in the 2001-02 Stellafane Mirror Class. Fine grinding refines the basic shape you have ground into the surface of the glass with rough grinding. The sequence of ever finer grits that you use smoothes the rough surface that was made in rough grinding, and prepares you for polishing.

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Please follow the this link from stellafane to learn and do it correctly. There are 2 major steps in grinding process. Rough Grinding – You start with courser abrasive like Silicon carbide #60 or #80 grit to hollow out the mirror quickly and move to the medium ones i.e. #120, #180, #220, #320 etc to smooth out the curve.

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Fine Grinding. The purpose of fine grinding is to smooth the surface generated by rough grinding and to get "good contact": ... Details of each step are provided in subsequent pages, along with plans to build your own tester - go back to the Stellafane ATM Index Page to …

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Once the fine grinding with the finest abrasive is done, next step is polishing. Many people won't believe if you show them the ground mirror and tell them that it will be polished to a mirror finish. OK, you need following to start the polishing… Pitch Lap (follow the link to see how the pitch lap was made) Polishing Mix (cerium oxide)

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During the grinding process, only the depth of the concave surface is measured. Good grinding technique will produce a spherical shape, therefore the only important property needing measurement is the depth of the concave surface at the center of the mirror. The easiest way to do this is by placing a stiff

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Fine Grinding a 20" Quartz Telpe Mirror. Rough Grinding on the Fixed-Post Mirror Grinding Machine. Hogging the Curve on a 20" f/4.5 Quartz Telpe Mirror. SkyBadger – Mirror Grinding Machine. ... Stellafane ATM: Materials & Tools.

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Purpose of this section is to show how to achieve the nice spherical surface free of any defect and zonal irregularities before moving to figuring or prabolization. It is a very important and critical activity. If you have been good in your fine grinding and polishing strokes, you will end up with a nice spherical…

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Recorded at the Stellafane Mirror Workshop - No Audio - Using very fine grit (Aluminum Oxide) but the same stroke, albiet with more effort and therefgore a slower pace, is used for rough grinding and polishing. This is an 8" mirror, so the stroke overhang is about 1.3" on each side for a 2.6" stroke length.

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However, for the best possible starting conditions, MD Largo should be used for fine grinding of materials with a hardness below 150 HV, and MD Allegro should be used for fine grinding of materials with a hardness of 150 HV and higher. Get Price Stellafane ATM: Fine Grinding

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For rough grinding a 6" mirror, about 1/2 teaspoon of grit is used per wet. With finer grits, proportionately less grit is used per wet. Grits in the25 micron range are often premixed with water to form a slurry, and water and grit are squirted onto the work together from a plastic squeeze bottle (not a spray bottle). Sprinkle on Grit

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Parabolizing 1. 03.06.2014. I used the parabolization stroke for thirty-five minutes and moved from strong spheroidicity to 2/5 wave. 06.06.2014. I continued with parabolizing strokes. Some turned down edge led to some tightening of the amplitude of the strokes. Then a hole in the center led to even more of a tightened amplitude, but with full ...

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From mid-November 2012 to mid-April 2013 I constructed a telpe from scratch … from grinding the mirror to building the tube. This site was initially conceived for family and friends to keep track of my progress. Early on I began to think the site could be helpful (and encouraging) for aspiring hobbyists. The telpe was a six-inch f/7.73…

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Looking for advice for building Foucault tester - posted in ATM, Optics and DIY Forum: Hello all, First time poster here. Im very excited to be working on my first telpe mirror, a 6 f/8. Really enjoying the process. I am currently progressing through fine grinding and as I get close to the polishing stage Im looking to build a Foucault tester.

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Astronomy. Grinding a 25-Inch F3 Telpe Mirror: Thinning and Flattening the Back. Gordon started with a 2" thick telpe mirror that weighed about 70 pounds. By thinning the blank, he's lightened the mirror by about 20 pounds!

