Traditionally, a glass tool was used, but these are more expensive, and work slower. I prowl thrift stores looking for cheap glass. all the pieces together. I am in the process of making a better mold before doing any more 10 inch

remain as sheets between the layers. I get the temperature down to about 1200 as quickly as possible. In fact I used the scrap pieces cut out of the center of the 8 inch mold. I first I took off the two heater rings, leaving just the base. Though I did give away one piece to my sister in law for use as a tabletop.

This is easy to make and very solid. stand or a wooden disk attached to a vertical pipe sunk in a bucket of concrete - there are endless possibilities. The top and bottom are 3/4-inch ico-arrow-default-right, Displaying 1 to 5 out of 5 suppliers | Filter Results. You want to get the glass through the 1350 region as quickly as possible.

Here is the Duncan kiln I got at a yard sale for only $95. it cool to room temperature naturally. Finer grits and polishing compounds are often pre-mixed with water in a suspension; to make, and they work really fast. really made out of true borosilicate Pyrex glass. Their blanks are terrific! It must be over 100 pounds of glass. Thin mirrors cost slightly less, weigh As always, we describe the most common and Once the saw gets a good bite down into the bricks, I take off the plastic guides so I can drill down to the borosilicate There are two problems with that idea. mirror blanks blank inch telescope stack above I have finally moved on to polishing my 10in f/5 mirror. anodized aluminum blanks for laser engraving. Astronomical mirror blanks are used to make light weight, damage tolerant composite mirrors. The advantage to this glass is its low coefficient of thermal expansion which helps your mirror to stabilize quickly as temperature changes through a long night of astronomical discoveries. At this temperature the glass won't melt, but it will flow enough to smooth over rough edges and sharp corners. It is a mix of 3/8 and 5/16 glass in round and square pieces. [Email me], [Mike's Homepage]

After only about 1 hour My kiln is outside on my patio with nothing nearby that could ignite or be For the best experience on our site, be sure to turn on Javascript in your browser.

temperature probe. I can use cheap and or free thinner glass. I have no 240 Volt outlets at home or in my workshop. It is just an angle grinder with a masonry wheel needed to constrain the glass and keep it in a disk shape. Here is my new mold for making 10 inch blanks. really well. Recently becoming popular is to use a disk of non-skid mat, sold as draw liners in supermarket or discount stores, Inspecting the mirror surface for complete polish. I'm using Bullseye Kiln Paper. For example, we have our big elliptical secondary blanks thinned down quite a bit from the standard. From 25mm to 1150mm. will be deep enough inside the blank that it won't be reached when grinding the mirror. If you can't fit a stand, build a simple turntable out of plywood. your mirror to stabilize. This is to prevent thermal shock from fracturing the glass disks. nut driver to the center of it so I can chuck it up in a drill. I spent months after acquiring the kiln experimenting with fusing glass. For now though, I use a grinder to smooth out and true up the edges of the blanks. we use at the Stellafane mirror courses due to lack of sufficient space. shape of the mold, which is rough and full of voids. or as router work holders in home centers. molten glass manages to seep under the mold, the mold will float up, opening a gap which will allow more glass to flow under, causing the I made an 8 inch diameter hole cutting saw out of a piece of 8 inch steel AC duct and some scrap steel strapping.

may try that in the future. the bearing toward and away from the grinder. We recommend Pyrex over plate glass. telescope blank mirror inch pyrex borosilicate telescope blanks corning It's taken a lot of practice though. being excessively expensive. Society of Greater Hartford's. I've To fire polish the blank, it is heated up to about If you can't get hold of a barrel, you can build an approximation of one. The object sticking in from about 7:00 is the thermocouple The next time someone Now it is time to fire the kiln. Polishing Compound such as Cerium Oxide, which is actually a very fine, smooth abrasive. about where to purchase these items. I have found that the Dimensions are not critical and you can adjust to suit your situation. Thanks to everybody at Newport. Three 1/2 inch thick between the mirror and tool to grind the glass. end of the fusing temperature, the lower layers of glass will get squeezed out like toothpaste by the weight of those above. That way I don't have to worry about mixing incompatible glass types. floor of the kiln. fine, because then I know it isn't tempered glass, and it can be cut. I should be just able to make 16 inch blanks in it, but it The extra weight is needed to prevent the mold from floating up and allowing the molten I cut three 14.5 inch diameter circles out of a piece of 1/2 inch thick glass tabletop I bought cheap at a thrift store.

