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Gina's Observatory Roll-Off-Roof Automation


Gina

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This should be the final print if it goes through without problem.  Sill using a 1.2mm nozzle but just 0.5mm layers and solid fill - no slim-line print this!  The previous run pulled a couple of shaves of glass off the bed.  This is without anything to aid adhesion - just a scrupulously glean borosilicate glass plate.

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let the bed cool down to room temperature, before trying to remove, & use a Stanley blade, gently eased under a 'corner' and left for a while, to start easing the print off.   

Shaved glass is one of the reasons I gave up on glass beds, soo much easier with PEI sheets.....

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The print had had hours to cool down while I was out this afternoon.  It wasn't stuck and seems to have pulled the glass off when it cooled.

I had thought of getting a PEI sheet but not cheap for a 300mm x 300mm bed.  And not available for my Giant printer bed!!

Edited by Gina
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This glass plate has only just started doing this though I've had the problem with the small plates before with ABS.  Don't think I've had the problem with PETG or PLA before.  The latest print, which went all the way though, started making cracking noises as it cooled and came off without any effort when cold.  I found it had taken a couple more chunks of glass with it!

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Time to throw the plate, there's a good chance it mat crack-up leaving very sharp shards lying around.... 

PEI sheets are getting cheaper, e.g. a 'named brand' https://www.amazon.co.uk/Aleph-Objects-Inc-KT-HB0000-LulzBot/dp/B018G59B82/ref=sr_1_4?crid=17WDDKYA0HWG4&keywords=pei+sheet+300x300&qid=1566116061&refinements=p_72%3A419153031&rnid=419152031&s=gateway&sprefix=pei+%2Caps%2C136&sr=8-4

or a cheaper 'no-name brand'  https://www.amazon.co.uk/SOOWAY-Printer-Adhesive-Compatible-Creality/dp/B07R6RBB5B/ref=sr_1_1?crid=17WDDKYA0HWG4&keywords=pei+sheet+300x300&qid=1566116061&refinements=p_72%3A419153031&rnid=419152031&s=gateway&sprefix=pei+%2Caps%2C136&sr=8-1

If you go for a PEI sheet just make sure you get a self adhesive one, and I just stick mine to the bed sheet (after misting with water, to ensure no bubbles).... 

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I'll try the SOOWAY one I think unless you think it worth going for the more expensive one.  Need new glass plate too.

Edited by Gina
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For the cost, its worth a shot, but as I said, I don't bother with a glass sheet, as that's just something else to lessen the heat for the bed, gets broken etc. especially if your bed is a flat milled ally sheet, else the glass plate may be needed to ensure a flat surface.

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I don't have a milled aluminium sheet for the bed, just a borosilicate glass plate and mains voltage silicone heater pad.  I do have a 500mm x 500mm x 5mm ali plate as one option for the print bed for my Giant printer the other being float glass plate both with 400mm x 400mm silicone heater pads.  I generally find glass works well with PLA and PETG.

Regarding PEI sheet, there were two lower cost option I was looking at one with 0.3mm and the other with 0.5mm thickness.  I guess the 0.3mm would be better for getting the heat where its wanted.

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Amazingly, I've found a PEI sheet big enough for my Giant print bed :-  PrimaFil PEI Ultem sheet 500x500mm-0.2 mm

I feel half inclined to buy it now before the pound drops still further against the Euro.  I'm pretty sure I shall be resurrecting my Giant printer before long.  I have done a lot of work on it and spent a fair amount of money too.

Edited by Gina
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Been out to observatory and fitted new small chain pulley.  Also altered fixing to roof where spring attaches to an eye bolt so that I can adjust the chain tension.  Photos to follow.  Having a cuppa break ATM.

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That operates the clutch.  Disconnects the motor drive (worm gear) from the drive sprocket so that the roof may be opened or closed without running the motor or in event of motor failure.  It's self-latching so one pull disengages and stays disengaged then second pull releases it and it engages.

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Raining now so just as well I've finished outside.  Did have a brief shower this afternoon too but nothing much.  But the rain has reminded me that I haven't mounted the rain detector in/on the observatory yet.  There always seems to be something else to do.

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On 18/08/2019 at 09:19, Dr_Ju_ju said:

Time to throw the plate, there's a good chance it mat crack-up leaving very sharp shards lying around.... 

PEI sheets are getting cheaper, e.g. a 'named brand' https://www.amazon.co.uk/Aleph-Objects-Inc-KT-HB0000-LulzBot/dp/B018G59B82/ref=sr_1_4?crid=17WDDKYA0HWG4&keywords=pei+sheet+300x300&qid=1566116061&refinements=p_72%3A419153031&rnid=419152031&s=gateway&sprefix=pei+%2Caps%2C136&sr=8-4

or a cheaper 'no-name brand'  https://www.amazon.co.uk/SOOWAY-Printer-Adhesive-Compatible-Creality/dp/B07R6RBB5B/ref=sr_1_1?crid=17WDDKYA0HWG4&keywords=pei+sheet+300x300&qid=1566116061&refinements=p_72%3A419153031&rnid=419152031&s=gateway&sprefix=pei+%2Caps%2C136&sr=8-1

If you go for a PEI sheet just make sure you get a self adhesive one, and I just stick mine to the bed sheet (after misting with water, to ensure no bubbles).... 

How long do the PEI sheets last and are they easy to remove & replace.

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PEI sheet and glass plate are on their way here so I'll be able to fix my Concorde printer this afternoon ready to make a bracket for the rain sensor.  I've decided where to put it and that's on the drop-down window, well away from the main roof in a clear, open space.

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Phew!!  Well I managed to get the PEI sheet on the glass reasonably flat - a few bubbles and ridges but not bad overall.  I'm not sure the PEI sheet was a good idea - the print, though cold is stuck to the sheet!! 

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I managed to get a thin, small screwdriver under one corner of the print and lever it off.  With just glass prints came loose when cool.  Also, the surface of the print against the PEI sheet is very rough unlike the mirror finish obtained with glass.  I'll try it a bit longer but so far I'm not impressed.

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Is it a vacuum/atmospheric pressure effect which causes the printed object to cling to the glass surface?

Why not just use baking paper if it is the print simply sticking to any surface it can adhere to? :smile:

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