It's worth noting that a brim isn't just there to make sure the first lines of your actual model adhere fine, it's to help them stay adhered instead of warping while you're printing. Printing on an unheated bed is doable (if you're using PLA). In my experience (and that experience does include a printer with an unheated bed) the key is surface area. Not the size of your model, I'm talking a smaller scale. A rough surface has a ton of little nooks and crannies or just slight changes in height that there's a lot more contact area than it looks like (or than a flat surface).
So with my unheated-bed printer (and no part cooling fan, either) I just did the classic thing. Blue painter's tape. Brush with very stiff bristles. Cover the bed in the tape, give it a good scratching up with the brush, print. Scuff it up a bit more between prints. When the tape starts to wear away, just replace it with some fresh stuff (and don't forget to give that new tape a half-decent brush before you try to print). Got to about a 90% success rate for initial layer adhesion. If you're going to start doing this from not having done it, remember that you'll need to adjust your Z offset because the tape adds a bit of height to the bed.
Recommended Posts
GregValiant 1,454
This subject of increasing the initial layer bed adhesion came up in another Github posting a couple of years ago. I had written a post-processor for the person and I suppose it might have some value for non-heated bed printers.
Unzip it and place the "InitLayerZWallsV2.py" file it into the "scripts" sub-folder in your Configuration folder. It will be available with the other post processors as "Initial Layer Walls Z-Adjust v2"
InitLayerZWallsV2.zip
It goes through the first layer and drops the Z for the inner and outer walls (by a user input amount).
Then it goes through the second layer and increases the flow for the inner and outer walls by an appropriate % to make up for the fact that the wall layers are taller and need the extra plastic to maintain line width.
So the gcode would look like this.
;TYPE:SKIRT G1 F600 Z0.2 ; Initial layer Z ;TYPE:WALL-INNER G1 F600 Z0.15 ; Walls Z ;TYPE:SKIN G1 F600 Z0.2 ; Initial layer Z ;>>>>>and the second layer ;TYPE:WALL-INNER M221 S125.0 ; Adjust Walls flow ;TYPE:SKIN M221 S100 ; Reset flow
The overall effect is to simply over-extrude the walls on the initial layer but the poster insisted that increasing the flow wasn't the same as adjusting the height. They were wrong but I did it that way since it didn't really make a difference other than about another minute to add the second layer flow adjustment.
Link to post
Share on other sites
CrazyIvan2 2
I am now looking at whether the first layer inherently suffers from under-extrusion, and whether is is possible to add compensation into the cutting mesh for the first layer (see above).
https://community.ultimaker.com/topic/46657-first-layer-thickness-–-compensate-for-z-offset-fdm/
Link to post
Share on other sites