 with shipping. Wood gets cut either way.

I've used good bandsaws in the 16"/18" sizes. Nice stuff, but they carry wider blades and have to more stable.

The bench scroll saw has to give smoother results than my old hand scroll saw. It just died, so I'm in the market for a replacement. (No, not a coping saw.)

Thanks, guys !

There were pictures recently on this Forum of a home-built with a professional layout. Structural strength from a rectangular cage in the middle and short tubes to the mirror cell.

This looks to be a common professional setup. A little unusual for ATM scopes.

Is there a name for this layout ? A reference to construction details ?

Thanks, guys.

The bench bandsaw is all we need for most prototyping and ordinary ATM construction. I followed advice and got one of the 9" models with the 1/3 HP motors.

Two items came up when I went over to check out Home Depot.

Power tools at 50% off: their jigsaw and 1/3 sheet sander are going for $14.00 each. The sander's very good for doing plywood. It's a two-hand model, not a palm sander. I think I can do better with it than with the one-hand type.

Yes, an ad for HD. More "White Castle" mentality....

"... (resistance to torsional bending) the second moment of
inertia of the individual truss members...which is the ability of the truss tube to resist bending/flexing.
(Second moment of inertia scales with the 4th power of the
radius. Boost your tube diameter by 50% and you get a tube
that is (1.5 ^ 4) 5.06 times stiffer!...yet this is not
reflected in (most ATM design books)"

< < Tom Krajci
< < Tashkent, Uzbekistan
< < -- the ATM list from a posting in 1994 --

Key point is the 4th power resistance to bending.

Trusses should be wider, not heavier. By far.

Compression is not significant after cool down. So design maybe should be aimed at vibration damping.

This little SAC7 has a white cord. That makes it a pariah.

The SAC web site says to go "Here" and eventaully download a driver from Philips.

Now the SAC site doesn't say which of three camera types is used in the SAC7. An "XS," "Fun," or "Pro" ??? How would I know ???

Doesn't matter.

The site gives an error message which ever one you choose. "Site being updated" is a Haliburtonian euphemism for "It ain't here." Same message three different days.

So what now ??? There's nothing. This camera was bought for about twice what an excellent secondary mirror would have cost me.

And the damn thing doesn't work. The seller absolutely dropped the ball. After five emails, there's nothing happening there.

How hard would it have been for SAC to save a copy of the driver.zip on the web site ??? Or to at least tell the buyer which camera's used ?

A waste of over $300. The SAC7 was what I bought, but the SAC7w was delivered. Useless.

How would I have known the difference between the SAC7 and the SAC7w ??? The manual is for the SAC7 (gray cord) and there's nothing for this SAC7w.

I put this aside for about a year and made another effort at it. Same result. A second evening wasted.

(*&^%$#@!@#$%^&*)(*&^%$!@#$%^........

Beware.

I've posted this on the CCD Imaging forum.

Does anyone here actually have the drivers for the SAC7w ?

This is an orphaned SAC7w with a white cord for the USB power connection. Hence the SAC7w designation.

Most SAC7s reportedly have a dark-gray USB cord. This is a white cord model.

The sac-imaging.com web site has a download named SAC7w.zip. It doesn't work. Drivers load that don't work.

What opens is a Philips VDownload window.. It hangs. Always and forever.

There are two drivers included, but they do not work with the SAC7w using AstroVideo software. The download from Philips is needed, but it doesn't happen.

Of course, I could have a bad camera. Major assurances from SAC that that's highly unlikely....

The seller is a dealer on Long Island, who says he checked this one out with his own system but not using the AstroVideo software.

For all the talk about mirrors and secondaries, how critical is it lining up the eyepiece ?

If it's off a degree or two, what's the expected effect ?

My 18" (almost 3" thick) looks to be coming home. It's being replaced by an SCT. Recently got a 16" from Obsidian that does a very good job. Knock-outs, both.

So that gives me the pleasing choice of going with one or the other. I can use the same poles for a truss-Dobsie. Actually, I could use the same

Any ideas, here ? Just going bigger... that's the default.

Portability has to be an issue. I like getting away from New York. (Who doesn't ?) The 18" is close to 60#. The 16" is under 25#.

The 18" was a load to roll across a patio; it was only happy in the back of a one-ton van.

Preferences ??? Recommendations ?

Once you have the triangles, it's nice to have a flex material. It doesn't have to bend much.

Carlon, Lamson and Sessions make Flex-Plus Blue for electrical applications. It is a flexible pipe with ridges. Easy to cut off evenly as you can sut between the ridges.

Ten feet of it cost less than $5 at Home Depot.

1" segments are fine for "stalks" to triangles. Raised washers from below let the center bolt move freely enough. I like 1/4-20 1.5"ers.

Easy solution to cell making. Dirt cheap, too.

Consider:

http://astromart.com/messages.asp?message_id=50852

Portable-izing this design looks to produce a backpackable system. Cut weight to the minimum.

The rocker looks good to sit on a backpack frame.