Jaegers objective
#176
Posted 26 May 2012 - 10:07 PM
Again... I can email you the original large size design diagrams if you like. If you decide to use these designs, please revise the measurements according to your build parameters.
Mel
#177
Posted 28 May 2012 - 08:00 AM
I don't take so much time with my plans, I just draw them out on paper full scale, using a roll of 30" wide kraft paper from Home Depot used for laying on the floor for construction or painting. I just tape it down on the shop desk and draw the thing out the lazy way.
By the time I took to learn AutoCad I could probally have the project built. I know engineering students take several classes in college to use AutoCad to it's potential.
marty
#178
Posted 29 May 2012 - 08:27 PM
Mel
#179
Posted 30 May 2012 - 10:11 PM
Note: The lens cell is not in this photo, but it has already been painted solely using flat black enamel spray paint.
Mel
#180
Posted 31 May 2012 - 08:11 AM
marty
#181
Posted 31 May 2012 - 10:34 AM
Mel
#182
Posted 02 June 2012 - 08:16 PM
marty
#183
Posted 17 June 2012 - 06:58 PM
Seeing your cell design looks you used 0.150 inch = 3.81 millimeters for the flanges to retain the lens.
is it really necessary to lose all of this aperture for a good support ?
#184
Posted 19 June 2012 - 08:16 AM
I've been following your build since this thread started. You're doing a great job.
On cutting the tube to length, on two OTA's I built I made up a sled similar to what you did. I use second hand focusers, in my case Astro Physics 2.7" with 4" of travel and mount it on a backplate and rotating ring as if I were going to mount to tube OTA. Not having an interest in bino's I set the focuser with diagonal and eyepiece on the sled with the focuser tube in the mid position ie: 2" of travel either way. I slide that focuser assembly to focus on something 1/4 mile away and measure from the back of the lens mounting ring to the front of the backplate. That's the length I cut my OTA to. I'm wondering if a focuser with 4" of travel would allow you find a position to use a bino or a diagonal without extensions?
Regards,
Jim
#185
Posted 20 June 2012 - 08:50 PM
Sorry I am just getting back to the thread to read your notes. I will have to strongly consider incorporating a binoviewer in the scheme of my build. Switching between the two setups is an easy proposition.
I was hoping to get the race trace done of recent, but other family matters took precedence. So, once I get the opportunity to resume, my plans may ultimately change to a binoviewer setup.
Mel
#186
Posted 20 June 2012 - 09:02 PM
Thanks for the kind words! Great points and notes, as well!
A binoviewer is still a tossup effort in my mind. But the idea is certainly calling me. For the moment, my project is on hold until I get through some home front matters. In any case, I like the method you used for determining your tube length.
I see that you will be using an Astro Physics 2.7" focuser! I have one of these focusers too, but I will be using mine for a 6" f/5 refractor project; to be executed after the 6" f/10 build.
Mel
#187
Posted 20 June 2012 - 09:09 PM
Is this a question for me or Marty?
Mel
#188
Posted 21 June 2012 - 05:24 AM
Hey gmazza!
Is this a question for me or Marty?
Mel
Hi Mel,
The question is for you, I am buiding a cell for the 108mm 8.5 and don't know the measure to be used in the retaining ring.
Best
Gustavo
#189
Posted 22 June 2012 - 10:02 AM
. I'm wondering if a focuser with 4" of travel would allow you find a position to use a bino or a diagonal without extensions?
Regards,
Jim
Yes it will but you have to measure everything very accurately and have a binoviewer/diagonal combination with a reasonnable optical path length.
Notice that when you unscrew the 2" adapter from the end of the AP's draw tube and rack it all the way in, the end of the draw tube will retract at least an inch into the body of the focuser. That allows you to add one of AP's threaded extensions to the draw tube to maximize the amount of travel to ~5.5". The Denks with the power switch consumes about 5" of optical path length. That's enough total travel to allow allow me to use my Denk II with the power switch and the AP diagonal without the need for a seperate extension tube. However, that does not leave a whole lot of room for extra in and out travel, which, in turn, may limit your eyepiece selection.
The Lumicon mirror and Baeder prisim diagonals have a shorter shorter path lengths than the AP diagonal and can provide a bit more travel capability.
Hope this is usefull.
Jeff
#190
Posted 22 June 2012 - 08:20 PM
Hey gmazza!
Is this a question for me or Marty?
Mel
Hi Mel,
The question is for you, I am buiding a cell for the 108mm 8.5 and don't know the measure to be used in the retaining ring.
Best
Gustavo
Hi Gustavo,
Actually, if you were to divide the .150" in half, you would get .075", which will translate into being the retainer intrusion supporting the edge of the objective. And my clear aperture will be 6" exactly. This is the same measurements as built into the standard Jaegers cells. I hope this clarifies the matter.
As for your 108mm f/8.5 objective, I would think that a .050" to .075" retainer lip would work for you.
Mel
#191
Posted 23 June 2012 - 06:55 AM
Best
Gustavo
#192
Posted 25 August 2012 - 01:49 PM
As you may recall, the last thing I posted on my efforts was the painting of the lens cell and focuser support components.
Skipping over much of the fluff on how I got to this point, here is a photo of the main tube being cut. The method I used produces a very smooth and perpendicular edge, even though I cut it with a hacksaw.
Mel
#193
Posted 25 August 2012 - 01:55 PM
Mel
#194
Posted 25 August 2012 - 02:02 PM
Mel
#195
Posted 25 August 2012 - 04:14 PM
Rest in piece, Mr. Armstrong! May your footsteps in heaven be as fulfilling as those you have placed on the moon.
Mel
#196
Posted 25 August 2012 - 08:56 PM
marty
#197
Posted 25 August 2012 - 10:46 PM
That's a nice aestheic lenght on that dew shield, Mel.
marty
Hey Marty,
The camera actually made the dew shield look quite long in comparison to the main tube. But not by a great amount. The next photo I take, I hope it portray the scope in true proportion. I believe my point-n-shoot has some pin-cushioning.
Mel
#198
Posted 02 September 2012 - 07:49 PM
The four baffles were fabricated with a Bosch model 1608 laminate trimmer. The trimmer is basically a small router. In conjunction with the trimmer, I used two different Jasper router circle guides to make accurate cuts. A model 200 jig was used to cut out the circumference of each baffle from the sheet of Lexan, and the model 400 to cut out the knife-edge inner circles using a carbide v-groove router bit.
#199
Posted 03 September 2012 - 11:01 AM
I wanted to FYI that you can get a 6 foot 1/4"-20 threaded aluminum rod from McMaster-Carr for $8.91. Or 5/16"-18 aluminum rod for $14.07.
Matching aluminum nuts and washers are also available from the same source.
McMaster-Carr never exploits the customer on shipping costs and usally ships same day. They are located in Atlanta, GA.
I have bought a lot of stuff from them over the years for both ATM and other machining projects; never been unhappy with the shipping costs or service, web site is very user friendly, much easier to navigate than Grainger.
marty
#200
Posted 03 September 2012 - 11:55 AM