Gina

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.

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.

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

I see he has updated that script recently. I use an earlier version on my RPi 3 and 3+ SBCs very successfully.

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!

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!!

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.

With the improved weather I've been able to take the pulley out to the observatory and check it. Fine for diameter but a bit too wide a groove so have adjusted the design and about to print another.

Now printing in white PETG.

Yes, I have PETG - my favourite type of filament for this type of application.

I think I'm wasting my time with the lathe. This pulley is too big for this lathe! I'm going for a 3D printed pulley. This is 130mm OD with bore to take a pair of 8mm x 24mm x 8mm ball bearings

Hmm... Looking at the extreme strength you get with your printing Chris I'm thinking I was misled by someone thinking a 3D printed pulley would not be strong enough for a pulley in the chain drive for my roll-off-roof, so I've been trying to turn one on a lathe that is too small for the job!

Nice job - as always

Turning is proceeding... Time for a cuppa break...

Quite a lot of cloud about here including some thin cloud in front of the moon.

Beautiful orange full moon has just risen in the east here.

According to my earlier posts on 31/01/15 in this thread, I turned the chain groove in the large pulley on my lathe but ATM I can't work out how. The pulley will fit in the lathe but there's a problem getting any tools far enough out to cut the groove.

That pulley has been putting up a pretty good fight. My lathe is too small really.

More lathe work on the pulley today.

Been turning the outer groove in the new small pulley. There's quite a lot of material to remove.

I found recompiling Marlin for every little modification did my head in!! Getting the Duet was a revelation - after many a dull dreary day, the sun came out!!

My Giant printer is in the upgrade process but shelved for the time being while I get some higher priority projects done. Next incarnation should have a printing volume of 500mm x 500mm x 800mm but it may not quite reach this.

That now give this as the latest update to the main diagram.

Here are my thoughts on the RPi to Nano connections :- SDA and SCL (GPIO 2 & 3) have 1K8 pull-up resistors I've read. The relatively low value should help reduce interference on the lines to the limit switches. These could connect to A7 and A6 on the Nano. The control lines from RPi to Nano can be GPIO 22, 23, 24 and be wired straight across to A5, A4, A3. The Schottky barrier diode can go to GPIO5 and D13. That keeps the connections as short as possible and all on the near side of the Nano.

This table shows the GPIO pin PullUp or PullDown state on Power-on.