Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

Alan64

Members
  • Content Count

    1,647
  • Joined

  • Last visited

Everything posted by Alan64

  1. My eco-friendly paint stripper, and a toothbrush, will remove every last bit of paint. That is, if I ever do get these mirrors re-aluminised. Although, I do realise that yours is a disclaimer in general, lest someone else comes along and wants to blacken their own.
  2. Shhh, for pictures speak louder than words... Glamour shots... I can't wait until I get my new GSO 32mm Plossl into this one, but it has to be blackened and flocked, too; so to wait.
  3. The jack-nuts were primed, then the cell masked and matte-blackened in select areas... Now to blacken the edge of the mirror itself...
  4. Three plastic spacers, .010" thick, to be inserted after the mirror is seated upon the silicone, and to ensure as perfect a centering as possible... All of these aspects must be made and checked beforehand, and before the grand finale.
  5. A toothpick-star, and each toothpick independently flexible... The epoxy encasing the jack-nuts was sanded, and the areas for the silicone were scored. Now to wash the cell, then to mask and blacken select areas...
  6. The silicone-placement template... "Star light, star bright, First star I see tonight. I wish I may, I wish I might, Have this wish I wish tonight." - Anonymous
  7. The screws were removed a while ago... I had used a short section of a spent cable-tie, as a spatula, and to draw and slope the epoxy up the six sides of each jack-nut... ...waste not, want not.
  8. The cell and the jack-nuts were washed with soap and water, then the magic of J-B Weld epoxy... Each has a sizable yet controlled and tailored glob of the epoxy all round. The plastic of the cell had been sanded previously, but was also scored with a knife in those areas. <tick-tock, tick-tock, tick-tock>
  9. The mirror now clears the nuts. Those nuts will be J-B Weld-ed into position., then blackened along with the rest. In preparation for the nuts to be epoxied and later blackened, their surfaces all over must be roughened, with at least 80-grit paper, or diamond-filed as in this instance... Such will ensure that the nuts will not pop off in future, particularly when under pressure and torqued.
  10. I hauled out the stationary belt-sander, and "whittled" them down... Whilst I was at it, I went ahead and ground down those for the cowling in addition... All six are done.
  11. I cannot and will not rely upon the threaded plastic mounting-holes of the primary-cell, nor upon those of the cowling, either. Zinc-plated nuts will be epoxied onto the inside instead... However, at the nuts' present thickness, the primary-mirror will not seat into place. I was hoping they'd clear, but now I know that they'll have to be ground down thinner into jack-nuts. I've been there, and done that, before... The same may have to be done for those of the cowling, but only if they threaten to jut into the light-path. All six stainless-steel screws will need careful measuring and then cut; joy, joy, joy, lucky me. I do wonder if others wonder why I am going to all of this trouble for this inexpensive, entry-level telescope. The answer is quite simple... When completed, I will have the reflective and therefore apochromatic equivalent of a Synta ST80 achromat.
  12. I thought it a wee bit odd that there were eleven, recessed, circular molding-marks within the cell... In any event, that got me thinking as to how many globs of silicone shall the mirror rest upon in the end; three, six, or eight? What about five? I haven't decided upon that yet, obviously. With that mid-section removed, the cell doesn't flex in the least. This plastic is rather hard. I was going to epoxy an aluminum ring at the bottom, to perhaps strengthen the cell further, but then my silicone contains acetic acid which will corrode aluminum over time. I think I'll bypass the use of aluminum in this instance.
  13. Immediately after freeing the mirror, I cleaned it, wrapped it in gift-tissue, then squirrelled it away for safe-keeping... The opening of the cell was then roughed out... Last night, the cell's opening was evened out, sanded and steel-wooled smooth, then polished; whilst the interior was rough-sanded for the matte-blackening... Why, it looks as though it arrived that way from the factory, yet did not. Would that it had. Pinched, distorted, the mirror will no longer be. It shall "breathe", acclimate, and as nature intended.
  14. First, I described a line in the center, to test, then I began to cut... The hot-knife did not cut through the plastic like butter. Quite the contrary, as I had to go over the lines, over and over; gruelling, tedious work. In the end... There's a piece of that infernal foam-tape peeking through. Using a snap-off knife, I slid it through and under each piece of tape, and until the primary-mirror was at long last freed from its prison...
  15. The hot-knife; a bonafide, genuine, grade AAA "Walnut Holler" hot-knife... Here goes nothing...
  16. As of this posting. this is where I'm at now, today, and at the back of the primary-mirror's cell... It's 5:30 in the morning here. Later today I will going out to pick up a pre-ordered hot-knife kit from a local crafts supply house.
