Sunday, February 8, 2015

Constructia reflectorului meu de 125mm F/4.5 / Making of my 125mm F/4.5 RFT reflector

Oglinda mea RFT cu D= 125mm si F=565mm ,deci F/4.52,asezata aici cu fata in jos.
Discul este un menisc de egala grosime cu raza de curbura RC=1100mm,debitat dintr-un ecran TV.
My RFT mirror ,with aperture of 125mm ,focal length of 565mm , F/4.52, face-down in the picture.
The disc is a meniscus of equal thickness with a  radius curvature RC = 1100mm, cut from a TV screen.


First,the mirror was cut, polished and parabolised  by amateur astronomer Attila Csillag  of Arad, in a series of three identical mirrors.Parabolisation of the first mirror went very well, is powering since then Attila's  RFT reflector.

                        On  the second mirror the parabola resulted zoned ,the zone  from 0,7R   outward being  in a parabolic surface with a slightly different focal length.
This become my RFT mirror.
Correction of the defect was made by the Hungarian optician Csatlos Geza  who resumed the process from the grinding with the finest abrasive.
In the picture ,one can see the signature of Csatlos Geza ,reflected by the Aluminium coating.
Oglinda a fost debitata ,slefuita si parabolizata intai de catre astronomul amator aradean Csillag Attila ,intr-o serie de trei  oglinzi identice.
Parabolizarea primei oglinzi a decurs foarte bine ,ea echipeaza reflectorul RFT al lui Attila.
La a doua oglinda insa ,parabola a iesit zonata ,zona de la 0,7R spre margine a rezultat intr-o suprafata parabolica cu un focal usor diferit.
Corectarea acestui defect a fost efectuata de catre opticianul Csatlos Geza din Ungaria care a reluat procesul de la slefuirea cu cel mai fin abraziv.
Se vede partial semnatura lui Csatlos Geza pe spatele oglinzii ,reflectata de stratul de aluminiu.









Am montat intai oglinda intr-o montura azimutala in furca cu un singur brat si pe care o avea Attila disponibila.
Initially , I mounted the mirror in an  azimuthal  single fork arm mount that  Attila had available.



Dupa ce a stat in acea montura vreo zece ani ,timp in care a fost rar utilizata ,am considerat ca a venit timpul pentru realizarea unei noi monturi.
After staying in the mount ten years, being rarely used, I thought it was time to make a new mounting for it.

Componente ale tubului optic.
La stanga ,portocularul filetat pe standard de 2 inch si placa adaptoare la raza tubului.
In mijloc,barilletul oglinzii principale.
La dreapta placa de montare a tubului optic pe montura.
Parts of the optical tube.
Left, the   2-inch threaded focuser and his adapter plate to the radius of the tube.
Middle,the cell of the primary mirror.
Right ,the mounting plate of the OTA to the telescope mount
  


Placa -suport a oglinzii principale este gaurita pentru usurarea ventilatiei naturale.
Oglinda va fi lipita la 0,4 R ,unde se vad petele galbene,cu silicon.
Suportii laterali ,din partea ''de jos'' a oglinzii ,sunt la 90 grade ,nu la 120 grade ,dupa cum ne sfatuieste Texereau
( in poza , reazemele laterale  din dreapta si din centru - sus ).
 The primary mirror plate is drilled for easy natural ventilation.
The mirror will be silicone glued at 0.4 R, where are the yellow dots.
Side supports ,( from the 'bottom' of the mirror ) , are spaced at 90 degrees, not at 120 degrees, as advises by Texereau.
(  the side supports at the right and  center - up ,in the picture).
Viitorul tub optic ,cu cateva dintre componentele mecanice.
Under development OTA ,with some of the mechanical parts.

Actualizare.Updating. 3 Mai 2015

Confectionare diafragma portocularului ,dupa recomandarile lui Mel Bartels.
Making the focuser baffle,according to Mel Bartels recommendations.



http://www.bbastrodesigns.com/baffle.html



Grunduire.Primer painting.



Vopsire interna si externa.
More painting.