329 replies to this topic

[John Higbee]

Couldn't agree more...the Tinsley 6" refractor OTA looked like this when I got it...so had to refinish  it...

 

 

Now it looks like this (after stripping, bondo-ing, sanding, priming and color-coating)...

 

 

John

Edited by John Higbee, 10 April 2020 - 02:53 PM.

[Peter Ceravolo]

Mount disassembly went fairly smoothly, with one exception that I'll cover later.

 

One starts by removing the setting circles. Here the RA circle is being disassembled, bugs!

 

 

I discovered the declination circle mount hardware is missing a screw. Has someone been here before?

 

 

 

 

[Peter Ceravolo]

Next was disassembly of the corroded elevation screw and captive nut assembly

 

 

The screw was very corroded at the end. A lot of the screw was exposed to the elements because of the high latitude the mount was set at. I had to use a thin file to get rid of enough rust to be able to thread the rod off the nut. It was hard to get at...

 

 

 

[Peter Ceravolo]

With the RA shaft housing pivot rod removal and the whole head came apart nicely.

 

 

[Jon Isaacs]

Old telescopes are just like old cars, there are different camps when it comes to preservation and restoration. Opinions span the spectrum from "don't touch it!" to "it's yours do what you want". I'm in the middle of the pack, I'm not into resto-mods but at the same time there is a limit to patina.

 

 

 

I should clarify my previous comment.

 

It seems it's true that the most valuable old cars are those that haven't been touched but it's also true that the least valuable old cars are those that haven't been touched.  The telescope or car determines what's appropriate.  

 

I keep forgetting this is a 4 inch F/16 so it has a head start on modern faster scopes. 

 

I love the intricate detail. How they did all that is amazing. It took time to build a scope.

 

Thank you for posting the progress.

 

Jon

[Kokatha man]

Mount disassembly went fairly smoothly, with one exception that I'll cover later.

 

One starts by removing the setting circles. Here the RA circle is being disassembled, bugs!

 

IMG_1816.JPG

 

I discovered the declination circle mount hardware is missing a screw. Has someone been here before?

 

 

...just don't blame that poor, dead bug..!  

[col]

 

I should clarify my previous comment.

 

It seems it's true that the most valuable old cars are those that haven't been touched but it's also true that the least valuable old cars are those that haven't been touched.  The telescope or car determines what's appropriate.  

 

I keep forgetting this is a 4 inch F/16 so it has a head start on modern faster scopes. 

 

I love the intricate detail. How they did all that is amazing. It took time to build a scope.

 

Thank you for posting the progress.

 

Jon

Just to add another angle to the restore vs over-polish debate, some years ago I attended  a lecture by a curator from the British Science museum and afterwards I showed him a photo of my alt/az 1902 lacquered brass Cooke 5" PV. He stated categorically that it had been restored and polished as Cooke refractors were always black. I didn't believe that was the case as I'd bought it from a friend who had owned it since the early 50s and he said to the best of his knowledge it had never been touched. A few years later I was able to obtain a copy of the 1900 Cooke catalogue and it showed that the brass finish was a two pound option on a PV scope. I guess even though the curator considered himself an expert, he'd only ever seen black Cookes of that size. I presume original brass Cooke PVs are less common as scopes of that size were very expensive (price of a house?) and  professional and institutional bodies would have chosen the more functional looking black finish whereas as wealthy Victorian amateurs wanted something prettier to show off to guests?

Apologies if I've gone too far off topic. Cheers, Col

[ccwemyss]

I love the intricate detail. How they did all that is amazing. It took time to build a scope.

 

Thank you for posting the progress.

 

Jon

What I appreciate about this time was how commonly available casting was as a manufacturing technique. Creating a model and a mold is an art that's nearly lost by comparison to today. Then sending it to a foundry was like sending a CAD file to a CNC shop. But now we try to design to reduce material removal and tooling complexity. With casting, there were design options that we would avoid with modern methods, including aesthetic features that would be hard to justify. 

 

For me, that's part of what makes a thread like this so interesting to follow. 

 

Chip W. 

[Peter Ceravolo]

Actually Jon your point that cars or telescopes, or any antique, with their original finish are more desirable is well taken. Enter the agony of antique restoration!

 

I poured a lot of money into my '81 Corvette, it needed body work and paint because the original finish was bad. Not long after I was in Vegas looking at 'vettes in a museum. The old gentleman showing me around pointed out the flaws in the cars from the 50's. If curators, collectors etc, don't see these flaws they know the vehicle is not original and that does affect their value, monetarily and otherwise.

 

So as I'm getting intimate with the Cooke mount I'm noting flaws in the original paint, paint runs in places you'd think they would make an effort to make it look good to the customer of this very expensive instrument.

