Rusted

The brackets, which fit the tube, appear to be bolted on and are projecting beyond the base plate.[See image] The holes in the brackets could be easily slotted outwards with a round file. To allow you to slide the brackets inwards. If the base plate is still too large then use a flat file and forget. Do NOT touch the threaded holes in the base plate. These are your bracket fixing points. The difference in curvature where the brackets fit the inside of tube is only slight. Any changes you make would be invisible once the cell is fitted into the tube. If any bare metal cause you sleepless nights then just use some paint.

Dark Matter is [just] gravity "leaking" between parallel universes. Dark Energy and expansion are caused by the pressure of photons leaking between parallel universes. UFOs & ghosts could be sightings across thinning of the membranes between universes. If the maths does not agree.. then it will later. They just don't know it yet. In a multiverse of unknowns then even my silly "theories" are equally valid. Billions of people, on this world alone, believe even sillier theories than these.

You can tell the aliens are highly advanced: They can disable any image stabilisation in our cameras. While simultaneously giving the imager severe Parkinson's.

Thanks Lars.

Lars, Thanks for sharing your visit to this fascinating observatory. Did you take any other pictures of the clock in the glass case? On the right while pointing up at the pictures of astronomers. Precision timekeeping was an important element in astronomy.

Here be dragons! 😱

Just a note: A drive pin on the face of any practical disk size would suffer from slippage. The variations in drive radius [on the disk] would fight each other across the length of the drive pin or width of a drive wheel. There would be simultaneous, multiple drive ratios depending entirely on the contact radius on the large disk. I built an equatorial platform half a century ago. Using a sharp edged rubber gramophone drive wheel and a long plastic cone for drive speed adjustment. The plastic cone drove a long, threaded rod and nut, via reduction spur gears, for altering the speed of the equatorial drive.

Thank you Lars. Do you have any recollection of the quality of the image of Jupiter in the big refractor? I must say that your images of the observatories and instruments are really excellent. Both in quality and detail. .

The problem with the English mounting and Yoke variants is providing the tall northern pier. I visited Herstmonceux with the Bath Astronomical Society well over 40 years ago. Now Bath Astronomers associated with the Herschel Society. We even got to climb on the Isaac Newton 98" mounting. That was before it was relocated. As were other instruments. The scale of which were truly breathtaking!

Thank you for continuing to share your fine images and details of these fascinating old observatories and instruments. I wonder if anybody here has any experience of using such large instruments themselves? Were these large telescopes really "rock steady" in use? Did they suffer from backlash? Not only did they mount one large refractor but sometimes added a second or third. Such confidence! There is no sign on professional mountings and instruments that weight was ever an issue. Most used generously sized iron or bronze castings and steel tubes. Aluminium was not even an option in those days. There are remarkably few amateur equatorial mountings today which pretend to support even modestly sized refractors. [Over 20cm aperture.] Mostly, I presume, because the amateur insists on easy mobility even in their old age. The reflector is the instrument of choice for many amateurs. With many large apertures now mounted on driven, plywood mountings. While the large refractor has become more of a historical curiosity.

Nicely crisp images Steve!

Milky sky and cloud crossing continuously. Seeing fairly steady and fairly transparent. Sharpness spoilt by the cloud.

Excellent animation!

HI, The downside is the inability to change focus quickly over any distance. Plus the need to handle the telescope continuously for some time. Very fine focus is an impediment to finding best focus in my experience. One ends up rocking back and forth. Rather than racking.

A superb set Nigella! Each a masterpiece in its own right! Including the finger paintings at the beginning. 😎

First chance for ages to get back out there: Cloud and a milky sky. 😭

The replacement adapter was fine. High standard of machining and protective detail for the optics and objective cell. Large nylon thumb-wheels for location. All good.

I specified that the adapter be suitable for the Baader 160mm D-ERF. No dimensions should have been required by an associate machining parts for an astro sales company. I too have been a machinist for decades and have owned a vintage machine room lathe for similar decades. I didn't have large enough bar stock to make my own adapter.

