IMG 2178New PETG print after nozzle change.Been messing around for two days trying to figure out how to get decent PETG prints off my A/C Delta printer. Then I remembered my PLA prints were looking a bit crappy for quite a while, too. But PETG is a far fussier material than PLA, so I was thinking, doing a little mental math… 2+2=3.14159265…

Then I looked really close to the printing going on with the top layers on the current test PETG print I was running. “Dang! That nozzle tip looks awful short!” I said to myself.  It’s drawing the shoulder of the nozzle across the top of the print!!

AH… 2+2=4!!  Now the pie is on my face!  The tip of the nozzle is worn off. That hole isn’t 0.4 MM.  It looks like at least 1.0 MM!!!!

Of course, I couldn’t see that at that moment, but it was obvious I needed to change out the nozzle.

With the (very) old nozzle removed, I was able to examine it under my photo microscope and grab these pictures.

Photo on 7 7 19 at 1250 PMThe new on the right the old on the left. Think there was a problem there.  

Lesson learned… Just because it isn’t plugged, doesn’t mean it’s still good…  DUH?!

Yeah, that old nozzle probably made at LEAST 100 good prints or more. The quality was dropping but the present PETG really drove the issue home. I’ll be changing nozzles a bit more often now I see how they wear. 

I was wondering about how nozzles change with time as I was doing my test prints. I have read the claim that flow through them with stuff like carbon fiber wear the hole bigger, but it looks to me that wear off the end is also a big problem. It depends on if the hole is tapered inside or has a fairly long parallel wall hole. This may be a combination of both.

I also read that some nozzles carbon up inside from overheating and the effective hole diameter gets smaller. I bought an expensive steel nozzle months ago and have never installed it. Not even now. I have run a lot of wood PLA through the old nozzle, but it says wood does not wear out the nozzle. That old nozzle has seen PLA. ABS, wood, and PETG. After a good purge, they all flowed fine.

Months ago, when I was playing with printing test parts for a U-Build-It 3D printer, the same spool PETG was not printing quite like I expected. I just blamed it on poor S3D settings. It was probably the point when I should (could) have changed out the nozzle. That old one was in there forever even then.

IMG 2177 Photo on 7 7 19 at 1225 PM
A camera microscope is a handy tool for nozzle inspection and photo capture. The left is the new nozzle. The right was exactly the same, now with at least a 4X bigger hole!
Photo on 7 7 19 at 1216 PM Photo on 7 7 19 at 1224 PM


Now wiser than I was yesterday, this old dog can still learn a few tricks…