If you get bored, that mirror cell still could use some help. Having the collimation bolts move the mirror independent of the mirror hold downs is a sure recipe for a pinched mirror. Also, I would not expect the cell to hold collimation over the length of even a short car ride, because there is no restraint to keep the collimation bolts from unscrewing under vibration. To avoid rebuilding it all from scratch, I would suggest screwing the support triangles and the mirror restraint towers to a single plywood board, thus solving the problem of having the collimation bolds driving the mirror into the supports. The collimation screws would then work on the plywood board to change mirror tilt. The addidtion of another screw next to each collimation bolt to push against the plywood board would lock the collimation, having the lock screw in compression, and the collimation bolt in tension. That puts enough force on the threads to keep them from moving under vibration. You should put a small metal wear plate where the lock screw bears against the plywood board to keep it from digging into the wood.
Nice work drilling the holes on the bolts without a drill press. The planets at the end look really nice with a smart phone, I would think think visually it would look 10 times better.
I was sweating bullets drilling and tapping those holes, afraid that I'd break the bit off. I used plenty of oil and went super slow with advancing the tap. Visually, Jupiter was incredible. I saw the red spot with my eye.
Great finish to an excellent series! Warning to others, be sure to only use blue loctite if you want to disassemble later. Red loctite is more permanent and requires a lot of heat to break it loose.
@@AstronomyGaragesorry, I did not explain clearly. Blue is perfect in this application. It will hold 100% until you purposely decide otherwise. Blue is made for later disassembly. I was warning people AWAY from red in this situation. It will not come apart, even if you want it to, unless you apply heat that will likely damage the wooden parts.
Purple is more of a thread sealant than locking compound and is much easier to remove without danger of breaking stuff. I have a 50ml bottle of 222 that gets used way more than red or blue
"I'll cut this off, obviously." Hmmm...maybe it's not that obvious, or perhaps, it could be a self-induced impediment that is not observed until the very last screw is attempted to be inserted but fails, and in so doing, requiring complete and total de-construction. Very impressed with the methods used by the original designer/builder on this scope, and, most assuredly, your skills in diagnosing the problems and providing remedies.
Sometimes I do have to do a total de-de-construction to fix a mistake on my part during re-assembly. If so, I usually eliminate the first portion because I'm a stickler for making these as short as possible (I realize 34 minutes is not very short). That may make me seem clairvoyant, but I assure you that I am not, lol.
Let me start by saying I know nothing about telescopes, but the algorithm works in mysterious ways. Your channel came up in my recommended the other day and ive been slowly binge watching your back catalogue... in a couple you have mentioned Stellarvue, I've been working at a pump company in the building next door to Stellarvue for the past 6 years. Showed the owner your channel today, and LSS keep an eye out he may be reaching out to you.
Thanks for watching! Stellarvue makes legendary telescopes - they solved the nearly impossible task of eliminating chromatic aberration from short refractors. It's like magic. Of course, they are way out of my league pricewise.
A potentially handy hint for unlocking threads locked-solid with super powerful thread lock. These materials can be be softened / denatured by heat. But there’s a problem, that you can’t use a gas torch or heat gun, because it would damage heat sensitive items and finishes in the vicinity of the nut. However, if you have or can beg borrow or steal (as the saying goes) a spot-riveter, the electrodes of the spot-riveter can be used to apply spot heat to a nut in a sub second welding pulse.
@@AstronomyGarage To be certain you need to read the instructions. As I understand it many are anaerobic, which means oxygen keeps the adhesive liquid, but when denied oxygen they start to set. Some Loctites can be accelerated by an activator. Loctites vary in their temperature resistance, so it would depend upon what grade you used. If you test the tighness and it doesn't move then leaving it out in the sun likely had no obvious adverse effect. My spot welder trick can reach high temperatures.
Very nice. Restored above and beyond original condition. Would be a real killer scope for showing people new to the hobby what's possible to see with just good ol' mirrors and light. Is it worth combining different filters' images to make a composite photo?
Thanks. I do think that astrophotographers do that - they take various images with different filters and mix them to get beautiful images. I'm a visual astronomer and only use my smartphone, so that skill is beyond me.
