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About Rusted

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    ATM, imaging, Solar system, photography, blogging, cycling.
  • Location
    Darkest rural Denmark
  1. Thanks, Peter. The half cylinder really has lots going for it. Unfortunately I couldn't get your design past the "planning committee." Geodesic was considered a bit too demanding and perhaps a bit fussy. So we finally settled on a 16 sided trapezium dome as a multifaceted compromise. The hope was to break up the outline against the background trees so it wasn't so [blindingly] obvious from the main road. I set up a half hoop of white conduit as a full scale dome outline and it could be seen for miles! We don't want people falling off the road while rubber necking my modest, rural carbuncle.
  2. Dome rotation motor slipping problem..

    Great discussion, problem solving, real progress and excellent images all make for excellent reference material. Well done, Jannis! I think those long, skewed screws will have to be replaced though. Push longer screws through some alloy pipe to act as straight and rigid stand-offs? Old aerials [scrap TV and radio antennae] provide lots of good aluminium pipe in a number of diameters.
  3. Still making progress on 16 sided, trapezium dome:
  4. Dome rotation motor slipping problem..

    I would not rely on the tubular rail remaining pristine or even dry. Even condensation will greatly reduce friction. Silicone lubrication and a friction drive is not a marriage made in heaven. ;-)
  5. Dome rotation motor slipping problem..

    A spring can be fitted almost anywhere. You just need to rethink the support system to isolate it. Change it from being fixed to the structure and made into a vertically sliding, or even a pivoted unit. A V-groove 'pinch' wheel will provide immediate and greater benefits over your hose drive. IMHO. The V-groove will have a different drive diameter to your present, slippery hose, of course. I wonder if a steel pulley might not offer higher friction than an aluminium one against your steel rail? Similar metals have much higher friction between contact surfaces than mixed metals. Do you have access to a lathe? Or a local school or college with a metalwork department? BTW: Normal [rubber] cycle inner tubes are very grippy but I wouldn't bother getting involved until you've tried a V-pulley. The rubber is not really designed for high local pressures and creeping friction drives. It will probably tear itself to shreds.
  6. Another update: Dome progress: Halfway:
  7. Dome rotation motor slipping problem..

    You have only point contact via the hose drive. The axes cross at your drive point. Instead of adding tyres I'd suggest the skinniest racing size inner tubes. 25x700C? As a keen cyclist I had loads of old tubes at one time. No doubt others do too. Or ask the local bike shop for some secondhand racing tubes? It is quicker on a ride to replace a tube than to mend a puncture. So over the years they build up in the bike shed. The inner tubes can be easily slit and glued in place. Rubber hose is still available. Gas welding kit or fire extinguishers? An alternative is to make a V-pulley which fits your exact needs. It will offer better contact on the tube buy jamming the tube in the V. You can [carefully] turn a plywood pulley on an electric drill if you don't have a lathe. Or rotate your pulley against a suitable router bit if you have a router. Drill plus router? I've made large pulleys from plywood using a drill and sharpened screwdriver cutting tool resting on a support block. And I still have most of my own limbs.
  8. Hi Just another heads up to say that dome rib production is well underway. These will be reinforced with sandwich battens on their outer edges. Then clad with trapezoid, plywood panels rather than conventional gores. The idea is to break up the dome's outline with facets to present a [hopefully] smaller "blot." Paul Robinson's Geo-Dome.Co.UK website may inspire: Trapezium Dome calculation tools
  9. Still progressing with the build: Veranda now planked with larch boards. Tried various mock-ups of potential rotating roofs/domes to ensure telescope clearance.
  10. Is a concrete slab really necessary? Pre-cast Carport footings/anchors are simply dropped into a hole and back-filled with soil. Inexpensive and needs no more than a spade and digging bar/crowbar if you hit rocks. Here are a few being put to good use:
  11. Be prepared to allow the farmer to choose the position and layout of your plot. He may need to get large machines or tractors and trailers around your 'obstacle.' So a strip close to your boundary may be best. Middle of a field not so much. If animals are grazed on the field it will need professional fencing and a secure access gate. We bought a triangle of adjoining land from the local farmer without serious issue. However, nothing was to be built on it and it was only landscaped as lawn. He arranged the pro animal fencers for a very reasonable sum. He kept bulls, horses, sheep and cattle in there so a strong fence was obligatory. Seriously consider discussing renting rather than purchase. So much easier for both of you. What's a crate of beer between friends? Above all, be flexible.
  12. Double Walled Observatory

