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Catsperch and Harford Homemade Observing Chairs


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I've been observing for just three years now, so I'm a newcomer to this field. I live in Maryland and have no specific interests yet, so when my friends who focus on DSOs are complaining about moonlight polluting their night skies, I'm enjoying the lunar views. I've jumped into observing with both feet as I have a NexStar 8SE (my initial scope), built an ExploraDome observatory in my backyard, and added a CPC1100 as my observatory scope. The addition of the observatory has really increased my time under the moon and stars so although I am a relative newcomer, I've had some time to play with various pieces of equipment. I'd like to tell you about my experiences in coming up with some great homemade observing chairs.

Astronomers often wax profoundly on the importance of quality equipment. Such discussions mostly center on the obvious things like telescopes themselves, eyepieces, finder scopes, scope mounts, etc. However, one of the most important pieces of equipment you should own is a good observing chair. Your observing skills will improve significantly when you are seated on a stable platform rather than observing from the unstable position of standing or stooping at your eyepiece. So if you don’t have one, or need a better chair, this review is for you.

You can buy a ready-made chair of course, but if you enjoy making things yourself I’m going to introduce you to two models that I’ve made and found to be very good pieces of equipment. Both are wooden and I recommend you use a hardwood like red oak which you can get at a local building center like a local hardware or lumber yard, Home Depot, or Lowe’s. I prefer wood because I think it looks beautiful and in the winter time, it isn’t so darn cold to the touch! Both chairs use a simple adjustable seat design that uses dowels in the seat support that engage/lock in notches in the seat back due to the weight of the seat itself and your weight.

The first chair is based on plans posted on the web by the Harford County (MD) Astronomy Club in 2001 by Bill Geersten. I think I paid about $50-60 for the red oak I used to build my chair.



The link to the plans is: http://www.harfordastro.org/izar/izar_chair/izar_chair.html

Bill provides all the guidance you’ll need including materials lists and detailed diagrams to follow, but here are a couple of additional tips based on my experience with the chair. You should position the dowel that connects the back legs so that when you remove the seat and fold legs against the chair the cross dowel nestles into one of the dowel notches on the seat back. That allows for a neater folded package. To pad the, seat I took a foam garden kneeling pad (~$10) and cut it to match the size of the seat. You could glue it to the wooden seat, but I prefer to just strap it on with a couple of Velcro straps. Finally, I added a washer and nut to the top of the bolt that sticks up through the cross dowel onto which you place the dowel that pivots down from the chair back. In the original plans, the bolt is simply held in place with a wing nut. The problem is that in the field at night when you take off the wing nut, the bolt and washer tended to drop in the grass. I use a little longer bolt, add a top washer and nut to permanently hold the bolt in place, then just drop the pivoting dowel onto the bolt and hold it in place with the wing nut.

This chair design has served me well for over two years and it is still the chair I use when I go on the road with my scope. The maximum seat height is 30-32” which is fine when using my NexStar 8SE on a tripod.



The Harford chair is great, but I found when I built my backyard observatory that I needed something with a little more height when viewing objects at a low altitude with my CPC1100 on a pier in my observatory. To address this issue, I calculated I needed a chair with a seat that would go up over 40 inches. I therefore chose to make the “Original” Catsperch ™ observing chair (max height ~48”) available through Cat’s Eye Collimation on the web at:

http://www.catseyecollimation.com/

You’ll find the Catsperch ™ links at the bottom of the left panel on the Cat’s Eye home page. There are four chair models ranging in maximum height from 36” to 58”. You can buy two of the four models in a number of forms. For mine, the “Original” Catsperch ™ , they offer: 1) assembled & finished ($293); 2) assembled & unfinished ($218); 3) unfinished, unassembled ($168); 4) plans & hardware ($42) 5) plans only ($25). I opted for the plans and hardware which I got for about $50 when you include shipping. I highly recommend ordering the hardware. You won’t save much money over buying it yourself and the kit includes some non-standard items like a folding hinge for the legs, cotter clip pins for the seat and foot rest dowels, and non-skid pads for the footrest. In addition to very detailed instructions and tips (read them all completely at least once before starting any work), the package includes full size templates that you can use to mark all the hole, notch, and screw positions needed. There are also plenty of clear diagrams in the instruction packet and a complete materials list. The reason I like the Catsperch™ is that it in addition to the adjustable seat, it adds an adjustable footrest so when you put the seat up high, your feet aren’t dangling in the air. I paid about $75 for the red oak needed to make my chair.

If you buy the chair ready made from Cat’s Eye, you have the option to have a 3-D astronomical graphic engraved in the top of the back of the chair. That inspired me to do my own artwork. In honor of my Orionis Observatory where the chair would be used, I decided to router out an oval area about 1/16” deep in the chair back. I then painted it blue with white stars depicting the constellation Orion (well there are a couple of orange ones: Betelgeuse and one in Orion’s shield).



My Orionis Catsperch is perfect for use with my pier-mounted 11” observatory scope no matter what position it’s in.



I still use my Harford chair for field work with my tripod-mounted 8” scope. If I had to do it over again, I’d just build the Catsperch™ model as it meets all my needs though there is a bit of a 'dead spot' in seat height due to interference with where the leg brace attaches to the chair. However, if you don’t need the height of the Catsperch™, the Harford chair is a nice piece of equipment. Either one is fun to build, attractive and will provide you many years of faithful service. So if you don’t have a good observing chair, build yourself a firm base for your astronomical observations with one of these wooden wonders.




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