Colorfabb XT Clear leaving burnt-looking residue

[JSanders2 0]

Hi Ultimakers!

I am printing on an Ultimaker 2 with clear Colorfabb XT.

I have the following settings configured:

-nozzle temp: 240C

-bed temp: 65C

-Print speed: 25mm/s for infill and inner shells, 10mm/s for outer shell

-Infill: 30%

I clean the nozzle before each print. When the print is done (90 min), it looks like this:

Some of the residue periodically falls into the part during printing, leaving non-removable brown spots:

Any idea what I'm doing wrong here?

Thanks,

Josh

[Labern 774]

Its just the nature of the material and its a real pain. One of the reasons why i don't use XT anymore.

For XT its best to print with thicker layers ( 0.2+ )which also helps with over hangs and curling. Both of these contribute to the brown build up. Using the thicker layers will also make your print more clear.

Edited April 1, 2016 by Guest

[JSanders2 0]

Its just the nature of the material and its a real pain. One of the reasons why i don't use XT anymore.

For XT its best to print with thicker layers ( 0.2+ )which also helps with over hangs and curling. Both of these contribute to the brown build up. Using the thicker layers will also make your print more clear.

 

That can't be it... Almost all online examples of things printed with XT are not covered in brown splotches... Anyone have a trick to share here? XT seems like a great material otherwise...

Edited April 2, 2016 by Guest

[chrisw 70]

10mm/s is very slow.  I'd try bumping those speeds to 35 infill and 25 perimeter, with the same temp setting.  At 10mm it could be slow enough to cause oozing... maybe the melted material is falling out of the nozzle faster than it's being pushed

 

Also, printing temperature is adjusted to suit the printing speed. If I'm printing fast I want a higher temp, slower printing: lower temp. For that reason I don't think it's optimal to have such a big difference between the infill speed and perimeter speed, because your temperature of 240 is constant during the print, and it may be an ideal temp for the 25mm/s infill speed, but way too hot for the 10mm/s perimeter speed.

Edited April 2, 2016 by Guest

[dafridgie 0]

Hi, I also use XT and agree with the replies about speed.I've found the optimal settings for XT seem for me to be:

242-245oC nozzle temp

Bed temp of 78oC

layer size .2

All speeds constant - 20-30mm/sec

minimum of three shells (3x nozzle thickness)

The 10mm speed is too slow, XT clear and White seem to be most affected by this leaving brown or burnt marks embedded in the print. I spent quite a while trying to get my settings correct, everything I tried at 0.1mm left a lot of burn marks, if you really need to print at 0.1

try.....

237oC nozzle temp

bed temp of 78oC

Layer size 0.1

all speeds at 30mm/sec

it'll be slower but should help, also ensure you dont have any restrictions in your extruder path, I've also seen problems with too much tension on the spool causing an underextrusion and what look like burn makrs in the print until I changed to the iroberts V2 extruder - https://www.youmagine.com/designs/alternative-um2-feeder-version-two

hope this helps, XT can be quite picky to work with, have you considered NGen ?