Recently, there was a big Obsession for sale for $2000, but it had some chips in the mirror. Seemed like a great buy, but I'm out of budget and space. Hitchhikers Guide To The Galaxy was my first text-based computer game (early 1980's)! Played that before reading the books.
This was quite an adventure. Great work John, your skills are impressive! Do you work as a machinist professionaly? Just curious :) And the mirror is awesome!! you should try out observing some double stars with it to really find out its stregths. Try Alberio in the constellation cygnus, the colors if this double system should come up beautifully in a big scope such as this. Also epsilon lyrae (the double double). I think your texas location, while not the best for light pollution, should award you at least with good seeing conditions. Perhaps in winter
I'm not a machinist, but I worked with one for nearly ten years. He taught me lots (I sortof know my way around a Bridgeport), but my skills pale in comparison to his. I'll see how the double star targets go. The stars are pinpoint sharp in this mirror.
That was a real worthwhile and nicely realized project giving you what looks like a very nice scope. Way to go! Have you thought about getting a neutral density filter that could swap in and out as needed?
The old addage is true: The very BEST telescope is the one that gets used. I still have my 3 inch Dob always ready to go! I even donated another one to my local cub scout pack.
This was a great series on the restoration! Thank you much. While I've been very infatuated of late with using a small smart telescope, this has made me think I need to explore a standard optical visual scope again. I have had so many over the years but always of limited success (e.g. can see Jupiter, Saturn, the Moon and Mars but not much more). You've got me thinking about finding one of these big light buckets, but what about the lack of electronic object finding and tracking? Aren't you pretty much limited to J-S-M-M without it?
For the most part, yes. In the city skies where I am, I get to see Moon, Jupiter, Saturn, Mars, Orion Nebula, Ring Nebula and a small white blur called the Andromeda Galaxy, and that is no matter what the size of the telescope. The secret isn't telescope size, but the darkness of your sky. A "small" 8 inch Dobsonian will blow your mind in a Bortle 2 dark sky. The fancy small electronic telescopes are impressive, especially since they can track and do photographic stacking all by themselves. For my big manual Dobs, I record video using my phone (in ProVideo mode) and then do stacking later that evening using PIPP, and AutoStakkert.
@@AstronomyGarage thanks for your reply and sharing your insight. This is very helpful. I think based on your feedback I will seek out an 8" Dob like the Orion XT8 without any complicated drive gear, and just use it when nights are dark and I can share some of the astronomy objects like you listed above with others. Thanks again.
Thank you for watching! Depending on how close you are to a big city center, used telescopes are common. Used wooden telescopes are a bit less common, but they do still pop up from time to time.
@@AstronomyGarage I'm on the edge of a town in the UK, bortle 6. I've bought a StellaLyra 8" Dob which is the same as the Zhumell z8/Apetura 8 so I should be able to transport it to darker sky sites. If I ever get the chance of a wooden Dob I'll certainly go for it.
The Apertura8 is probably the nicest 8" available. Ball bearing azimuth, accessories, etc. I have a Zhumell 12 inch metal tube Dob and it's the same as the Apertura. I think the previous owners lived near a sand-blasting factory because it's one of the only mirrors I've ever had to get professionally recoated.
John, wow wow wow!!! SUPERB...I know it is a big scope, and you can sell for good $$$...BUT...I think this one should stay with you!!! How does the Double Plossl work for you??
That Double Plossl is VERY good. Sharp all the way to the edge. It was custom-built by Steve Case - he uses old binoculars to make them. He bases them on Red Henry's Double-Plossl design. As for selling this telescope, I might have to. I've sunk a lot of money into the next two videos. And.... I'm out of space.
Fantastic video for closing out this restoration. Two quick questions, what is the focal length of this monster? And what is the job of the wing nut on the sling, wouldn't the first nut hold the bolt and sling in place?
Believe it or not, only 60 inches. The wing nut replaces a second wrench necessary to tighten that joint after adjustment. Slightly easier and safer than having two wrenches flying around near the mirror.
If possible can you please include some technical details like what is the magnitude limit for this telescope. What percentage is the secondary mirror to the working aperture and lastly why didn't you put caster wheels on the base itself instead of having the support wheels.
