Inconsistent base layer

[attaklysm 0]

Hi,

I printed out a few parts last night and when they were finished I noticed that a couple had a strip, about an inch wide, where the print was raised, inconsistent and of a generally bad quality. I'm not sure if it's a build plate heat distribution issue or something along those lines. I'm new to this so just guessing at the moment.

Does anyone have any advice?

Any help is greatly appreciated.

p.s. I've taken a photo but don't know how to attach it to the post.

 

[gr5 2,172]

Click on gallery on the top left of this page, then the big blue UPLOAD button. Then after you finish uploading picture post a new topic and click "my media" next to smile icon.

It could be many things - most related to leveling. If leveling leaves too big a gap then the PLA doesn't stick well and kind of falls down onto the bed - you want it squished. It leveling leaves too small a gap and you have a UM2 then the extruder will skip because it can't get all that PLA in such a small gap but the skipping will cause underextrusion. Picture would help.

 

[attaklysm 0]

Thanks for the advice :smile:

 

The raised strip ran from the front of the bed toward the back about 100mm. going between two separate parts (one of which is below).

 

I've printed since I had the issue without problems. Which is a good thing I guess. I would like to understand the problem though.

 

[gr5 2,172]

Wow! Never seen that before! It's so... consistent!

Is your bed lower there?

Could it be that the gantry moves the head up in that region?

This is not a STL issue because it would have outlined the higher region - but it didn't.

Is this a UM1 or UM2 or another printer? Something seems to be raising the print head higher as it travels over this location. I would push the head around back and forth over this region and see if something causes the head to lift a tiny tiny bit (only about .1 to .2mm I think).

Does this strip correspond to a particular slice of blue tape?

I really think this is a gantry issue.

 

[attaklysm 0]

Thanks for the fast reply.

It's a UM2. only had it a few days.

I wasn't present when it was printing in these areas so didn't see what was happening. I have scanned the bed with my infra-red thermometer and the heat seams consistent throughout.

I have since printed on the same area of the bed without issue (bed is flat). There doesn't seem to be a mechanical issue with the gantry either.

I used glue not tape. Would you recommend tape over glue?

Could it be that the movement of the head put tension on the filament causing it to pull back slightly in these areas? I can't see how that would happen really, I'm just trying to think around the problem.