Upgraded i3S to 3.9 and now have blobs and layer shifts  

RE: Upgraded i3S to 3.9 and now have blobs and layer shifts

Exactly the same problem here. Chalk and cheese in terms of the printing quality after updating.

RE: Upgraded i3S to 3.9 and now have blobs and layer shifts

I agree, the FW 3.9 does not work for me either.

RE: Upgraded i3S to 3.9 and now have blobs and layer shifts

I actually downgraded to 3.8.1, and I'm still having the blobs issue.  I didn't have layer shifting with this print, though.  I never see the blobs happen, but sometimes they are right in the print, and other times they are laying on top of the print.  When they are laying on top of the print, they will get knocked off, and end up as "debris" on the print bed.

I've got some research to do to figure this out.

RE: Upgraded i3S to 3.9 and now have blobs and layer shifts

I don't have blobs, but I'm having a very bad problem with layer shifts. Tried to print 7 setup bars that are only 6.3mm high and fill up the entire MK3S bed and I have not been successful. Did this three times and wasted a lot of filament and time (9 hour print job). The place where the layer shifts occur seem to be random. First print job it was at the beginning. I aborted that print. Second try, it shifted about the middle, had to abort that also. The third time I thought it was going to be successful, but after it finished the top of the parts shifted, so I ruined the entire set of setup bars that I was trying to print. Going to have to downgrade my MK3 to the previous 3.81 final. (BTW, I tried the beta releases of 3.9 (RC1 and RC3) and they all had layer shift problems. Wasted a lot of filament trying the beta's. Thought that the official 3.9 would fix the layer shifting but it still doing it. ☹️ 

RE: Upgraded i3S to 3.9 and now have blobs and layer shifts

I just finished my second 14 hour print job after upgrading and didn't see anything unusual. Prints look great. Not sure why some folks are seeing issues and it may well be due to the firmware upgrade but if so it doesn't seem to be affect every one or every print. 

RE: Upgraded i3S to 3.9 and now have blobs and layer shifts

I think I figured out the blobs.  I bought some "rainbow" pla off Amazon, and it would stop extruding.  The seller thought it was a clogged nozzle.  I doubted it, but humored him and took off my nozzle and made sure it was clean (it was). But when I put the nozzle back on, I didn't do a hot tightening (that may not be the right phrase for it).  You have to heat the hot end to 285C and then tighten the nozzle on.

Anyway, I did that, and found there was a ridiculous amount of filament on the top of the heater block, so I took apart the print head assembly to get to it and clean it up the best I could. When I put it back together, I had some extra screws! So I put it aside for the night and I'm going to try and tear it down and put it back together today to see if I can put all the screws where they belong. 

RE: Upgraded i3S to 3.9 and now have blobs and layer shifts

@rick-s7

I upgraded my printer today from 3.8.1. to 3.9 and my printer started crashing on the X-axis. Something is up with 3.9.

My printer is 3 months old and it was printing flawlessly until the update. Reverted back to 3.8.1 and it's working again.

RE: Upgraded i3S to 3.9 and now have blobs and layer shifts

Well, I tore the carriage apart again today, found where I left out the screws, but broke one of the wires on the heating cartridge!  New one will be here Tuesday, and then I'll put it all back together.  I'll have to disable the firmware version warning, as I don't intend on going back to 3.9.  I'll wait for the next version.

Having said that, I have a TON of faith in Prusa as a company and as an individual.  I know that the next version will be spot on.  Everyone makes mistakes, or course.  It's the track record before that mistake that I have faith in.