Jay: Couple of things. Take a look at your cell that holds the mirror, 1" mirrors have advantages (weight, cooling times, cost, etc.) but they need better support than a 2" mirror. I have a 1" thick 16" mirror on my Dob and use an 18 point floating system that works well, in general more points are better. Also the 1" mirror may affect your focus point now that your mirror is going to be sitting lower, make sure it is within range of your focuser, if not you may need to make some changes to compensate for the loss of length. Couple of ways you can do that if it's needed: raise the cell (best), shorten truss tubes (not without problems). Weight will be another issue, the 1" glass is going to be much lighter. If possible try to adjust the bearings on your mirror box by raising them to move the center of gravity lower. I would try to drop the mirror box as low as possible, this will reduce the need for counter weights. It's all about the balance point, set your scope horizontally on a 2x4 and find out where your balance point is, let that be your guide on how you adjust your scope. Bob -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Jay Eads Sent: Friday, July 15, 2011 11:55 PM To: Utah Astronomy Subject: [Utah-astronomy] Advice to Mod a Scope A question to ask, well several and I would welcome opinions. I sent an email to Mat but I don't think he'll get it before Monday. If I were to put a 14 inch diameter mirror that is 1 inches thick or so, compared to the current 2 inch mirror that is currently in my 14 inch, I know I would need to adjust the counterweights to accommodate for the loss in weight to balance the scope, and thus my first question. On the XX14i that i own, it came with 3 counterweights in the back behind the mirror that screw on. If I replaced these with a heavier counterweight that was slightly larger than what is there, would the additional counterweight impact cooling time? I would assume not since the Carl Zambuto mirror would be lighter and already take a shorter cool down time. Is that correct? I also know I could keep the current counterweight system and add a bag full of lead shot and attach it to the lower tube for increase weight. That option seems to work also. Next question. Since the weight of the scope would change would this require a build of the lower base to correct for the new center of gravity the scope would have or would the current system still work? Just thinking aloud here and testing a few ideas among other tests so just seeing what a lighter mirror's impact would be at the 14 inch level. I know when I tested the 10 inch Zambuto mirror, the new mirror worked just fine in the stock tube and mirror cell. I had no balance issues. Anyway, if you have a thought let me know what it is please as I study for finals this weekend for Monday. -- Jay Eads _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php