Gregg 10" f8 Newtonian 12.5" F 4.5 Cave Astrola Unitron 114 w unihex , Unitron 128, Tasco 7te, Tasco 7te-5,Criterion 4000
1st Caveman Award!Maynard Clark 8" f/8The Horsetrail Cave 12.5" f/7.51975 Cave 8" f/7 Lightweight Deluxe1972 Cave 8" f/4.5 RFT DeluxeCriterion RV-6Logitech HD C615 Webcam for Imaging
"The White Zone is for loading or unloading of passengers only. No Astrophotography." Cosmic Acres! Greatest restoration challenge: Tulley and Sons 3" achromat on Altazimuth mount, circa ~late 1820s
Quote:Looks like your "calculator" also comes from the 1958 S&T!
Quote: Quote:Looks like your "calculator" also comes from the 1958 S&T!
Cave - 1976 10" Custom Deluxe, 1977 8" Light Weight Deluxe, 1955 6" f/4 RFT
Unitron - 155C, 1960 142, 70's 128, 1954 128, 1960 114
Swift 1962 831
Monolux 60mm altz
Quote:In any equatorially mounted telescope there are three axes about whichmoments have to be determined. It is important which order these areconsidered. They are as follows:i) radial equilibrium about the tube axisii) longitudinal equilibrium about the declination axisiii) declination equilibrium about the hour axisIf the telescope tube is not in radial equilibrium it will not be possibleto adjust the system cg to the intersection of the declination and houraxies, for all possible attitudes of the tube assembly. Radial balance isthe most awkward to achieve, and is crucial. Radial out-of-balance is themost common cause of the complaint, "My telescope will not balance in allpositions."To determine the radial momenta about the tube axis, measure the offset ofall the non-symmetric tube furniture (i.e. rackmount, finder, guide 'scope,accessory mounting brackets &c). Ignore symmetric items, i.e. the primaryand secondary mirrors & cells, the spider, cradle rings &c. Weigh, orcalculate the weight of each item. Adopt an arbitary reference plane,transverse to the tube's mechanical axis. A useful reference plane might bein the direction of gravity when the tube is horizontal, pointing due south.Call this plane X-X'. Prepare a scale diagram depicting the tube profile,and each weighed item. Measure or estimate the angular distance of eachitem, anti-clockwise, looking down the front of the tube from the referenceplane.The radial momenta of each item will then be:Moment = radial offset x weight x cos(angular distance from X-X')Always measure the angular distance from the same reference, using 360°notation, in the same anti-clockwise direction. Repeat the procedure using areference plane rotated 90° clockwise. Call this plane Y-Y'. Sum the momentaabout each plane.As an example, I performed the calculation for my 10-inch f/10 Calver, withthe following results:Moments about X-X'rackmount = 12" x 7lbsf x cos270° = 0inlbslower counterwights = 8".75 x 56.68lbsf x cos270° = 0inlbsCooke 2-inch finder = 12" x 7lbsf x cos330° = 73inlbsmounting bracket + 400mm lens = 9".75 x 11.8lbsf x cos0° = 115inlbsmounting bracket + 150mm lens = 9".75 x 10.8lbsf x cos180° = -105inlbsupper counterweight = 8".75 x 22.42lbsf x cos90° = 0inlbs4-inch Guide 'scope = 10".25 x 7lbsf x cos135° = -51inlbsOttway 2-inch finder = 9".25 x 2.625lbsf x cos210° = -21inlbsMoments about Y-Y'rackmount = 12" x 7lbsf x cos0° = 84inlbslower counterwights = 8".75 x 56.68lbsf x cos0° = 496inlbsCooke 2-inch finder = 12" x 7lbsf x cos60° = 42inlbsmounting bracket + 400mm lens = 9".75 x 11.8lbsf x cos90° = 0inlbsmounting bracket + 150mm lens = 9".75 x 10.8lbsf x cos270° = -0inlbsupper counterweight = 8".75 x 22.42lbsf x cos180° = -196inlbs4-inch Guide 'scope = 10".25 x 7lbsf x cos225° = -51inlbsOttway 2-inch finder = 9".25 x 2.625lbsf x cos300° = 12inlbsSum of momenta about X-X' = 11inlbsSum of momenta about Y-Y' = 387inlbsTo calculate the weight (W) and orientation (A°) of a counterpoise necessaryto bring the tube into radial equilibrium, we must adopt a suitable radialoffset for the counterpoise (e.g. r = 8".75) and solve the followingsimultaneous equation:i) 8".75 x W x cosA + 11 = 0ii) 8".75 x W x coa(A+90°) + 397 =0divide (ii) by (i) (cos(A+90) = -sinA)hence 8.75.W.sinA/8.75.W.cosA = tanA = 387/-11 = -35.182(sinA positive - 2nd quadrant)therefore A = 91°.63subst. A in ii) hence 9.75.Wcos181°.63 = -387& solving for W W = 44.25lbsfTo check the calculation, determine the resultant sum of the radial momenta:about X-X' = 8.75x44.25cos91°.63 + 11 = 0inlbsabout Y-Y' = 8.75x44.25cos181°.63 + 387 = 0inlbsWhere the counterpoise is located along the length of the tube is arbitary.It is its orientation with respect to X-X' which is important. I decided tosplit the counterpoise into two equal weights, placed either side of thedec. axis.Once you have determined the radial equilibrium, calculating mometa aboutthe declination and hour axes is a matter of simply weight x axial distance.
Sears 4-6305 60mmX900mm
Meade LX-50 10" with LX-200 Classic forks
John Higbee Tasco 60mm 5VTE Refractor - 1964 Edmund 4.25" f/10 Palomar Junior Reflector - 1967 Celestron C8 "orange tube" SCT - 1976 Zhumell Tachyon 25x100 binoculars (2010) w/ Petersen Engineering E-Z Binoc SuperMount - 2013 Edmund Spilhaus Space Clock - 2010 Cave Astrola 12.5" f/6 Reflector - 2012 Criterion RV-6 Dynascope - 2012 Meade ETX90EC - 2013 Meade ETX125PE UHTC - 2013 Towa Model 305 Refractor (60mm, f/15) - 2013 Tower Royal Astro Refractor (76mm, f/16) - 2014
Refractors Reflectors Two Cats A few eyepieces