Auto vs Manual extrusion width

[KDan]

The extrusion width setting is one of the most important and at the same time one of the most poorly documented settings.
BaronWilliams did a good job of trying to explain this a few messages back, but unfortunately I think he may have presented too much information at once.

I think simply renaming this setting would go a long way towards eliminating some of the confusion.

The setting would be more aptly named "extrusion path spacing" or something like that. When people see a setting named extrusion width, the first instinct is to think that it somehow controls the width of the extrusion of plastic. It absolutely DOES NOT. The width of the extruded plastic is controlled by the extrusion rate.

I've run into more than one person who was confused by the "auto" setting. ( I was at first too). It doesn't seem to make sense to set a 0.4mm nozzle to squirt out 0.48mm of plastic. What people don't often understand is that already happens - despite the extrusion width setting. The extrusion width setting is simply a way of COMPENSATING for the squishing of filament from a round column of filament into a wider flattened oval.

By compensating for the squish, inside and outside tolerances can be much more accurate. The difference is really noticeable on small inside dimensions such as holes and slots. By allowing the slicer to compensate for the squish, your holes will come out being much more accurate, instead of always being undersized. If you have the nozzle size and the extrusion width setting set the same, the slicer can not generate a tool-path that takes into account the true width of the extruded plastic on the surface of the part. For those familiar with CNC machining, this is a lot like setting the cutter radius compensation incorrectly.

[totalitarian]

Thanks for the info guys. One thing I can't wrap my head around is if a 0.4mm nozzle extrudes roughly 0.48 of filament, we was the default setting set to manual.0.4, shouldn't it have been set to auto or manual/0.48?

[kabali16]

From my personal exp, Setting 0.4 width for 0.4 nozzle size works fine. However, if you see too much overlap between the roads of plastic, you can turn up the width to 0.48. Setting it to auto does not really do anything except do the 1.2x automatically when you change nozzle size.

[totalitarian]

Thanks. The only issue I tend to get it top / bottom layers not filling properly despite me having several layers

[billyd]

The other thing extrusion width does is limit the physical size of a feature of a solid model that is sliced. In other words if you have elements in your solid model that have .3mm wide features and you set your print width to something more than that, say .5mm, features narrower than that will not be sliced and therefore won't print.

[kabali16]

For the gaps, try increasing the extrusion multiplier

For the small features not being included in slicing, that is due to the S3D works right now. They have explained that in the Print quality guide.

[totalitarian]

Here are a few tests. The left is 0.9 extrusion multiplier, the middle is 0.95 and the right is @ 1.0

https://goo.gl/photos/hiKFauDhPo5M3ccX9

[TylonHH]

However, if you see too much overlap between the roads of plastic, you can turn up the width to 0.48.

NO!

You did'nt understood what BaronWilliams said:

Likewise, If lines are printed too thick and are overlapping each other, adjusting either Extrusion Width or Layer Height will NOT fix the problem. For example, if you have a 20% overlap between walls, and you make your Extrusion Width smaller, your overlap will still be 20%, but will now be a smaller overlap because your lines are now smaller and closer together (the print resolution is higher). You didn't get rid of the overlap, you just shrunk the lines, and the line spacing, so the 20% overlap appears thinner, but is still there at 20%.

My question in this thread here:
As I see the actual nozzle diameter is very important. How do I measure that? I hope there are some print test to get the actaul size.

[jfkansas]

Nope, no test for that except to use wire gauges in a clean nozzle. Plastic when extruded swells a bit. Measure your filament coming out of the nozzle sometime, a .4 nozzle will extrude about .5 to .55mm in free air. When you extrude to a substrate that .55 gets smashed to .6 or more wide. Different plastics swell out of the nozzle a little differently. One example is carbon filled filaments generally swell less than a pure ABS.

[TylonHH]

That's not accurate for me.
I know that my nozzle was/is 0,4. But I need to know if it's 0,41 or 0,42 or else.