Big Telescope Restoration: (PART 2) Is The Mirror Wrecked?

[@danielbrowniel]

You're officially the only telescope dude online that has even connected Musou Black to telescopes.. I have no respect for money, maybe I'll do it?

[@AstronomyGarage]

I'm working on a video that compares how good the Mousou result is comparing paintbrushing vs. airbrushing. I've heard good things.

[@Will_Nis]

Another terrific video. While I will probably never own a telescope this big, I really enjoy watching your restorations.

[@AstronomyGarage]

Thank you for the kind words. As for owning a big telescope, you just never know. When you least expect it, you'll see a big telescope at a garage sale or sitting by the side of the road. I bought this one on the second day of an estate sale when prices were 50% off. Clear skies!

[@craigsawyer6453]

What great timing for a video. I like to set my flat black paint cans in the sun before painting. I usually wait about twenty or thirty minuets then shake and paint. I had just come in after setting my paint out and found this video. I am repainting the equatorial mount and stand on my first telescope, that I saved up for when I was ten years old. Earlier I was viewing sunspots. I used a clear glass globe of the earth when I made my projector. Today I decided to forgo the stand I made and use the smaller base that the globe came with... I should have guessed that things would get a bit hot with the prism effect. I mention this because you said you might use a globe as well. I did not want any one to get hurt because of one of my crazy ideas. The sun spots were amazing! Thank you again for the video about how to make the projector.

[@AstronomyGarage]

It's so warm here that my paint cans are always quite warm.

[@craigsawyer6453]

@@AstronomyGarage Yes, that is the downside to living in paradise here in California, it cools off at night and so do my paint cans. It does make for smooth air in the mornings for amazing RC flying.

[@johngiromini5745]

Is that cool or what??!!! That vendor appears to be a higher quality of construction than the one you worked on from Burleson (?). The mere fact the vendor was still around is, of and by itself, amazing. Learning alot by watching your methods of analysis and reconstruction. It's just a hot old mess out in the garage right now. I need to look back at Part 1 and see how the secondary mirror is attached (to broomstick or not to broom stick...).

[@AstronomyGarage]

I was really surprised. The guy that started it in 1987 is still running the show. He's been super responsive to my questions. I bought a couple of upgrade kits (they are on the way). No broomstick on this one - it's very traditional in that regard. However, that brings up a good point. When I do the final collimation, I'll show more of the secondary mirror.

[@deepskymike767]

Another very enjoyable video John. Loving the great work you’re doing with these scopes. I use flocking material for the blackening of the mirror box and upper cage. Here in the Uk they come in 1 or 5m rolls. Just cut it as required and peel off the back and it sticks very nicely. It’s super easy to use and very black although looking at all the cut outs in that mirror box I think spray painting is definitely the way to go. Very much looking forward to part 3.

[@AstronomyGarage]

Agreed. Flocking material would be perfect for this if it had flat sides, but this thing is filled with pockets.

[@janomacko5764]

Good Job! It's pleasure to see the restoration being done in such a professional way. Looking forward to the final part.

[@AstronomyGarage]

Thank you. I'm trying my best to do these restorations properly (there's no book on the subject, lol).

[@EvenTheDogAgrees]

Nice. Looking forward to that colimation fix. Hope those T-nuts stay put when you hammer them back in. Otherwise, a smidge of 2k epoxy in the holes for the teeth, and scuffing the teeth up with coarse sandpaper to give the epoxy something to grab onto might be an option. Or maybe some wood glue on those teeth is sufficient? Any woodworkers in the house?

[@AstronomyGarage]

I'm going to use a piece of metal pipe to surround the bolt and hammer them back in (without hurting the collimation bolts themselves). I'm going to use epoxy because of the potential for the entire weight of the telescope to be on them. To that issue, I'm also going to install four one-inch long dowels to take the brunt of the load, so this doesn't happen in the future.

[@dbgarlisch]

Another great video! The level of detail is appreciated. Looking forward to part 3

[@AstronomyGarage]

Thanks! Waiting for parts to arrive in the mail (today?) to finish it up.

[@JoeJaguar]

thanks john another great DIY video how to fix telescopes

[@AstronomyGarage]

Thanks Joe. This has been a fun project.

[@JoeJaguar]

@@AstronomyGarage as long as its fun thats great

[@koi_fish6706]

Good luck on the project! One way ive found to get ultra-black for cheap is to use sawdust,fine sawdust. So basically you spray a coat of black paint onto a surface, evenly dispurse the sawdust onto it,let that dry and spray on another coat of paint. Ive found the finnish to be REALLY Black!!

[@AstronomyGarage]

That's very clever. Does the micro-bumpy surface create a lot of shadow regions that, together, make it look ultra black?

[@koi_fish6706]

@@AstronomyGarage yes it does! Once i fully painted my newt's tube with it and looked through it at the focuser it was like black hole. One thing with this method is that if your paint isnt sticky enough,or if you use too much sawdust it could flake off alot

[@dalefife9854]

Great 2nd video. Anxious to see the outcome. I'm sure happy with mine. I'll be finished this weekend. Looking forward to your overall assessment.

[@AstronomyGarage]

I'm having fun with it. I have a box of parts coming from AstroSystems. I bought an upgrade to the power pack system and a shroud. Should be here by Monday.

