... 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...
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...
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...
... 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...
... and ... a ... something ... action ... That is a very interesting and creative approach to the problem. Of course, there is all that acetone + disolved...
... 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...
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...
... 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...
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...
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,...
... 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...
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...
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"...
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...
... 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...
... 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...
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...
... 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...
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...
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...
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...
... 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...
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...
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...
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...
... 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...
... 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...
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...
