You also need to ensure proper mirror support and do fine grinding and polishing the mirror face up One of the main techniques to success is by frequently rotating the mirror when working on it That prevents nonuniformity into the mirror, Direct in person instructions from a skilled mirror maker near your home is probably best Workshops and classes would be nice but some are conducted over a Mirror Grinding Take A Class Or DIY? Cloudy Nights
The initial rough grinding process uses grit sizes of 60, 120, and 180 to carve out the basic spherical cavity The mirror is then fine ground with grits of sizes ranging from 220900 For large thin mirrors, say 12 inches [30cm] or greater and 15 inches [4cm] or thinner, the mirror back must be ground flat, or at least regular in shape before beginning fine grinding the mirror's face Cast a tool specifically Joy of Mirror Making: Fine Grinding BBAstroDesigns
Mirror Grinding at the Spring 1998 Stellafane Mirror Workshop in the McGregor Observatory Rough Grinding The purpose of rough grinding is to start to cut a spherical concave surface into the mirror blank For a 6" Figure 1: Polishing pads applied to a 9 inch grinding tool Another local ATM has also tried the polishing pads with abrasive and CeO His own 175" mirror took about nine hours to polish out Fast Mirror Grinding & Polishing The ATMs Workshop
Construction of a primary mirror requires, as a final step, the aluminization of the mirror’s surface This critical step is not a home DIY task You would need to find A metal ring of half the mirror diameter is ground against the glass, stroking across the center and overhanging a bit at each end Half sized ring tools are the best compromise between grinding in a curve quickly and Joy of Mirror Making: Rough Grinding BBAstroDesigns
To achieve a smooth mirror surface, you’ll need to use the same technique as fine grinding It is best to do these sessions in small groups over the A layer of grit is sprinkled on the blank Then water is sprayed onto the grit and the machine is turned on to spin the grinding tool More grit and water is added as needed The coarser the gritExplore how telescope mirrors are made
The initial rough grinding process uses grit sizes of 60, 120, and 180 to carve out the basic spherical cavity The mirror is then fine ground with grits of sizes ranging from 220900 In both grinding processes, the grit is harder than the mirror blank and tool, resulting in a concave mirror and complementary convex toolFor large thin mirrors, say 12 inches [30cm] or greater and 15 inches [4cm] or thinner, the mirror back must be ground flat, or at least regular in shape before beginning fine grinding the mirror's face Cast a tool specifically Joy of Mirror Making: Fine Grinding BBAstroDesigns
Mirror Grinding at the Spring 1998 Stellafane Mirror Workshop in the McGregor Observatory Rough Grinding The purpose of rough grinding is to start to cut a spherical concave surface into the mirror blank For a 6" It must be difficult to put a price on the pride you must feel having successfully ground, polished and figured to reasonable Strehl your very own mirror, really what ever size However, I do understand those First mirror grind advice DIY Astronomer Stargazers
To achieve a smooth mirror surface, you’ll need to use the same technique as fine grinding It is best to do these sessions in small groups over the course of one or two hours You can check the surface after polishing it for a few hours Cerium oxide and jeweler’s rouge were used to create a very fine rust powderIf you want to grind a big mirror (say 20") and have the project be successful, then start with a small mirror (say 68") with a moderate focal length and complete this one first Instructions: Google Mel Bartels:: bbastrodeking/Introhtml #3 LarsMalmgren Messenger Posts: 477 Joined: Wanting To Grind A 20" Mirror Where Do I Start? Cloudy Nights
I made the overarm from 125" steel tube, cut and fitted to size Buttwelded, cleaned up with a grinder, painted and trial fit It seems too low, but I will build sandwiched plywood layers, glued together and put everything up on that You do not have the required permissions to view the files attached to this postWith mirror on top, overhang mirror about 40% of its diameter over the tool, so that most of the grinding action is concentrated on the center of the mirror and the edge of the tool Take straight strokes such that the Stellafane ATM: Guide to Strokes
Figure 1: Polishing pads applied to a 9 inch grinding tool Another local ATM has also tried the polishing pads with abrasive and CeO His own 175" mirror took about nine hours to polish out The MoM is a marvellous machine due to its simplicity and yet refined design It is extremely flexible accommodating mirror sizes from 4 inch up to 20 inch (with slight modifications) and can be used for all three steps MirroroMatic mirror making machine ATM pages
