Layers after the first layer are incomplete
Hi there,
I am facingg a problem with my printer, where the layers (the stable infill) after the first one, are often incomplete and not well made. It is like one line or several are totally fine, but the next couple ones are either not there at all, or not well made, and really thin. This happens randomly, and also affects the stable top infill. But like I said the first layer is totally fine. I already tried increasing the extrution width, and the flow, but it didn´t help.
Re: Layers after the first layer are incomplete
That looks like intermittent jamming of the extruder, or excessive resistance to pulling filament off the spool. Try increasing the hot end temperature 5 or 10 degrees, and maybe increase the tension on the idler. Also make sure that filament feeds reasonably easily off the spool.
Re: Layers after the first layer are incomplete
Thanks for replying, I tried all these things, but it didn´t help. But I thought about the difference between the first layer and the following layers. And I found it´s only the bridge fan, that is active with the other layers. So I disabled it and until now everything seems to be fine, though the print isn´t finished yet. It may be, that the fan cooled the filament down too much.
Re: Layers after the first layer are incomplete
Good point. I have definitely found that having the print fan running does cool down the nozzle tip, which means the plastic starts to solidify (or at least get more viscous) before it gets all the way out of the nozzle. It's basic physics: the heat is being applied several mm above the nozzle opening. Blowing air across the nozzle will set up a competition between heat going in at the top and heat going away at the bottom. If you get to a part of the print where you really do need fan, then you may have to increase the nozzle setpoint temperature even more. For most plastics, there's no damage caused by being 20 or 30C above the standard melting point.
You don't want to leave PLA sitting stationary in the hot end at high temperature for a long time because it will start to "char", but flowing through while printing is OK.