Jump to content


Photo

14" Hubble Optics Project

  • Please log in to reply
151 replies to this topic

#126 KenScharf

KenScharf

    Sputnik

  • -----
  • Posts: 45
  • Joined: 16 Dec 2012
  • Loc: South Fla

Posted 17 December 2012 - 07:46 PM

It's been a while since I last looked at Kriege's book, but you seem to be following it closely. I'm in the process of making a 7" mirror and will probably make a miniature version of his design. I'm giving some though to making the truss clamp blocks by sand casting aluminum a-la Gingery instead of out of wood (though I'd have to make wooden patterns to make the sand molds!).

#127 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 18 December 2012 - 06:53 AM

Good progress Brian. You will be looking forward to the night of first light. Nice tidy work shop.


Yes, while I like using my binoculars its just not the same as a telescope, first light will not come too soon for me. The workshop is the basement of my house, it is clean out of necessity, If I keep a messy shop I end up tracking stuff into the main living quarters...which I hear about from my better half :lol:. About a year ago I bought a Ridgid 1450D shop vac which attaches to the dust ports on my table saw, chop saw and a few other tools I have, it really keeps things clean. It has major suction, very highly rated on Amazon.

#128 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 18 December 2012 - 06:55 AM


very clean. :grin:


A coat of flat black paint will make them look like a professional made them :lol:

#129 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 18 December 2012 - 07:21 AM

It's been a while since I last looked at Kriege's book, but you seem to be following it closely.

I do have the book and started out intending to follow it closely but I've drifted away from it in several respects. Reading this and other forums has given me several ideas to incorporate into the build.

I'm in the process of making a 7" mirror and will probably make a miniature version of his design. I'm giving some though to making the truss clamp blocks by sand casting aluminum a-la Gingery instead of out of wood (though I'd have to make wooden patterns to make the sand molds!).


Thats interesting about sand casting the truss clamp blocks in aluminum. If you end up doing it I hope you start a thread about it on the forum.

#130 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 16 January 2013 - 06:44 PM

After a break I"m back at it in the shop. I hope everyone had a good holiday.
I made a cover for the mirror box to protect the mirror, nothing special just 5mm ply with a piece of 1" dowel for a knob

Attached Files



#131 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 16 January 2013 - 06:46 PM

I got a new Bosch router for Christmas so I routed out the altitude bearings and glued and clamped on the ebony star

Attached Files



#132 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 16 January 2013 - 06:47 PM

Then the fine touches with a file

Attached Files



#133 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 16 January 2013 - 06:51 PM

Tonight I set the bearing at 30 degrees to the mirror box and clamped it in place. Tomorrow I"ll drill the holes to anchor both of them.
I came up short of plywood so ordered another sheet that will be in tomorrow, then I can make the ground board and then put it all together. Then the test under the stars...

Attached Files



#134 sopticals

sopticals

    Viking 1

  • -----
  • Posts: 569
  • Joined: 28 Mar 2010
  • Loc: New Zealand

Posted 16 January 2013 - 07:32 PM

Looking good Brian.

Stephen.(44deg.S.)

#135 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 17 January 2013 - 10:44 AM

I installed the bearings this morning and put the telescope together. It balances!!! With nothing in the focuser the ota drifts up just slightly, with my 21E, 13E, and 6.7ES it stays wherever I put it :grin: I did the balance calculations based on the weight of the 13E which is less than the 21 but more than the 6.7.
I was hoping to take the scope for a test run this weekend but now I see the forecast calls for cloudy and snow, maybe I"ll wait until next weekend when it is -30 :smash:

Attached Files



#136 sopticals

sopticals

    Viking 1

  • -----
  • Posts: 569
  • Joined: 28 Mar 2010
  • Loc: New Zealand

Posted 17 January 2013 - 05:12 PM

Really nice Brian.WOW!!! look at all those great "hogging :jump: tools" in the back ground.

Stephen.(44deg.S.)

