Compacted layer prints
I have a 3 year old Ender 3 with an auto level and extruder direct drive attachments which has seen moderate to high usage. The printer is within extraction box and I am in the UK. After much experiment I find that I get good prints with a smooth glass plate blue-tac(ed) on to the machine bed (I find clips twist the surface) with the bed temperature raised to compensate for this arrangement. I typically use a Sunlu PLA+ filament with a tip temperature of 225 and bed temperature of 80.
As I said before I normally get good prints from this arrangement, however on some larger prints, semi-circular with a diameter of 155mm and height of 36mm the top 10mm has been compacted to about 4mm i.e. the first 25mm of print is as expected but the last 10 is not such that the 36mm part is coming out at about 30mm and the finished surface is rough. Layer height is set to 0.15mm with a wall thickness (sides, top and bottom) of 1 mm and an infill density of 10%. The component has different diameters and section that is deforming is shaped similar to gear teeth and therefore I am using support. I have found that I need to slow the travel speeds to improve the print finish and this part is taking around 16 hours to complete. There maybe a little wear but smaller prints don't seem to suffer from this problem.
After two attempts to print this part and third at one which is slightly different and I knew had a problem. At first I thought that the extruder supply cable had got caught and checked and this seemed to sorted it out, as I printed 2 No with no problems. However it has returned. Any thoughts? If by coincidence over the last 6 months operation of the Z axis downwards causes a high screeching noise, although it is normal when it is going up.