Gina's Observatory Roll-Off-Roof Automation

[Gina]

The instruction booklet appeared to have around 50 pages but when I looked at it, only 7 pages of English and the rest in all sorts of other languages.  Most of the space is occupied by rather poor diagrams/pictures and the assembly info is decidedly scant   But doubtless I can work it out   Somesmall errors in translation...

Anyway, I need to get my health better before I can do anything about sorting out the fitting.

[keithatrochdale]

Don't forget there is a light that turns on when you use the opener, maybe change it to a red LED?

Hope you are feeling better.

[Gina]

Don't forget there is a light that turns on when you use the opener, maybe change it to a red LED?

Hope you are feeling better.

Thank you Keith   Yes, I know about the light.  It goes off 2 mins after the operation though so shouldn't be a problem.

[Gina]

Been looking into this but the essence of the problem is that both the scope room and warm room are smaller than the roof and, more importantly, the distance the roof needs to travel from closed to fully open is more than the length of either room.  What with that and the toggle latches to clamp the roof down for storm protection getting in the way, it seems that the fixed linear garage roof opener is a non-starter.  If the garage door opener were rated for outdoor use I could put it outside, but it isn't.  It states categorically that it needs to be kept dry

Looks like it's back to the rope and pulley system.  Plastic pulleys running on SS axles and marine grade rope will work outside perfectly happily.  The 12v winch was adequate for operating the roof and the only problem was separating the two lots of rope on the drum.  The winch was designed principally for such jobs as hauling boats up a ramp (and lowering them) with tension on the steel cable all the time.  I guess it would be possible to use a weight to pull the roof one way and the winch the other way, but don't like that idea very much.

I think I can make use of the garage door opener for it's intended purpose once I've repaired the garage roof.  I think it could be arranged to operate the current up and over door.  I would need to arrange the side door to open for access if the auto system failed or in a power cut.  The opener has a release mechanism for that eventuality.  That will be another job for the better weather (spring or summer) if we get any

[Gina]

Post #69 shows the basic arrangement but it will need a modification or two.   The winch nearer the partition wall to clear the roof clamping toggles and the big pulley further along the running rail (towards the right in the diagram).  It might also need an extra pulley or two to get the winch lower down to clear the toggle camp fitting on the roof carriage but I don't think that would be any problem.

Edited December 25, 2014 by Gina

[Gina]

Here are new diagrams of the ROR and winch - with rope shown in blue.

[perfrej]

Gina, spooling is a difficult thing to tame! I strongly recommend a chain instead. If you stick with the winch, in whatever configuration, add a big low ohm resistor in series as a shunt so that you can measure the current and abort if it gets too high. A winch will rip the roof and everything off if left alone to do its thing...

If you want I can help you get a 800 N 12V chain drive motor from a garage door opener as a spare part. I bought one here in Sweden and had the supplier direct ship it to Olly's. I think it was about £150 including UPS freight.

/per

[Gina]

I agree that spooling presents some problems but I haven't been able to sort out chain drive.  With my observatory design, it doesn't seem to allow all the drive system inside.  At least the chain would have to be out in the weather.  If I were starting again I would probably have used a different design but hindsight is a wonderful thing   I could certainly add a current measuring system with a low resistance in series with the supply.

I'll have another look at using chain drive.  Thank you for your offer to sort out a 12v chain drive motor - I'll let you know if I work out a way to use one.  Unless I use the chain from the garage door opener, I will need to find a source of chain.  The other problem is how to disconnect the drive in event of failure.  The 12v winch I have has a manual dog clutch and when free, the cord can be pulled off by hand.

[perfrej]

The drive I use has a clutch. Chain is standard bicycle chain available on every corner for close to nothing... Our's runs partly outside - no issies.

[Gina]

The drive I use has a clutch. Chain is standard bicycle chain available on every corner for close to nothing... Our's runs partly outside - no issies.

I might be able to modify my winch to sprocket drive.  Then the cord could be replaced with chain (in one length, rather than two pieces of cord) going round the sprocket on the winch.  I guess a well greased (or oiled) chain might be alright outside - the main worry would be dirt/grit getting on the chain.  I might be able to reduce the amount outside.  Must admit I do like the idea of a chain drive.

[Gina]

I'll have to measure the length of the links on my bicycle then work out how many links I want - the listings seem to quote number of links rather than length.

These chains look reasonable - 114 links.