#137 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 17 January 2013 - 07:21 PM

You are showing your real colors Stephen, only a true glass pusher would see weightlifting equipment and think "hogging tools"!!! :grin:

#138 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 30 January 2013 - 09:41 AM

The telescope is finished, except for some varnishing on the rocker box and ground board. I've done some sanding on the ends of the truss poles so they slip into the lower truss connectors easily and also, cut them all exactly the same length so collimation doesn't change from setup to setup. Well, sometimes I need to tweak one of the secondary tilt screws but I think it holds collimation pretty well.
A couple of days ago I took the scope out for its first light and was disappointed, at least at first. My eyepieces all came to focus but I had a hard time bringing the stars to points. I had let the scope sit about 45 minutes outside but apparently that wasn't enough, I came back about an hour later and the difference was like night and day, stars were much sharper. The scope had been in my basement at 70F before taking it outside where it was a cool windy 15F, so maybe it takes more time with that kind of temperature difference. Hubble Optics advertise that these sandwich mirrors cool down really quickly but maybe I was asking too much for that temperature range. The clouds rolled in and ended my session way too early.
Today I played with the mirror a bit, the top post(wood dowel) that holds the retaining clip was rubbing against the mirror so I backed it off and I think that may have helped the images tonight. Glass seems to be really sensitive.
I set the scope up outside about 4 pm and around 7pm I went out and found M42 in my Stellarvue finder then put the Ethos 21mm in the focuser, what a sight, I have never seen M42 like that before, so much detail I didn't realize was there. The 21mm is so wide and the dust lanes were streaming out in all directions. This was really the first time I"d got to use the 21mm, having acquired it a few months ago while the scope was under construction and I had no way to try it. I adjusted the Stellarvue to more precisely line up with the scope and swung around to Jupiter, really nice, put in the Ethos 13mm and just took it all in. My other scope was a 10" and with this 14" there really is a big difference. I can definately see more bands and they seem sharper. I put the Explore Scientific 6.7mm in the focuser to have a closer look but for some reason I couldn't really get the detail the 13 & 21 were showing. I"m not sure why, maybe the seeing wouldn't support the power.
I am noticing the stars away from the center of view are pretty fuzzy, I suppose that is coma and I'll probably have to get a Paracorr, no sense having expensive wide FOV eyepieces unless the whole view is sharp.
I played with the focus, both at zenith and various angles towards the horizon, the stars seem to get harder and harder to focus to points from around 45 degrees down to the horizon. The cell may need to be re-done, changed to a sling, or something else but first I'll need more viewing sessions to make sure what is going on.
All in all I'm very happy with the telescope, a great fun project, frustrating at times but rewarding. I couldn't have done it without all the help I got here on the forum, in this thread and from other forums as well, also, Reiner Vogel's excellent website was great in helping me understand some of the geometry and design concepts. Thanks everyone.

Attached Files



#139 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 30 January 2013 - 09:44 AM

The scope sporting a black shroud. I bought the nylon-lycra material for $18 and a local seamstress put it together for $10.

Attached Files



#140 PaulEK

PaulEK

    Viking 1

  • *****
  • Posts: 585
  • Joined: 25 May 2008
  • Loc: Wisconsin

Posted 30 January 2013 - 01:41 PM

Looks great!

I've been following your thread, in part because I'm hoping to build a scope around the Hubble 14" sandwich mirror, but I plan to put mine on an EQ mount. It's good to hear that the mirror seems all right. I do plan to have mine sent directly to someone who can test it, and then re-figure it if needed.

I also have a 10" reflector. It has a Hubble mirror that gives fine views, but that didn't happen until after it was re-figured by this same person. He figured it was about 1/3rd wave or worse before re-figuring, and about 1/10th after. The difference in viewing was vast!

#141 sopticals

sopticals

    Viking 1

  • -----
  • Posts: 569
  • Joined: 28 Mar 2010
  • Loc: New Zealand

Posted 30 January 2013 - 05:03 PM

Hi Brian, :bow:

What a great :jump: result. You will be looking forward to lots of clear :roflmao: night skies.

Best regards
Stephen.(44deg.S.)

#142 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 01 February 2013 - 08:18 AM

I've been following your thread, in part because I'm hoping to build a scope around the Hubble 14" sandwich mirror, but I plan to put mine on an EQ mount.


Hi Paul, that sounds like an interesting project, I hope you document it here on CN, I have been kicking around doing something like that.
Having looked through only two telescope mirrors in my life I"m no expert on whether a mirror is a good one or not. It seems good but I am concerned that I couldn't get much detail with the ES 6.7mm while observing Jupiter. More observing sessions are needed for sure.
Was the Hubble Optics 10" a recent purchase or older? Sad a mirror needs figuring right out of the box.