I honestly don't know the magnitude limit. The mirror, despite looking very good, does have some degradation near the outer 25%, so I suspect that will reduce the magnitude limit. The secondary mirror is about 2.1 inches by 3 inches. I usually don't put castors on telescopes that are excessively heavy (this one is). Plus, the ground base is quite small. I think the new Telekits have bigger round bases.
I worry a bit about those self adhesive batteries. The strength of the adhesive is only as good as the bond of the black paint. It's easy to imagine them coming loose and causing trouble. You might want to make up some sort of hold down clamps for them.... just to be sure.
@@AstronomyGarage The thing I would probably do is make up thin metal brackets/straps to screw down over the batteries. A strip of (say) 20ga galvanized steel about 1/2 or 5/8 wide could be shaped up by bending it over a battery-shaped wood block. With the two central bends in place, use the vise to help form the "feet" for the screws. Be careful drilling the holes in the feet, so the work does not catch and spin. You can probably use the vise again here if you put a couple of sacrificial wood blocks on top of the jaws. Alternatively..... straps could be made of plastic cut from a milk bottle. These would work just as well and not require any pre-shaping.
@@robertmacpherson9044 That's a good idea. I also have an old black belt that I could cut up into sections. Or... velcro. I have self-adhesive velcro strips. ALthough they might run into the same paint adhesion issues.
@@AstronomyGarageVelcro sounds like a fine idea if you screw it to the wood. You will want to put washers under the screw heads, or else use those big-headed screws they sell for attaching expanding mesh for stucco. They are available at the local hardware store, in the fastener isle.
This is a good point. One of the reasons I used the plastic washers was to reduce the torque that those nuts sensed. The plastic washers making collimation a snap as far as turning those bolts. I'll keep an eye on it.
That is a very good question and I never found a good answer. I suspect it was an attempt to make it as rigid as possible to hold shape, although this isn't really done nowadays.
Oh yes. The mirror has a focal length of 60 inches, so the truss rods are cut to a very specific length to make the light path measurements all work out. I've since thought of a reason for the mirror being so thick - weight. This thing is so front heavy that the extra weight from the mirror offsets the weight balance.
@@AstronomyGarage I just found this video, "Telescope Building with John Dobson'" - a real gem. He states that the mirror glass is thick to prevent it from flexing and throwing off the optics. th-cam.com/video/snz7JJlSZvw/w-d-xo.html
By far the best DIY telescope channel on TH-cam. Keep it up!
Very kind words. Thank you!
Before overnight no Band-Aid.
After overnight Band-Aid.
Great job with the restoration!
Thank you for watching!
If you get bored, that mirror cell still could use some help. Having the collimation bolts move the mirror independent of the mirror hold downs is a sure recipe for a pinched mirror. Also, I would not expect the cell to hold collimation over the length of even a short car ride, because there is no restraint to keep the collimation bolts from unscrewing under vibration. To avoid rebuilding it all from scratch, I would suggest screwing the support triangles and the mirror restraint towers to a single plywood board, thus solving the problem of having the collimation bolds driving the mirror into the supports. The collimation screws would then work on the plywood board to change mirror tilt. The addidtion of another screw next to each collimation bolt to push against the plywood board would lock the collimation, having the lock screw in compression, and the collimation bolt in tension. That puts enough force on the threads to keep them from moving under vibration. You should put a small metal wear plate where the lock screw bears against the plywood board to keep it from digging into the wood.
Nice work drilling the holes on the bolts without a drill press. The planets at the end look really nice with a smart phone, I would think think visually it would look 10 times better.
I was sweating bullets drilling and tapping those holes, afraid that I'd break the bit off. I used plenty of oil and went super slow with advancing the tap. Visually, Jupiter was incredible. I saw the red spot with my eye.
Great finish to an excellent series!
Warning to others, be sure to only use blue loctite if you want to disassemble later.
Red loctite is more permanent and requires a lot of heat to break it loose.
That's good to know. I probably should've used the red, but in this case the blue was rock solid (it'sall I had). Fingers crossed that it holds.
@@AstronomyGaragesorry, I did not explain clearly.
Blue is perfect in this application. It will hold 100% until you purposely decide otherwise. Blue is made for later disassembly.
I was warning people AWAY from red in this situation. It will not come apart, even if you want it to, unless you apply heat that will likely damage the wooden parts.
wow!! Great! restoration!
