Rusted

Very tasty! What's the weight limit of these printed rings? Or does it depend on the printing material? Skywatcher and others had better increase its range of tube rings if they are not to lose out to home printing! I can never find rings for my odd sized, DIY tubes. So I end up with hugely oversized rings with plywood inserts. I tried various camping mattress, foam packing but the OTA just slides through as it nears the vertical. Somebody should be offering rings printed to order but not at the usual ridiculous prices of "CNC'd" designer jewellery! Orion UK's "made to measure" rolled rings only look safe carrying a finder! I wouldn't trust them with a whole 40lb OTA!

Thanks, Dave. I noticed later that the image was taken from a book. One I have obviously missed. The problem with any normal wood skeleton construction is the sheer weight. We should be borrowing canoe and lightweight boat construction techniques. Thin marine ply, epoxy, CF and disposable copper wire. Not heavy plywood struts. Few domes will need to survive whitewater rafting. Not unless sea level rise has been badly underestimated.

Hospital School? Perhaps they wanted their wheels back?

What's the history of the wooden structure, Dave? I can't even imagine the weight of the rotating parts. Convenience and a ready-made solution are probably worth the premium of buying a commercial dome. But only if the solution really is convenient, offers instant gratification and long term satisfaction. Building a DIY dome is expensive and hard work over quite an extended period. It is only rewarding if the result lasts and you place absolutely no value on your own labour. Imagine if I had paid myself only £10 per day for my own labour. That would have bought a Pulsar dome by now. Unfortunately [?] Pulsar did not offer anything large enough to house my instruments of choice. The upside is I get to use my brain and stay fit into old age as I ponder the wisdom of making so much noise and sawdust. The cost in tools and materials has never been calculated but I bet it probably makes a Pulsar dome seem quite good value. Fiberglass domes are much lighter than wooden constructions. So might actually be much more user friendly than wood. Never enter into such a building project unless you have both eyes firmly closed to reality. Don't be fooled that you will save any money [at all] unless you have some useful skills or badly need a project for your own sanity. Take Peter's lead and build a half cylinder. You know it make [little] sense.

Allow me to disagree, Dave. Silo conversion is very hard work geometrically. Particularly if you want to view beyond the zenith. Being galvanized steel, they are sharp, heavy in any useful size and difficult to cut. They also have weird, structural hoops which may impede the observation slit. GRP work is relatively low skill and uses everyday tools. Yes, it produces itchy dust and needs a proper mask and goggles. Though lots of users do seem to survive to tell the tale. EDIT: There are UK dealers: Some links: http://www.holm-laue.de/index.php/iglu?ln=en-GB#ad-image-0 Holm & Laue GmbH & Co. KG | Iglu Calf Husbandry, Calf Igloos & Verandas | Calf Igloo BTW: I'm fairly sure my completed 10' plywood dome is going to be heavier than the 14' calf igloo.

Orbsey is no more, it is dissolved, deceased, gone to the observatory in the sky...

Rog never updated... should we worry?

Hi Gina. I've given this dome conversion quite a lot of thought and was close to purchase until I discovered the weight. I work alone and needed the dome to be lifted fifteen feet off the ground. I should have hired a Manitou telescopic loader. Not everyone wants an ROR and the value of these Calf Igloos is truly remarkable for such a large obs. organ donor. The central roof panel is thick, smooth GRP and unobstructed well past the zenith. A couple of raised marine plywood ribs would be glassed internally [GRP fillet] for the observation slit and shutter. These would provide the necessary strength from cutting away the observation slit. A smaller [cosmetic] fillet using a matching colour will weatherproof the ribs externally. The large opening can be very easily closed off with a flat, plywood panel carrying a suitable access door. Or, a female pattern can be made from the dome surface and a spherical mould taken from that and affixed to "the arch." I did this for my GRP sports car to make it into a proper hard top. Where a previous owner had cut a huge hole for a folding, rag top, sun roof. The sturdy, existing base rim of the Igloo can easily be furnished directly with wheels on brackets. Or a plywood base ring bolted on for rotation on wheels on top of the obs. walls. Any further questions? Apologies to the OP for hijacking his thread. I weep for you as one who came close to ordering a 3.5m dome from Pulsar. Non availability seems to have saved my <cough> Danish bacon. ?

You can buy a really sturdy 4.4m = 14' diameter fiberglass dome known as a calf rearing igloo for under £2000. Cut your own observation slit in the roof, add a shutter and rotation rollers and you're golden. They are produced by an agricultural silo manufacturing company in the southern EU. External finish looks fine and you even get a free front door frame to add your own door to taste. LOTR anybody? Available in plain, high gloss white [or neatly ribbed, grass green from an alternative source.] Downside is the size and weight at 480lbs which will require a lot of friends or [better] a crane/hoist. If I had a clear southerly view I'd snap one up without a moment's hesitation for my 7" refractor and f/8 10" newt. They'd make great astro club observatories if anyone has the skills to do a decent obs. conversion. I probably shouldn't share copyrighted advertising material here so took a pic at a local calf breeder's farm. His is years old and well used so make some allowances for the cosmetics.

I've often wondered if substituting the working surface with diamond nail files or diamond paper would help. The price of diamond "abrasive materials" has fallen remarkably in the last couple of decades.

