Dual extruder, second extruder knocks/drags on print only after rafts are done...

[codejoy]

Got a lot of help from my other thread here:

http://3dprintboard.com/showthread.p...7179#post77179

I have been printing other things, this hello kitty one I printed for my kiddo worked great:

http://www.thingiverse.com/thing:25609


So after getting that print, good cube and a decent other print of my many tested meeple:


http://www.thingiverse.com/thing:403964

I wanted to revisit my catan tile:
http://www.thingiverse.com/thing:26979

So i was happily printing it out, using makerware (last time I tried it was replicatorG) and I had my cooler PLA setting , warmer build plate setting all from suggestions above. I had my filament size dialed in and all that so I began to build the tiles...though something new has sprung up has me pulling my hair out.

The build plate has been leveled..time and time again like they say put a sheet of paper and twist nobs till it just barely fits...so I do this to me barely fits is when there is no longer friction sliding the paper around the extruders.

I even used a tiny level to double check build plate it is level everywhere...and that paper fits.

So I begin to build this tile and after all the various rafts are built and it starts to build, the right unused extruder keeps hitting the plastic piece as its being constructed (while the left extruder being used is happily extruding it out)...actually it looks like it is going well but the right unused extruder knocking the plastic on its passes to me is not correct. So I cancelled the build....I cannot figure out why it starts knocking it isn't during the rafting being made either. Is it a cooling rate of the PLA ? it sort of seems like it curls up.. or I noticed on my meeples and others the corners curled up ... it doesnt from the build plate just the top most layer does. No idea what is going on here... I think that is what is causing the knocking is the extruder dragging... this wasn't an issue till this build. It doesn't drag across the build plate just the plastic piece..perhaps the z travel is off or what not on the build plate? Or the sheet of paper is too thin a gauge in reality? Does this mean I have to print a 20mm cube before every print to make sure things are configured correctly or no idea how or why the extruder on the right now sort of drags across the upper layers of a 3d print? And only after the rafts are done and the actual print begins... I could back off the knobs lowering the build plate for clearance but this seems way too far (3mm or so) and I am guessing I am missing something?

[ServiceXp]

Try this thread, I believe it's the source of your problems.

[curious aardvark]

I always calibrate to the point that a 90gsm sheet of paper is tight between the nozzles and the bed. ie: there is a fair bit of friction.

Sounds like you have too large a gap.

bear in mind that once the raft is printed the print head then leaves a small gap between the filament and the surface of the raft. So if you're fairly loosely calibrated to begin with, this gap will become significant and probably cause issues.

Also if you're using pla - why are you using a raft ?
Totally unnecessary. just slaver a fe wlayers of gluestick pva on yhe bed, calibrate tightly and you only issue will be getting the model off the bed ( do it while the buildplate is hot)