Multicolor petg  

RE: Multicolor petg

Ok… I figured it out. The actual temperatures of the nextruder’s heater is waaayyy hotter than the settings say. See my post on another stringing problem. 
Gettin toolchanging to work well and without priming or stringing requires tight tolerances on the extruder temperatures. Too hot and it takes too long for the material to cool and be less watery. As such the retraction out of the melt zone won’t be reliable. Test again tomorrow. 

RE:

Trying again this time with the extruder temp at 220c. Minimal stringing! That’s stringing at both within and between tools. That is, strings that occur going to and from the tools’ parking place as well as stringing between travels with the same tool.

This new extruder has a smaller hot block and the heater is inserted in a different orientation. As such the melt zone shape and size is very different. Characterizing the melt zone on a toolchanger is essential since the tolerances for how hot the liquid material is at specific moments can be key to optimal results. The hotter it is the longer it takes to cool and when you change tools you need to control that. As I always suspected Prusa, who’ve only built Mendel styled machines, would not know this and as usual will depend upon a shrinking cadre of super users.

I did try to warn them! Regardless, this machine is quite amazing!🤩 

RE: Multicolor petg

Another interesting lesson learned with PETG color prints…

You can’t control where the toolpath ends when you paint color on to the model with PS. As such it’s very possible that the zipper will be on the outside of where the two materials meet making for a yucky result. Something to keep in mind when one uses the awesomely amazing paint on color capability PS gives us.

RE: Multicolor petg

Still getting blobs and gaps. So far, multicolor PETG is not so great. I’ll try again with a prime tower, but not optimistic.

RE: Multicolor petg

My experience with SunLu PETG is 205/80 first layer and 215/85 for other layers.  This gave an excellent result with no stringing on a large 200mm cylinder. There was a "disturbance" on the outside wall about 2/3 the height of the cylinder. Looks like a zipper.   I was only using one color black.  I tried 220/80 and it had some stringing.  Has anyone built a temperature tower for the XL and PETG?

RE:

I turned on the prime tower and this time all the blobs went there. See the pic. This is actually not a good solution nor is hiding blobs within infill. Any blobs anywhere can cause a nozzle crash and or knock a print off the bed. Print on the left shows the blobs and gaps, note this object is thin walled. On the right the print had the prime tower.

RE: Multicolor petg

For me,  blobs in petg other that prusament are nearly always because the extrusion multiplier needs to be decreased.  I basically start with .98 for any non prusament petg and usually end up at .97 before all blobs are eliminated.  

RE: Multicolor petg

That’s a different kind of blob. I see blobs with PETG from two sources. The first is from material that did not get drawn up out of the melt zone when the tool is disabled. When the tool is picked up and the material detracts it can spit out this tiny amount as a small blob. The prime tower always gets this blob.
The second blob I see is from a build up of the typical fine whisps of material that PETG always does no matter the temp no matter what the printer is. That’s PETG. It is what it is.

If the flow settings are off (as with ext multi) there’s a lot more defects then just blobs of material!

RE: Multicolor petg

My 2 2kg spools of jet black prusament just shipped today so I expect I'll be doing some multicolor petg prints in the next few days.   I'll see how I fare.   I'm still easing into testing the XL lol