New Observatory or what I like to call it, getting ready for retirement.
Hi all
After building several small observatories, I thought it time to invest in a proper dome observatory. Something I can settle back and enjoy in my future retirement.
So where have I been in regard to DIY observatories. First endeavour was a garden shed converted to a roll of roof for a 10" Newtonian on a Samson EQ mount in Wagga. Failed to use this due to joining the Army. Second endeavour was as Roll off box design for a Meade 10" LX200 Classic. It worked well for about 12 months but then we sold up and move house.
Third endeavour was again a garden shed converted to a roll of roof. This housed two telescopes, an ED120 and a Meade 14" LX200. Failed to use this after a period of time due to working in the telescope sales business. Didn't feel like doing astronomy after talking about it all day with customers. Forth endeavour was converting the above roll off observatory into a structure that would rotate. Something similar to a ScopeDome. This housed a Skywatcher 16" Goto Dob, nice telescope but crap observatory.
Final endeavour was back to the Roll off box design, which like the Mill Park version works a treat. Currently house a Meade 12" LX200GPS. During this build I reinstate the pier on the original pier foundations I created when I did the Roll off Roof observatory. It is a substantial piece of concrete, coming in at about one cubic meter. I cleaned and level the top, put in Rebar and used a 10” Storm water pipe as a former and filled it with concrete, very solid.
I have added some photos for a bit of a visual journey of my past endeavours.
Where to now, well after some research and quite a bit of Googling I have settled on Observatory Dome by Charles Baetsen (https://va3ngc.weebly.com/obs---dome-1.html) which includes a plan in PDF format. Currently I am in the process of drafting a scaled up the design. I am working on an outside radius of 2.61m and an inside radius of 2.43m for the dome. This will sit on a square support structure with surface area of 6.8m2 . Overall structure height not to exceed 3m, so as to stay inside council building guidelines so as a building permit will not be required. I still have the paperwork ready in case I need a permit.
Also have fleshed out ideas for the roller, shutter and even a drive system to move the dome. Anyway, tomorrow I will be starting to route out the ring and frame for the dome.
Stay tuned and see you at the next post.
Last edited by anthony2302749; 23-05-2024 at 08:26 PM.
The dome design requires several large plywood rings to be constructed. These are created from arcs of plywood cut to the correct radius and then laminated together to form said ring. I cut out 20 today, enough for 3 rings which will be the base ring for my dome.
I made a tangent arm for the route to allow me to cut out the correct radii. After a little hiccup at the start due to bad maths, one sheet of plywood met its feint.
Today's task was to trim and stack the plywood arcs to form the dome support ring. To get the desired curvature I used a bit of timber as a tangent arm which was measure and drill for the inside radius of the dome, which in my case was 1215mm. This was nailed between the decking boards into the joist below, this allowed me to align the plywood arcs nicely.
The process after this was to align each plywood arcs joint using the tangent arm as a guide, trim if need to get a nice butt joint and repeat. This was done for each of the three layers. Total thickness of the Base ring is 36mm. By the way the bricks are there to hold everything together
Point of note is that the routing was so well executed the inside radius of the ring was near perfect.
Quite the journey Anthony. The new build is looking very nice and I was so happy to see the real drawing equipment just like I learnt to use, not a computer CAD thing. My son can do it faster with full 3D rotation in some engineering program complete with stresses (with no training) but I did 3 years of drawing training with an engineering course and I like my manual stuff, I can't use the computer thingies.
What glue are you using?
I like bondcrete myself, it's basically PVA but waterproof.
Quite the journey Anthony. The new build is looking very nice and I was so happy to see the real drawing equipment just like I learnt to use, not a computer CAD thing. My son can do it faster with full 3D rotation in some engineering program complete with stresses (with no training) but I did 3 years of drawing training with an engineering course and I like my manual stuff, I can't use the computer thingies.
What glue are you using?
I like bondcrete myself, it's basically PVA but waterproof.
PVA, didn’t think of Bondcrete. Extent of my drawing education was at high school. The compass set in the picture is my original from high school, it’s going onto 42 years of age, still in good condition for a Czechoslovakia made set.
So, after a trip to the market for some lovely crepes, then Bunnings, I got started with laminating the first layer of the dome support ring. This meant I had to unstack yesterday's work, raises the bottom ring up on to 25 blocks of 90x45x100mm timber so I could clap the work. Also raised the tangent arm.
I happen to have a stapple gun, hence the compressor in the picture. I realigned the plywood arcs, glued, then clamped and then tacked with two staples. This was done on all seven joins.
Next stage was to glue and laminate the second ring into place. By the way, always good to number your pieces to help with assemble. Glue was applied to each surface which will be in contact with each other. Plywood arcs were then placed into position, overlapping the joins on the bottom ring, clamped and screwed into place. Repeat 7 times.
While the decking is reasonably level, I still went around the dome base ring with a spirit level and made small adjustment to ensure it is sitting level as possible.
Depending how I pullup after work this week I may do the last lay before next weekend.
