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the Grattavetro

Rotating table for meniscus mirrors

Environment and tools

Rotating table for meniscus mirrors

A simple rotary table for working mirrors, homemade with some carpentry tools...

by Massimo Marconi

Centrifugal casting (spin casting) epoxy mold for convex core in collapsing refractory (slumping) for meniscus blank.

Science and Technology

Centrifugal casting (spin casting) epoxy mold for convex core in collapsing refractory (slumping) for meniscus blank.

The escalation towards the amateur construction of increasingly powerful Newtonian Dobsonian reflector telescopes (thanks to parabolic mirror lenses of ever larger diameter trying to contain their weight) it collides head-on with some technical problems that grow exponentially with respect to the benefits provided.

by Giulio Tiberini

TO START

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ALL THAT YOU NEED IN THE MIRROR MAKER ALIAS "GRATTAVETRO"

Making an astronomical mirror is not difficult, if you study the rules of the game well

LOOK IN THE MIND (AND IN THE HEART) A GRATTAVETRO

At the curious reader, passing on this blog, it might cross your mind…

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WHY BUILD AUTO-MIRROR AND TELESCOPE

The reasons are differents and subjective, and an outright answer can not be given …

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OBSERVE THE UNIVERSE, QUESTION OF NANOMETERS

In “scratching the glass” the most important of all reference number is 68.75 nanometers high.

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TECHNIQUES OF GRATTAVETRO

Techniques

26 September 20142 October 2014

We have seen how the past with W races constitutes one of the most effective methods for the approximation of the parabola starting from the spherical surface. Let's examine ...

Techniques

Determining the focal work in progress: a useful method in the phases of grinding

8 September 201419 October 2014

In the design phase of our astronomical mirror, it is essential to determine the focal length at which you want to reach, since the measure depends on the focal length itself ...

Techniques

7 September 20143 October 2014

This type of technique can be used in the first phase of the generation of the parabolic shape of short focal mirrors or large diameter, the ...

Techniques

Stroke 1/3 COC: easy easy method for the right amplitude of the past

4 September 20143 October 2014

In the past 1/3 COC, the movement of the mirror on the tool (being the focal reduction) or viceversa (in the process of increase of the focal) they must be ...

Techniques

26 August 201422 September 2014

The techniques with sub-diameter tool, try to solve some problems that arise with the use of full-diameter when the dimensions or ...

Techniques

24 August 20143 October 2014

Before starting any mirror processing phase, it is essential to make sure that the edges of both mirror that tool are blunted. This precaution ...

Techniques

15 August 201417 July 2017

La pass with races “W” It is the main technique used in the process of parabolizzazione. Normally it runs with mirror above and below the tool, it can also be ...

Techniques

17 July 20143 October 2014

DESCRIPTION La pass with racing 1/3 center over center ( shortened: COC = “C. o. c.” ) is the classical stroke, the most used because it can ...

Techniques

12 July 201413 February 2018

DESCRIPTION The past is the chordal excavation technique more aggressive and effective towards our mirror. In fact it allows to remove a large amount of material in ...

MEASURE YOUR MIRROR

Foucault Test

6 July 201418 July 2017

A Foucault Tester, with fixed light source fixing to be carried out with devices which commonly have at home (webcam and a pen / USB stick ) screwdriver ...

Foucault Test

7 July 201422 May 2018

The WHAT, the reason why', the WHEN and HOW: Let's start from WHAT: The Couder mask is a technical tool of cardboard, or other material ...

Ronchi Test

19 July 201428 October 2016

When you run the Ronchi test, we often find ourselves dealing with figures of shadow lines that can be different ...

Ronchi Test

21 July 201428 July 2016

As regards the control of the optical mirror, simplest and most widely used tests, especially at the amateur level, It is definitely the Ronchi Test. This ...

Foucault Test

9 August 20146 March 2016

For those looking for ideas to gear up realizing what it takes to lead the Foucault test, I present a gallery of images of the ...

Ronchi Test

26 August 201425 January 2017

One of the tools needed to run the Ronchi test is the namesake grating. It is a series of parallel opaque lines spaced equally in ...

Foucault Test

11 September 20141 April 2017

The TEST AMATORIALI The need to perform the tests on the optical processing in, typically with parabolic reflective surface for Newtonian telescopes, is aimed at ...

Foucault Test

14 September 201416 February 2019

NOTE for those who are going to read this article already having previously read the two articles 1) “FOUCAULT TEST; what is it for ...

Foucault Test

200F6 mirror: Test Foucault 1 with manual sample calculation (V)

16 September 201423 January 2021

As described in the previous article entitled "Preparatory phase to Foucault's test", We have prepared the room, lined up mirror and testers on their tables as well ...

Foucault Test

28 September 201425 September 2022

WHY’ STUDY WHAT MANY SOFTWARES OFFERS’ READY TO USE Studying the results of the Foucault test is very important to be able to evaluate ...

Foucault Test

1 October 20149 October 2018

Now that, with previous articles we did a little 'light on the road to complete the construction of a mirror, let's go through that ...

Foucault Test

3 October 201427 November 2016

With the previous article we saw the mirror 200F6 working with parabolization's corrections derived from five successive retouch actions and following Foucault tests controls. ...

Foucault Test