 

 

Here is one on the side of the Dec saddle plate and tube ring mounting surface.

 

 

So, these little things that are of possible interest to historians and collectors alike will get wiped out by refinishing. I don't feel good about that...

 

Peter

[Peter Ceravolo]

Just to add another angle to the restore vs over-polish debate, some years ago I attended  a lecture by a curator from the British Science museum and afterwards I showed him a photo of my alt/az 1902 lacquered brass Cooke 5" PV. He stated categorically that it had been restored and polished as Cooke refractors were always black. I didn't believe that was the case as I'd bought it from a friend who had owned it since the early 50s and he said to the best of his knowledge it had never been touched. A few years later I was able to obtain a copy of the 1900 Cooke catalogue and it showed that the brass finish was a two pound option on a PV scope. I guess even though the curator considered himself an expert, he'd only ever seen black Cookes of that size. I presume original brass Cooke PVs are less common as scopes of that size were very expensive (price of a house?) and  professional and institutional bodies would have chosen the more functional looking black finish whereas as wealthy Victorian amateurs wanted something prettier to show off to guests?

Apologies if I've gone too far off topic. Cheers, Col

Col not of topic at all, post a scan of that page if you still have that catalog, I would love to see it!

 

What's the condition of your 5" PV objective? That center element deteriorates, I'll be posting about that in the coming days as time permits.

 

Peter

[Bomber Bob]

That center element deteriorates, I'll be posting about that in the coming days as time permits.

 

Looking forward to your post.  The only triplet I have is that 5" F5, that I think came from an aerial camera or similar non-astro instrument.  Its center element has a very thin edge, and I think that's how it got that large clam-shell:  It extends 3mm inwards, and runs 28mm around its base.  A prior owner painted its shape on both the sky & eye lens faces, which makes for a crazy star test.

 

Edited by Bomber Bob, 12 April 2020 - 01:54 PM.

[col]

Col not of topic at all, post a scan of that page if you still have that catalog, I would love to see it!

 

What's the condition of your 5" PV objective? That center element deteriorates, I'll be posting about that in the coming days as time permits.

 

Peter

Hi Peter, You can see my scope and the centre element of the objective in this earlier cloudynights topic (link below)  on page 2 and towards the bottom of page 1. I think your objective also features. I'll have a look for the appropriate catalogue pages for you. 

Let me know if the link doesn't work and I'll look for the original photos. Cheers, Col

https://www.cloudyni...elescope/page-2

[Dave1066]

Hi Peter, You can see my scope and the centre element of the objective in this earlier cloudynights topic (link below)  on page 2 and towards the bottom of page 1. I think your objective also features. I'll have a look for the appropriate catalogue pages for you. 

Let me know if the link doesn't work and I'll look for the original photos. Cheers, Col

https://www.cloudyni...elescope/page-2

Very interesting read on your Cooke 5" refractor there Col, I see back in 1900 you state your telescope sold for £117. With the appreciation of the pound from 1900-2020. If telescopes were still so specialist and few and far between, and items of the wealthy. You would have to spend £14,475.49p for the same telescope. Puts into perspective just how affordable telescopes are in this day and age.

[col]

Very interesting read on your Cooke 5" refractor there Col, I see back in 1900 you state your telescope sold for £117. With the appreciation of the pound from 1900-2020. If telescopes were still so specialist and few and far between, and items of the wealthy. You would have to spend £14,475.49p for the same telescope. Puts into perspective just how affordable telescopes are in this day and age.

Indeed, especially if you consider the higher quality Chinese refractors.

Interestingly, as I mentioned that that amount of money in 1900 (or so I was told) would buy a house somewhere in the UK, would you be able to do that now?

[Dave1066]

Indeed, especially if you consider the higher quality Chinese refractors.
Interestingly, as I mentioned that that amount of money in 1900 (or so I was told) would buy a house somewhere in the UK, would you be able to do that now?

No you would not be able to buy a house outright with £14,000+. In some parts of the south that could be a deposit for a flat. But you'd need a 90-95% mortgage. In more northerly climbs you could buy a small house but with a 90-95% mortgage.

David

[Bomber Bob]

Thanks for the link to the Taylor article:   http://www.europa.co...e/hdtaylor.txt 
 

CN is like an Astronomy College within Open University.

[Jon Isaacs]

What I appreciate about this time was how commonly available casting was as a manufacturing technique. Creating a model and a mold is an art that's nearly lost by comparison to today. Then sending it to a foundry was like sending a CAD file to a CNC shop. But now we try to design to reduce material removal and tooling complexity. With casting, there were design options that we would avoid with modern methods, including aesthetic features that would be hard to justify. 

 

For me, that's part of what makes a thread like this so interesting to follow. 