Thanks! It was a lot of fun.
Purple loktite is probably what you should be using for most of these applications
I'm hoping that with the addition of the milk jug washers, the torques will be so low that my loktite will work, but you may be right in the long run.
Purple is more of a thread sealant than locking compound and is much easier to remove without danger of breaking stuff. I have a 50ml bottle of 222 that gets used way more than red or blue
Nice work, John. I'm just staring.😀👍👍👍
These restorations are a lot of fun. I recommend everybody does at least one. :)
"I'll cut this off, obviously." Hmmm...maybe it's not that obvious, or perhaps, it could be a self-induced impediment that is not observed until the very last screw is attempted to be inserted but fails, and in so doing, requiring complete and total de-construction. Very impressed with the methods used by the original designer/builder on this scope, and, most assuredly, your skills in diagnosing the problems and providing remedies.
Sometimes I do have to do a total de-de-construction to fix a mistake on my part during re-assembly. If so, I usually eliminate the first portion because I'm a stickler for making these as short as possible (I realize 34 minutes is not very short). That may make me seem clairvoyant, but I assure you that I am not, lol.
If I didn’t live so far away I think I’d be queuing up to buy it from you. Great job!
Let me start by saying I know nothing about telescopes, but the algorithm works in mysterious ways. Your channel came up in my recommended the other day and ive been slowly binge watching your back catalogue... in a couple you have mentioned Stellarvue, I've been working at a pump company in the building next door to Stellarvue for the past 6 years. Showed the owner your channel today, and LSS keep an eye out he may be reaching out to you.
Thanks for watching! Stellarvue makes legendary telescopes - they solved the nearly impossible task of eliminating chromatic aberration from short refractors. It's like magic. Of course, they are way out of my league pricewise.
Cant wait!
And it's published! Enjoy. :)
excellent video series. Thank you for sharing.
Thank you for watching! It was a really fun project.
A potentially handy hint for unlocking threads locked-solid with super powerful thread lock. These materials can be be softened / denatured by heat. But there’s a problem, that you can’t use a gas torch or heat gun, because it would damage heat sensitive items and finishes in the vicinity of the nut.
However, if you have or can beg borrow or steal (as the saying goes) a spot-riveter, the electrodes of the spot-riveter can be used to apply spot heat to a nut in a sub second welding pulse.
Now you've got me worried. I used a lot of Loctite and I set it out in the sun for an hour to help it cure faster. Did I actually weaken the bonds?
@@AstronomyGarage
To be certain you need to read the instructions. As I understand it many are anaerobic, which means oxygen keeps the adhesive liquid, but when denied oxygen they start to set. Some Loctites can be accelerated by an activator.
Loctites vary in their temperature resistance, so it would depend upon what grade you used. If you test the tighness and it doesn't move then leaving it out in the sun likely had no obvious adverse effect.
My spot welder trick can reach high temperatures.
you can use alcohol to soften it up. i think it goes without saying if its been on the bolt for decades it will take a little longer to soften it up
Great video
Thank YOU for watching. Clear skies!
Sheesh man that mirror is killing it
It is a beast of a mirror! In hindsight, I should've weighed it.
My 12.5" has the same thick mirror. You definitely have to wait till it comes to temperature before doing any serious observing with it.
This was a lesson I had to learn for sure.
Excellent, You made that scope look stellar!
Thanks! I sure was glad that AstroSystems is still in business.
Superb is an understatement John.dont know if you intend to keep or sell it but im sure you will get big bucks for sure!
Haven't decided yet, but space in the workshop is tight and I already have a 12 inch Dob (metal tube). :/
Good job, both on restoration and making these videos!
Thank YOU for watching. These projects are fun.
Very nice. Restored above and beyond original condition. Would be a real killer scope for showing people new to the hobby what's possible to see with just good ol' mirrors and light. Is it worth combining different filters' images to make a composite photo?
Thanks. I do think that astrophotographers do that - they take various images with different filters and mix them to get beautiful images. I'm a visual astronomer and only use my smartphone, so that skill is beyond me.
Watching this makes me feel sick with envy. I missed-out on a Obsession 18" F4.2 UC that went for a song.
Enjoy your TH-cam identifier. Perhaps Douglas Adams will smile upon you.