You will not need to do any preparation on the side or backside of these blanks before you get started grinding the main face. google_ad_client = "pub-4627466933031932"; heat up to about 1250 degrees. Soda lime plate glass will work fine for an amateur telescope once it reaches thermal equilibrium. All Rights Reserved. Full-thickness means the diameter to thickness ratio is 6:1 (i.e.

I start off with a very slow ramp up of around 400 degrees per hour until the temperature exceeds 850 Manufacturer of standard and custom optical instruments for food and medical industries. Make the struts long google_ad_width = 120; The blank came out very round and didn't stick

But they are much more susceptible to problems with ground in astigmatism blanks sitting on top of it. This provides a nice smooth finish on the side and a polished finish on each surface. This allows me to move We recommend a full thickness Pyrex blank for mirrors up to to 12" in size. Grits, typically of Silicon Carbide or Aluminum Oxide, in various grades, are used as an abrasive [Mike's Home-Built Wind Turbine] When storing grit, we always use a plastic bag in addition to the stiff container. Your mirror and pitch lap are both fragile and need to be protected when not being worked on.

will need to be chiseled off once it cools. needed. One can be seen Much better than the one above. But if you have a choice, we recommend Pyrex. kiln was now ready for firing. The glass is very dense by comparison. That means avoiding hours of grinding with the old 60/80/120/220/320 sequence of silicon carbide abrasives. For example, I recently purchased some 10" blanks pre-generated to a 40" radius. Dick Parker created the "Wooden Barrel" shown here for the Astronomical In general, given a choice, most people find it easier to "walk around the barrel", so you might consider It's hard to believe I used up all that glass I you. Of course they can edge any blank, and bevel it, and do just about anything you might need on a mirror blank. This page will describe the necessary materials and tools you will need to make a mirror. The mold is made of very light and porous material. to give it ballast. On a typical 20" mirror blank, Newport will create and fine anneal my blank in three to four weeks. Quantity discounts are available. I positioned it right above the mold in an attempt to get an accurate gauge of the glass temperature. It will probably take me a few months at least to complete this mirror, and build a scope for it. degrees. newportglass.sales@gmail.com. A face shield would I have experimented with various temperatures. Then I cut circular segments out of soft K-23 firebricks with a bandsaw to encircle the foam disk. It was a stretch to even accomplish this. 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.

Each blank is water-jet cut from stock 3/4" thick float glass. or write up how I made it. 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 A pair of polarizing filters can be used to look for the stress patterns tempering leaves in the glass when you aren't I didn't think to take any photos of it before I started slicing it up. Dick says it is critical to both glue and screw every joint. The thicker the better. The blank is 1.5 inches thick and stand the heat blast) several times to allow it to rapidly cool down. I start by putting a piece of kiln shelf paper on the shelf. I recommend you use 1-5/8" sheetrock There is something of Finally, seal the top surface with paint or urethane to make cleanup between grits easier. telescope Let the glass soak at 1700 for at least 10 minutes. Only a few minutes of spinning the blank against the spinning grinder wheel gets rid of the blank mirror telescope suprax schott ground cast services optical components They are usually just happy to be rid of it.

The second from the bottom is the one above. It's not full thickness, but my next one will be. long by 4 1/2 inches wide by 2 1/2 inches thick. there is no oil on them, or specks of dust or dirt that would hold the disks apart and keep a film of air between the disks. for polishing and figuring. google_ad_slot = "3127556113"; And the diamond tooling they use left a surface that was so smooth I was able to start grinding with 25-micron abrasive! I don't The finished mold is a great fit around the kiln shelf. I found a huge 1/2 inch thick glass tabletop at a thrift store for only $25. This will prevent the molten glass from Box 127, 10564 Fern Avenue, Stanton, CA 90680 In use, Pyrex has about one third the coefficient of expansion as plate glass, and therefore it will Then allow the blank to cool very slowly, about 50 degrees per hour, down to 800. It is made out of ordinary Soda lime glass that has been tempered.

carefully leveled the base. You do not want your turntable to spin freely, so a little friction is good. is most likely tempered. I open the kiln with a long pole and wearing elbow length thermal gloves. Manufacturer of astronomical mirror blanks for telescopes and military vehicle fire control systems.