Uneven Printing/Extruding

[funnyluke 0]

Hello together,

I have some problems with my ultimaker.

During the printing the extruder turns all the time. But not all the time the filament is really extruding.

My printings look like this:

http://imageshack.us/photo/my-images/823/y6nb.jpg/

Sometimes perfect extruding with perfect quality. sometimes bad quality because the material is missing.

The filament looks like this after printing:

http://imageshack.us/photo/my-images/856/ndhe.jpg/

As you can see, sometimes the extruderis drilling some material out of the filament and does not push it into the tube.

What can I do to fix this. Already tried to tighten/loosen the extruder screw. But it did not work. Also other filament has the same problem.

Thank you for your help!

 

[illuminarti 18]

Can you post some photos of the extruder drive mechanism, showing it open and closed? Also, what speed settings are you using?

Perhaps you could attach a gcode file as well, so we can see what settings you are using?

 

[olivierc 3]

What temperature are you using? If the temperature is too low, maybe the filament is just stuck because it's not melting properly

 

[mgg942 0]

May be worth pulling out the extruder drive knurled shaft and checking if there is some material residue in the knurling. If so, of course, is should be cleaned out.

 

[gr5 2,167]

You clearly have a problem called "underextrusion".

It's hard to tell without further information, but I think your extruder mechanism is probably fine because of what I see on the filament. More likely your print head is either too cold or your volume through the print head is too high.

Here are some printing speeds that are on the fast end. Printing colder or faster than these will result in underextrusion so either print hotter or slower than these until you are successful. Then you can experiment with colder and faster:

210C 50mm/sec .2mm layers

210C 100mm/sec .1mm layers

240C 100mm/sec .2mm layers

240C 200mm/sec .1mm layers

Note that if the layers are thinner you can print much faster without problems - the overall limitation is how much volume of plastic you can pass through the tiny nozzle without pressures getting too high.

 

[funnyluke 0]

Sorry that it did not answer for a while, I had a busy time.

Right now i started again with the (damn) printer.

As before I'm having some serious problems.

When I start printing the first layer of the raft (thick layer) looks awesome. Than the second layer of the raft (very thin one) has already some serious problems with underextruding. Wheel is spinning but it's not pushing the material. Than the first layers of the print itself are barely even there before for some reason the material is pushing again, After a while it's not pushing, than its pushing again and so on. (Picture 1)

At some point (sometimes) it will stop at all and the printout will look like this: Picture 2

If i remove now the filament, the head will look like this: Picture 3

The crazy thing is, if it gets plugged and I don't do anything besides removing the scrap part and start a new printout, it will work again: no plug, nothing, until it comes to the second layer of the raft....

So what could be the problem?

50 mm/s (everything faster doesn't work at all)

240°C

all other settings standard

I also tried different temperatures, printing speeds and so on, but nothing works consistently :-(

Any ideas? Thank you!

1 http://imageshack.us/photo/my-images/694/32t3.jpg/

2 http://imageshack.us/photo/my-images/694/hqk5.jpg/

3 http://imageshack.us/photo/my-images/827/pc5n.jpg/

 

[aaron 2]

I have had a similar problem but not as extreme as yours. This also only happens when I am using lower temperatures (195-205). What I usually do is preheat the hot end manually and let is sit for a few seconds. Then I use the jog function to manually extrude until there is a steady stream of molten plastic extruding from the hot end. It prints fine from there. Also, be sure that the spring on your extruder screw is compressed between 11 and 11.5mm. Hope this helps. Good luck.