I would not want to discourage anyone from grinding own mirror, but as I recall the 13.1 Coulter was an f 4.5, maybe to fast for first attempt. The Coulter mirror was outstanding, the tube assembly not so much. I think someone recommended using it for a planter. I would also recommend thinking long and hard about where the focuser will be place for comfortable viewing. I have come to the conclusion that a 16" f5 would be my ideal. I would also not recommend building a large scope with another person. Make out a written contract if you do. Erik --- jimgibson00@yahoo.com wrote: From: Jim Gibson <jimgibson00@yahoo.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Subject: Re: [Utah-astronomy] 13.1 inch Coulter Carcass, free Date: Wed, 7 Jan 2009 03:51:27 -0800 (PST) Jay, If Brent Watson was still around he could probably tell you exactly, but I think Chuck’s amount was probably about right. I took a class from Brent about 6 – 7 years ago and as I remember it cost like $350 - $400 for the mirror kit, another couple hundred for the Craford (sp?) focuser, $75 - $100 for either the 1/4th or 1/8th wave secondary, and of course you will need at least 1 lens. But lenses are like potato chips; you can’t eat just one. We started our class in January and ordered our stuff. I got a 12.5” mirror. It took a few weeks for delivery and came with all the materials for grinding accept the grinding wheel which we made ourselves. We ground our mirrors one night a week (7 -10 pm) under Brent’s tutelage and finished our mirror and scopes, which we built at home (Carcass part), by May. Oh yeah we also made our own Ronchi (sp?) tester which you need to complete the figuring of the mirror. I kept copious notes, but like most things, there are stored away in a box somewhere…lol. I guess my point is, if you have never made a mirror before, don’t do it alone. The other point is that making your own is a very rewarding experience. If it costs you about the same either way, making a scope at least once in your armature career, I think, is very worth it. But you need the right guidance. jg --- On Tue, 1/6/09, Jay Eads <jayleads@gmail.com> wrote: From: Jay Eads <jayleads@gmail.com> Subject: Re: [Utah-astronomy] 13.1 inch Coulter Carcass, free To: "Utah-Astronomy" <utah-astronomy@mailman.xmission.com> Date: Tuesday, January 6, 2009, 7:47 PM How hard and how long would it take to make the mirror (yes, I'm attending the SLAS meeting this month) for someone who hasn't done it before? What would the estimated cost be for the materials for the mirror? Is there anyone here or in SLAS who would be available for advice? I'm interested in making my own mirror but it depends on cost (you know, the wife/CFO). If all these add up I'd take the dob tube and the rocker box. I would assume the first step would be to make the primary mirror, then to get a secondary and a focuser. So I guess if this is a project that I can assemble over time as money comes up, I'd try it. Thanks, Jay On 2009-01-06 22:56, Patrick Wiggins wrote:
I understand the "how to make a mirror" video that we were not able to screen at the solstice party last month is going to be shown at this month's SLAS meeting.
Perhaps after watching that several people will want the carcass to use with their new homemade mirror.
Grins,
patrick
On 06 Jan 2009, at 09:48, Josephine Grahn wrote:
We have the empty carcass of a 13.1 inch blue Coulter dob, if anyone would like it. No optics, no focuser, just the empty tube and rocker box. It does have the mirror cell, but no primary mirror, and it does have the support for the secondary, but no secondary mirror. Free, you just have to pick it up. Located East side SLC.
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com