First layer issues

[tottenham12712 0]

Hi all, finally got my UM2 fired up and I printed most of the test prints with UMs PLA perfectly fine. I switched over to colorfabb XT black and did a few more test prints to get my temps right. Then I attempted to print a part for real and ran into some bubbling/stringing/hair on the first layer.

First I printed at 245C with the bed at 70C, the first layer is printed at 20mm/s with the default first layer thickness as well, fans were on 100% from start. This didnt go very well.

Than I dropped the temp down to 243C and put the bed at 60C, increased the bottom layer speed to 30mm/s and set the first layer height to 0, and added a brim. This helped and Im letting this one run to finish to see how it turns out. Im assuming this is a temperature issue? It seems to bubble up off the bed as if there was air or something under it.

Any help or pointers would be greatly apreciated!

 

[Dim3nsioneer 490]

Relevel the bed as the distance between nozzle and bed is a bit too small.

 

[yellowshark 149]

Also if you have a 1st layer height of 0 then that will cause you problems After you have re-levelled the bed, and check it carefully and again, set 1st layer height to .300 (do not go below this whilst learning, it only makes life harder). Try reducing extruder temp to no more that 220; you don't say what your print speed is but 220 should cover you for most things and certainly OK for 1st layer. Have fans turned off for the 1st 2 layers (no fans on 1st layer!!). Probably set fan to max 40-50%.

Do you have a digital thermometer/ If so check the bed is 60 pretty much all over for a large part before starting print.

 

[tottenham12712 0]

Relevel the bed as the distance between nozzle and bed is a bit too small.

 

Ill try to re-level again, are the test prints not very "difficult" to print if the bed leveling isnt perfect?

 

Also if you have a 1st layer height of 0 then that will cause you problems After you have re-levelled the bed, and check it carefully and again, set 1st layer height to .300 (do not go below this whilst learning, it only makes life harder). Try reducing extruder temp to no more that 220; you don't say what your print speed is but 220 should cover you for most things and certainly OK for 1st layer. Have fans turned off for the 1st 2 layers (no fans on 1st layer!!). Probably set fan to max 40-50%.

Do you have a digital thermometer/ If so check the bed is 60 pretty much all over for a large part before starting print.

 

So the first layer is set to 0 but its not actually 0, its set to layer height which in my case is .2. Color fabb recommends printing XT at 240-245, im not sure if I could go down too 220 without underextruding or having to go very slow. (http://learn.colorfabb.com/print-_xt/)

Im printing at 50mm/s, the reason why I turned the fans on is because of the bubbling issue. I do have a laser thermometer that I can use, Ill check before I print again.

 

[yellowshark 149]

Sorry I did not realise you were using XT - best to go with their recommendation in that case not mine!!

 

[yellowshark 149]

... even though you said XT in your 1st para - doh! If you search on XT there are some threads on the forum with people's experience on XT

 

[tottenham12712 0]

Sorry I did not realise you were using XT - best to go with their recommendation in that case not mine!!

 

 

... even though you said XT in your 1st para - doh! If you search on XT there are some threads on the forum with people's experience on XT

 

No worries I did find a few threads here regarding XT, but none really had the same issues I had on the first layer.

Ive been reading up on bed leveling and I think I did the paper method wrong and it is indeed to close. I downloaded a gcode file to help adjust the bed leveling as well so ill report back tonight

 

[tottenham12712 0]

Ended up entirely being my bed levling. It looks like UMs PLA likes to be slightly closer than ColorFabbs XT. After moving the tip out maybe a 16th of a turn, my prints are perfect

Thanks for your input guys!