Second Layer Blues

I have been experiencing an issue with the second layer of a print. I have a failure rate of 75% where the first layer apparently is created correctly but the second layer fails to extrude anything. This always happens when the layer height is set to less than 0.3mm or I am attempting to print with PLA. PLA has a 0% success rate.

I have tried increasing the extruder temperature and slowing down the print, but so far, nothing. I figure that the problem is that the pressure on the extruder is too high, but I do not know what to do about it.

I have performed a few tests with extrusion and retraction using the buttons on PrintRun. I set the length to 15mm and attempted extrusion, but only ~7mm fed. I retracted, and 15mm retracted, then I extruded, and 15mm extruded (well, fed into the extruder). I then attempted to extrude again and only got ~7mm. This is fairly consistent. I was able to get PLA to extrude 15mm consistently by setting the temp (for PLA) to 220 and the extrusion rate to 50mm/s. For ABS, the temp is 240 and the extrusion rate is 50mm/s as well.

I have attempted to SLOW the prints down, but it only works for “draft” (i.e., 0.30mm+ layer heights) prints using ABS. Everything else results in print failure.

Any ideas or suggestions?

Others will have more advice, but here’s a quickie. Possibly lower the temp and increase the speed… What PLA are you using? PLA has a pretty broad range–some prints around 170C better than 220C.

Can you print the Lulzbot Octopus from the gcode with PLA?

I’ve been able to get a part that small working fine with PLA, but once the part is much bigger (particularly with a large solid layer), I get failures pretty fast with the stock TAZ. I ended up using Scott’s fan mount and that combined with increased temp got me up and running for printing big parts.

You can see the fan mount here:

And get the STL for the mount here:

My PLA extrudes fine at 180C when just extruding into the air, but I found I needed to use 195C whenever I was printing bigger parts. Of course, when I do that, I start getting heat creep which is when I had to start using the fan mount. Before, I was getting a failure as early as the second layer of my prints, but I finished a 5 hour print just the other day using the higher temp + fan combo.

One other thing to check is your idler tension. If you pull the filament out after a print fails, is there a little half moon carved out? If so, it’s probably tight enough, but you may need the higher temp and/or fans. If there isn’t a gouge, then your idler may not be gripping tight enough so you’ll want to tighten it down a bit. I ended up backing my idler off one full turn on each screw (from the tightness I use for ABS) - I don’t know if that actually helped my prints, but the print worked so it didn’t hurt.

One other tip some users suggested is turning off retraction entirely. You’ll get more ooze that way, but if your filament is getting stripped by the hobbed bolt turning retraction off may help. I didn’t have a lot of success with this (the print might have gotten a little further, but never successfully finished), but it’s worth a try.

  • Adam

I will give these suggestions a try and let you know how it goes.