There's a Reason it's called "The Drunken Ferret."

This post is for my technical friends, especially those that either have worked on printers, or who enjoy the printer maintenance and modification as much as the other parts of the hobby. It's about an Flsun SR printer, but the experience applies to any printer you may want to upgrade. 

I've been on a much-longer-than-expected journey to upgrade my third 3d printer to bring its print quality (primarily) and performance (secondarily) more in line with my other two printers (A Creality K2 Plus and an Flsun T1 Pro). 

What triggered this is that I have several on-going jobs that would do well on my third printer, leaving my other two free for more immediate projects. I had originally thought that this would be a couple of evenings of installation and calibration. It's now almost two weeks, and I'm just now starting to even approach my old, lesser-quality output. 

A quick timeline that might help others: 

• First, I was going to change from a Bowden setup to direct drive (see my other posts for details on why). I got the parts for that. 
   
• While installing the direct drive, I started having problems with the hot end, with the heat break failing. As long as I was going to have to replace the heat break, I decided to upgrade the hot end, since it was minimal cost and could give me better quality, easier operation, and a wider range of available materials. 
   
• I rebuilt the hot end and direct drive. After some initial calibrations I started a few prints. Absolutely terrible (see picture - that's supposed to be a basic box for testing pressure advance)! 
  
  That particular print has given this printer its permanent name, regardless of how well it ultimately does: "The Drunken Ferret." 
  
  Several nights of calibrating and on-line searching had me try several items. I had some more parts failures and had to order some more replacements. While waiting, I noticed that I had the wrong-size nozzle installed (think garden hose water going through a fire hose. Hard to direct). 
   
• Last night I got the new parts and was convinced that this would fix everything. To my great disappointment it was only slightly improved, still way worse than original. Finally I tried changing retraction, one of the things that must change when you go to direct drive. 
  
  I thought it was primarily to avoid clogs. After correcting retraction, I printed a temperature tower (a test to find the best temperature for the material you're using). To my surprise, the print quality was MUCH better. 
  
  I didn't know retraction could affect print quality so dramatically, especially if it was too high.
   
• It's still not as good as original, but it's nearly there. I know it has the potential to surpass the original, and I know my hardware is good -- in fact, better than what I started with. 

What's working well: 

• e-steps. I calibrated them and retested last night. They are precisely dialed in, excellent.
   
• Temperature. It's much lower with the new hot end, something I didn't expect. It may be because of a longer heat zone and a bi-metal heat break. I was printing PLA at about 220 before; it now shows to be best at 200. 
   
• PID Heating - it's dialed in, and with the new hot end, it both heats and cools much faster than the old setup. 

Steps forward: 

• Retraction calibration. I adjusted last night, which put me in the neighborhood of correct. I need to fine-tune it. 
   
• Flow calibration. I think I'm again in the neighborhood of correct, but fine-tuning also needed. 
   
• Fans. When I added the new extruder, I had to remove a part fan to make room for it. I'm going to find or design a new mount to add that fan back in. Additionally, the wires came free from the other part fan, so I'll have to re-solder them back on. 
   
• Resonance testing. I already did that before the latest iteration, but it wouldn't hurt to verify. Additionally, if I have both fans mounted back, it changes the weight, so it will change the results.
   
• Pressure advance. I tested that recently, but with all the other issues floating around, I want to verify once I think I have the basic quality back. 
   
• Dimensional test - 20 mm cube. I think I'm right on the mark for dimensional accuracy, but I'll check to make sure nothing has changed. 
   
• Later on, I may test max flow rate so I can get the best performance out of the printer without overdriving it. 

At a minimum, my goal for tonight will be to do a retraction calibration and a flow calibration. If successful I'll move forward. 

Anyone with further ideas are welcomed.