First Layer Width Question and Clarifications.

[wirlybird]

Hi all,
So, on the old first layer width topic. If I increase the first layer width to 150% let's say it will extrude more plastic but also move the extrusions further apart. Am I understanding this correctly?

If this is the case then what is the point or purpose of the first layer width setting?
Would you use a higher first layer width for a large open area to reduce the number of passes? Something like that maybe?

Thanks for any thoughts or opinions on this. It is a setting I have never really used so just looking for a little insight how I might take advantage of it.

Thanks!

[dkightley]

In brief....Yes....and Yes.

The theory behind increasing the width of the first layer is that it introduces more plastic in contact with the bed....but having said that, if the first layer is squished so there is a totally smooth surface on the bottom of the part, then the setting is sorta irrelevent!

[wirlybird]

Thanks Doug, at least that confirms I am understanding it ok.

I will need to experiment with the setting to see the results.

I think I could see an advantage on a larger print to reduce the number of passes for the first layer - maybe!

With other settings dialed in maybe a wider path for each pass could offer a little better adhesion. Might really be negligible in most cases though.

[SWCNT]

When it's useful depends on an interplay between printing material (PLA, ABS, PC, PETG, etc) , bed surface (glass, buildtak, etc), and nozzle width.
Nozzle Width:
For the same material, the larger your nozzle width, the less likely you need to mess with first layer widths. For example, if you run a 0.8 mm nozzle, your width is already good enough for proper adhesion for PLA with a heated bed. Doing 150 or 200% is pointless. A 0.4 mm nozzle can be printed at 100% first layer width, although some people find it easier to add a bit extra. Also it depends on the model and whether the person properly dialed in the z-axis (bed leveling doesn't solve all issues as marketers would like us to think). If you have small details that won't have much surface area with the bed, you will probably need >100%. If you use <0.4 mm nozzles, that first layer may even require a raft for good adhesion.
Material/Bed material:
PLA is easy, but other materials can be less forgiving. For example, PC, it significantly harder to "stick" and will require some (or much) playing around. You can also have situations where a material sticks too well. If you use PETG with Buildtak, you can easy fuse the PETG to the Buildtak, usually I need to add a z-offset for a PETG profile on Buildtak because it adheres way too well. You could also have a first layer width <100%.

So I'd say if you are printing PLA with a heated bed and a 0.4 mm nozzle, your model (assuming your z-axis is properly calibrated) will dictate if >100% width/height are needed. Most cases, you can just go with 100%. For other situations, it's more complicated and that's why the option is there.

[wirlybird]

Interesting. I didn't think about if using a smaller nozzle such as a 0.2 that increasing teh width can help with adhesion but it does seem to make sense.

Gives me more to think on, thanks.