Printer will print perfect calibration cube but spaghetti for everything else..

[3DPHRINT]

Hi - New to this and scrabbling about for some pointers. I have an Ender 3 Pro. After setting it all up I found a 20mm calibration cube, then I did the slicing bit on Ultimaker Cura - Used PLA that came with it. It came out perfect and was 20mm all round. Printer heated base reasonably flat. After a couple of days I thought I'd try and print something useful to me, got it off Thingiverse and this time it would not stick to the base and nozzle was dragging it around - So I double cleaned it with alcohol and after much messing about with slicer, clicking adhere tab, quality changes etc decided to change reel to PETG (with corresponding new slice file/temps). Still no good - I changed the nozzle (hot little buggers are they not...) still no good. Last thing I just tried was putting PLA back in and did a calibration cube - PERFECT. Any ideas please - is it possible it is a bad print file from Thingiverse?. Any assistance appreciated...

[Bikeracer2020]

Suggestion........

Clean and level bed.

Any of the free cad programs will let you draw a square 60 x 60 and just 0.2 thick (one layer thick)
Export this as an STL/step file etc, whatever you are happy with.

Print this, prefereably in several places and look at the result. Use a generic slicer setting for PLA or whatever filament you are using

If you can see daylight between each layer line your nozzle is too far from the bed, if any look like a rough sea the nozzle is too close. Adjustments can be made in the 'Z' offset setting in the slicer, use 0.01mm to 0.05mm plus or minus incremental adjustments until you are happy.

Loads of Youtube videos on getting a good first layer which will then give you good bed adhesion.

[3DPHRINT]

Suggestion........

Clean and level bed.

Any of the free cad programs will let you draw a square 60 x 60 and just 0.2 thick (one layer thick)
Export this as an STL/step file etc, whatever you are happy with.

Print this, prefereably in several places and look at the result. Use a generic slicer setting for PLA or whatever filament you are using

If you can see daylight between each layer line your nozzle is too far from the bed, if any look like a rough sea the nozzle is too close. Adjustments can be made in the 'Z' offset setting in the slicer, use 0.01mm to 0.05mm plus or minus incremental adjustments until you are happy.

Loads of Youtube videos on getting a good first layer which will then give you good bed adhesion.

Thanks for your reply - I'll give that a go. If I'm reading this correctly, I can specify where on my printer base this actually prints?

[Bikeracer2020]

Where you place your files on the bed in the slicer will determine where the printer prints.

The 'Z' offset slicer setting is just to tune the first layer and is separate to and not to be confused with the 'Z' settings when leveling the bed.
Some printers let you adjust the offset on the fly.

[3DPHRINT]

Suggestion........Clean and level bed.Any of the free cad programs will let you draw a square 60 x 60 and just 0.2 thick (one layer thick)Export this as an STL/step file etc, whatever you are happy with.Print this, prefereably in several places and look at the result. Use a generic slicer setting for PLA or whatever filament you are usingIf you can see daylight between each layer line your nozzle is too far from the bed, if any look like a rough sea the nozzle is too close. Adjustments can be made in the 'Z' offset setting in the slicer, use 0.01mm to 0.05mm plus or minus incremental adjustments until you are happy. Loads of Youtube videos on getting a good first layer which will then give you good bed adhesion.

Thank you - It does appear to be a bed issue as in order to get the centre of the bed to have paper thickness clearance, on return to home the nozzle clashes with the corners. I hadn't realised I could reposition the item in the slicer software so after this advice on here, I just got it to print nearer a corner where i could correctly adjust the clearance - Works perfectly. No idea as to why the calibration cube works ok in the centre though? Thanks for all the tips and replies!

[Bikeracer2020]

It could be that the bed itself is not flat or is warped slightly.

[3DPHRINT]

Yes it clearly is - its printing something now and is quite happy producing stuff closer to the edge. I assume there is no way of correcting this without replacing the bed, I did think maybe I could lower on the Z axis onto something and force it up in the centre but I expect it wouldnt stay flat anyway? Any way of straightening them?

[Bikeracer2020]

You could always search Youtube for ways other people have had a workaround.

One way is to determine where the low points are by printing a set of squares or discs just one layer thick and then shim between the bed and the buildplate with adhesive backed aluminium tape that you can buy in rolls similar in size to duct tape.

From memory it's about 0.03mm thick.

Or buy a new bed which might or might not be any better.