Hi Guys,
Sorry it took me so long to reply and thank you all for your positive remarks.
I'll try to answer you questions the best I can.
Just about all the building materials came from my local Bunnings hardware store.
The pier is made from 4m x 90mm laminated Merboo posts. Being laminated ensures that they remain perfectly straight.
I selected these because steel, althought probably better, would have been far too heave for me to handle alone. I bolted 4 postes together as shown.
I can say now that the pier has pereformed very well and although very stable, it is not as stiff as an equivalent 300mm diameter steel pier would be.
The deck is 4m x 3.5m and the osb is 3m in diameter.
The wall is made from the lowest cost doors Bunnings had.
They are inside doors and cost about $20 each at the time.
These had to be cut to the right height (yep, that's looks about right
).
The cut end of the door had to be resealed using 30mm square pine.
The door was then painted with high quality (Dulux) oil based sealer, undercoated and painted to ensure protection against the weather.
I already knew this approach would work because I made my garage door (folding) in a similar way 12 years ago and they are as good today as when I bought them.
The doors are joined using full length brass piano hinge. Bunnings sells it by the roll. One roll was enough for the whole job.
This also allowed me to position the doors correctly without having to cut any angled edges. Worked a treat.
Then I made a top plate from 150mm x 20mm dressed hardwood, one piece for the top of each door.
These were cut to the correct length and angle and fastened to each door as well as the ends being glued together.
I embedded caster wheels in the top of each door. One per door. I would now recommend using two rollers per door and wheels around 50mm diameter.
A second top plate identical to the one on the doors forms the base of the dome.
This had 50mm aluminium angle around the outside edge as can be seen in the photos and this is used to secure the aluminium bar that forms the dome ribs.
The dome ribs are made from 4m lengths of 50mm x 3mm aluminium bar.
One end is clamped to the angle as seen in the pics and the other end is flexed and secured by directly oposite.
Easy to do providing you use the right number of doors.
When you decide on the diameter of the obs, make sure you have an equal number on each side of centre.
The two ribs that form the slit are installed first and then, all the other ribs just flex over these and screwed to the slit ribs.
This can be tricky so make sure you have plenty of clamps to hold everything securely during this step.
Once all the ribs are screwed in place, the parts that overlap the slit can be cut off with a hack saw and the dome will remain in place and correctly formed.
I then formed a circle around the inside edge of the lower top plate by securing 50mm x 3mm aluminium bar and flexing it all the way around.
It is secured where it contacts the middle of each segment of the plate and forms a track for the inner guide roller (skateboard wheels).
Buy cheap skateboards for the wheels. MUCH cheaper than buying wheels and bearings.
The dome is made from 3mm flute board sheeting (also from Bunnings).
These were not long enough to go the full length and so I had to join each one.
In hindsight, it may have been possible to get the correct length sheets from a plastics supplier, but it all worked out OK with the joins.
The sheets are marked and cut to size and then glued to the aluminium ribs with Contact Adhesive.
The glue is put on both surfaces and alowed to dry until just tacky and then the sheet is put in place and trimmed to the center of the rib where the adjacent sheet will be put.
This takes some time to do but it isn't very difficult.
The end of each sheet is glued and screwed to the angle.
Now a word of caution.
Make sure you make the slit wide enough to allow both main and guide scope to get a clear view.
If you only intend to use refractor telescopes then this should not be too much of a problem.
Now finally, the slit cover is made from 4 sections of overlapping flute board with the lower section at the back of the slit, glued in place and three sections able to slide over each other forming a weather seal.
These sections slide in a "track" made from strips of 4mm flute board glued together to form an E shaped end cross section.
When I want to view, I remove the front cover section and slide the top sections back past the apex of the dome, giving me a clear view overhead.
This has proven itself to work very well, however I have made provision for a flat strap that I use to secure the slit cover in high winds.
Well I hope that this brief sumery is somewhat helpful if any of you decide to use my approach
and would like to discuss any of this further, just drop me a line.
Cheers
Luke
).
Now that's an interesting design. I'd love to see a picture of the inside.
