Last updated: 10 October 2004
Subject: Homebrew, low profile, top end counterweight instructions Sent: Friday, October 8, 2004 12:21:22 From: Neumann, Eric M. (firstname.lastname@example.org) I wrote you a few days ago about this and I'm finally getting around to writing it up and sending pictures, hope you like it. I've really enjoy your site and it has greatly increased my enjoyment of my ETX-90. I hope you are on Meade's payroll, or at least get lots of perks from them Clear skies, Eric Here is a simple and cheap method to make a primary end counterweight for any Schmidt or Maksutov telescope, just adjust the procedure to suit your particular needs. These instructions are specific to my camera and Meade ETX-90 EC Telescope. I'm using my trusty Pentax K1000 camera body and Meade's standard t-tube. I used a digital balance and actually weighed the force that the camera was putting on the OTA when level (the alt axis lock must be free). I then weighed a measured short piece of #8 bare copper wire and determined a weight per foot for the wire. I also measured the moment arm for the camera as mounted ont the scope (the distance from the alt axis to the back of the camera * weight as measured)and using the length from the alt axis to the front end of the OTA to find that I needed about 15 feet of #8 wire. I then wound the wire around a piece of 3" PVC pipe in a very tight coil. I actually drilled a hole big enough to poke the wire into to hole the wire while winding. The coil springs out when you let go and is almost big enough to go around the OTA. I then trimmed the bent end off of the coil. Then I slipped the coil up and over the end of the OTA one turn at a time. After I had about 1 or 1 1/4 inches of coil pushed onto the end of the OTA, I rewound the rest of the coil over itself to keep it reasonably short. Finally, I wrapped the coil with black electrical tape to hold it together. The weight is compact and holds itself tightly to the OTA and my scope is balanced to within a couple of ounces with the Pentax attached. The copper is soft and although leaves copper colored marks on the front lens cell they rub off easily enough. Installation and removal requires a slight twisting motion in the direction that expands the coil.
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