How to get the smoothest top and bottom layer

[desman]

What are the best settings to work with to get the smoothest top and bottom layer.

[KeyboardWarrior]

What are the best settings to work with to get the smoothest top and bottom layer.

There aren't universal best settings for this, as with many things in 3D printing it will depend on your printer, filament, etc.

However some advice:

Use 3 to 5 top and bottom Solid Layers in the Layer tab.
Increase your Extrusion Multiplier until the top is smooth and doesn't have holes.
-Do not print with a raft, instead look to print on top of something like PET or Kapton tape.

[KDan]

One thing that seems to be a general rule of thumb is that if you have a lower infill percentage, you need more top layers. Low infill requires more bridging and needs more layers on top to clean up. I find that is is often necessary to have at least 4 top layers if you don't have at least 25% infill. This will vary somewhat with the part (size, shape, etc)
Defining a special fan speed setpoint (to temporarily speed up the fan) for the first layer where the solid exterior infill in laid down on top of the patterned infill also often helps a little. Make sure you create a setpoint to immediately set it back to your default fan speed right after the first layer or two of the exterior infill has been laid down.

YMMV

[Tetraodon]

Silly question - can you change your extrusion multiplier for top/bottom layers and not for the rest? I'm finding lots of gaps in the tops of my prints (though haven't messed with the settings much - first time using PLA instead of ABS)

[dewme5]

Silly question - can you change your extrusion multiplier for top/bottom layers and not for the rest? I'm finding lots of gaps in the tops of my prints (though haven't messed with the settings much - first time using PLA instead of ABS)

Setup an extra process for each time you wish to change. Adjust the heights accordingly.

[Tetraodon]

Silly question - can you change your extrusion multiplier for top/bottom layers and not for the rest? I'm finding lots of gaps in the tops of my prints (though haven't messed with the settings much - first time using PLA instead of ABS)

Setup an extra process for each time you wish to change. Adjust the heights accordingly.

Would that affect the edge perimeters (like the thickness of the walls of the model visually) for those particular layers?

[dewme5]

Would that affect the edge perimeters (like the thickness of the walls of the model visually) for those particular layers?

No. You are manually slicing the model, prior to the automatic handling it.

0 - 1.0 mm do solid floor
1 - 25mm do body
25 - 26mm do top.

Each process will have separate rules to follow, and all 3 will be selected to run through the slicer, resulting in one gcode program in the end.

[KC_703]

Hmm... I was going to write, As long as you keep most parameters the same for the three processes, the exterior finish should be the same. But if you think about it, the extra extrusion has to go somewhere... if its just width, then you should be fine and accomplish a solid top layer, but if the extra extrusion comes out as a change in layer height, then it could be a slightly different finish.

You'll have to experiment...

BTW - there is a first layer extrusion width that can be set on the "Layer" tab. This should help you get a smooth/solid bottom.

[Fred B]

One thing that I've noticed with my new resin printer is how well printing parts at angles works. Any time you can print near vertical that side will have a better finish. By printing the part at an angle with supports turned on you can get a uniform look on the part.

This may not be the smoothest but it will look the most uniform. Oddly, the number of top and bottom layers matters less with this method as well. even 10 or 15 degrees will make the part look better.

I normally try to choose a bottom side that can be sanded and just deal with it. Playing with the supports can really help the bottom finish though.

[mitchfx]

BTW - there is a first layer extrusion width that can be set on the "Layer" tab. This should help you get a smooth/solid bottom.

I may be mistaken, but doesn't this setting also adjust the spacing of the lines accordingly? In other words if you specify 200% width you end up with half as many lines in your base layer, so in theory the amount of overlap (and thus gaps) remains the same.