Rusted

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.

The square TS bases have tilt adjustment. Here is my FT2.5x3.5: https://fullerscopes.blogspot.com/2020/10/16102020-starlight-instruments-feather.html

Play it by ear. Or rather by eye. Minimum tilt to achieve your aims.

When I were a lad... you could buy sanitary ware in all sorts of hideous colours. 😱 They look horribly dated now IMO but white seems to have become the norm again.

It's a nice, neat installation Paul. You should see the mess in mine!

I agree. On both counts. Your Pulsar has had a makeover from earlier styling. Smart!

Thank you Peter.

In my own experience plastic tubs don't last long when exposed to cold and sunshine. I used an inverted water butt and it soon cracked across the bottom. Which was facing upwards. The spiders and birds moved in too. I had a nest of Blue tits in the forked mounting base. Cheap [woven] tarpaulins are garbage for outdoor use. Quality PVC tarpaulins last well. Heavy and stiff. As does genuine, rubber, pond lining material. But it's very heavy and stiff! A drop-over, marine plywood box would last and provide some insulation from the sun. Thickness and insulation to taste and permitted weight. Not in contact with the ground though.

Full sun today. Fairly steady seeing and fleetingly transparent before the sun-seeking cloud arrived. I was quite pleased with this one after retuning the etalon and refocusing.

I too turn the dome/slit to shield my face when I am solar imaging and observing. I always wear a dark green "baseball cap" when I am imaging. It shields my face when I move into the sunlight.

The 2" Lacerta wedge heat sink used to get hot after hours of tracking the sun with my 180mm/7" f/12. Nothing to worry about though. The inside of the heat sink became discoloured after a while. But then so did the outside of my 1.25" Lunt wedge. Which only received ambient sunshine. The matt black finish eventually faded to brown. A suntan?

Wrapping the tube with straight tape or paper to provide a guide ensures close proximity to squareness to the axis. I've used the technique for decades. With tubes up to 18" Ø.

Jeremy. I have to ask: Why did you think my post was funny?

Remove the focuser and stuff the tail end baffle with tissue or a soft cloth to stop dust entry into the OTA. Tape a thick roll of paper or masking tape to guide the saw blade and protect the CF tube from cosmetic damage if you slip. Use a fine toothed hacksaw and work slowly steadily. Ideally you want a B&D style workbench. With the jaws opened just enough to act as a well padded cradle to suit the diameter of the OTA. NOT WITH THE OTA TIGHTENED BETWEEN THE JAWS! Once the tail end has parted from the CF tube you can rub the cut end on sandpaper to true and smooth it. I'd glue the sandpaper to a scrap of plywood or metal to keep it flat.

Check out a boat supplies company for paint suggestions. You will probably have to abrade the surface all over to get a key. Nasty! This dome colour problem is far more complex than you might realise. White domes are traditional for one very good reason. Solar heat rejection. I painted my raised, plywood dome with white primer before it quickly became sage [not grass] green. Grass green stands out just like white! There is no grass green in nature. 😱 The white dome was visible for as far as the eye could see. Sage green, much less so. Round things are a blot on the landscape! White, round things are rarely seen in the countryside. Yet white caravans are relatively huge but pass almost unnoticed. Even in quantity. Caravans are white for a reason. To stay cool in summer when they are most used. A green caravan would be intolerable! It would fry the occupants. Now I am building an even larger dome [4.3m /14'] in grass green coloured GRP. Yuck! Green GRP gets very hot in direct sunshine. I have repeatedly measured 150F/66C surface temperature with my laser guided thermometer. BUT, I still can't paint it white for "carbuncle" reasons. It would be seen from space! So I plan to paint only the shutters white. Then park the dome with its green back to the public view when inactive. This will also help to keep the dome cool when I am solar imaging. The bi-parting shutters also shield lots of dome surface from the sun when open. Pulsars have "up and over shutters" so don't have this advantage. Bottom line: Keep it white. Cover it with a camouflage net. Or even horticultural shade netting when inactive. Here are some images to give you a better idea than 1000 words.

Sheer luck the moon was just the right height on my morning walk. Though I had to stand out in a muddy field. Lumix TZ7. Scarpa boots.