Well, I was only able to pour a 3/8" thick fullsized lap. I was shooting for 1/2" but did not have enough pitch to reach my goal. The good news is that the...
5040
Ken Hunter
atm_ken_hunter
Jan 4, 2005 6:47 am
... there are ... Well, almost 100% true... Flexure in a 3 point cell WILL be transmitted to the mirror but only as tilt. (mis-collimation) Ken Hunter...
5039
John
owl18200
Jan 4, 2005 1:47 am
... That's probably true Dale but I've used this pitch a couple of times on hydrocal tools. I put the tools in the fridge then tapped the pitch off the face. I...
5038
atmpob
Jan 3, 2005 10:41 pm
I always thought that if the pitch is thin enough to strain through cheesecloth then it is too hot and will loose some of it volitiles and then become too...
5037
Richard Schwartz
theoboehm
Jan 3, 2005 8:54 pm
The rule is that there must be three primary support points. It there are three, then it is impossible for flexure in the mirror cell to be transmitted to the...
5036
Richard Schwartz
theoboehm
Jan 3, 2005 8:51 pm
It has been very rainy in California, but it was clear and beautiful on January 1 for the Rose Parade and football game (which I hate). The traffic jam in...
5035
John
owl18200
Jan 3, 2005 6:49 pm
... Now why didn't I think of that! How simple. John A...
5034
James Mulherin
jamesmulherin
Jan 3, 2005 6:47 pm
... night. Since you're using an 18" tool I insist that you pour into the mirror and lower to tool into the pitch. Coat the mirror with a layer of thick cerium...
5033
James Mulherin
jamesmulherin
Jan 3, 2005 6:47 pm
Randy: This is all good advise. James The technique you are talking about, in my opinion, is the only way to make a lap. I would pour with the pitch fairly...
5032
Ken Hunter
atm_ken_hunter
Jan 3, 2005 3:08 pm
If you are worried about the tool sinking into the pitch, put 3 softwood spacers around the outside of the mirror and lower the tool to the spacers. Wait until...
5031
Randy Smith
wsihci96140
Jan 3, 2005 8:16 am
John, It is absolutely a pain to pour large laps. I only made one full size lap for the 22" and promptly scrapped it. It was just to big to work with. I used a...
5030
John
owl18200
Jan 3, 2005 7:22 am
... don't ... there ... was ... the ... with ... Hi Randy, Yes, this blank is a quality piece of glass of Pyrex. I was afraid to try this technique with the...
5029
Randy Smith
wsihci96140
Jan 3, 2005 3:19 am
John, I have not been following your progress from the beginning so, I don't know if the mirror is pyrex or plate glass. If the mirror is pyrex there is no...
5028
Mitchell
moonman1867
Jan 3, 2005 1:16 am
... Thanks, I think I've seen that book before, I might order it someday. I'm mainly collecting a list of designs that was at some point used, but there are...
5027
pdebaan
Jan 3, 2005 12:42 am
... so ... from last night. Thanks, John And a Happy 2005 for all, Be shure to preheat the mirror in hot water before pouring the hot pitch, Peter DB...
5026
Greg
gregfurtman
Jan 2, 2005 11:21 pm
Mitch Check out the book "Unusual Thelescopes" http://www.powells.com/cgi-bin/biblio?inkey=4-052148393x-0 ... telescopes ... Maksutov- ... Herschelian ... a...
5025
Mitchell
moonman1867
Jan 2, 2005 10:09 pm
Hi, the title of this post does have something to do with this and with astronomy. I've been courious just how many types of telescopes are out there. So I...
5024
Mitchell
moonman1867
Jan 2, 2005 3:05 pm
I know I posted the link to the partially translated french site ( http://astrosurf.com/altaz/index_e.htm ) But I thought this link to the Hercules 41.5"...
5023
John
owl18200
Jan 2, 2005 7:49 am
James, I'm updating my current progress on preping for the polishing on my glass. I've poured the 18" hydrocal 105 base and have had it in the oven-getting the...
5022
Randy Smith
wsihci96140
Jan 2, 2005 7:35 am
... I don't think the cost goes up exponentially for an amateur. I built my equatorial mounted 22" for about $4K. In todays dollars I suppose that would be...
5021
Randy Smith
wsihci96140
Jan 2, 2005 7:34 am
Mitch, Some confusion here. The first lens is made of a type of Borosilicate Crown Glass called BK-7. The second lens is made of a type of Glass called Flint,...
5020
Bob May
a52chevybob
Jan 2, 2005 4:10 am
Mitchel, There isn't a F4 lens and a F12 lens in a refractor. Rather there is a complex (ya gotta do some calculations) set of curves on the 4 surfaces for a...
5019
Mitchell
moonman1867
Jan 2, 2005 3:53 am
... is very ... be ... something ... of ... will ... I'll have to read some books, I don't quite understand how one lens is f/12 and the other f/4. I'm sure I...
5018
Randy Smith
wsihci96140
Jan 1, 2005 9:31 pm
Mitch, I am working on a 7" f12 refractor. The first lens is BK7. and the second lens is F4. All of the surfaces are spherical. The design is very tolerant of...
5017
starzkey
Jan 1, 2005 5:28 pm
... for ... Thanks, Mitch, for the link. There is indeed a wealth of advanced ATM stuff available through this page, even if I can't read French (some of the...
5016
starzkey
Jan 1, 2005 5:26 pm
... and ... a ... something ... action ... That is a very interesting and creative approach to the problem. Of course, there is all that acetone + disolved...
5015
starzkey
Jan 1, 2005 5:19 pm
... About 90 pounds or thereabouts. Not too bad if you have a lift, or a friend. But it is interesting that you found that a thinner tool worked well for...
5014
Mitchell
moonman1867
Jan 1, 2005 3:58 pm
Hi, I know one of you is working on a 32" mirror. This is a site for french people or something but I got the translation, it has a 1 meter, 32", and aother...
5013
Ken Hunter
atm_ken_hunter
Jan 1, 2005 2:24 pm
The 1 meter glass blank I was offered had a cellular cast shape and was to have been supported on the machine face up after having a aluminum flashing dam...
5012
Ric Rokosz
radicell2
Jan 1, 2005 1:42 pm
... That 2 inch edge thickness must make the tool pretty heavy.For my first 24 incher,used hydrostone that produced -by design- an edge thickness of about 3/4...
