Posts Made By: Bob Chester

Here is a link to the Denver chair.

http://www.schlatter.org/Dad/Astronomy/chair.htm

But I like the Catsperch design better.


http://www.backyard-astro.com/equipment/accessories/Cat/cat.html

Have fun,
Bob

Tony,
I built the pictured mount below with no machining skills what-so-ever. A hand drill, Dremel tool and palm sander were the only power tools used. I did have a shop weld the heavy mounting flanges to the ends of the shafts. I copied the design from Optic-Craft. 1" shafts.

http://www.opticcraft.com/

It is nowhere near as elegant as Steve's mount but does function very well. The tough parts are the drive gears and drive electronics. It has a 9.3" Thomas Mathis drive on RA and a Byers 7-1/2" starmaster on Dec.. The picture shows it with the AC drive motors with an inverter/corrector mounted in the pier. I have since replaced the AC system with a Losmandy G-11 drive and motors. I had good results imaging with my 6" (40 min exposures) with the ac drive, have not imaged with the dc yet but don't foresee any problems.
Now for the second part of your question.
Is it worth the effort?
It was for me. I was living well below the poverty level, a single parent, and could not purchase a mount outright, but I could spend 25-50 bucks on parts every other month or so.
Cost: Less than $300 on alum., bearings, shafts, pier etc.. $600 on drives and electronics. 10 years (maybe more) from start to current iteration, and there have been many iterations.

Bob

Really, REALLY nicely done.

Bob

Jim,
As per Dave's suggestion to make a smaller ring to glue to the lid you could instead glue it to the interior of the bottom portion and use the sonotube as part of the lid as the picture shows.

Bob

A well educated and informed populace is difficult to control........ Of course, a well educated and informed populace need not be controlled.

Bob

Dan,
Before you click on the links below please be aware that PE is caused by the worm, not the main gear or its' size.

Here is a source for drive gears and some info.
http://www.opticcraft.com/

Source for worms.
Use left product list, go to gears/worms. Then you can filter your search.
https://sdp-si.com/eStore/

For drive electronics this is the cheapest I have found for the do-it-yourselfer. No computer required in the field. One is needed to program the box for your specific drive gearing. It may be easier to design your drive to work with a used Losmandy G-11 drive system. They come up for sale pretty regularly here in the classifieds. I paid 200 for mine, 2 motors, hand pad, electronics box, and all cables.

http://www.bbastrodesigns.com/BBAstroDesigns.html

Hope it helps,
Bob

Emanuel,
Below is pictured a polar scope holder from a CG-4. If yours is similar there should be a rubber O-ring that grips the scope firmly just ahead of the 3 alignment screws. Check to see if the O-ring is still in place. You may have rolled it out of it's groove when you installed the scope. Unscew the pictured unit and see if the O-ring drops out.

Hope it helps, Bob

Wayne,
I do not own the Tuthill unit but do use the same calculations for my homebuilt version. So, the quick answer to your question is, NO. No alterations to the formula are needed for your side of the pond. Using our own time zones takes care of that.

[COLOR="Red"]However[/COLOR],
I do have another related question. When I started using Tuthill's formula (early 90's) the starting point for the calculations was the 9th of every month. For example,9pm, Jan.9 = 330°. The last unit I saw for sale here on astromart had a sticker on it with the starting point being the 14th of every month. Do you (or anyone else here) know if the date changes as the years pass and at what rate?

Bob

ps. Just curious, what is the starting date on your card and do you know the date of manufacture?

Bill,

Here is a good resource for your task.

http://www.astronomyboy.com/cg5/

Hope it helps,
Bob

Musician and custom picture framer. Both industries in serious crisis. I too may be competing for a job at Walmart soon.

Bob