JoeBowler300 wrote: ↑
Sun May 12, 2019 9:33 am
I have a tough time understanding that “Initial Layer Flow Rate”. Should it be set higher or lower then the “Flow” parameter?
Equal to or higher -- I can think of no practical reason to go lower than the normal flow of 100%.
Conceptually, if your printer's e-steps is set perfectly, and your filament diameter is accurately measured and entered into Cura, then your Flow should be 100%.
Conceptually, if your printer's bed is perfectly level, your X and Y axis have no "flex" in them, and your z-offset is set perfectly, then one can argue that setting the "initial Layer Flow Rate" to the same 100% will be correct -- it will extrude just enough filament to perfectly establish that first layer. So primarily, setting that to larger than 100% is intended to 'squash' more filament onto the first layer, making up for variances from perfection.
(That said, if I understand the initial layer settings correctly, that in the case of "perfection" you may find visible lines on the bottom of the object -- In other words, I think that you may need a bit of over-extrusion in order to get that perfectly-flat bottom with minimally-visible lines that some folks are looking for.)
The way I approach the initial layer setting is to first work on the Flow rate -- I prefer to adjust my esteps myself (I don't use the settings on the label on the extruder), and I measure the filament diameter frequently as the roll is consumed. This may or may not make the non-first-layers look great -- I often tweak the extrusion temp and the fan settings to get proper adherence and such. But, once I'm happy with what the layers look like near the middle and top of the object, I'll then focus on the first and close-to-the-bottom layers. For most of my prints, where there's a lot of contact with the bed relative to the object height, I'll go with 100% for the initial layer flow, and just double-check the z-offset. For small objects, I shift the object close to the corner of the bed (eliminates any trouble with the z-axis drooping near the middle to the x-axis). For objects with little contact relative to height, I may adjust the initial flow to 110 or 120 percent -- if the initial layer isn't critical to the object's appearance, or if the object geometry makes it easy to trim off the excess "squeeze-out" on that first layer. If the first layer is important, I've experimented and tried everything I can think of, and in the end even though it feels like a "kludge", I find a raft is the best way to get a perfect first layer of the object while still getting the appropriate bed adherence in the face of imperfections in bed height and level-ness.
So in summery - I'd encourage one to adjust e-steps and measure the filament to get that 100% Flow rate, and then if the first layer can be trimmed, set the initial layer flow a bit higher than normal -- and if that first layer cannot, well, set to 100% if you can and use a raft if the object has trouble staying stuck on the bed.
There's a lot of room for personal preferences here - the above is just my strategy for this!