    My own experience is that metal roofs make a racket in heavy rain. We stayed at a farm with a corrugated metal porch across the yard and it was dreadfully noisy! I clad my home-made shed in 12mm plywood [with factory machined grooves at 4" intervals] 14 years ago. I haven't touched it with any sort of paint or protection from new and it is still fine. It has remained flat, strong and quite attractive if you like the grey/brown [long abandoned building] "knotty pine, weathered" look. The shed has decent ventilation but wood and plywood stored inside gets spotty and my iron tools rust slowly. My fuzzy logic suggests that insulating an observatory will delay cooling and retain any daytime heat buildup. Shiny aluminium remains the coolest useful surface material I have tried so far. Shiny stainless steel and galvanized iron temperatures absolutely soar in warm sunshine! Only new, white, fiber cement roofing & cladding boards are cooler if you can manage the weight and relative fragility. Roofing felt is by far the worst material on the planet for obs. roofs. IMHO. Not only is it very heavy, but temperatures inside soar as you would expect with a dull, black and rough, solar absorbent surface. I built a fairly large workshop with a felt roof on plywood and recorded 103F with the doors and windows wide open! When I covered a 4-6" thick, concrete slab, shed roof, with recycled aluminium sheet, it made it instantly habitable as a workshop. With the original black felt covering it regularly went up to 100F inside, day and night for ages, after hot sunshine. My only experience with white paint was two thick undercoats on a bare, GRP car. That made it cooler in sunshine. Though the windows probably dominated in solar gain. Titanium white paint has a good reputation for rejecting solar gain. Dense shade plants are probably even better provided you can still find the sky. Big pots of shading/concealing plants can easily be moved/rolled/sack-trucked away when needed. Louvered/slatted blinds must have some useful purpose for shading/ventilating an obs. All the sunshine which never reaches a building never needs to be rejected/reflected, AC'd or insulated against. Not a lot of architects, builders, engineers and/or planners seem to know this.
  13. Building an Observatory DIY

    Hi Lars The wind drag on a structure increases as the cube of velocity. Your building might seem safe in a breeze but a gale will quickly move it to Norway, Denmark, Finland or even Russia. Anchors and steel cable guy lines might help if the structure stays together in the first storm to hit it. During the Great '99 storm in Denmark the wind speeds reached only 35m/s. It ripped solid brick and block buildings to shreds, removed whole roofs and damaged thousands of others. It snapped off vast swathes of conifer forest half way up the trunks of the trees and felled lots more. Our neighbour's corrugated steel, double garage roof had been there for years. It was rolled up by the wind and thrown 200 yards over the intervening houses and 50' trees. It ended up half buried in a field behind a farm which looked as if it was hit by a very large bomb. Adding weights wont help. It needs fixing down! Yes, I live in Denmark but I'm British and hoping to remain in exile.
  14. Building an Observatory DIY

    Hi Lars Did I miss the picture of where you anchored the observatory down to stop it blowing away? You could drill the rock and embed studs [threaded rods] in the special adhesive designed for this purpose. BTW: Don't trust the lightweight tarpaulins [presenning] if you want real waterproofing. The heavy PVC tarpaulins are much safer. Or, you could place an inverted PVC water butt or barrel over the mounting and pier to protect when not in use. Regards/ Med venlig hilsen Chris
  15. Hi, Thanks for your interest in my project. It all helps to keep me going. Here's another image taken yesterday after I trimmed and fixed the obs. floor. I had to be careful to isolate the 12' tall 4x4 pyramidal pier posts from the floor. Boarding the veranda is next. Each section will run parallel with the octagon sides. Then I shall need outer railings for safety. And a dome, or rotating roof, of course.