Need some suggestions with a problem...

[Daniel Porter]

So I also posted this on the Reprap forums here:
http://forums.reprap.org/read.php?1,200144

In short the problem is this -
1) waviness in the wall profile
2) hot end eventually starts to touch the top print layer

I installed the new MK-IV hot end and calibrated it.  The black (Octave) ABS extrudes but requires a little more force than usual (this has been reported for the MK-IV hot end before).  The new hot end has been cleaned with acetone and an air gun.  It was spotless and the prints I have in the link were done afterwards.  E was calibrated using a 100mm jog that I printed from Thingiverse (measured it with calipers too, it is dead on 100mm); I tell it to extrude 100mm at 50mm per min and it does 98mm pretty consistently.  Measured the X, Y, and Z with 3x10mm moves... the distance is dead on 30mm.  Played with the tensioner and looked at the filament afterwards... looks like a good hold.  The extruder has been cleaned thoroughly by dis-assembly and an air gun.  The new hot end seems pretty rigid.  Belts are reasonably tight.  Slic3r settings seem to be pretty stock and the ABS sticks very well to my kapton and slurry.  Using 0.4mm MK-IV and I even measure the extruded filament which was about 0.56mm (the amount the g-code file calculates).  Trying to do 0.2mm heights.

Some history to the problem that might be of interest are:
-The original hot end only had PLA in it and eventually clogged pretty badly.  This caused some prints where plastic did not extrude and eventually had the E-gear eating the PLA in a c-shape.
-Cleaned the old hot end and it now extrudes perfectly... but it is having the same problem as the new hot end which leads me to think it is something else.

Any ideas you men of real genius?  Anything will be helpful.  Been fighting this for two weeks.

Thanks
Daniel

[#]

i dunno much but usein the black octave an same print head  i normally print at 196c but with the black i set it at bout 202c which printed better and also enclosed my printer which really really helped with my prints curling or distorting ,        hot end touching your print sounds like bed leveling needs to be redone maybe i dunno 

  im useing marlin firmware on a Sanguinololu with slic3r i can share my profiles if that helps ,  im no where near the machine so ill have to post em later

  other then that i dunno ,,

Daniel

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[Daniel Porter]

Did you insert a new thermistor table for the new MK-IV hot end?  Sounds like your using the default one for the Epcos 100K to use 196C. 

I checked the bed leveling and it is great on all four corners (far distance). 
The rubbing  seems to be the worst at the edges of the print.  I wonder if the plastic is compressing in the hot end and gradually oozing too much, thus causing a lot of build up right out of the nozzle.  Maybe adjusting my retraction length would help.  Been using 0.5 to 2mm retraction for now. 

Adjusting the Z-axis when it was fine before seems like a bad idea; though maybe temporally increasing the number of steps per unit on the z-axis can be tried.  My worst fear is if the steppermotor w/ gear tran is damaged but it seems to operate fine.  Might just rip my hair out... if I had any.

Daniel

[#]

http://www.youtube.com/watch?v=JZGdMc2ebPo

//// Temperature sensor settings:
6 is 100k EPCOS - Not as accurate as table 1 (created using a fluke thermocouple) (4.7k pullup)

also you can play with the Extrusion Multiplier in slic3r seemed to me i needed to change it there  .50 .79 .75  ,etc,,        .75 for that head seems to work for me

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