#143 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 01 February 2013 - 08:21 AM

Hi Brian, :bow:

What a great :jump: result. You will be looking forward to lots of clear :roflmao: night skies.

Best regards
Stephen.(44deg.S.)


Thanks Stephen, I appreciate the kind words. I've been reading your epic adventure on glass pushing on another forum, you have inspired me to dust off that 14" piece of glass in my basement.....next project :grin:

#144 PaulEK

PaulEK

    Viking 1

  • *****
  • Posts: 585
  • Joined: 25 May 2008
  • Loc: Wisconsin

Posted 01 February 2013 - 01:08 PM

Brian:

I bought the lens on eBay about 4-5 years ago, if I recall correctly. I'm no expert on optics, either, but it was clear right away that this one had problems. I've read that they sometimes do make great mirrors, but like so many mass-produced items (not just from this company), quality control is a big issue, so they have also made not-so-great ones. It's too bad, and in my opinion, bad business practice. If they could develop a good reputation, based on consistent product quality, it could do nothing but help them grow. Even if they never made fantastic mirrors, but always made okay mirrors, they would be better off. They might be working on this now; mine is fairly old. But they claimed in their ad that it was 1/34th wave, with a Strehl ratio of .996! I knew that was too good to be true. And it's another reason to be concerned.

Still, I don't regret buying it at all. Even after re-figuring, it cost far less than an excellent mirror made by a firm with a better reputation. And it is now an excellent mirror.

My concern with the sandwich mirror is that I read a post somewhere that told of one that could not be re-figured by someone making the attempt, because of the sandwich construction. I don't know if it was that particular mirror that was the problem, the person's re-figuring skills or tools, or a problem inherent in all of them. I need to do more research -- or hope for an answer on this thread! :)

I still think it's possibly going to be worth the risk, especially since it's probably the only way I'll be able to afford a mirror of this size.

#145 PaulEK

PaulEK

    Viking 1

  • *****
  • Posts: 585
  • Joined: 25 May 2008
  • Loc: Wisconsin

Posted 01 February 2013 - 01:18 PM

Oh! Your other point, about the build I hope to do: It will be a few months before I get started, but I do plan to post about it here. Right now, I'm thinking about a thin plywood skin over plywood rings. I want it to be round, so I can rotate it for eyepiece placement. Here's a source for thin plywood, from 0.4mm to 6mm. I need to find about about weight, since I want it as light as I can make it, while also having a strongly built tube. But for what I'm hoping to do, I think a sheet that is 61" x 61" will work very well. In fact, I don't think there will be any extra bits left.

#146 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 01 February 2013 - 05:42 PM

Still, I don't regret buying it at all. Even after re-figuring, it cost far less than an excellent mirror made by a firm with a better reputation. And it is now an excellent mirror.


That crossed my mind too when I bought it.

#147 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 01 February 2013 - 05:49 PM

If you haven't already read Albert Highe's book "Engineering, Design and construction of Portable Newtonian Telescopes" you might want to give it a look. He talks a lot about thin plywood, design stiffness and such, how to determine weight, etc, lots of engineering stuff. It might be helpful to you in your project. He also includes a cd in the back cover that includes several Excel spreadsheets for determining balance, bearing sizes, etc. Its a great book!

#148 PaulEK

PaulEK

    Viking 1

  • *****
  • Posts: 585
  • Joined: 25 May 2008
  • Loc: Wisconsin

Posted 01 February 2013 - 09:32 PM

Thanks, Brian! I've heard of the book, but didn't know it went into those kinds of details: it sounds like it might be just what I need.

#149 star drop

star drop

    contra contrail

  • *****
  • Moderators
  • Posts: 71153
  • Joined: 02 Feb 2008
  • Loc: Snow Plop, WNY

Posted 07 March 2013 - 02:46 PM

Excellent job, Brian! A type 1 Paracorr will work fine.

#150 starman345

starman345

    Wait, I'm Thinking

  • *****
  • Posts: 9245
  • Joined: 06 Jul 2010
  • Loc: New Brunswick, Canada

Posted 07 March 2013 - 03:10 PM

Thanks Ted, I"m holding off on the Paracorr until I get my mirror back. I sent it to Normand Fullum for testing, he said it was an average mirror but he thought he could improve it so its now being re-figured. Its an f4.5 so I imagine the coma will still be the same but I want to have a look through it first before I cough up the money for a Paracorr. :)






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics