[ADDED] Wider extrusion width for first layer

[cdub]

I ran of a series of test parts to illustrate my point.

I ran copies of the same stl file with different settings. One had 70% first layer height, 50% first layer height and 30% first layer height.

I also ran one with coasting turned on, one with a -0.4 extra restart distance, and one with neither.

Ignore all of the defects on the walls that were due to those settings and just look at the bases. I put a punch in one of the pictures pointing at the flange.

Any ideas?

[jsc]

If you do not want a first layer flange, you need to have first layer height at 100% so that it prints like any other layer. I've checked the gcode, and changing the first layer height does not adjust the extrusion speed to match the layer height. That is, if you print a first layer at 50% of .20mm, it is printing at a height of .10mm but extruding as if it were printing a .20mm height. This is so people can drop down first layer height to "squish" the first layer for better adhesion. Well, it may help with adhesion but squishing necessarily entails a thicker extrusion.

I have moved to 100% first layer heights and have had no problems with bed separation using Elmer's glue stick in both PLA and ABS. If something in ABS warps, it delaminates higher layers. It has also gotten rid of the flange.

You must have a properly calibrated z end stop. It should just contact the bed at z=0 when everything is at printing temperature.

[Dssguy1]

All of this info (and more) is included in the support docs at:
http://www.simplify3d.com/support/tutor ... rst-layer/

You will actually see that "First Layer Height" does two different things depending on if you are over or under 100%.

[laird]

All of this info (and more) is included in the support docs at:
http://www.simplify3d.com/support/tutor ... rst-layer/

You will actually see that "First Layer Height" does two different things depending on if you are over or under 100%.

Keep in mind that I love this software and promote it to everyone I know who prints. But I'm going to complain about this one 'feature".

Interesting document, though the software appears to do things that are quite confusing, since the behavior is weirdly different between "under 100%" and "over 100%", which is a clue that they've combined two things that shouldn't be combined. Worse, in neither case is it actually controlling the first layer height. Changing the layer height should simply change the layer height, with all other parameters (e.g. proper extrusion volume) behaving normally. Instead they've constructed a weird set of interactions and special cases that pretty much never does what you want.

Instead, for "over 100% layer height" it actually uses 100% layer height, making it useless, because the entire point of increasing the layer height for layer one is to actually increase the layer height. Instead, it counter-intuitively leaves the layer height unchanged and over-extrudes, which has nothing to do with layer height. Confusing people because it's not doing what it says it will do.

And for "under 100% layer height" it does actually reduce the layer height but extrudes for 100% of the layer height. That's not the layer height, that's adjusting the Z calibration down to squish the print into the print bed. And it confuses people, because it's not doing what it says it will do.

To clarify this confusing mess, I'd suggest:

- Layer one height should be a numeric setting (e.g. 0.3 mm) for the height of the first layer. No special meanings or "clever" side effects.
- If you want to over-extrude layer 1, add a "Layer one extrusion rate" setting that would be a percentage multiplier to the properly computed extrusion rate. e.g. 110% would extrude 10% too much plastic, to help squish onto the print bed. Over-extrusion is sometimes useful, but you need to know that's what you're doing, explicitly.
- If you want to have an offset to Z=0 height, they should add that as a setting, though IMO it's a bad idea. Normally setting Z=0 is done in the firmware or by turning screws on the print bed or Z end-stop, not in the slicer. If it's done in the slicer you end up generating bad gcode to compensate for a mis-configured printer, so as soon as you properly configure your printer your prints fail, and it's much better for all concerned to get the printer configured consistently, so you don't need to re-slice everything whenever your print bed wiggles. Remember, gcode has a longer lifespan than a single print - you can re-print a file a week or a month later, and it should still work, even if you've re-leveled your print bed.

[JoeJ]

laird - I'm not seeing the same thing as you. If I increase the first layer height beyond 100%, it does EXACTLY what I think it should. The height of the first layer increases and the extrusion flow rate is also increased accordingly. It works really good for my high quality prints so I can use a slightly thicker first layer for better adhesion and absorbing some of the small defects on my build plate.