@@johngiromini5745 Like many others, I regret his passing. He had so much more to offer.
Recently, there was a big Obsession for sale for $2000, but it had some chips in the mirror. Seemed like a great buy, but I'm out of budget and space. Hitchhikers Guide To The Galaxy was my first text-based computer game (early 1980's)! Played that before reading the books.
@@AstronomyGarage
The one missed out on was £1500, but it was an easy drive and it came with at least £1k of accessories. I was so stupid.
There will always be another.... just a matter of time.
This was quite an adventure. Great work John, your skills are impressive! Do you work as a machinist professionaly? Just curious :)
And the mirror is awesome!! you should try out observing some double stars with it to really find out its stregths. Try Alberio in the constellation cygnus, the colors if this double system should come up beautifully in a big scope such as this. Also epsilon lyrae (the double double). I think your texas location, while not the best for light pollution, should award you at least with good seeing conditions. Perhaps in winter
I'm not a machinist, but I worked with one for nearly ten years. He taught me lots (I sortof know my way around a Bridgeport), but my skills pale in comparison to his. I'll see how the double star targets go. The stars are pinpoint sharp in this mirror.
Love your videos and your passion! M'encanten els teus vídeos i la teva passió!
These videos are a lot of fun. Glad you enjoy them. :)
Diameter of mirror?
12"?😮
It's a 12.5 inch mirror.
John this looks awesome
Thank you. It's been a fun project.
That was a real worthwhile and nicely realized project giving you what looks like a very nice scope. Way to go! Have you thought about getting a neutral density filter that could swap in and out as needed?
I haven't yet, but have considered a UHC filter.
Nice scope, though nothing to compare with my 3" tabletop Dobsonian.
The old addage is true: The very BEST telescope is the one that gets used. I still have my 3 inch Dob always ready to go! I even donated another one to my local cub scout pack.
This was a great series on the restoration! Thank you much. While I've been very infatuated of late with using a small smart telescope, this has made me think I need to explore a standard optical visual scope again. I have had so many over the years but always of limited success (e.g. can see Jupiter, Saturn, the Moon and Mars but not much more). You've got me thinking about finding one of these big light buckets, but what about the lack of electronic object finding and tracking? Aren't you pretty much limited to J-S-M-M without it?
For the most part, yes. In the city skies where I am, I get to see Moon, Jupiter, Saturn, Mars, Orion Nebula, Ring Nebula and a small white blur called the Andromeda Galaxy, and that is no matter what the size of the telescope. The secret isn't telescope size, but the darkness of your sky. A "small" 8 inch Dobsonian will blow your mind in a Bortle 2 dark sky.
The fancy small electronic telescopes are impressive, especially since they can track and do photographic stacking all by themselves. For my big manual Dobs, I record video using my phone (in ProVideo mode) and then do stacking later that evening using PIPP, and AutoStakkert.
@@AstronomyGarage thanks for your reply and sharing your insight. This is very helpful. I think based on your feedback I will seek out an 8" Dob like the Orion XT8 without any complicated drive gear, and just use it when nights are dark and I can share some of the astronomy objects like you listed above with others. Thanks again.
Such an awesome telescope, keep up the good work!
Thanks!
I have really enjoyed watching this series of videos, great job. I’m new to astronomy and find your videos inspiring, keep up the good work.
Thank you for watching! Depending on how close you are to a big city center, used telescopes are common. Used wooden telescopes are a bit less common, but they do still pop up from time to time.
@@AstronomyGarage I'm on the edge of a town in the UK, bortle 6. I've bought a StellaLyra 8" Dob which is the same as the Zhumell z8/Apetura 8 so I should be able to transport it to darker sky sites. If I ever get the chance of a wooden Dob I'll certainly go for it.
The Apertura8 is probably the nicest 8" available. Ball bearing azimuth, accessories, etc. I have a Zhumell 12 inch metal tube Dob and it's the same as the Apertura. I think the previous owners lived near a sand-blasting factory because it's one of the only mirrors I've ever had to get professionally recoated.
John, wow wow wow!!! SUPERB...I know it is a big scope, and you can sell for good $$$...BUT...I think this one should stay with you!!!
How does the Double Plossl work for you??
