Gina's Observatory Roll-Off-Roof Automation

[Gina]

With opening and closing the roof this morning I found where it was/is binding. This is evidently due to things settling a bit over time due to the weight of the roof. Quite easily fixed with a rasp. I though it was getting a bit more difficult to open and close but put it down to me getting weaker

[The Sailor]

I have to be honest I am finding this observatory building a bit crazy, heres me after starting in the yard to building an observatory which I have to say works perfectly and now I have started another build this time in the attic. Each time a build has been started we have come up with ideas and have overcome obstacles to see the ideas a reality, you Gina have your moving roof, for me it's how to put a mount in without putting it through the window in error . Another piece of my puzzle has arrived this afternoon, time to build

Jim

[Gina]

Took my winch apart to see what I could do to stifle the noise but quickly put it back and put it in the plastic tool box, the rubber is between the box and the roof.

Jim

Ah yes.

[Gina]

Well, everyone knows I'm crazy But almost every time I use my observatory or work on it I look at all the woodwork and can hardly believe I built it. There are still a few details that aren't right but for the most part it works and works well and I feel proud Sorry to blow my own trumpet.

[Gina]

Well I've fixed the binding Too a bit more effort than I thought - two pieces of wood needed trimming down. The facia board I managed to take off - after struggling with a stuck screw. Evidently it has rusted in (maybe I should have spent a few hundered more on the job and used stainless steel rather than galvanised woodscrews. Tried unscrewing, drilling out the head etc. but eventually pulled the screw thread through the wood and got a hacksaw behind and sawed it off. Deepened the slot that covers the running rail with circular saw used as dovetail cutter. Then I had to take a tennon saw to the end of the framework. Then put it all back together...

Anyway, now I can push and pull the roof with one finger as I used to be able to do - success! Amazing how much easier it moves on 4" wheels with roller bearings than on wood to wood contact!!! I think there's a chance that the winch might work now Not that I'm doing any more on that today I don't think - need to save myself for a massive imaging session tonight as the forecast is clear well into the early hours (4am). Clear sky now apart from a little cumulus right on the horizon to the south, probably over the sea.

Edited February 6, 2013 by Gina

[Gina]

Did a quick test this afternoon with the polyester cord and the winch easily opened the roof from it's fully closed to fully open position with no trouble at all Intermittent drizzle meant that I couldn't do much. I now have the coach bolts to secure the winch but not the weather. I've also got a much better pulley for the pull open cord.

[Gina]

Bit more progress - made the divider for the winch drum. Made out of plastic - an offcut of UPVC shiplap I used on the back porch with the "lumps" trimmed off. This material is easily worked but quite strong. Glued onto drum with Araldite Rapid adhesive.

[Gina]

I've found out what the knob does on the top of the winch. It'a a spring loaded dog clutch mechanism. When you pull it up it disengages the drum from the motor. It's got a little cross bar and when it's pulled up and turned this holds it out and the clutch free. In this position it's possible to turn the drum though it's quite stiff.

[The Sailor]

Ah, I know you mentioned that in a previous post but wondered if you were on about something else. I found it by accident myself when taking the winch apart looking for a way to put a barrier on the spindle . I used it in helping me to put the start of the cable on.

Jim

[Gina]

Yes, being able to disengage the drum from the gearbox is a great help - I was using the power drive to position the drum when I had it in position

[Gina]

I'm thinking of resurrecting this project once I have the new track and wheels done.  The ability to make pulleys to my exact specification will be a great help

[Gina]

I now have some billets of acetal (a hard plastic with low friction and very low water absorbancy)  6" diameter x 20mm thick and could use one to make a large pulley for the ROR cord.  I'm thinking I might put one outside the scope room at the side of the warm room.   The cord is polyester and waterproof and the acetal pulley running on a stainless steel bolt would also be quite happy in the wet.  The cord could pass through a hole into the scope room to the winch.

Here are some photos of the area in question.

This shows the immediate outside of the ROR in the closed position - south side,
 

And this is the inside - roof closed.

 

Inside - roof open

 

And finally, the other end of the south ROR track showing the peg that stops the roof lifting off at that corner.

[bodtwo]

wonder if i could convert the other halts potting shed?

[Gina]

A tiny step forward in this project - turned the big pulley from an acetal blank   Hoping to finish off the new ROR wheels tomorrow.

[Gina]

To be able to automate the ROR the rubber tyred wheels running on timber are being replaced by V groove acetal wheels running on aluminium angle attached to the timber such that the 90 degrees angle is uppermost for the wheels to roll on.  This will provide guiding sideways so the the pins used for preventing the roof lifting off in storm force winds will line up with their holes automatically rather than needing the roof waggling to line it up.

Here are some photos of the V groove wheels.  For axles these will run directly on 12mm SS partly threadded bolts (the wheels run on the unthreaded part).  The spacing between the 100mm x 22mm timbers of the carrier frames is about 45mm so spacers are required as the wheels are only 22mm wide.  These will be cut from acetal rod when I have finished measuring up.  The south side is already measured and with the running rail offset nearer the outer frame member, the spacing is about 5mm that side and 18mm the other side. 