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"Truss System" 2014 November 1. I've been going back and forth on the whole strut/truss thing. The idea of lugging around and keeping track of eight polls for a typical open-tube ATM Newtonian has bothered me from the beginning. I've kept circling around the idea of using a four-strut system. Highe describes both and identifies…

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Stellafane ATM: Grits, Polish & Pitch

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The aim of metallographic planar grinding is to remove roughness from the metallographic cutting process and to achieve flatness of the ground surfaces. The abrasive itself depends on the material to be ground. For soft materials, this is essentially silicon carbide (SiC) as paper, foil, disc or stone.For harder materials ( 300 HV, e. g. hardened steel or ceramics), diamond discs are …

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Stellafane ATM: Materials & Tools. The Tools: Grinding & Polishing. You will need two tools: A hard tool for rough and fine grinding, and a soft tool, or pitch lap, for polishing and figuring. Traditionally, the pitch lap was made on top of the grinding tool. We recommend using plaster disks for tool …

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Stellafane ATM: Fine Grinding. Fine grinding refines the basic shape you have ground into the surface of the glass with rough grinding. The sequence of ever finer grits that you use smoothes the rough surface that was made in rough grinding, and prepares you for polishing. You are also refining the shape of the surface to be a section of a ...

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stellafane atm fine grinding jaw stone crusher with iso90012008 reliable company ball grinding 03 rock phosphate grinding modern techniques list of heavy industries in kanpur worldcrushers stone crusher plant in sangli maharahtra pabrik suku cadang pasokan dan permintaan ...

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Optics: Spider and Secondary Mount. The spider and secondary mount began straight from the stellafane site but evolved as I chatted with my expert advisors. The mirror is mounted to a length of dowel. A bolt runs up the dowel and out and through a hub that is a milled cube of aluminum. The corners were milled out of the cube; so that from above ...

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Fine grinding. A series of ever smaller grits are employed in order to repair the damage caused by rough grinding, concluding with aluminum oxide which leaves much smaller pits and fewer fractures compared to the silicon carbide. This stage is called fine grinding.

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Fine grinding: includes Fine grinding, Measuring Sagitta; Polishing: Foucault Testing; Ronchi testing; Spectators are welcome to look and listen, but please don't touch anything unless invited by one of our instructors. Let's Get Started! The Stellafane Telpe Makers have a great website that will help you get started! Overview of Mirror ...

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Page 2 of 2 - How to hold convex mirror blank for grinding? - posted in ATM, Optics and DIY Forum: Considering I dont have another glass blank for a 6 tool, would you suggest just making a flat tile tool and skip the hogging step on my 6 mirror? I feel like the 10 mirror might just be an opportunity to mess with the grinding process and gain some more …

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Parabolizing 2. 2014 October 01. The question is whether to continue figuring the mirror or to be happy with what I have. A strategy: to do a star test. In September we attempted to get a tumble-down jig up to speed. Even though we got the pieces of the jig together, the streetlights around the community center reflect too brightly off the ...

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Page 1 of 9 - Getting started on my 6" mirror blank - posted in ATM, Optics and DIY Forum: Years ago I began grinding a 6 mirror blank with the Stellafane Telpe Makers in Springfield VT. I lived in Southern CT and worked as a planetarium supervisor so my attention got stretched thin and the mirror was one of the first things to drop. My wife and I moved to Seattle …

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A large list of links to other web sites we hope you will find useful. We try to list sites that complement or augment the information on our site. The inclusion of an off-site li

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Mirror Making Material Stathis' Firstlight. Grinding and polishing compounds I have nearly always in stock A complete material set includes silicon carbide grit #80, #180, #320, Aluminum oxyde with specific flat grit shape and tight size distribution Microgrit WCA 25my, 15my, 9my, 5 my, 3 my, polishing powder CERSKX (a very fine and pure cerium oxide) and optical pitch of 28° …

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Dobsonian Mount. In making the mount, I by and large followed the instructions on the Stellafane site. Where I diverged most was in the so-called tube cradle, which I replaced with my adjustable curtain-track trunnion system. To build the mount I purchased (my major wood outlay) a piece of ¾" red oak plywood, which because of a ...

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how to reduce sagitta? - posted in ATM, Optics and DIY Forum: Im currently rough grinding my first mirror. Its roughly 8.25 diameter, and Im shooting for f/6. I overshot my sagitta by a bit. Im currently at about 0.110 sagitta, which puts me a little under f/5. I dont want to make my figuring work more difficult than necessary, so Im trying to get back to around f/6.

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