3D Printing Just installed a Micro Swiss hotend -- fan question

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Bill Hanson

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Finally got some downtime between projects and have installed a new Micro Swiss all-metal hotend for my Ender 3 Pro. (also switched to Capricorn tubing) The install was pretty straightforward, and I followed the video instructions on the Micro Swiss website.
I had to adjust the z-stop slightly upward and after a quick re-level it seems to be working great. The 20mm XYZ cube came out very nice. I'm going to run another complex print test, but so far so good.
At the end of the install video, Micro Swiss suggests reducing the retraction to no more than 4mm -- easy enough.

They also suggest keeping the fan on 100% at all times, which raises a question. I'm printing PETG, and my current settings are:

0 fan for the first 3 layers
Regular fan speed 60
Max fan speed 80
Initial layer speed 20 (for 2 layers)
Print speed 40
Extruder 245, Bed 75
Initial layer height 0.3

I'm thinking they meant the advice to keep the fan on for printing PLA rather than PETG. Can someone give me a sanity check on this?

Thanks in advance!
Bill
 
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Hot end fan should run constantly to keep filament from melting in the feed area, part cooling fan is dependent on what you're printing. Are you possibly confusing the two different systems?
 
I get best results on most parts printed in petg using no part cooling fan at all. When you get into taller/larger diameter prints you can actually hear "cracking" noises as the print head moves to another area due to the material cooling too quickly being so far from the bed heat. That's where heated enclosures would be a good thing.
 
You also might want to try reducing initial layer height a bit while adding a percent or so to your extrusion multiplier for a "better" first layer. And try slowing it down to around 20mm/s for print quality. Every thing I've printed slower to date has had a much better fit/finish.
 
Hot end fan should run constantly to keep filament from melting in the feed area, part cooling fan is dependent on what you're printing. Are you possibly confusing the two different systems?

Could be. The Micro Swiss instructions just say “fan”. I wasn’t aware that you could turn off the hot end fan in the slicer settings — at least in Cura 4.0
 
Progress report. Tried with just my regular PETG settings (see OP) but got lots of stringing on the test prints, plus some elephant foot.

After a lot of iterations, I ended up dropping the temp 5 degrees to 240 (opposite of what Micro Swiss recommends), kept retraction at 5mm and increasing travel speed to 160 mm/s and accel to 6000 mm/sec^2, plus enabled coasting from the experimental settings section.

Other settings stayed the same. Printed at 20 mm/sec, 0 fan first two layers, plus first layer 2x height. Then 40 mm/sec and 80% fan the rest.

Before/after pics below. Still not perfect, but certainly acceptable.
Got a little front left corner warp on the large test print, but that’s another problem.

IMG_7510.jpg
IMG_7511.jpg
 
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