Even with a fair amount of sophisticated equipment, I found myself wanting a simple "grab and go" setup that I could use without having to plug in electronics, polar align, etc. I was looking for something that I could take to school star parties and other public events that would be easy for a novice to use. I also wanted something that I could use while my main rig was in use for astrophotography. After researching products on the web, the mounts I found were either too expensive or too flimsy (I won't name brands).
The rig I wanted had to:
Not finding what I wanted commercially available, I looked in my scrap pile and parts
bucket and figured I had just about everything I needed to make one. As it turned
out, the only thing I didn't have laying around was the black paint! I don't think
there is anything used in the construction that can't be easily found at your local home
improvement store. The dovetail adapter I used can be purchased direct from Losmandy. I modeled my mount after a high-quality mount made by Televue.
I just made it beefier. I had a tripod from a Meade LX-50 that is fairly substantial
and would work well for my purpose. Unfortunately, even extended it was a little too
short for use with my two refractors. So, I built a 12" extension. Below
are some images of the final product with notes on its construction.
Note: this project required a fair amount of metal work including cutting, welding, drilling and thread cutting. Although mine is constructed from metal, one could easily build it from wood.
|The final product showing
|A close-up view of the mount.
The mount frame is made from 3" X 1/4" steel flatbar. The bottom has a 3/8" hole drilled through it with a female threaded knob that secures it to the bolt on the top of the extension. I used two layers of thin plastic cut from a coffee can lid between the mount and the extension and a plastic spacer between the mounting knob and the mount. This gives the mount a very smooth motion in azimuth. The side pivots are knobs with 1/4" threaded studs that pass through holes in the outer arms and into threaded holes in the inner arm. There are 1/4" nylon washers between the arms as well as between the knobs and the outer arms. These act as bearing surfaces. Motion in altitude is also very smooth. Adjusting the tightness of the altitude and azimuth knobs allows for fine tuning of the mount movement. The holes in the sides of the two arms allow for adjustment of the mount to hold different telescopes.
|Another view of the mount.
A Losmandy dovetail adapter is mounted "upside down" to the inner arm to accept the scope's dovetail bar. A wood riser is used to allow clearance for the dovetail adapter's tightening knob. The width of the inner arms is 9" and is wide enough to accommodate either of my refractors with 125mm rings.
|The mount holding a telescope.
This is my Orion 120ST (5 inch objective) scope on the mount. It is a fairly heavy instrument. The scope, rings, and dovetail weigh in at just over 13 lbs. The mount handles it with ease. The dovetail adapter allows the scope to be moved forwards and backwards to balance it.
|Scope at the zenith.
The same scope. The angled arms of the mount allow the scope to be pointed straight up to the zenith. The holes in the arms allow the scope to be mounted so everything is balanced in this orientation also.
|Wide shot of the mount holding the scope.|
|The mount with me for a sense of scale.|