You can verify this yourself. Go change the first layer height from 100% to 200%. Then just look at the gcode files for the first G1 Zxxx command. You will notice that the Z-coordinate increases exactly as you would expect.

For values under 100%, I definitely don't want them decreasing the flow rate any! Usually, you only use this option if you're trying to squish the layers closer into the build plate to force the thing to stick better. So lowering the flow rate as you lower the layer height would completely defeat the purpose.

I for one am quite happy with the current implementation and their tutorial explains it well.

[Mobilinkd]

So, I'm on the opposite side of this. I'm running S3D V2.1 and printing on a MakerGear M2. I primarily use the default settings of 70% layer height and 50% speed for the first layer. I set my bed level and zstop such that a 0.15 mm shim fits everywhere and a 0.25 mm shim doesn't fit anywhere.

My parts all come out like the first layer perimeters have been over extruded. When I get the part off the printer they all have sort of a "flange" all around them. I've been printing with no raft because I like the solid surface that comes with printing directly on the kapton tape. However, I would like to turn down my first layer settings so that my part is more dimensionally correct.

I've played a little with the first layer height setting, but it doesn't seem to make a difference. I know that if I increase the gap I'll have adhesion problems. What is the right way to reduce the extrusion rate on the first layer?

I'm in the same boat. I am a new S3D user and I have some very small holes (1mmx3mm) in my part that are entirely closed by the shell from the first layer. The remaining layers seem OK. I am printing ABS with the same first layer height as the rest (100%). I do print the first layer very slow (33%). The problem seems worse after I increased the first layer height and slowed it down from the default values. But that has helped my adhesion considerably.

Like I said, I am very new to S3D. Can anyone suggest an adjustment I should try?

[laird]

My comment is based on Simplify3D's link posted above, which claims that the behavior is not really adjusting the layer height, it is generating (in two different ways) over-extrusion to try to stick prints to the print bed.

Adjustments to the First Layer Height allow you to vary the amount of pressure the filament exerts against the bed. There are actually two ways to adjust the height and pressure: 1) a height below 100% or 2) a height above 100%.

Percentages under 100% will reduce the height of the layer being printed. For example, if you entered 75%, your first layer height is reduced while your extrusion remains at 100%. Another way to think of this is that 100% of your extrusion will be forced into a space that is 75% of the layer height. This reduction in height generates extra pressure and more surface area for that layer, which will help the first layer adhere to the print bed.

That is, they're not simply changing the layer height, they are extruding a 100% height layer, but positioning it lower to press it into the bed for better adhesion. That's useful, but it's not really layer height, and by calling it that it creates confusion. Though since there's not really any case where you'd want to make the first layer height lower than the normal layer height, it's harmless.

In other cases, using a percentage above 100% is helpful. For example, if you are printing at very fine layer heights, such as 0.05mm, a tiny variance in your bed leveling can result in a poor first layer adhesion. In these cases, use a percentage above 100% for the First Layer Height. When you enter a value greater than 100% for the first layer, such as 105%, the height of the layer will remain at 100% but 105% material is extruded, resulting in more pressure and surface area for that layer. This additional surface area will help minimize the impact of an improperly leveled bed.

Note that they claim to not make the first layer higher, but instead to print at 100% layer height, but over-extruding plastic. That's what I think is a bad idea. If, as you say, they don't do the very odd behavior that they document, but instead actually use the 'first layer height' to control the height of the first layer, then all is good on that front.

[laird]

I'm not sure what the 'first layer height' actually does - I'm wondering if they changed functionality between the three versions I've tried.

After trying a few options, I'm getting consistent results by setting up two "processes", one that applies to the first 0.3mm and another than applies starting at 0.3mm, generated as a single continuous print. The first process slices at 0.3mm layer height, so it sticks but has no over-extrusion, and the other process slices the rest however I like for a particular print. It's a little more work to set up, but it's easy to load parts in and print them. You do have to tell it to apply both processes, continuously layer-by-layer, then it does the right thing. The slice different parts/heights with different processes is very powerful. I have one print which is a plate full of parts, and it's great to be able to get the base solid everywhere, then have individual pieces sliced different ways above that base, all in one print.

[S3D-Jason]

As of version 2.2, you can now explicitly set a first layer extrusion width