That Double Plossl is VERY good. Sharp all the way to the edge. It was custom-built by Steve Case - he uses old binoculars to make them. He bases them on Red Henry's Double-Plossl design. As for selling this telescope, I might have to. I've sunk a lot of money into the next two videos. And.... I'm out of space.
Beautiful
Fantastic video for closing out this restoration.
Two quick questions, what is the focal length of this monster? And what is the job of the wing nut on the sling, wouldn't the first nut hold the bolt and sling in place?
Believe it or not, only 60 inches. The wing nut replaces a second wrench necessary to tighten that joint after adjustment. Slightly easier and safer than having two wrenches flying around near the mirror.
thanks john for that fix that took you alot time it seems. are you giving it back to the owner or keeping it?
Unfortunately, my workshop is bursting at the seams, so I will likely have to pass it on to a new owner.
If possible can you please include some technical details like what is the magnitude limit for this telescope. What percentage is the secondary mirror to the working aperture and lastly why didn't you put caster wheels on the base itself instead of having the support wheels.
I honestly don't know the magnitude limit. The mirror, despite looking very good, does have some degradation near the outer 25%, so I suspect that will reduce the magnitude limit. The secondary mirror is about 2.1 inches by 3 inches. I usually don't put castors on telescopes that are excessively heavy (this one is). Plus, the ground base is quite small. I think the new Telekits have bigger round bases.
I worry a bit about those self adhesive batteries. The strength of the adhesive is only as good as the bond of the black paint. It's easy to imagine them coming loose and causing trouble. You might want to make up some sort of hold down clamps for them.... just to be sure.
I've thought about using some type of tie or plastic tie down system to augment the self-adhesive.
@@AstronomyGarage The thing I would probably do is make up thin metal brackets/straps to screw down over the batteries. A strip of (say) 20ga galvanized steel about 1/2 or 5/8 wide could be shaped up by bending it over a battery-shaped wood block. With the two central bends in place, use the vise to help form the "feet" for the screws. Be careful drilling the holes in the feet, so the work does not catch and spin. You can probably use the vise again here if you put a couple of sacrificial wood blocks on top of the jaws. Alternatively..... straps could be made of plastic cut from a milk bottle. These would work just as well and not require any pre-shaping.
@@robertmacpherson9044 That's a good idea. I also have an old black belt that I could cut up into sections. Or... velcro. I have self-adhesive velcro strips. ALthough they might run into the same paint adhesion issues.
@@AstronomyGarageVelcro sounds like a fine idea if you screw it to the wood. You will want to put washers under the screw heads, or else use those big-headed screws they sell for attaching expanding mesh for stucco. They are available at the local hardware store, in the fastener isle.
I wish the telescope was more broken than it was so that we would have more episodes.
I'm finding it harder and harder to find wrecked telescopes. I think that's a good thing for the hobby overall!
Gz on new shirt
I don't know what Gz is, but I hope it's good! :)
@@AstronomyGarage congratulations :) and thanks for your videos
Purple loc-tite is less forever.
This is a good point. One of the reasons I used the plastic washers was to reduce the torque that those nuts sensed. The plastic washers making collimation a snap as far as turning those bolts. I'll keep an eye on it.
I’m so glad I stuck with a 8” Dob. Easier to move around. Not much difference in visual to lug around a 12”.
Whenever anybody asks me, I only recommend the 8 inch Dob. It's the best of all worlds.
Is there a reason for the mirror to be that thick?
I have no idea. Perhaps to insure structural rigidity?
Why is the mirror so thick and heavy? Is it to balance the tube?
That is a very good question and I never found a good answer. I suspect it was an attempt to make it as rigid as possible to hold shape, although this isn't really done nowadays.
Does the length of the truss poles matter? Would changing the pole lengths change the focal points?
Oh yes. The mirror has a focal length of 60 inches, so the truss rods are cut to a very specific length to make the light path measurements all work out. I've since thought of a reason for the mirror being so thick - weight. This thing is so front heavy that the extra weight from the mirror offsets the weight balance.
@@AstronomyGarage I just found this video, "Telescope Building with John Dobson'" - a real gem. He states that the mirror glass is thick to prevent it from flexing and throwing off the optics. th-cam.com/video/snz7JJlSZvw/w-d-xo.html