Posts Made By: Eric Daugherty

Hello,

I'm kicking around building a truss style dob in the 12.5" to 15" class. I plan on basing it largely on K & B's design. But I have quite a few questions about some of some of the components.

1. The Mirror Cell. This is probably the most complicated issue I have. So I shall just ask all the things I can't quite figure out.
1. Is 1" steel really necessary on a smaller dob? I know Ed Tachyert used 3/4" steel on his 18" and Michael Zammit used aluminum. Could I get away with less or lighter material than steel?
2. What the best alternative to a kevlar/nylon sling? My friend had an 18" Obsession and hated collimating it. So I want to improve it there. Do stainless steel slings work better? Or are the double wire slings best? I'm really not too hopped on wiffle tree support or removable cells. The thought of my clumsy self handling such precious cargo as my primary mirror in the dark gives me the willies. I would consider making a tail gate to make it easier to clean.
3. Should the cell be finished black or is raw unfinished metal fine?

2. Connecting the trusses. Does anyone have any experience with Moonlite's units? I was thinking about using the captive blocks on the mirror box and ball and sockets on top. Any comments would be appreciated. Is the a better alternative out there?

3. Spider. Are curved vanes helpful enough that I should consider them for my scope? I know in lager aperature the struggle to maintain enough tension to hold the secondary still, so is it worth it to put them in or would a high quality unit from Protostar or Astro Systems be better? Also should I offset it?

Thanks in advance.

Eric

First of forgive me on the lack of specifics. But, I saw this at work where have about 5 kajillion candlepower available making it a wee difficult to see all that many stars.

What I did see however was an extremly bright object in the northern sky heading roughly east to west. It was about as bright as Venus as a good estimate. I saw for a few seconds until it faded from few. I did not see its start however. It did seem to have a bit of a tail. But sadly it was too bright here to see if there was anything else trailing behind that.
This happened at about 10 PM EST on November 8.

I'm located just east of Findlay, OH.

Did anyone else see it?

Eric

Has anybody else saw this on Teeter's web site? It's an interesting way of sitting up a tall dob. Kind of like those 14.5" Starmasters. I'm sure if he's using it on all his Planet-Killer truss dobs it's got to work at least ok.

For those who haven't seen what I'm talking about look here, http://www.teeterstelescopes.com/twistring.htm

The innovation in the Dob building field is pretty impressive right now when you think about it.

Eric

Hi,

Does anyone have any first hand experience with the Moonlite ball and socket truss connectors? How rigid a connection does it make? How easy are they to assemble?

I'm interested in using them for a dob project.

Eric

Hi,

I want to build a telescope and I've finally settled on a 15". Originally I had kicked around a 18"-20" but that was just too big for my current living arangment and vehicle. So I've settled on a 15". 15" seems to be a good blance of photon guzzling power and portability.

I'm seeking a bit of advice about the focal ratio and who should make it.

I'm split between f/4.5 and f/5. An f/5 mirror would make me use a step stool at zenith but would have less coma and make using a 2.6" diagonal for more feasable. An f/4.5 mirror would requite no step stoll but thye coma would increase and that 2.6" diagonal would more than likely have to become a 3.1" diagonal which makes the central obstruction larger.

I'm thinking of getting my mirror from either R.F. Royce or Steve Swayze. It would more than likely be 2" thick, because I'm using the Kriege book as my guide and 2" seems to be the rule. Though I might change my mind.

Also why I'm at it here's the rest of my ideas as to what I would put into this dream dob.

-Protostar secondary mirror and diagonal mount.
-Cable sling like the ones that Stellar Cat sells.
-Feathertouch focuser.
-Obsession aluminum side bearings.

I'm still not sure on which clamp system I will use for the trusses but they probably won't be wood. Wood is far to moisture sensitive for my tastes. Obsession, Moonlite and Aurora Precison all sell interesting units.

Thanks in advance.

Eric

I saw that posted on another forum.Very tempting indeed. If the QC is as good as the other Orion dobs I've seen it should be a good light bucket for lots of astronomers.

One little wish though. It would be super cool if they would release a "classic" version of it. Not that I'm against digital setting circles but a stripped down version would be nice.

Wow. I really want to see the completed scope. How much will the whole thing weigh? Did you use are really thin mirror or not?

Eric

Very nice. I should do something like that with big blue. Big Blue is my 10" f/5.6 dob that is in the least over-built. How hard was it to build? Where do you get carbon fiber?

Thanks

Eric

I'm alive as an astronomer under Ohio skies can be.

What coatings did you get the standard or the semi-enhanced? It's odd I was just talking to a guy in my club about coatings at the last meeting. Small world.

Eric

I'm in the same boat as you Tom. IF I had $2700 I'd grab that scope up in a hurry. I really like the fact it already has an optical finder on it and not just a unit power finder. But alas I'm poor as dirt at the moment. Oh bother.

Eric