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I don't have to buy or scrounge for hard to find, full thickness glass to cut into blanks. This usually takes about 24 hrs. I get the temperature down to about 1200 as quickly as possible. Astronomical You will not need to do any preparation on the side or backside of these blanks before you get started grinding the main face. For the best experience on our site, be sure to turn on Javascript in your browser. Click the photo for a larger view. To fire polish the blank, it is heated up to about It is a fine-looking, near full-thickness, 10 inch diameter blank that I intend to grind and polish into a 1st class telescope mirror. These have a checkerboard patter of rubber bumps and holes, and grip Here is one of the kiln shelves. In fabrication, you do not risk shattering your mirror due to thermal shock The glass blanks have a lot of internal stress that needs to be relieved. Don't waste your time with the tempered stuff. Usually I have the back of the blank "Blanchard ground" to a very flat surface. And the diamond tooling they use left a surface that was so smooth I was able to start grinding with 25-micron abrasive! There is something of bother fire polishing all my blanks. The same way, a client might order a 20" mirror that is 1.75" thick. I don't This is what it looks like inside the kiln at about 1700 degrees. I still have to wrap the glass with kiln shelf paper first. That first mold worked so badly that I'm not even going to show any photos These are from the glass sticking You will do more observing, and less waiting for If a piece of glass has chipped edges or You will need something that seals well, as you do not want your grit to get contaminated. All Rights Reserved. accepted tools and materials - items that we feel will give the novice the greatest chance of success, and without Containers, Grinding Stands, and Miscellaneous Traditionally, mirror makers used a wooden barrel, and phrases like "Walk around the Barrel" are still in the wooden wedge at bottom left to prevent rocking on an uneven floor. Ceramic glass blanks, ultra-low expansion, borosilicate, soda-lime, fused silica, fused quartz, zerodum astrositall, Pyrex, telescope making kits, custom molded blanks, mirror generating/machining services, finished mirrors, secondary mirrors, coating services & other related items. So here is the completed blank after removing it from the mold and truing up the edge on my grinder. really well. turntable is more than adequate. blanks sitting on top of it. You do not need a fancy pivot; a screw sunk in the base and a blind hole in the trapped between the layers of glass. Custom manufacturer of astronomical mirror blanks. These folks are great to work with, and they are SPEEDY! That means avoiding hours of grinding with the old 60/80/120/220/320 sequence of silicon carbide abrasives. styrofoam. it from all directions. The insulating properties of the mold might also inhibit proper annealing. Skip to the beginning of the images gallery, Logo Copyright Firsthand Discovery, LLC 2011. So I no longer go much above 1700. The thing I really appreciate about Bill and Ray and Christene is their willingness to make up special blanks for me. Stay up to date on industry news and trends, product announcements and the latest innovations. It measured 30 X 60 inches and weighed a ton. A 6 inch aperture telescope is a great size for the beginning or expert amateur telescope maker. I can use the thinner blank below it as the grinding tool. [Mike's Home-Built Wind Turbine] Once cleaned, I only handle them by the edges. so there is no advantage to using Pyrex cookware. I spent months after acquiring the kiln experimenting with fusing glass. I'll need to find some more thick glass. But they are much more susceptible to problems with ground in astigmatism google_ad_client = "pub-4627466933031932"; Today, the cost difference is minimal, and Pyrex has two advantages: Many fine mirrors have been made from plate glass, so if that is all you can obtain, don't be discouraged. The strips are held in place with tiny pieces of Scotch tape. A 5 gallon bucket of sand would also work, but you would have to put the bucket inside Then I cut circular segments out of soft K-23 firebricks with a bandsaw to encircle the foam disk. B2-20120091-4, Wholesale telescope mirror blanks borosilicate glass. for polishing and figuring. Note small See How to Make a Tile Tool. The glass must not be tempered, or it will simply shatter into tiny pieces if any attempt is made to cut it. Only a few minutes of spinning the blank against the spinning grinder wheel gets rid of the one of the freestanding stands first. Your grinding stand should be about waist high, and it needs to be stable, as you will be vigorously pushing So I have the kiln at it's highest setting to get to 1700 as quickly as possible. Here is an action shot of me, pushin' glass. an 8" full thickness mirror is 1.3" thick). kiln shelf and about to have the mold clamped around them. and easily withstand the glass fusing temperature. Since the bit would be in the seam between the two bricks, it wouldn't be much help anyway. UPDATE I like to fabricate as much [Mike's home-built jet engine] into the soft bricks. stand the heat blast) several times to allow it to rapidly cool down. or write up how I made it. Astronomical mirror blanks are made of materials including aluminum foam, reticulated vitreous carbon foam, and silicon, and silicon carbide foams. You can also see the wires of the thermocouple temperature probe coming into the top of the kiln from the upper right. Manufacturer of standard and custom lightweight mirror blanks and finished mirrors for opto-mechanical applications that require the highest performance. I start by putting a piece of kiln shelf paper on the shelf. furnace cement. Later I used furnace cement to glue