Hi Originally it would have had matt black, wrinkle paint. I inherited it with scruffy black paint so decided on an update. The first Hammerite I tried was light metallic blue. It looked too awful to find polite words to describe it. So something a little less "sudden" was in order. It has lasted well out of doors under cover with two original coats about 15 years ago. A bit of rust is showing on the steel pier now. I thought I'd paint it all white one day but never have. It might put off the birds which like to nest in the base fork.

I am still using my MkIII and the MkIV. Both have the original bronze wormwheels. 7" 366T on the MkIV. Both were bought secondhand and fitted with stainless steel shafts to end their long battle against rust. Both live outside under tarpaulins. Which doesn't suit the plain steel worms. The MkIV handles my 6" f/8 refractor quite effortlessly. Solid as a rock. A 5" f/15 was okay too. My 7" f/12 was slightly beyond its limits. Though I used it for imaging the Mercury transit with a Neximage. A 10" f/8 reflector was more of a struggle. Yet Fullerscopes showed a 10" on the MkIII. Both mountings rely [heavily] on massive, welded stands each too heavy to lift manually. I had a contact who fitted an AWR belt drive Goto on his MkIV. Another was restoring a Fullerscopes 12" Cassegrain. The image below is my MkIV just after I completed its restoration. Engraved setting circles need a magnifier to read. I had the Skytracker VFO to go with it until I fried it with the endless Mercury transit.

Are used kidneys allowed in the For Sale/Swap forum?

With the greatest respect, Sir Peter: The thread title clearly says "Show us your Solar Observing Equipment." Nobody stipulated H-a. I remain Your most obedient servant, Sir... Rusted Esq. [Presently sans H-a.]

I'm nor sure whether this qualifies but it has a Baader solar film filter. Mercury Transit 7" f/12 R35 iStar on an old Fullerscopes MkIV. The transit lasted so long I fried the original VFO drive electronics! Images from Neximage camera.

Hi Peter I've searched around the subject of your H-alpha conversions but still don't have enough info to DIY my 7" f/12 R35 iStar. Or even know if it is a suitable donor for conversion. So I've PM'd you in case you'd prefer to keep your exact methods a secret.

Thanks for the honest and realistic review. Everything in life is a compromise. The dealer and wholesaler are expected to make a profit and then there's the freight and VAT. It doesn't leave much for the manufacturer to spend on making the instrument itself after they've paid their wages, taxes and heating bills. Use this thread as an important lesson in OTA length V class of mounting. Bresser are not alone in hiding the great length of their refractors by using a ridiculously long drawtube. Vixen did it on their refractors at both ends even on their 90mm F/11. They hide a ridiculously extended lens cell inside a ridiculously stumpy dewshield. [Add dew, to taste!] And then use a ridiculous length of drawtube to reach focus even with a star diagonal. All, so they can use a much shorter main tube like it's a pretend Apo to the desperately wishful thinking. Bottom line, for me, is to decide whether the objective lens quality of this 'scope really warrants scrapping everything except the nice lens in its cell. It really wants a longer alloy tube, proper rings and dovetail and a decent focuser. Now add in the cost of a much better commercial mounting, tripod or pier. Bresser only offers the illusion of a quality OTA to those expecting quality well above the asking price. Reality is [arguably] several hundred dead squid above the very low retail price. Instead of buying a more expensive refractor I'd suggest using the plastic clam-shell to add a couple of plywood, altitude bearing disks. Then mount the Bresser on a Berry-style, counterbalanced, offset, plywood fork on a simple but solid wooden post pier tall enough to be really useful with a refractor. Years of fun at ridiculously low cost for what sounds like a fairly decent 90mm refractor lens. Add an ATM solar-foil filter for solar fun without the flames. Transits anybody? Add 'proper' rings and a couple of altitude bearing supports for serious support. The cast rings cost absolute peanuts whether new or secondhand! CNC really means massed produced by unskilled, bored and unhappy workers. My generation would have given several kidneys apiece to own a half-decent 90mm achromat. The initial purchase is just the starting point of a lifetime of ATM improvement and free, manual skills training. Then there's the years of enjoyable observation brought to you by Bresser at remarkably low cost. Just think of the savings, spread over a lifetime, compared with chasing the endless, commercial rainbow of over-optimistic expectation and exploitation of those acquisitive desires!

An offset fork, Berry style, plywood, Dobby, altazimuth mounting can be made by anyone who can wield an axe or blowlamp, or both. Teeth or saws optional. When I were a lad... 1980s? 5" f/15. [12" f/5] The second image shows the "raw" refractor on scaffolding tripod.

Hi Many thanks for all the positive comments and the "likes." Most of my collection of astro "bits" was bought secondhand except for the 7" iStar objective. My heavy duty GEM was built almost entirely from scrap metal to cope with the long and heavy load.

Just a selection of my refractors. The piers are self welded and far too massive to lift. For decades I longed for Fullerscopes mounts. I started with a used, driven MkIII and then bought a driven MkIV as well. Vixen 90M f/11 on a MkIII. Celestron CR150HD on MkIV. iStar 180 R35 f/12 with stumpy dewshield very under-mounted on the MkIV. And finally, the same 7" lens "folded" with two 1/20th wave, optical flats in a DIY Porsa framework on my home made GEM with 2" shafts on a temporary test stand.