GriffinUcos

Well, after a lengthy wait the re-aluminised mirror is back! The wait was due to me being tight and not wanting any shenanigans with customs. So the mirror flew out on Ryanair and sailed back on Brittany ferries. My thanks to Terry at Vacuum Coatings for doing a fantastic job and for arranging to take delivery of the mirror from my friend Jimmy who happened to be visiting a relative in a hospital just round the corner. I love it when a plan comes together. The "scratches" proved to be only in the coating and not the glass so I just need to mount it onto the backplate and give it some light. Oh, and converting a homemade 3 axis pcb routing table into a foucault tester, sorting something out with Robo_USB and grinding the other mirror....... Have fun all and kind regards.

There is a lot of truth in the adage, "Don't look at the lens, look through it" Good view of the moon, Jupiter and M42 last night so I'm happy enough. I eyeballed Polaris through the hole where the polarscope should be and got a good enough alignment for visual use. Thanks all.

Hello! As suggested flipped the first element and now focuses OK in daylight. I'll try a star test this weekend if I can. Tried cleaning again with Baader wonderfluid but still have white-ish marks on the lenses. It's an old scope and is what it is. Many thanks for the advice.

Back together. Lenses are marked and the image looks like it's smeared with vaseline. Some rearranging to do. I'm tempted to try and find replacements as the scope itself is fine.

I was considering replacing the out of date polarscope in my EQ mount. Most seem to be 2012-2032 and way too expensive. I'll be sticking to Dr Clay Sherrold's Kochab Clock and rack of eye.

Thanks, Franklin. The lenses are back in the cell and ready to adjust. I'm going to do it for the experience. Sadly there is some marking on the lenses, probably fungal attack. Hard to tell if it's just the coatings or whether it's in to the glass.

Thanks rl. I'm happy about the front to back orientation, I'll just have to rotate them to minimise astigmatism. Glad you think it's all there. I'm not keen on direct contact glass to metal but what's the alternative? Slivers of self-adhesive tape on the ledge? Franklin, thanks. Err no! Not sure why I didn't, I will have to put that down to advancing years. Once the scope is back together I'll rotate the front element and try to find the best alignment. Many thanks.

The lenses don't look too bad. Waiting for the wonderfluid. The rear element appears to sit on the bottom ledge. It's a very close fit on the sides. The foil spacers are in place. There is no mark on the side and I was unable to get both lenses out as one, so I'll have to investigate the alignment. The front element has an arrow pointing forward. This was followed up by an O ring and the locking ring. No O ring in the recess between the two cell pieces. Not sure if there should be one but I think probably should to stop humidity ingress.The alignment grub screws are in place but rather short if there was a seal.

Thanks rl. I have the wonderfluid and cloth on order. I'll get some photos tomorrow.

Hello all. I have this very old Skywatcher in need of some TLC. The two lens elements look really poor. Fungus attack that seems to have had a go at the coating but not much in evidence on the glass. Washing them in Ammonia at the moment. I know it's an old model as the elements are separated with three small pieces of foil. I'm wondering if anyone has dismantled one of these before. My concern is that the rear element sits directly onto the ledge on the back part of the cell. Should there be something between the surfaces? The locking ring and O ring are fine but when I split the two sections there seems to be an O ring channel but no O ring. Should there be one? Sorry I can't post an image yet, the paint is still wet! Many thanks.

Update! The mirror has been stripped and ready to go for re-aluminising. The tube and stand have been painted and ready to be re-assembled. Sadly the Astro Systems label is long gone. The package has arrived from Stathis. The mirror blank looks superb, no sign of stress or bubbles. To simplify things I purchased a 6" grinding kit to go with it. When it returns the original mirror will go back on the Astro Systems back plate. I'll have to design some sort of tube extension to carry the new mirror in a cell. Undecided yet whether to do that or to grind the blank to a shorter focal length so I can just add the mirror cell directly onto the tube. There again maybe a new tube. So much to do so little time. Original David Hinds 6" f6

Yes and now I'm glad I didn't buy it. To etch copper I've used Ferric Chloride but then moved on to HCl and copper ions. I wonder if perhaps he meant Sodium Persulphate, which would be safer and works on copper. Chemistry, I remember trying to silver a mirror with Nitric acid and Silver nitrate. If it gets above 18C turns in to fulminate. I think I still have a copy of Blackie's " Constructing an Astronomical Telescope" circa 1951. Sorry, even further OT.

Look what I found in the old parts bin. Might make a half usefully spherometer with some legs.

Well....... I might have a cunning plan! The Astrosystems 6" is now in bits and some painting has been done. I went to the local electronics shop to buy Ferric Chloride. Sorry but we don't sell it any more, how about some nice Sodium Perchlorate! Quick intake of breath. No thanks, definitely don't want anything with sodium. I've ended up mail ordering the Ferric Chloride. I'll have a closer look at the mirror surface when it's clean and hopefully send it for re-aluminising. While I'm waiting I've ordered a 6" blank and grits from Stathis Kafalis in Munich http://www.stathis-firstlight.de/ Very much looking forward to trying my hand at making a decent mirror. I bought the mirror o matic disk in 2004ish but never had the time or opportunity to do anything. Perhaps the Hinds mirror on the backplate and the new mirror on an adjustable cell. Looks like it might be a long road! Kind regards to all.

NGC 1502 the 10" is indeed still available. What a scope and what a bargain! Go on, resistance is futile. You are correct about the re-figuring. I might have chanced it with a suitable tool blank but not from scratch. Far too good to ruin. I like thread drift, now I wonder if Ryanair would class that 10" as cabin 🧳. Have a great weekend all.