Yeah, if you're squishing the first layer, you have the Z-stop set with the bed too close to the nozzle for that filament.
Calibration is the best way to fix it, and it needs to be done at least once for each spool of filament, because I've found that it changes quite a bit, even between rolls by the same manufacturer. The various colorants/additives/water content/etc. in the plastic just make each thread extrude a bit differently.
Since I switch back and forth between colors and manufacturers several times daily, I don't want to mess with re-setting the Z-stop every single time. It would take forever.
So I cheat.
I set the Z-stop height once using a feeler gauge, (.006" or .15 mm), while the bed and nozzle are heated up to filament temperature, then make adjustments in S3D based on the size of the calibration square for each spool of filament. Jin's write-up of Ed's calibration routine can be found here:
viewtopic.php?f=3&t=1964
In the
G-Code section of the printing parameters in S3D, there is a
Z-Offset slot. After I print the first calibration square, I measure the height with calipers,
subtract it from 2.0 mm and then enter that number into the
Z-Offset slot for that spool. (If the square is not tall enough, you'd enter a positive number, if it's too tall, you'd add a negative adjustment.) A positive number moves the bed farther away from the starting point for the first layer, so that the thread gets laid down evenly instead of getting squished out. A negative Z-Offset adjustment number brings the bed in closer before printing, so that the thread can stick to the plate.
I run a second and maybe third square, just to fine-tune it, until I get a square exactly 2.0 mm tall. (Or within the tolerances of my extremely squidgy calipers.) I've discovered that i usually have to back off the initial adjusment by -.03....don't know why, I just do.
After that, i calibrate for the extrusion width according to the steps outlined in Jin's post using Ed's instructions.
Last step is to change the number of layers and infill to what you usually use, and then
Export the S3D settings for that spool, so you can just switch to that profile when you pop on that roll.
It sounds like a lot more work than it is - each spool usually just takes a few minutes to calibrate, and the guys did a fantastic job explaining it. You'll get great prints as a result...(unless you are using a spool with a lot of variation in the filament width. But that's another problem.)
And it really keeps you from over-extruding that first layer. I got lazy the other day switching to a new roll and didn't bother to calibrate it first.....that was a mistake. That print wound up with a sharp little skirt as a first layer, that had to be tediously filed off.
Hope that helps some!