Intriqued by Specialty Filament Materials - Part 2

It was a bit more of a struggle than it needed to be but I finally have my first good print using a carbon fiber reinforced material!

I had assumed that any new material was going to require some calibration and this did take a little time and a couple prints.   What I had not anticipated was that my attempt to save some time by leveling my build platform using some PLA filament would jam up my new stainless steel nozzle!   The result of this was a complete and total inability to consistently achieve good adhesion of that all important first layer!

The filament that I am using is from ColorFabb (XT-CF20) so I contacted them first.   They were very responsive and me through some settings to try but to no avail.   I then contacted Carl at 3dSolex (who was also very responsive) and a couple of emails into the conversation he hit on the PLA issue as a possibility.  I asked if an atomic clean would help and he suggested maybe ten or so!

Having nothing to lose I started doing some atomic cleans.  First I tried with the XT-CF20 and no matter how hard I tried using different extraction temperatures the filament was breaking off above the nozzle.   I also tried some ABS with the same result.   Then some more XT-CF20 also with the same result.   Then it occurred to me that the reason I invested in a stainless steel nozzle was because of the abrasive properties of the carbon fiber filament so I just sat there and pumped some filament through the nozzle.

The end result was a nozzle that layed down the XT-CF20 nicely!  Basically just like my other filaments with a couple of caveats that will be discussed below.

So learning #1:  Don't print PLA through your nice new stainless steel nozzle!  That is what the brass ones are supposed to be used for (and why you invested in that nice upgrade that lets you change nozzles in under a minute)!

My other learnings in regards to calibrating for the XT-CF20 material were as follows:

• Even with the nozzle working again the XT-CF20 seems to be more sensitive to the condition of the build platform than PLA or ABS.  Make sure it is level and then clean it really well.   I used a liberal layer of hair spray as that is one of my go-to bonding agents but others will probably work as well.   
• The stainless steel nozzle does not heat as well as brass which demands a slower print speed than you might be used to with other nozzles/materials.   I use Simplify3D with a base speed of 2400-2800mm/min for most stuff that I print in PLA or ABS.   I will use 1800-2000mm/min for really quality results.  With the stainless steel nozzle I printed the above piece at 1400mm/min!   I suspect that I can go faster but will need to find out where the ceiling actually is.

The Simplify3D profile that I used can be found here.  Some of the key attributes of that profile are as follows:

• Extruder temperature of 255c from beginning to end.
• Build platform temperature of 90c to start and 80c after layer 1.
• Fan of 40% to start and 100% after layer 1.  This seems counter intuitive to the higher build platform temperature for layer 1 but I did find that it helped where layer 2 started on top of fresh layer 1 material (which Simplify3D is apt to do given its tuning for speed).
• First layer 100% extrusion rate (make sure your bed is level and don't use this setting to try and cheat)!
• First layer 50% speed (50% of slow is really slow)!

I think the above sums up the most important of the parameters.

As I mention above, I am now able to consistently print with the carbon fiber reinforced material.  I think that I still can improve on the calibration a little but now I need to remember what it was that I really needed to print with this really cool stuff!

In my next post on this topic I may try some rigidity and strength tests but we will see what else distracts me first!