Having made a mistake in boring two of the wheels I decided to combine the spacers with the wheels.  So I bored out the centres to around 18mm and turned down the 25mm acetal rod to take the wheels with a tight fit - plus drilling and reeming the rod to 12mm to be a tight fit on my aluminium lathe mandrel.  Photos 3 and 4 show these wheels fitted to the rod and that in turn fitted tightly enough on the mandrel to enable turning.  These wheels complete with added hubs, will be right for the south side wheels.

The other wheels were held on the mandrel with M6 screw in internally threaded hole in the mandrel and a large aluminium washer.

Edited January 24, 2014 by Gina

[yesyes]

This makes me want to get a lathe. Luckily (?) I don't have any space for it...

I wonder if 3D printed wheels would be strong enough?

[Gina]

I wonder how strong 3D printed stuff would be too   A 3D printer would be nice but so would a milling machine and numerous tools and attachments to go with it.  I keep thinking of things I might be able to "print" - certainly an attractive proposition   Not so sure about the time and effort required to assemble and adjust the kit

Edited January 24, 2014 by Gina

[Gina]

I've been looking into how using angle for running rails would affect the way the roof rolls back.  Currently only the south side has pins and holes to prevent the roof lifting off in high winds - the north side is well sheltered from the wind by high ground and sheds.  These pins and holes mean the roof wants to be at the same level as now unless I were to change these.  Raising the roof on the southern side would cause other problems too so I intend to retain the same level. 

The problem is that the ROR wall framework has several vertical members that stop just level with the bottom of the wheel carrying frame/carriage and this is only 2-3mm above the timber rails.  The aluminium angle stands about 12mm from base to top of the V.  So it has been necessary to make way for the angle in the botton end of these uprights.  So far I have gouged out the west and east ends with drill and chisel but when I came to try the wheels and aluminium angle this afternoon between bouts of rain I found I'd completely forgotten about the middle supports   I'll have to see what I can do about that tomorrow when the weather is suppoed to be a bit better.

The north side has similar uprights to support the roof but it seems that side has come out slightly lower so I may be able to raise that side to clear the angle.

Here are some photos :-

1. Underside of western end of south wheel frame and uprights
2. Ditto from another angle
3. Groove roughly gouged out to clear aluminium angle
4. Groove cut it eastern end
5. Underside of western end of north wheel frame with uprights

[Gina]

Here are a couple of diagrams showing the new ROR opening and closing system with the large pulley attached to the timber rail just outside.  Terylene yacht rope shown in blue.

[Gina]

I've managed to carve out a V slot in the bottom of the middle upright on the south side to clear the angle.  I now have the V wheel taking the weight and the second wheel all ready to put in - it fits fine   Unfortunately, the weather has put paid to any further progress today it seems, as it's now raining as well as very windy.  If the rain stops I may be able to open the roof again, prop it up and swap the remaining south rubber tyred wheel for the acetal one and get the angle all the way in.

Here's a photo of the south west wheel running on the aluminium angle.

[Gina]

It did stop raining for a while and I was able to open the roof and swap the wheels over.  Also, with the roof propped up I slid the angle runner all the way home.  Then I lowered the wheels onto the angle and tried the action.  I think something is rubbing a bit as it needed a bit of pushing but it's too cold and windy to check that out ATM.  It will open but it's a bit stiff.

Here's photos of the SE wheel with the wall flap in the background - wheel running on angle - and the gouging out to clear the angle track in the middle.  I'll tidy that up later when the wind doesn't go straight through me!

[Gina]

Hmm...  I thought I'd posted more in this thread as I have progressed this project a fair bit since the last post above.  I have new 3D printed wheels and wheel carriers.  Wheels are 100mm OD with ball bearings fitted between printed halves that are bolted together.  The carriers take either axles or the bearings directly and ledge under the timbers that form the ROR carriage.  As with the turned wheels above these have a V grooves and run on inverted aluminium angle.  3D printed carriers provided an easy way of getting the axles at right angles to the rails.  I'll see if I can find the photos.

I'm posting now as I've done a little bit more to this today.   Progress has been delayed due to mislaying a couple of bearings wanted for the north side - the south side is finished.  This morning I finally gave up on trying to find the missing bearings and ordered some more. Then this afternoon I removed the winch that I was using to pull Tim's wheelchair up the steep ramps outside the house, ready to install in the obsy to pull the roof on and off.

Edited September 22, 2014 by Gina

[Gina]

OK - Found the Fotos

Firstly the wheel carriers.  Design model and printed part for the south side.  These take an axle (a smooth shanked SS bolt).

Modified design to do away with axles for the north side which is much lighter than the south side.

And now the wheels.

Cross-section of wheel showing where the ball bearing fits in the middle

3D print design for the wheel halves.

And the printed wheel parts, bolted together with the ball bearing in between.

[Gina]

The ball bearings came today so I'm hoping to install the new wheels on the north side shortly - maybe tomorrow

[Vox45]

Just WOW ! I read in the thread that there used to be a  webcam link ? If there is one availlable I would be interested in following this live