mk8 randomly under extrusion

[kylon_982@hotmail.com]

Hello i would like know, if someone has or had the same problem as me, and could help me to solve it.

Sometimes while im priting, when the extruters retract the filament, the next line printed experiment under extrusion, and i have to push a little bit the filament down in order to keep working, if i dont do this the printer keeps printing without any filament coming out of the nozzle.

I've checked the microsteping motors voltage all them are at 8.57v, measured them, while it loads filament and when its not. The measure give's the same voltage.

Then i checked the nozzle but as i said, its a problem that randonmly appear after retraction, anyway i checked it and its ok, same for the teflon-ptfe tube both are ok.

I've checked the extruder motor, which seems to work ok, and the tensioner, in my case i got the plastic version, but works well too.

In the configuration, i got 40mm/s retrating speed, and have lowered the distance from 1.5mm to 0.8, and still happen the same.


If someone could give me an idea about what its happening, i would thanks alot.

FInally, to add some extra info, i tried to calibrate the extruder the standar firmware is at 93 steps/mm, once i check the real filament load vs the distance expected, there a diference about 6.30mm each 50 mm. I calculated how much the value should be, in order to calibrate it well but, once i change the supposed correct value, it overload more filament than it should....

As i said before... any idea about what should i check or do, i would thanks!

[William]

Hi,
Did you check the gear on your extruder motor?
Was it OK?

[kylon_982@hotmail.com]

Yes i took it off, checked, and reasambly everything, tooth were ok, and it was well tight

[William]

How about exchanging a driver and setting the restraction value to zero?

[kylon_982@hotmail.com]

printed a new plastic feeder and replaced it, under extrusion problem disapeared, but once i try to calibrate the extruder, still happening the same, i change the value from 93 to then needed one to extrude 10cm, and still not changing

[William]

Can't be the feed cause it??I'm suspecting it...
How does it look like?Can you attach a picture?

[kylon_982@hotmail.com]

the one i have its the plastic version of the mk8 that ur selling, that feeder long time ago, got the bearing sticks that holds it broke, i fixed it using a 3 mm stainless steel rod, i worked pretty well after that, a few days ago, i started to had that issue, checked all as i explained on the frist post, so decided to change the feeder and printed this one.

http://thingiverse-production-new.s3.am ... atured.jpg

after assambly and test it, i did this test:

http://thingiverse-production-new.s3.am ... atured.jpg

it printed perfectly w/o any problem, so the underextrusion problem seems to be solve.

But now as i asked before, the question is... why each time a measure 10cm of plastic and load it, it extrude less than 10cm

[William]

got the bearing sticks that holds it broke, i fixed it using a 3 mm stainless steel rod

What's this part?
Obviously,it's the feeder system caused it.Think about what parts you've switched,maybe you can try a new feeder kit?

[kylon_982@hotmail.com]

Here's the feeder kit i had, with small change i had to do

http://imgur.com/a/pcvoK


if i finally should upgrade the feeder kit, would you recommend me the plastic one, or the classic version sold before?

[William]

The metal version may be better i think.