[@TheStevecas9860]

Wow that is a beefy mirror I,m glad it cleaned up so nice! You make such interesting and informative videos!

[@AstronomyGarage]

Thanks! Yes, this mirror weighs a ton.

[@FleshWound42]

Fine job, if you were to add a drop of paint and wipe off the excess, to your newly stamped truss rod locators, the paint will remain in the embossed area and should make them a lot more visible. I've since retired, but in the coatings plant where I did work, they have "flatting base", mainly a silica based powder, that reduces the sheen of the paint. Keep up the great work, and I'll keep on hitting the like button. Looking forward to the next part.

[@AstronomyGarage]

Thanks! That is a great idea. I'll figure out what would be a good paint color that isn't too bright, but still shows up.

[@RoofMonkey911]

I believe the set screw on the center bearing bolt would be for installing an encoder for digital setting circles.

[@AstronomyGarage]

That's a good point. That must be it.

[@tomcaron9113]

Similar scope I had built, 14”. Mirror identical dirt covering. Thanks for the cleaning tips.

[@AstronomyGarage]

Go slow. Be careful. You'll have a clean shiny mirror in no time.

[@hednik]

Looks fantastic. Keep it up!

[@AstronomyGarage]

Thanks. So much sanding.....

[@-vermin-]

The grub screw in the centre pivot is for a DSC encoder shaft. I lined my mirror box with self adhesive flock paper, might be cheaper than your Ninja black paint.

[@AstronomyGarage]

That makes a lot of sense. Thank you.

[@StuffyToaster]

I’m keeping my eye open for a find like this. You’ve definitely motivated me to tackle a restoration.

[@AstronomyGarage]

Here's my search methods: Facebook Marketplace, OfferUp, CraigsList, Estate Sales, Garage Sales.

[@TheStevecas9860]

Great stuff John, look forward to the next part?

[@AstronomyGarage]

Thanks! The next part will be the final step in this restoration (and testing).

[@RobertRidgley]

The hole in the center bolt is for an encoder. I have an original 12.5” Star Master dob the came with a Sky Commander digital setting circles. Interestingly it still works.

[@AstronomyGarage]

That makes good sense. Thanks for the info!

[@bill5982]

It seems to me that you don't have to sand the old paint off. You can roughen the surface of the paint with sand paper so that the new paint sticks. Additionally roughening the surface should create tiny pockets and hills in the new paint where the light gets trapped making it darker. I suggest trying it on a piece of wood to see if my suggestion works.

[@AstronomyGarage]

My main concern is painting the enamel over an acrylic. Some of the reviews said that they had peeling problems. I'll work up a test panel to see how it goes.

[@tubedude54]

When I saw that mirror I knew it would clean up but I also knew it was going to take more than just dragging the cotton balls across it. That haze is from atmospheric pollutants and it gets coated on it just like the aluminum surface does it seems. I live in an industrial area and my mirrors after a few yrs turn just like that one was. I use the 'safe' method to get all the dust and junk off I can but then it really comes down to some muscle to get that haze off. I ground and polished a 12.5" when I was in high school and that mirror is the standard thickness for that time... got my kit from the old Edmund Scientific company. Still have that scope and converted it to a dob... tube weighs 85 pounds!

[@AstronomyGarage]

The mirror is about 95% cleaned up. There are a couple of areas that have a "mother of pearl" iridescence to them. The bug spots are gone, but some have left a tiny little imperfection. I'm still very happy with it.

[@AmatureAstronomer]

Good work!

[@AstronomyGarage]

Thanks for watching!

[@richardwalker9330]

Cotton batting is much better to use. Some cotton balls may have wood fibers in them, especially anything meant for "cosmetics". Cotton batting for first aid is pure cotton.

[@AstronomyGarage]

I hadn't heard of that - thanks for the tip!

[@bill5982]

2.5 inch mirror, that must take a huge amount of time to cool down even with the fan.

[@AstronomyGarage]

Agreed. I have a surface thermometer. I'll have to do a little test.

[@neilathm]

Where are you souving parts? Having a really hard time.

[@ivolol]

Could get a nice beefy battery power bank with a DIY usb > 12V boost board to generate 12V for the fan (or even perhaps 9V if you want it slower) One paint says "Flat black", and the other only says "black" right? I'd be suspicious right there...

[@AstronomyGarage]

True, but they say non-reflective. A few months ago, they both said ultra-flat.

[@ivolol]

@@AstronomyGarage Damn. Well nice of the manufacturer to make it right

[@AstronomyGarage]

@@ivolol I was surprised when they would send me replacement spray cans under their performance guarantee. Excellent customer service.

[@MAGISTER9]

Do you know why mirrors in reflectors are so big and heavy; I can understand big thick glass/lenses in refractors but in reflectors they are just bouncing off lights in that case coatings are more important.

[@AstronomyGarage]

I believe it is because they have to be very rigid, to maintain optical consistency. This assumes they are a uniform temperature throughout the disk though.

[@MAGISTER9]

@@AstronomyGarage you remind me of the school master verse from the glorious The Deserted Village. And still they gaz'd and still the wonder grew, That one small head could carry all he knew.