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Equatorial was the mode for many years. I tried fork mounts and side saddle mounts. Nothing is permanently
finished. I am still machining on the parts for my 12.5"f4 nova search scope. It will be done some day! before all the
super-nova are found.
| Thing 12.5" on Pipe Fork and Open Truss |
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| Did this shake and shake. |
| Light weight RAIL telescope mount |
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| Open air cooling on a steel RAIL |
The development of telescopes range from the over weighted to the light weighted. Inorder to test
mirrors on a telescope i came up with the RAIL system. Pictured here are several of my 12.5" RAIL systems.
F4 nova search system with CCD.
and
F10 a planetary system with long focal lenght requiring a 6" folding flat to return the beam throught the
middle of the primary mirror.
In some cases of a 10"F10 i used a 4" flat to return the beam
above the telescope primary.
Here are some modification to your Dobsonian AZ-EL mount that will
work cheaply to convert it from AZ-El to Equatorial.
The standard AZ part of the Dobsonian mount requires some getting use to when you try to track and object.
Even the special Az-El tracker motor systems can only track for short periods of time.
How about converting you Dobsonian to this PERRY WEDGE. This can be made of many materials depending
on how deep your pocket change might be. All aluminum, stainless steel, or just plain wood.
Here are a series of photos of the Perry Wedge Equatorial conversion. Contact me if you would like one made
or have any questions.
| Equatorial Conversion of a Dob Az-El Mount |
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| Figure 3: Wood Equatorial wedge open view |
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| Figure 4: Open view of Equatorial Wedge 4" and 5" PVC pipe fittings |
You see the idea. Just build a wedge of wood and screw some large
PVC pipe fitting to the AZ base and insert it into the wedge. The 4" PVC pipe fitting will fit with out machining into
the 5" PVC pipe cup. Go to your local home plumbing store and get one each. Screw one to the Dobsonian AZ base of your telescope,
and install the other one through the back of the wedge. You may have to do some cutting to get the dob to fit all the way
in and run smoothly.
Here are anothe series of pictures showing how to improve the wedge. The wedge can be made to
fold up and work like the AZ-EL mount, or fold out and be a RA-DEC wedge.
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| Figure 5: The Folded Out RA-DEC wood wedge base |
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| Figure 6: The folded down AZ-EL wood wedge |
This last picture shows the side wood braces that fold down into the Wedge
box. You hinidge the front wood, and the two side woods so they will fold down flat. The wedge then becomes the standar AZ-EL
Dobsonian mount. Don't forget to make the angle of the front wood near your North Polar Latitude angle so the RA-DEC tracking
will work.
You can add a wire drive to the PVC pipe that sticks through the front wood board. This option has
not been tried yet but should be doable. Use a large pully and wrap fishing stainless steel leader wire around it several
times and wrap the other end of the wire around the small motor pully. That way you get some friction and it won't slip. If
you want to machinea clutch system the fits over the PVC pipe that would be another added feature.
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| FIgure 7: Perry Wood Wedge being folded down into the box. |
| Novel 16" F4 using an OFF SET SINGLE FORK |
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| This took some machining and tweeking |
If you go to the obsurde size then you are looking into a whole nother animal in telescope design and ballance.
Here is my 32". This started out with the glass required by a 27" mirror of standard thickness. I
had Schott Glass of Jena press the 27" mirror into a 32" mirror with precurved F4. That sounded like a neat idea. Save the
glass you would grind out and maximize the surface area.
So this primary mirror is 80cm in diameter but only 3.5" thick at the edge. The sagitta in the middle is
about .7" deep. This mirror ended up F2.4. This is the 3rd fastest known mirror in the WORLD. There are only two French
80cm mirrors that are slightly faster in F number for Schimdts.
Inorder to control the figure i ground and polished and figured the mirror on a large draper machine. I
tested the polished surface by tipping the mirror up on its edge. Potatoe chiping of the mirror surface is noticable.
The first curve on the mirror is an 80 percent parabola, or ellipse. The Dall-Kirkam secondary is then a
6" sperical convext mirrror. This gives the overall F# of F17.. Way Way too strong. The new seconary to be done
soon (20 years later) will be a 10" giving a total F# of F8. This should be more practical.
The image of jupiter at F17 is like 1" across.. Totally useless as the atmosphere is tearing up the image
quality anyway.
Aligment of the 32"f2.4 with 6" secondary turned out to be much more critical than first thought.
Good images are not possible with Dall-Kirkam when the primary is less than F4.
The next step will be to refigure the primary to parabolic 107% Ritchey-Creitien formulae. Then null
the secondary as required. Some time in the year 2010 it might be done.
| In 1972 this was the worlds largest amateur scope? |
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| The really big 80cm F2.4 with F17 secondary on Trailer |
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