Raft very poor quality / poor adherence

[jeff.winterbourne]

Hi all,

I'm new to the Simplify3D software, but pretty comfortable with the fundamental settings on a 3d printer. I've been trying to address some pretty significant issues I'm having laying down a decent raft on my Wanhao Duplicator i3 - the raft layers significantly underextrude, leading to very poor lower layers ( first layer infill doesn't touch perimeter, very little adhesion between first layer and second, second and third etc). I've checked the diameter of the filament is correct (1.75mm) and all the usual suspects, but I can't identify a setting that will affect the quality of my raft! The printer prints a good shell, but the infill is also pretty poor (like the "stringy" example on the Simplify3D guide).

Things I've checked / investigated:

- Extrusion multiplier. I upped this to 200% in increments and measured the diameter of the first layer with 1 micron calipers. The width remained at 0.2 mm (I have the default 0.4mm MK10 hot end). I could not get this value to affect the amount of plastic extruded.
- Print speed. Just to be sure, I am conducting my tests at 20 mm/s with a 50% underspeed for first layer
- Bed height - well calibrated with good first layer adhesion (BuildTak)
- Manual extrusion check - with nozzle away from bed, filament extrudes accurately with +/- 0.02 size.
- Infill settings - played with the extrusion multiplier here in case it affects it.

In short, I'm baffled! Is there any setting I have missed or obvious calibration issue? Cura's rafts print fine, but I want S3D's additional flexibility...

[CompoundCarl]

How about not using a raft? The i3 really doesn't need it, and if you're having trouble holding parts down, a brim will work much better

But anyways, to help with your problem, if you are doubling the extrusion multiplier and no extra plastic is coming out, then you probably have a nozzle clog or some other extruder slippage. So there's no point adjusting any other settings until you get that figured out. Doubling the extrusion multiplier should extrude twice as much plastic. If it isn't, then something is wrong with your extruder.

[Rebekah_harper]

I find when using a raft that the first layer speed is at default speed and not the reduced speed for perimeter and solid infil.

I change the first layer speed in the GCode file directly and set it to 1500. seems to work well.