Sudden Under Extrusion

[merakiexpo 0]

I'm having a problem where my prints suddenly start experiencing under extrusion even though the print has been perfectly fine for multiple layers before. Additionally I see that the filament is grinding out in the back of the extruder.

I checked my printer settings based on this guide and they are withing the acceptable limits of 8mm3/s.

Also here is an example of my retraction settings as well.

I'm experiencing this on both an Ultimaker 2+ and Ultimaker 2 Extended. I dont believe there are any problems with the model as it is nothing radically complicated or lots of over hangs.

I'm printing with PLA filament from Hatchbox. I've printed numerous other things before and have not experienced these problems before.

[gr5 2,170]

8mm^3/sec is basically the max speed for .4mm nozzle.  You will get occasional problems going right at the limit like that.  And that's for 230C.  For lower temps like say 210C you are even more likely to have problems.  Typically it just barely works for 30 minutes and then it finally grinds the filament too much and starts slipping too much and you get a failure (ground down filament) at the feeder.  Typically.  It's very hard to say if this happened to you but 90% chance that is what happened.

So try printing hotter and/or slower.  Try maybe 230C or 240C or if you care more about the quality cut the layer height or print speed in half.  Maybe this never happened before  because it's a filament that needs a little more heat.

[merakiexpo 0]

8mm^3/sec is basically the max speed for .4mm nozzle.  You will get occasional problems going right at the limit like that.  And that's for 230C.  For lower temps like say 210C you are even more likely to have problems.  Typically it just barely works for 30 minutes and then it finally grinds the filament too much and starts slipping too much and you get a failure (ground down filament) at the feeder.  Typically.  It's very hard to say if this happened to you but 90% chance that is what happened.

So try printing hotter and/or slower.  Try maybe 230C or 240C or if you care more about the quality cut the layer height or print speed in half.  Maybe this never happened before  because it's a filament that needs a little more heat.

 

Thanks for the feedback. I'm going to try to print it at about 7mm^3/sec. The other guide I read said 10 was the max but i'll try the slower speed and see how it turns out.

I'm printing with PLA so the max temp recommend is 210. What temp would you recommend?

[danilius 118]

Max temp with PLA will depend on a variety of factors, including the brand (or not) of filament you are using, and sometimes the colour as well. So, if you are printing 0.2mm layers at 60mm/sec you might be able to go quite safely to 235C. If you are using a 0.8mm nozzle for 0.4mm layers you will probably want to go lower than that, amazingly enough. I have printed as high as 255C in some specialised cases.

Essentially, the less time the plastic spends in the nozzle, the more heat it's going to need.

So, what you really want to do is use your nose while printing. If the plastic smells very sugary, you are going too high. Also, if your layer edges look a bit droopy, the temp is too high. The shape you are printing will also determine the temperature. For instance, printing a 100mm x 100mm box at 60mmsec will require high temps, but something organic of the same dimensions will require lower temps, because in the case of the box there is plenty of room for the head to accelerate to full speed, but something organic will never get up to full speed, as the head negotiates every little nook and cranny.

[merakiexpo 0]

I tried going hotter and slower print speeds but I'm still having print failures. I might try lowering the layer height and printing slower than 7mm^3/sec.

I would assume it's the models themselves but I used Netfabb to repair all of the shapes. Plus one is just a basic cylinder and not that complicated.

[gr5 2,170]

 

@merakiexpo - what happened to your images? Now I forget what your problem looked like. Now other people will come to this thread for help with some unrelated problem and will get the wrong advice :(