Improvements to DIY parallelogram mount

[michael.h.f.wilkinson]

Some time back I made a parallelogram mount for my bins, as posted here:

http://stargazerslounge.com/diy-astronomer/154871-diy-parallelogram-mount-made-my-15x70s.html

Though it worked well for my Omegon 15x70 bins (Revelation/Celestron clones), the new Helios Apollo 15x70 HD is a full kilogram heavier, so I needed a different counterweight. The counter weight mounting I used had a problem: due to the way t is attached, the position of the weight on the bar I could in principle attach, has no effect on the balance. This means you can only balance the mount by adding or removing weights, which is cumbersome. With that in mind I made a new set-up, in which I attached a redundant counterweight bar from an EQ1 mount (which donated the tripod head and counterweight as well), to the top arm of the parallelogram. The bar is attached by drilling holes for M6 screws at right angles through a long M12 nut, and attaching that to the parallelogram. The bar can be removed for storage by unscrewing it. Shifting the weight now adjusts the balance, as it should be. The difference is shown in the first two photographs.

The new mount is shown in the third image, and the new altitude axis has been improved quite dramatically by the addition of Teflon washers (fourth image). The next two images show the difference in the azimuth axis and its mounting. In the original, a single, long M10 bolt was both axle and attachment screw, fixing the mount to the tripod. This is not good for a number of reasons, as I tended to need two tools to set the mount on the tripod, whilst balancing the awkward mount at the same time. This might result in colourful language being used . The second was that each time you have to put the right amount of tension on the nut, which controls the degree of friction and play.

I now have a set-up with some more discs of wood, with the upper part being distinctly taller than before, and consisting of two halves which can be secured (semi)permanently by 6 M6 screws. Inside the top hollow section, a nut secures the altitude axis permanently now a much shorter M10 bolt), and is set to the right tension. Teflon and steel washers inside, and an ebony-star and a Teflon disk between the moving and fixed part of the mount ensure silky smooth operation. The bottom half has a special M10 nut embedded in the wood, which can be attached to an bolt inside which slots through a hole in the disk of wood at the bottom of the whole assembly. I mad a wooden knurled knob which attaches to the M10 attachment bolt (last photo).

The result is a mount that can be attached securely to the tripod without any tools, and has correct tension on the azimuth axis. Should that need adjustment, I release the 6 M6 screws, readjust the tension, and assemble the mount again. I used it in earnest on March 23 for the first time, and am very pleased with the result.

[swamp thing]

That looks excellent Michael.

I will get round to making one of these at some point.

Regards Steve