Rough Grinding The first milestone is putting a curve into the mirror face The curve's depth dictates the mirror's focal length The curve should be spherical Creating the curve can be done by several methods: The curve is ground into the mirror face using a grinding tool The curve is pregenerated for youThis video shows preparations for grinding a 22" f/40 telescope mirror This is the first mirror of a pair that will become a 22" binocular scope! GordonPreparing to Grind a 22" f/40 Telescope Mirror
There is a lot to be said about being able to vary the speed especially during figuring it's a huge advantage Check into a VFD 115 volt motor and controller I"d like to but I can't seem to find a 110v input single phase in/out controller, they're either single phase inout 220v or three phase outGrinding tools can be made of a variety of materials, but most common is glass, plaster, or ceramic Waite Research Making a telescope mirror To start, a new mirror blank is “sanded” downExplore how telescope mirrors are made
The initial rough grinding process uses grit sizes of 60, 120, and 180 to carve out the basic spherical cavity The mirror is then fine ground with grits of sizes ranging from 220900 In both grinding processes, the grit is harder than the mirror blank and tool, resulting in a concave mirror and complementary convex toolFor large thin mirrors, say 12 inches [30cm] or greater and 15 inches [4cm] or thinner, the mirror back must be ground flat, or at least regular in shape before beginning fine grinding the mirror's face Cast a tool specifically Joy of Mirror Making: Fine Grinding BBAstroDesigns
Mirror grinding and figuring consists of four major steps (plus aluminizing) Rough and Fine grinding use hard tools (glass, tile or metal) and harder then glass abrasive grit (Silicon Carbide or Aluminum Oxide) Polishing It must be difficult to put a price on the pride you must feel having successfully ground, polished and figured to reasonable Strehl your very own mirror, really what ever size However, I do understand those First mirror grind advice DIY Astronomer Stargazers
Basically there are two types of grinding/polishing machine The ‘traditional’ type which involves the mirror rotating at a relatively slow speed, a few rpm for a big mirror (1620 inches) with the Gordon Waite is probably one of the better mirror makers using this machine and have incorporated some of his ideas into my plan I like the fixedpost plan vs others with eccentric drives, because it gets the heavy grinding done in an automated manner, but still give you the chance to handfigureBuilding a fixed post mirror grinding machine
A metal ring of half the mirror diameter is ground against the glass, stroking across the center and overhanging a bit at each end Half sized ring tools are the best compromise between grinding in a curve quickly and With mirror on top, overhang mirror about 40% of its diameter over the tool, so that most of the grinding action is concentrated on the center of the mirror and the edge of the tool Take straight strokes such that the Stellafane ATM: Guide to Strokes
The MoM is a marvellous machine due to its simplicity and yet refined design It is extremely flexible accommodating mirror sizes from 4 inch up to 20 inch (with slight modifications) and can be used for all three steps This video shows preparations for grinding a 22" f/40 telescope mirror This is the first mirror of a pair that will become a 22" binocular scope! GordonPreparing to Grind a 22" f/40 Telescope Mirror
Rough grinding on both blanks was done for less than 10 minutes each on the same tool 90/60 grit was used The tool rotates on the machine while hand stroking about 25% length I will use hand grinding until the tool and mirrors get into very good contact Then I will change to a MirrorOMatic and work my way down the gritsÝÝÝÝÝÝÝÝÝÝÝ In his Codice Atlantico, Leonardo offers two of sketches of mirror making machines Ý One machine is designed for grinding concave mirrors of small focal lengthÝ The other machine, a much larger piece to implement, grinds mirrors of large focal lengthsÝ Though Leonardo da Vinci creates sketches of mirror grindingLeonardo Da Vinci's mirror making machines Stanford University
There is a lot to be said about being able to vary the speed especially during figuring it's a huge advantage Check into a VFD 115 volt motor and controller I"d like to but I can't seem to find a 110v input single phase in/out controller, they're either single phase inout 220v or three phase out