floor of the kiln. and distortion due to support in the telescope unless additional precautions are taken. From 25mm to 1150mm. here plastic squeeze bottles (also squeezed-style mustard containers) can be used effectively. inch to make the kiln floor level. I start off with a very slow ramp up of around 400 degrees per hour until the temperature exceeds 850 Here is the Duncan kiln I got at a yard sale for only $95. the blank, and remove it from the kiln. I ground and polished it myself too. More Glass!! Thanks to everybody at Newport. The mold fills the height right before I did final assembly with glue. I have finally moved on to polishing my 10in f/5 mirror. Precision Annealed Supremax Telescope Mirror Blanks, Standard Supremax Telescope Mirror Blank Size List, Telescope Mirror Blanks Made to Your Specifications, Precision annealed material (6 Mu or less guaranteed), Edges diamond ground with a 220 grit finish, Main face diamond ground flat to .033 with a 120 grit finish, Curves diamond generated to +/-1% of radius with 120 grit, AGI can manufacture mirror blanks up to 40 in diameter, AGI can diamond machine ID holes into your mirror blank, AGI can produce elliptical mirror blanks in 45 degree and 90 configurations, AGI can manufacture mirror blanks from any of our. That may sound like a long time, but in the glass business that is very good service. Thomas Regional are part of Thomasnet.com. It is infused with ceramic. Suitable for alignment and scientific instruments, scanning and weapon systems, microfilm readers, refractometers, bar coders, photoelectric controls, telescopes and other applications. total polishing time, the surface is starting to take on a nice shine. I'll often buy glass tabletops or shelves to cut up. needed to constrain the glass and keep it in a disk shape. It's neat. You will need two tools: A hard tool for rough and fine grinding, and a soft tool, or pitch lap, The blank is 1.5 inches thick and I also mounted a lazy-susan bearing on a piece of plastic between fixed guides. If anyone knows where I can get one I started with a shelf that was well coated with kiln wash, sitting on three feet. the photos below show how I did it. //-->, [Back to Mike's telescope workshop] The most popular storage solution today are round plastic food storage containers, which come and scraping my knuckles on the sides as I work. There are two problems with that idea. ask me why I don't melt down Pyrex cookware and cast glass blanks. A great deal! enough to bring the work surface to just below your waist (36-inches is a work typical height). Find materials, components, equipment, MRO supplies and more. The kiln only has a 12 inch inside diameter, which will limit the size glass was very difficult. mounted on the edge of a table. I am always afraid that residue from the burning I used a metal nibbler to cut teeth into the edge of the hole saw. These mirrors have a mass 1/3rd to 1/6th that of conventional solid mirrors and due to the rib structure's low MSF errors. to the mold causing the sort of bad chips I saw with my first mold. Pitch is used to make a soft, conforming pitch lap for polishing and figuring. Manufacturer of astronomical mirror blanks for telescopes and military vehicle fire control systems. I just wanted to try it with this one to see how it looked. There are also always two vertical parting lines where the two halves of the mold come together. But few use wooden barrels anymore. I ruined a lot of glass, but I learned a lot. bottles or plastic food storage containers work well here; a plastic spoon can be used sprinkle grit on you we use at the Stellafane mirror courses due to lack of sufficient space. If you choose to follow tradition and pour it on your grinding tool, you eliminate the possibility of returning I always I build telescopes. Also in this photo you can see the four terra cotta pot feet I use as weights on the corners of the mold. I then coated the inside of the mold with kiln wash to prevent the molten glass from sticking to it. I only do it outside. Connect and transact with thousands of top North American companies today Mirror blanks meet MIL-I-45208. on other pages in this series, under the topic to which it applies. This allows me to move tabletops I bought for only $15. heat up to about 1250 degrees. Ok, so this process isn't really quicker or easier than my friend's trepanning saw, However, my kiln is smaller and quieter than his saw, and the need weight. If not There was also a long soak at 1200 degrees to eliminate air between the layers, and a soak at Products include achromatic, aspheric, plano and double convex, projection, condensing, Fresnel, ball and rod lenses, beam splitters, cones, filters, lens arrays, homogenizing rods, mirrors, polarizers, reflectors, waveplates, windows, opal and black glasses, filters, optical flats, prisms and wedges. It Box 127, 10564 Fern Avenue, Stanton, CA 90680 This gives us a lighter mirror, and a lighter upper tube assembly. You need to add ballast to the bottom, and as you can see, Dick uses six 8x16 patio blocks to provide Grinding Tool: We recommend using a plaster and tile tool for grinding: The are inexpensive and easy Copyright 2022 Thomas Publishing Company. Here you can see it with one of my older 8 inch Working on the mirror for only a few hours, one day a week at the This annealing cycle relieves all the internal stresses in even thick blanks. Your lap needs to be stored in a container that will not rest on the lap's surface (and deform it). soft, and easy to cut and shape. The bricks are 9 inches It is used with a I can use one blank as the mirror and Due to the very large mass of glass, cool-down took a very long time (over a day) before I could handle zip-closure food storage bag, inflated with air so that the bag does not rest on the lap's surface. Inspecting the mirror surface for complete polish.