Pierre Schwaar's 8" F/4 Binocular Chair Restoration.

Pierre has left us, but his legacy lives on in his myriad optical creations. This page will chronical the rebuilding of one of them-his motorized, 8" F/4 binocular chair. I happened onto it during one of the first SAC ATM meetings. A lot of Pierre's equipment and supplies were left behind. Some were brought to the metting for input on what to do with it. Someone was suggesting we split the optical tube assemblies into two 8" F/4 Dobs to be used as club scopes for newbies. I found this idea abhorent, so I volunteered to take it all home, evaluate its disposition and refurbish it if possible. I had a plan to install it in the rolloff roof of my Stone Haven Observatory, for use by visitors to star parties I regularly give. It's only been recently I've been able to find the time to look into the restoration. I believe I'll have most of the materials I need on hand, but some restoration of the building is now in order. More on that later. In the mean time, I'll take pictures of the chair in its present state and as it gets fixed. I'll also be entering the plans into a CAD program to document all dimensions and so on. I hope you're sitting comfortably...

The chair consists of four basic structures. The base, the azimuth box, the chair section and the optical tube assembly. This page will describe the optical tube assemblies, (OTA) and subsequent pages will describe the other major parts. Hopefully, this arrangement will cut down on the load times for all the pictures I'll need to include. The OTA consists of two, 8" F/4 telescopes mounted such that the light beams come to focus between the two separate tubes. They are rectangular boxes made of plywood and hardboard and are held stable relative to each other with 1" aluminum tubing at three strategic points-one above at the center and two below on either end. At the center of mass of both units is mounted an altitude bearing that allows the unit to be rotated upward, allowing the user entrance to the chair. The OTA is then lowered such that the user's eyes can access the eyepiece/focuser unit mounted between the two tubes.

This view is of the top of the chair section and shows the cradle for the OTA. Bearing surface is only felt pads here. The rollers keep the OTA from sliding off the front, I think. Just in front of the rollers, you see a black material, hardboard, that extends further in front and has a point facing upwards. One of these points is broken off and will be repaired. Their funtion isn't known at this time, but once the OTA is again in the cradle, I'm sure their function will become clear.
Anyway, the bearing surfaces arrangement will be evaluated once the chair is together, and I wouldn't rule out teflon and Ebony Star in their future. :-)
The OTA assembly from the business end. This picture is kind of busy, so it's hard to tell what's going on here. Answer: Mostly nothing. You can see the main mirrors and their associated secondaries mounted on single strips of aluminum inside the tubes. The front of the focusing mechanism is visible and its associated colimation screws, but not very clearly. Also, you can see the chrome tube in front, used for lifting the assembly on its bearings for access to the chair. the front brace holding the tubes together is also seen.
This oblique view is slightly better. The entire left optical tube is seen, with the left side bearing and clip to accept the spring from t he chair assembly. The center aluminum brace is seen ot top. The angled piece of aluminum stock between the tubes is the actuator for the headrest adjustment. Another example of mystery that should become obvious once the whole thing is assembled.
From the back, it looks like about any small scope, except there's two of them. I really hope collimation isn't achieved using the mirror cell straps seen at 3 points around the mirrors here. >eek<
At any rate, the top and rear bracing tubes are clearly seen, as is a better view of the left alt bearing.
Here's a good view of the focuser section from the front. The angled aluminum strip on the right is the headrest actuator. Lower left is the focuser knob-a leather bushing held tight between a couple washers and mounted on a rod that rotates the gear on top. A transversal gear meshes yet another gear that moves the whole shebang toward and away from the viewer. The hollow tube seen at the top of this assembly is the sliding carriage for the eyepieces, not seen behind.
Just above the focuser knob is seen the 6x30 finder scope. Above and to the right of the finder's objective is the collimation section. These are the adjustment for ligning up the separate scopes to come together at the eyepieces. The first time through, I didn't get to figure these out. They didn't seem to do what I wanted them to do, so my assessment here may be all wet. Perseverence will prevail though. :-)
I could have gotten slightly closer on this one, but here goes anyway.
This is where you look to be amazed. It's also one of the only parts I was able to work on right after I got the chair. The old version had a couple of teardrop shaped aluminum pieces with 1.25" holes cut in them to mount presumably matching eyepieces. The were connected at the narrow end of the teardrops and moved relative to each other to adjust the interocular distance, as in a binocular of reasonable size. Those I'm in contact with are unanimous in their consternation at this particular adjustment. My philosophy in this is, if it's a binocular chair, why not use a binocular i nterocular adjustment? I happened to have a pair of binoculrs that were beyond help, the prisms having been knocked tragically out of alignment, so I borrowed the eyepieces AND interocular adjustment and installed them on the focuser here. Now, once again, I haven't had much chance to play with this arrangement, but what I did see, seemed to work well. More refinements are in order.
Anyway, in this view is seen the above mentioned bino EP's, the finder scope EP at lower right, the back side of the focuser gearing, along with an obscured view of the focus knob and the headrest adjustment lever.
Ok, same view from farther back shows all of the above and the business end of the headrest adjustment lever. (Yeah, that square, plastic block with the round hole in it. You're guess is as good as mine...)

This concludes the rundown of the chair as it existed on January 25, 2004. New construction has commenced and will be documented in further pages to be added when I get/make the time.

The new, refurbished parts of the chair will be described here.

Page URL: http://www.stargazing.net/Astroman/ATM/Binocularchair.html

Copyright 2004, Steve Dodder
Webmaster: Steve Dodder
Created: 01/21/04
Last modified 01/21/04