In case anyone has forgotten what dual extrusion entails: You sit there, print a little turd, ahem, test piece, like this, figure out what went wrong, change some setting, and repeat for hours, days, or longer on end only ending when the filament grave pile is taller than you are.
This is why we made tool changers and Y splitters.
But that said, @Brook_Drumm #adoptabot is doing his first dual extrusion.
Nothing worse then dual extrusion … up till now I never got my z nozzle height calibrated … not for lack of trying. The only successful print I had was the dual color trafic cone and a 2 colored cube after that I only printed with 1 extruder
Yep! I have parts of my life I can’t get back spent tuning 2 hot ends!
Love my BCN3D Sigma R17 duel extruder…wouldn’t want to be limited by single extruder…
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Right extruder laying down thin layer of support material as directed by Simplify3D…easy clean up with v4.0.
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Hmmm, I’ve built and tuned 5 dual head machines. Wouldn’t trade them given what I can do with them. While the tuning process takes a bit of time (most of it you only do once) it was quite straight forward and produces excellent results.
If there are others interested I’ll post my procedure…
I’m interested Jeff. Convince me on not bothering with a Chimera
not sure why my post was deleted…
No one deleted anything, g+ is just being finicky, again.
@Jeff_Parish Obviously… We are looking for some good procedures.
Now try getting 50um layer heights!
With a 0.2mm nozzle, 0.05mm layers is the plan…
How are you tramming the two nozzles? Sounds especially hard on a Printrbot plus without bed leveling
Different printer for the 0.2 (dice) and I might use a Y splitter for that.
On the Pb it does have a bed probe and I am doing Smoothie 3 point leveling on it.
I set Z0 then loosened both extruders and let the hotends drop onto a piece of paper. Chimera principle.
The nozzles seem aligned.
@Felix_Garcia_Chaco and @Selvakumaran_Ganesan I’ll prepare and post a write up of what I do. I’ll put a link to it on this thread. It is specific to the ReliaBuild 3D and older Rigidbot printers but many of the concepts are applicable to other brands that can handle two independent nozzles on a single carriage.
One critical element is a mechanically precise printer. If you need to use a Z-probe for your first layers due to poor mechanical design or a warped bed or bent rods then forget about making dual heads work unless they are totally independent of each other. One head will always be too high or scraping off the print of the other if they are on the same carriage.
Another critical element is calibrated filament. Not just mechanically but thermally as well. Your micro steps as mathematically calculated from the mechanical properties of your printer should not change from filament to filament. The physically measured diameter of the filament is not enough. You need to have a way to determine the compensation required for the thermal expansion or shrinkage of a filament as it cools and compare this to your other filaments. you want a perfect transition between the two colors with no over or under extrusion between the two.
Stay tuned. 
@Mike_Kelly_Mike_Make 0.05mm layers with dual heads. That’s typically the tolerance between the bed and tramming the two nozzles to each other. I’ve only tried 0.1mm layers with 0.4 or 0.3mm nozzles. While I print all the time with 0.05 mm layers using a single nozzle looks like there is a new bar to reach with dual.
Go IDEX, and put each hotend on a rail and a fine pitch screw, be able to micro adjust the height on each one when you are calibrating.
You can compensate for variability between the two nozzles using the bed with idex. Assuming your second nozzle is offboard enough to not interfere. Challenging part is measuring the precise position of the nozzle
Right, I guess IDEX is the proper term for two independent nozzles/carriages. Solves some issues and introduces others.
My techniques focus on two heads on a single carriage since that is such a common setup.
All the different ways to accomplish something is one factor of 3D printing that I find fascinating.
@Felix_Garcia_Chaco and @Selvakumaran_Ganesan the basic steps of the process I follow can be found here: https://plus.google.com/113930448883604105560/posts/bepoTcLLkLH?cfem=1
