ETX TECHNICAL TIPS
Sent: Friday, December 22, 2000 16:27:14 From: firstname.lastname@example.org [no longer valid] After a bit of investigation, I came to the conclusion that the Mead #833 tripod and the ETX125EC weren't made for each other. I think that the scope is a bit too heavy for the tripod mount when in the Polar Mode. Therefor I decided to build something that was sturdy and reasonably transportable plus being a bit cheaper. This is what I came up with and if it'll help anyone else out then that's a good thing. The actual column is made out of two pieces of 6.25"O.D. sewer pipe (whole the comments). As it turns out it's sturdy and doesn't 'cold flow' ( new sewer pipe is recommend). The rest of the structure is 3/4" birch plywood left over from a W.A.E.A. project I did a while back. The sector plates for the wedge is made from 0.125" 6061-T6 AL. Add the nuts, bolts, Tee nuts knobs, screws, glue etc and the total outlay was about $30.00. ( I count my time as free but it was about 30hrs of spare time not counting splinter removal time. The project was extended a bit by having to explain almost every step to my 4yr old grandson, but worth it, even with filling in the extra holes and hammer dents he made while helping....). There are two ways to build stability cheaply. One is to build it super rigid structure and the other is to give it mass. I did the latter. I can fill the column with sand and its as stable as my block wall. (It does put a bit of a cramp on the transportability though if you don't dump the sand). The column is in two sections so the base plate may be located 40" or 26" above the ground (standing or sitting height). There is a 5/16" threaded rod down the center holding the wedge base plate in tension with the three leg sections. There is a 3" thick plug joining the two sections and 3/4" plugs at the top and bottom ends for mounting. The wedge base and plug also has a thrust bearing made of a sheet of Teflon to facilitate alignment tweeks. The three legs are removable by the way with one bolt and a wing nut each. The wedge base plate is drilled to mount in two positions. The one shown is so the scope CG is over the column in the polar configuration. the second set allows the plate to center up the CG over the column in the AX/ALT configuration. Setup and break down time is about 5 min providing your grandson isn't using them to 'fix' the VCR... I have a AZ and LAT vernier adjustment screw device that I'm working on and should install soon. This will make polar alignment a snap. Doug
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