retraction - clean parts!?

My printed parts are really good, the perimeters stick together; I nearly do not get any bending of my parts BUT:

I always get those filament lines when the machine is traveling from part to part - those lines can be cleaned easily on the outside but if you're printing a thread as I did it's not useable.

Can anyone please assist in solving this?

Reprap Prusa
ABS 243°C, white
glassbed, sugar-layer, 100°C
perimeter speed 50
travel speed 50 (usually I travel with 200mm/s but as I printed in the night I do not want my neighbors to stay awake...)
retraction: 1mm (see screenshot)
retraction speed 90 (see screenshot)

WOW!

I can say, I've not seen stringing like that.

I can only offer the usual advice, try lower ABS temperature. I run at 200C - 220C. I find that a higher temp makes my ABS leak more (and cause strings)

With a lower temperature, you might find you need to re-calibrate your other speeds. (slow down your infill, and perimeter speeds)

In another thread I seem to recall someone saying that a slower retraction seemed to help.

Good luck - let us know how you fix it.


Regards

Try slowing down the retraction. Not sure what your setup is mechanically, but 90 seems way excessive. Try 10 and see if the stringing goes away, if it does bump it up to 20 and see what happens. My guess is that at 90 mm/s your filament is actually slipping on retract.

Edited 1 time(s). Last edit at 02/16/2013 11:08AM by Atac572.

Might also try lowering nozzle temp some.

Thanks - also thought about that.

But when I have to print parts with a high volume I have to print with at least 50mm/s (perimeter and infill) - if I also let slic3r fill every second layer my extruder is not able to melt my 3mm ABS properly to press all melted ABS out of my 0.42mm nozzle.


...so I tend not to reduce the temperature of my extruder

Read this thread... I had a very similar problem and following the advice in that thread solved the stringing and blobbing problem completely.

Printed the parts with a much higher retraction length and: SOLVED!

Now I have only small blobs left which do not cause any problem - will slightly tune the values (retraction speed to 10mm/s, try to reduce length) and see what happens.

Edited 2 time(s). Last edit at 02/17/2013 10:04AM by Irgendwer_Aus_Irgendwo.

So my prints were fine for a while BUT:

I changed the settings for retraction now several times -
reduced and increased retraction (0,5-3mm), speed (3-30mm/s) and pressure of the hinge (with the ball bearing) but every few hours of printing the extruder is not able to force the filament through the nozzle and rubs a groove so that the printer is running without extruding material

The temperature sensor gives correct values, I cleaned (Acetone!) the nozzle, checked the extruder + cleaned everything, tried different temperatures (ABS 220-250°C) but after several hours the extruder stopps pushing material out of the nozzle

Please see the picture of the hobbit screw attached - seems to be perfect!?

Edited 2 time(s). Last edit at 02/20/2013 03:21PM by Irgendwer_Aus_Irgendwo.

When it fails, is the hobbed bolt very warm to the touch?

If that bolt gets warm, it will simply chew through your plastic, as the plastic will be softened. I've seen that happen before with various sorts of extruders (particularly those with metal gearboxes), but not recently with a wades extruder.

With a wades, this is usually caused by too much heat rising from the hot end into the extruder.

Note: This applies only if that bolt is hot. If it's not then I don't know what your issue is.

Irgendwer_Aus_Irgendwo Wrote:
-------------------------------------------------------
> So my prints were fine for a while BUT:
>
> I changed the settings for retraction now several
> times -
> reduced and increased retraction (0,5-3mm), speed
> (3-30mm/s) and pressure of the hinge (with the
> ball bearing) but every few hours of printing the
> extruder is not able to force the filament through
> the nozzle and rubs a groove so that the printer
> is running without extruding material
>
> The temperature sensor gives correct values, I
> cleaned (Acetone!) the nozzle, checked the
> extruder + cleaned everything, tried different
> temperatures (ABS 220-250°C) but after several
> hours the extruder stopps pushing material out of
> the nozzle
>
> Please see the picture of the hobbit screw
> attached - seems to be perfect!?

So you solved the problem?
I have the same problem with pushing material. I stop printing, do the reverse of the filament. At the end of filament i see thickening as shown at the photo. I think that it cause.

> So you solved the problem?

Solved the issue by using a better hobbit bolt (looked not much different but my printer works well now).
Additional to that I increased the pressure of the ball bearing a lot - now my springs on the screws are nearly blocked.

The thicker part can be normal as the filament enters your extruder -> the barrel with the PTFE hose and finally your nozzle where it is heatened up - maybe your inner diameter of your nozzle is slightly larger than the diameter of the hose - so don't worry about that.

Many thanx for answer. Now my printer working properly ><