Cheers
Last edited by anthony2302749; 26-05-2024 at 08:40 PM.
This part has been quite annoying part of the project. I have scoured the internet looking for a lower profile castor/roller with bearings. Most low profile castor here in Australia are roughly 80mm high and anything suitable outside of Australia was out of the question due to cost and other reasons.
I may have come up with a DIY solution, call it an epiphany while enjoy a morning coffee. My solution to a low-profile roller is to use a 1" aluminium tube (which I have plenty of due to ATM project) inserted with two 22mm bearing at each end, 8mm axle (again plenty of). Whole assembly fitted into the top of a PVC pipe cut to length. I am thing of rapping the rollers in heat shrink tube as a form of rubberization.
This roller idea will allow me to set the gap between the dome base ring and the observatory top ring to any height just by adjusting the length of the PVC Pipe which is a cool idea. The rollers will be recessed into the observatory top ring to keep with the low profile. The top of the rollers should not need to sit any higher than 25 to 30mm above the observatory top ring. Just enough space to allow the adjustable steel carriage to fit with out binding.
Also help with keeping the whole structure under 3m. Other reason is I want the entrance door to be tall as I can get it for easier access, back is not getting any younger.
Also pickup from Bunnings today was four of the Rolltrak Adjustable Steel Carriage and Acetal Roller, thought it would be a good means to keep the dome aligned. Hope four is enough.
Anyway, the two pic upload is proof of concepted of the roller idea and the Rolltrak Adjustable Steel Carriage And Acetal Roller.
Cheers
Last edited by anthony2302749; 27-05-2024 at 06:16 AM.
PVA, didn’t think of Bondcrete. Extent of my drawing education was at high school. The compass set in the picture is my original from high school, it’s going onto 42 years of age, still in good condition for a Czechoslovakia made set.
I have a set made in Czechoslovakia and it's amazing quality.
Though I recently did something stupid with my Rotring compass from my several hundred dollar drawing set (including pens) and I can't get the tiny part anywhere. It's an old set 25 years or so but in new condition but the compass itself is no longer available or the parts to fix it (the small thing which holds the lead or needle).
The roller you've made in the last image looks good but how much load will be on the PVC pipe?
I think it would be a possible wear point where the axle goes through the PVC but that would be load dependant.
I have a set made in Czechoslovakia and it's amazing quality.
Though I recently did something stupid with my Rotring compass from my several hundred dollar drawing set (including pens) and I can't get the tiny part anywhere. It's an old set 25 years or so but in new condition but the compass itself is no longer available or the parts to fix it (the small thing which holds the lead or needle).
The roller you've made in the last image looks good but how much load will be on the PVC pipe?
I think it would be a possible wear point where the axle goes through the PVC but that would be load dependant.
Hi , +1 for Leo's comment about axle/pvc wear. Maybe a metal collar could be glued into the pvc pipe to fit the axle into. Anyway watching with interest Anthony.
Cheers, Richard
The roller you've made in the last image looks good but how much load will be on the PVC pipe?
I think it would be a possible wear point where the axle goes through the PVC but that would be load dependant.
👍 it is a concern particularly flexure as it is easy to squeeze the tube and deform the PVC so not a good idea to use standard 50mm PVC. However was back at Bunnings today getting some stuff for work and I had a look in the Plumbing section particularly for PVC which should stand up to the rigours of supporting the rollers and dome.
Found a 50mm Pressure PVC Solvent Weld Coupling which has 5.5mm thick walls so should be strong enough for the task at hand. I will make a Mk 2 version over the next night or so and see how it works.
Other alternative is aluminium tubing or some other method.
Hi , +1 for Leo's comment about axle/pvc wear. Maybe a metal collar could be glued into the pvc pipe to fit the axle into. Anyway watching with interest Anthony.
Cheers, Richard
Going to try 50mm Pressure PVC Solvent Weld Coupling with has a 5.5mm thick walls with should survive the rigours of supporting the rollers and dome. Mk 2 prototype should give me a good idea if not aluminium tube would be the next idea.
Going to try 50mm Pressure PVC Solvent Weld Coupling with has a 5.5mm thick walls with should survive the rigours of supporting the rollers and dome. Mk 2 prototype should give me a good idea if not aluminium tube would be the next idea.
Cheers
Sounds well worth a try. Would be easier and cheaper than aluminium.
Definitely easier and cheaper than going with alloy but the 5.5mm wall thickness should hold up a lot better to wear.
The other simple solution I've used myself is RivNuts (rivet nuts). Now that may have you scratching your head but they are available in alloy and steel (possibly stainless steel too, I'm not sure), if you pop them in then drill the thread out where the steel axle is going through they work well as a sleeve/bush to prevent ware on the softer PVC piping and are cheap and very easy to work with.
If you don't have a rivnut gun they can be secured using a bolt and washer arrangement and I believe there's a lot of information on doing exactly that available online.
Food for thought.
Remember to pop them in place before drilling/grinding the thread out and a smear of grease (lithium spray is good and often cheap).