  17. On the outside of the optical-tube, the holes were filled with J-B Weld epoxy... Those look like witches' hats. All six fillings were then sanded down flush... All six will be painted over with gloss-black when the time comes. There are some scratches to paint as well. Now, the main goal is to seal said areas, not to make them invisible, as they most certainly will not be afterwards.
  18. Then turning back to the optical-tube, I had this to remedy. All along, I wanted whichever finder to be closer to the focusser, and so as not to have to crane my neck as far over to look through it... 1. ...the original holes for the inadequate post-screws. 2. ...where I got the "bright" idea, back in 2017, to position a Vexen-type finder-base there. 3. ...yes, you guessed right, the final location for the finder-base. Four holes to fill, not to mention the two larger ones where the dovetail-bar was once fixed. But first I needed to back them with thin aluminum sheet. I used 5-minute epoxy for this operation... Where the dovetail-bar was once attached...
  19. The secondary-mirror and its stalk, before and after... Note the now-correct off-setting at right. Incidentally, I had epoxied a white-nylon washer on the back of the stalk, and for the new set-bolts to bear against; and as opposed to the "milk jug" solution. The side of the hub round is black-anodised, but since it will be obscured by the secondary-mirror and -hub, I won't be blackening or flocking it. However, I did blacken the secondary-mirror itself... Glamour shots... The cowling, in toto, is completed. Oh, these are the new set-screws, or bolts rather...
  20. What of the secondary-mirror, and an integral part of the cowling? I'll tell you what of it. Just have a look... At left, that wonky rotational-position speaks for itself. At right, I wasn't certain at the time if the off-setting of the mirror in relation to the stalk was correct, and for an f/4 Newtonian. It turned out that it wasn't. The mirror was originally secured with double-sided foam-tape; was, that is... This is an absolutely wonderful resource for situations like this... http://www.deepskywatch.com/Articles/replace-offset-collimate-secondary.html I never cared for mathematics, yet despite that combined with what few blond hairs I have left, I was able to understand it. In the end, it required a distance of 9.15mm from the edge of the primary end of the secondary-mirror to the edge of its stalk. I used aquarium-safe silicone as the adhesive... I applied the silicone as shown here... ...and used round toothpicks for spacing... I took that shot from about three feet away. I tried to get closer, but it shouted out, "Don't touch me!" So I backed away, slowly.
  21. The final washing of the cowling... The cowling was then masked... ...primed... ...and painted front and back with chalkboard-black... ...lovely. All the additions are still clear of the edge round the primary-mirror...
  22. This, a rare image of an epoxying operation in action, and made possible by the slow curing-rate of same... Incidentally, I braced the the third mounting-hole area opposite the stalk in addition. I had to scrounge round the house for clothes-pins, eighteen to be exact... I had let that set whilst I went out for a spell, and when I returned home I removed the pins and secured the cowling onto the optical-tube for the final curing of the epoxy... That did the trick. The stalk is now immovable.
  23. The cowling was placed over the primary cell, and to check for clearance... ...all clear, and with no blocking of the primary-mirror. Ah, but I can't blacken the cowling quite yet, for after I had removed the other stalks, the lone stalk is rigid, but the frame flexes a bit when the stalk is wiggled. Now, when inserted into the optical-tube, it's more rigid. Still, that's not quite good enough. Fortune has indeed favoured the foolish, as two of the three mounting holes of the cowling flank the lone stalk... Bracing the frame from both sides of the stalk to just past those holes should increase the rigidity of the stalk considerably more. Two strips of 1/32"-thick aluminum, veneer if you will, 11mm and 14mm in widths, and for these... ...and scored on the opposite side...
  24. I had made the depressions for the plates a little too deep, so I then floated both with more epoxy... The favoured stalk in toto, completed... A silhouette... Note how the favoured stalk overall had narrowed as the modification progressed; the thinner, the better. The other two were then cut out... In the end, I do have one of the hub's set-screw holes aligned with the focusser... ...and just as it should be...
  25. The aluminum-splint and the plastic-stalk must be made as one. For the next step, I made a small rule, or straight-edge rather... I then marked each side of the plastic stalk, ground them out flush with the aluminum-splint, and scored the depressions... Bronze plates; and custom clamping-pads of maple, hard-felt and wax-paper, which ensure that the plates lay perfectly flat...... The plates were epoxied into place, and clamped until the epoxy cured. Here, the removal of the clamping-pads... ...then the wax-paper... The stalk and splint are now as one.
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.