 

Chip W. 

Chip:

 

I think that today, casting is a very common manufacturing technique and far more sophisticated than it was 120 years ago.  

 

Jon

[ccwemyss]

I know of quite a few machine shops in the area, none of which use casting as a regular part of their process. In the 19th century, almost any manufacturing shop could create molds and send them off for casting at a relatively local foundry.  It was the easiest way to get complex shapes, and was cost effective even for very small runs of parts. Today, with CNC machines, it is simpler to start with standard stock, and remove material, especially for short runs. Casting, now, is typically reserved for larger runs, where the higher setup cost can be amortized. 

 

But that does lead to a different style of design. Who, for example, would program a CNC mill to generate raised lettering, rather than engraved lettering, on a part? When making a mold, it's easy and low in cost to raise the lettering. When milling, it means taking a whole surface down to a lower level around the letters. 

 

I was saying that I have an appreciation for these differences in the many small-run parts that one sees in antique mounts that were built from castings that often incorporated aesthetics that appealed to the maker. 

 

Chip W. 

[Peter Ceravolo]

The one item I had a problem with disassembly was the polar shaft/Dec housing and the sector gear being sandwiched between them. There was no obvious was to take it all apart, I though the shaft was pressed into the Dec housing. I pondered the problem for some time, planning how I could force the two pieces apart to free up the sector gear and make refinished the components easier.

 

 

 

 

 

[Peter Ceravolo]

When one is not sure how to proceed it's best to do nothing. So I set it aside for a bit and contacted a collector with Cooke experience for advice. Good thing! It turns out that the shaft is simply threaded into the Dec housing. So a bit of heat, a vice grip and a few whacks with a mallet freed up the shaft.

 

 

 

[macdonjh]

Perhaps restoration window sash cord would be appropriate?  https://www.amazon.c...0/dp/B003T82A30

I was thinking jute rope, myself.  Perhaps hemp?

 

Regarding polishing:

 

I was watching one of Jay Leno's car shows and the most valuable classic cars are those that are in decent condition and unrestored.

 

Beautiful scope. Being a mechanical engineer, I love those old designs that relief on mechanical ingenuity rather than electronics.  A modern mount with a separate RA slow motion control would be awesome. This one doesn't need a clutch.

 

Jon

I'm with you regarding the appeal of mechanisms over electronics for entertainment value.  However, can you imagine how much Software Bisque would have to charge for a gravity driven drive with a governor and planetary gearing for slow motion controls?  The mind reels.  My first job was in an old refinery and I used to joke with the instrument engineers about the original mimic panels with pressure gauges tubed all the way out to the process piping and control valves being operated on a 3-15 psig pneumatic system being better than all those fancy electronics they were forever fixing and calibrating.  But they didn't listen to me.

 

here is an image of the worm housing disassembled.

 

IMG_1853.JPG

 

The interesting aspect of this worm housing is the manner in which the worm shaft can be displaced laterally to engage the two right angle gears.

The end of the worm shaft on the left looks like it's threaded but it's not, those are grooves that allow the shaft to rotate but be restrained laterally.

There are 50 grooves per inch for fine lateral motion to properly engage the gears with out the need for clamping collars on the shaft.

 

IMG_1859.JPG

Well shoot, I was hoping those rings were a labyrinth seal for worm journal bearings.  Journals will work at one revolution per day, right? 

 

With regard to preservation vs restoration: from the photos posted so far, my opinion is most of the parts are past "patina" and into the realm of neglect.  If it were my project I'd consider the scope and mount to be best served by cleaning, polishing, blasting and painting.  But those are just my two cents, I can't wait to see what Peter Ceravolo does.

[col]

 

A couple of relevant pages from the Cooke 1990 catalogue plus an extract from the Cooke Photo Visual order book with my 5" PV marked. Note that the famous astronomer Sir Norman Lockyer has ordered a 4" and a 12" and in the period 1889 to 1901 he ordered another 4" plus a 6".

 

Col

[Kokatha man]

Cooke 1900 catalogue-4 inch resize.jpgCooke 1900 Catalogue-5 inch resize.jpgCooke order book extract-4.jpg

 

A couple of relevant pages from the Cooke 1990 catalogue plus an extract from the Cooke Photo Visual order book with my 5" PV marked. Note that the famous astronomer Sir Norman Lockyer has ordered a 4" and a 12" and in the period 1889 to 1901 he ordered another 4" plus a 6".

 

Col

This is when a typo stands out..!

[col]

This is when a typo stands out..!

So much for proof reading your own work!!. It's there for eternity now as there appears to be no edit option.

[Peter Ceravolo]

Than you for posting that catalog info Col. So if we decide to finish the tube polished brass we won't feel guilty!

 

Peter