Were I copying your idea I'd probably go all OCD and drill a hole in the shafts for a grease nipple and a small collar on the axle but I have a metal lathe handy. Come to think of it I'm such a lazy b@stard I'd be more likely to give them a squirt of silicone spray or WD40 when the squealing started hurting my ears. I have to be honest. I do like to think I'd do everything properly but sometimes cheap, easy and no fuss wins, only 80% of the time though, the other 20% I'm pedantic (that means my son gets in my ear).
Gotta be honest with at least myself!
I use to be particular about everything until an OCD perfectionist plumber friend informed me when I saw him doing a rough plumbing job "I've had to accept it's not a perfect world"
I was shocked, this guy was the perfectionist of perfectionists.
I told you my son would get in my ear, he's smarter than I am!
He just mentioned the issue of getting two sleeves square to each other for an axle. Now I'm a quick thinker (it's the only thing I can do in any sort of reasonable time frame) and came up with an instant solution, if you use a suitable length bolt (or threaded rod), a sleeve and a few nuts and washers you can align the two Rivnuts and compress them into place together. Then you only have to drill or Dremel the thread out reasonable square.
Well, that didn't take me as long as I thought. The 50mm Pressure PVC Solvent Weld Coupling is 70.7mm long and 70.7mm in diameter with and internal diameter of 60mm, which equates to 5mm walls. Slightly larger in diameter then I want but it will do.
Process was pretty straight forward, part the 50mm Pressure PVC Coupling in half on the lathe. Marked and drill 4mm below the top edge out to a diameter of 8.5mm, added a couple of 4.5mm spaces and jobs done on Mk 2.
Roller Mk 2 work very nicely and looks solid compared Mk 1, probably pin the axle into place which should be straight forward on the drill press.
P.S. Having the correct tools make the job easier.
Definitely easier and cheaper than going with alloy but the 5.5mm wall thickness should hold up a lot better to wear.
The other simple solution I've used myself is RivNuts (rivet nuts). Now that may have you scratching your head but they are available in alloy and steel (possibly stainless steel too, I'm not sure), if you pop them in then drill the thread out where the steel axle is going through they work well as a sleeve/bush to prevent ware on the softer PVC piping and are cheap and very easy to work with.
If you don't have a rivnut gun they can be secured using a bolt and washer arrangement and I believe there's a lot of information on doing exactly that available online.
Food for thought.
Remember to pop them in place before drilling/grinding the thread out and a smear of grease (lithium spray is good and often cheap).
Were I copying your idea I'd probably go all OCD and drill a hole in the shafts for a grease nipple and a small collar on the axle but I have a metal lathe handy. Come to think of it I'm such a lazy b@stard I'd be more likely to give them a squirt of silicone spray or WD40 when the squealing started hurting my ears. I have to be honest. I do like to think I'd do everything properly but sometimes cheap, easy and no fuss wins, only 80% of the time though, the other 20% I'm pedantic (that means my son gets in my ear).
Gotta be honest with at least myself!
I use to be particular about everything until an OCD perfectionist plumber friend informed me when I saw him doing a rough plumbing job "I've had to accept it's not a perfect world"
I was shocked, this guy was the perfectionist of perfectionists.
I told you my son would get in my ear, he's smarter than I am!
He just mentioned the issue of getting two sleeves square to each other for an axle. Now I'm a quick thinker (it's the only thing I can do in any sort of reasonable time frame) and came up with an instant solution, if you use a suitable length bolt (or threaded rod), a sleeve and a few nuts and washers you can align the two Rivnuts and compress them into place together. Then you only have to drill or Dremel the thread out reasonable square.
Yep, know what Rivnuts are, and interesting ideas keep it in mind if there is a Mk 3 version. I don't think I will get a lot of wear on the PVC. The roller are fitted with 22mm sealed bearing so the 8mm axle can be pinned in place as it does not need to rotate with the bearings. The main issue would be the downwards force causing wear and tear on the aluminium axle.
Probably should create a Mk3 with a Steel axle. Thanks, Leo for your feedback.
With the 5mm wall thickness and the bearings I don't think wear is going to be a problem at all for some time, depending on the load.
I like people who come up with easy solutions for complex problems, it's what I've done my entire life and my son is even smarter. We often use what's laying around for whatever we have to do. The engine crane which removed the 4 litre engine from my Falcon when it blew up I got it bored and rebuilt it myself) consisted of old water pipe welded together and a rotating head utilising a Ford head bolt. A chain block hung from it and the main frame was chained to the steel fence posts. It worked like a dream, until I lifted my big Lincoln TIG welder I bought used from the TAFE with it, damn, my engine was supposed to be around 250KG, I have no idea how heavy the welder is but the 7x4'6 trailer didn't like the load travelling the thing. It now sits in a friends farm shed because I didn't have 2 phase power and was too lazy to design and build something to run it from my single phase house wiring (qualifications in electrical and electronics, and welding and other useless stuff I've long forgotten). I'm looking forward to seeing the progression of your build!
Would be easier and cheaper than aluminium.