Later...  Found another - 116 links 147cm - so that trlls my the length

Edited December 26, 2014 by Gina

[perfrej]

I'm in a bar right now, but I'll get you the motor details tomorrow morning [emoji12]

[Gina]

Cheers Per

I reckon I'll need at least 2.5m of chain - with the arrangement above, more like 5m.  That's 17 or 34 chains and  @ around £4 a chain that means at least £68 or more like £136    Better to use the chain from the garage door opener - the whole lot only cost £80   Maybe the door opener chain is less weather resistant than bicycle chain - it's certainly a lot cheaper!

Edited December 26, 2014 by Gina

[keithatrochdale]

Could always do what we used to do, warm some grease in an old biscuit tin until it melts then immerse the chain in it. We then just used to hang the chain from the garage roof to drip, with the tin underneath to catch the grease. Repeat as/when necessary.

[perfrej]

They last a long time when greased properly, that's for sure. I recall paying about £3.50 for the chains and we bought 3 or 4 of them. Maybe I should just source it for you... 116 links, standard 1/2" by 1/8" bicycle chain, SEK 39 according to the web site...

/per

[Gina]

Oops... I think I got my cm mixed up with my mm    Chain length of 147cm = 1470mm which means I will want 3 or 4 chains as Per said.  Phew!  Thought there was something wrong

Thank you Keith and Per

Edited December 27, 2014 by Gina

[Gina]

1/2" x 1/8" chains seem to cost a bit more than 1/2" x 3/32" chains as might be expected but the difference isn't that much in the overall scheme of things

I wonder if 3D printed ABS would be strong enough for sprockets

[msh1]

gina this is the stuff you want to use for chains and some latex gloves http://www.ebay.co.uk/itm/Putoline-Chain-Wax-1kg-Tub-Boiling-Wax-motorcycle-chain-lubrication-/350087147453

used it on my motorbike chains

mark

[perfrej]

Yes, they are 1.47 m each. So four of them would cost you in the neighborhood of £12-15. Are you sure you can live with that cost?

/per

[Gina]

gina this is the stuff you want to use for chains and some latex gloves http://www.ebay.co.uk/itm/Putoline-Chain-Wax-1kg-Tub-Boiling-Wax-motorcycle-chain-lubrication-/350087147453

used it on my motorbike chains

mark

Thanks Mark   Already have latex gloves.

[Gina]

Found some printable sprockets on Thingiverse I might try  

[Gina]

One problem with chain is that it only bends in one dimension.  With rope/cord I can mount the winch parallel to the wall which is much easier and gives good access to the clutch.  With chain it would have to be mounted at right angles to the wall with the clutch knob nearest to the wall.

This photo shows one of the winches used as a hoist.  I though I had one of when I had it set up before to open/close the roof but I can't find it.  The clutch knob can just be seen at the left end of the winch next to the spool.

Edited December 27, 2014 by Gina

[Gina]

An alternative I thought of to avoid spooling was to use a V pulley with notches to "grab" the rope and drive it that way but getting enough grip is the problem.  I don't like spooling because it can pile up any old how and also the total length of rope/cord changes as it spools and unspools.  It's partly cancelled out as it winds one end up and unwinds the other but far from ideal.  And I had a problem with making a strong enough partition for the spool to separate the two pieces of rope.  I used Araldite to glue the two halves of the partition to themselves and to the spool but it didn't hold

[Gina]

Been out to the observatory and looked at the situation.  Also took some photos which I'll post shortly.

If I were to change the wall flap from openening inwards to some other arrangement, I could mount the winch on the eastern wall where the flap goes when it's open currently.  That would be a lot easier than mounting it on a heavy bracket at right angles to the side wall.  The partition wall is not available due to the sliding door.  This is how I invisage the design.

[Gina]

Been out again and had another look.  I think I might be able to cut down on the length of chain - particularly the amount of chain that's outside.  The "fly in the ointment" has been the toggle clamp fastening on the ROR carriage as seen here with the roof half open.

However, The dividing wall upright is 75mm wide so could take a reasonable sized pulley - say 100mm OD.  The end of the chain could be attached to the carriage using a block to space it away by some 30mm to line up with the pulley.  ie. the chain and pulley would be clear of the toggle clamp part.  I had originally planned to drill the running rail timber to take the pulley axle (12mm SS bolt with partly smooth shank) but then the pulley would be close to the rail and ROR carriage and would foul the toggle clamp top part..

To get the roof fully open the pulley will have to go further out than the present weatherproofing allows by cutting a piece out of the piece of wood pointed to by the red arrow in the photo below.  The green arrow points to the partition wall upright.  I would have to change the arrangement to stop rain getting in where the pulley will be but I dare say I can work that out

This photo shows the outside with red arrow pointing to the piece of wood that would need notching.  Roof closed.

So this would be the new arrangement of chain and pulleys etc.

Edited December 27, 2014 by Gina