Telescope Observing Stool - Model "22X4"

Rod Nabholz

 

Why a Seat?

OK, I'll admit it, I like to sit while I observe. Call it lazy if you want, but I find that I am a better, more patient observer when I am relaxed and comfortable. I also find that I have a lot more stamina to stretch the sessions later into the night/morning when I have spent less time on my feet.

My Needs

My main scope is a 13" f4.5 dob. I determined that I needed a chair that would provide a comfortable sturdy seat in an adjustable range from about 16" to 26". Sturdy is a key consideration. Many of the designs I have seen out on the market and on the net are really well conceived and constructed, but as a big man, in my mind I could hear cracking wood and envision serious orthopedic trauma when thinking of myself perched on some of them. I needed something that I could be confident would work without fail and allow me to relax and concentrate on observing.

The Design

In reviewing the some of the existing designs, I began to feel that a simple stool would work best. Supporting the weight with it bearing straight down, rather than leveraged or offset seemed to be the easiest way to make sure the structure would hold up.

To keep things affordable I wanted to use inexpensive and readily available materials on this project. I came up with the idea of using sections of 2x4's as a column and a length of pipe and a flange to provide an adjustable seat.

By arranging the 2x4's in a box shape, I created a channel down the length of the box/column. The pipe and flange move up and down through the channel. The height is adjusted by the insertion of a "pin" through a set of regularly spaced holes bored through opposite sides of the column. The pipe rests on the pin and the weight of the observer insures it remains in place.

 

The column needed feet to provide a nice wide stable base. Again turning to my 2x4's, I simply attached a 12" length to each side of the column with glue and screws. It is very stable and solid.

 

 

Construction Details and Hints

I did use 2x4's for the construction, just 2 2x4 studs (the origin of the name "22X4") but I did rip the width down. I found that to accommodate the 1/2" pipe I used for the seat support, the channel in my column box needed to be just 7/8ths" square. That meant that each piece of the box need be only 2 7/16ths wide to make for a snug fit, but one that would allow the pipe to move freely. If you decide to use larger pipe you can adjust that dimension to fit. A reasonably snug fit for the pipe becomes important as the seat height is increased in order to prevent the seat from feeling loose.

I did also rip down the 2x4's used in the base, in this case to 3". This was purely an aesthetic decision.

All of the joints were glued and screwed. Be sure to predrill the holes for the screws to avoid splitting the wood. Don't skip the glue, it makes a big difference in the sturdiness of the stool, especially in the leg joints.

The pipe is screwed into a pipe flange at the top. The flange is then attached to the seat. In my case, for a seat I used a scrap of 1/2" Baltic Birch Plywood cut to a 12" circle. I attached the plywood to the flange with four 1/4" bolts and lock nuts. Be sure and put the bolts in with the heads on the seat side, you don't want the end of the bolts causing "discomfort". I used lock nuts to avoid things loosening later, once upholstered, tightening them back up will be impossible.

I topped off the column with a 3/4" pipe flange. It protects the top of the column from wear and the 1/2" flange on the seat rides perfectly on top of it when the seat is at it's lowest position.

 

For the seat height pin, I used a 1/2" hex bolt. I drilled the holes 2" apart and used a 5/8ths bit. You don't want the fit of the pin too tight, it makes for aggravation out in the dark. I also drilled a 5/8ths hole about 2/3rds of the way down from the top side of one of the legs to serve as a storage hole for the pin when the seat is all of the way down. Finally, I drilled the pin near the head and threaded a fishing leader through it, attaching the other end to the column with a screw. This keeps the pin handy and prevents losing it during transport or use.

 

I upholstered my seat with vinyl obtained from the fabric section of a local department store. I padded it with 2 layers of 1/2" closed cell foam from a camping sleep pad (from the sporting goods department of the same store). A helpful hint here is to cut the foam with an extra 1/2" all the way around. This extra foam will be drawn around the edge of the seat and keeps the edge smoother and softer. I am no upholstery expert, but a lot of tugging and lots and lots of staples and it looks pretty good.....from the top side anyway.

I also added a handle on the column to make carrying and moving more convenient (not pictured here).

I finished the wood with multiple coats of polyurethane. You could just as easily choose to paint it.

Conclusion

This an easy weekend project. Materials will probably run anywhere from $25 to $45 depending on what you might already have on hand (screws, glue, staples, scrap plywood etc.) You can easily scale this to your particular needs by varying the length of the column and pipe.

As I mentioned, I built the stool originally to be used with my reflector. I also use the stool with a 4" equatorial refractor, an alt/az short tube and a couple of different binocular mounts. It works great for all of them.

This particular stool is the latest I have made. The original Model "22X4" is pictured here. It has been my constant observing companion for 10 years and has performed beautifully for that entire time. I retired it this year to serve as a seat in my garage workshop after rebuilding the 13" scope it was partnered with. It has lots of service left in it and lots of great observing sessions to it's credit.

 

 

 

 

Attention Stool Builders!!

If you are inspired to build a stool based on this idea, I would like to hear about it - even better I would like to see it! Let me add a picture of your completed stool to this page.  Show me how you have interpreted or improved on what I came up with. Email me a photo and I will add it here for everyone to see.

 

 

I welcome your comments and questions at

rnabholz@yahoo.com

 2005 Rod Nabholz

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