T-S adapters are very expensive and may take several attempts to get it right. I needed a 160mm D-ERF adapter to fit on the cell of my 6" iStar objective. I falsely assumed that any machinist would know what fitting a certain diameter meant. So I [naturally] expected a sliding fit for the [standard] D-ERF glass. How else could it possibly fit in there? They made it an interference fit by exactly matching the diameter of the [standard] Baader D-ERF. So it had to go back in the post with all the inevitable delays going both ways.

All the plans... Both wedges worked fine for visual views. I could see the disk through cloud with quite a deep bite at 11.00. 12.00 and Maximum was clouded out and actually raining. This time I took my TZ7 with me. Not a single useful image. The sun came out on my drive home and was nuisance for reflecting off the wet roads straight ahead.

I just had a bit of a brainwave. Stop laughing at the back! I can't be at home at max for the 1/3 partial eclipse today. 12.00[CET] Check your local timing! So I thought I'd take my 2" Lacerta solar wedge with me. Then I can safely view the sun and even take a few digital snaps through it. The Lacerta's polarising filter + Brewster Angle + built in ND should provide comfortable viewing. Though I have never tried it without it being attached to a telescope. This will avoid my taking anything more bulky with me. The Lunt 1.25" wedge is even smaller but probably less useful for photography. I could pass it around the class for a bit of outreach if it proves worthwhile. As long as they don't drop it! I'll have to go though my 1.25" filters first. To see what helps. I'll update as soon as the sun rises. [If ever] So I can check for visual light throughput of these wedges. If it is still too bright I'll use a reflection off a window to kill the excess light. Exact Solar orientation may be subject to some confusion. 🤣 Be safe out there! 😎

I use screw adjusting engineers dividers for removing rings. The larger models are pretty stiff and provide accurate spacing to fit the slots in the retaining ring. Some filing or grinding of the divider tips might be useful to give flat working surfaces in the slots.

A very reasonable response considering my [hopefully constructive] criticism. If you have a drill then you make holes in plates to clamp over the present construction. No doubt the slots in the "techno-bars" allow standardized T-headed bolts. Carbon fibre plate is available online. Thick section printing is much like casting in layers. Pouring metal one ladle at a time. As long as we agree on the basic idea that's all that matters. The printing material is relatively weak and flexible. At least it is compared to cast iron and aluminium. Use carbon fibre reinforced plastics? Print a whole new mounting in very thick sections to simulate castings and reduce flexure. I suppose that might be costly an time consuming?

I envy you your view Steve. It probably accounts for your fine images. My landscape is blocked by trees. 😱 Not decorated by them.

Pretty, but I wouldn't start from there. I predict a jelly on steroids when loaded with a telescope. It has lots of parallel tubing held only at the ends. There is no triangulation anywhere. Except the PA by accident. Where there was no choice. There is no boxing anywhere to provide accumulated plate stiffness in all planes. There is no strength from 3D thickness in solid castings. All the computerised adjustments are potential flexure points. Firmly skin the open tubing assemblies in aluminium or CF plate. Gain from the well known "stressed skin" effect. Then you might be able to hang a telescope from it. Though I still rather doubt it myself. If I really, really had to use a printer I would be designing thick castings. Using very large diameter axes and thick, large junction plates using only sliding bearings. The Dobsonian taught us that the largest amateur telescopes can be mounted on plywood. Your design committee could easily do the same. If they stopped using spindly, off-the-shelf components. Good luck! Chris Miserable old git with 60 years of DIY telescope mounting experience. Here is my polar axis opened up for photography. That side is usually closed with another 10mm plate. Using all-plane highly compressed, box sections using multiple studs [threaded rods] in the absence of castings. 10mm aluminium plate. Compressed in all planes by large diameter studding. [Threaded rods up to 16mm Ø] 50mm stainless steel axes/shafts. Oversized, self-aligning, flange bearings. 180mm Ø thick disk using multiple studs at the Declination 'T' junction. All this could more easily be achieved with a 3D printer using thick section castings. And basic engineering principles from the Victorian era. And, you probably won't even need a chain hoist to lift it.