Nice description. Thanks!
By the way, wouldnt be posible to do all that work at the slicer level ?
I mean, the slicer can make a layer smaller or even move up the Z-axis a bit beofre printing.
Wouldnt be nice to have some "Reduce elephant paws effect" switch on Cura? :-)
In the advance tab, there is a first layer line width. Reducing that might help some but it reduces it for the entire layer so infill may not completely "touch".
Precise leveling calibration is critical to not having the elephant foot. It's also important to have the nozzle primed to the right pressure. Change the skirt count to something like 5 so the pressure can equalize before the actual part is printed.
Also, I've been play with gears a lot. You can get a better result by putting a small bevel on the teeth so the first few layers aren't actually part of the teeth so that the "elephant foot" has a little room to spread before the teeth would meet the other gear.
Finally note is that this may not really be "elephant foot". My understanding is that EF occurs when the bed is too hot causing the layers to "run" outwards because the material is too hot for too long. Instead, you might be over extruding due to slightly off leveling and printing a 0.3 mm layer into a space of 0.2mm or 0.15mm etc or because the nozzle was primed just before printing and has a higher than normal pressure build up. However, the results are the same.
If you have the original CAD files, you can put a small chamfer on the bottom edges, to compensate for the flange that the bed creates.
vis-à-vis :
use the chamfer, use fresh pla/glue and really push how little squish you need to get the part to stick to the bed. When I am printing small inter meshing parts I hardly squish at all and go for a lower initial head temp - some failures, but no flashing. (.e. all the things you would normally do - but for special parts.
do the chamfer first - it really works.
You boys did read my message ? :-) I said "without changing the CAD model!".
The gears I want to print are not my models, And I have some dozens to print !
What the other guys said is the best approach when it's possible.
But since it's not in this case, well... it's going to be tricky. You're going to want to dial in the bed height very precisely so that the parts have just barely enough "stick power" without the first layer being smooshed. It might also help to print without any heat on the bed as well (but this also makes it harder for stuff to stick). You can also experiment with the first layer thickness. Maybe going with a very thin first layer makes the excess thin enough that it can be worn away during the first few turns?
In short, you're going to have to experiment and swear a lot about parts coming unstuck until you get it right.
does first layer height helps if its smaller than 0.3?
The standard advice for 1st layer is to reduce speed and increase bed and extruder temps. I never increase the extruder temp. As you cannot change 1st layer extruder temp in Cura I suspect that most users use their print temp. for the 1st layer. So if your optimal print settings are say 210c at 40mm/s then if you print the first layer at 20mm/s you will get over extrusion, inevitable. If it is important to me I reduce the dimensions of the first layer by 0.1mm i.e. say it was a cylinder in vertical orientation that would be 0.1mm off the diameter. I do though think that using a chamfer is possibly a better solution, maybe.
And yes Emilio it would be nice if the slicer compensated for you 
..oh and I am guessing, because I have never tried it, but if your 1st layer speed and print speed were the same you may well avoid it, i.e. trying 30mm/s say. Also though you have the fan difference between 1st and subsequent layers and I am not sure what impact that might have on shrinkage
... So if your optimal print settings are say 210c at 40mm/s then if you print the first layer at 20mm/s you will get over extrusion, inevitable...
Well, not really The fact that the plastic will ooze more at higher temperatures is one thing. On the other hand, while the printer is extruding (no matter which layer), the volume of the extruded plastic is controlled by any other parameters but temperature. It's true however that increasing the temperature can allow the plastic to slightly "expand" over expected shape and therefore producing an aspect similar to overextrusion.
Yes I agree, mainly. Certainly temperature is not (I think) a parameter that affects the pressure created for extrusion. But I have seen over-extrusion in a print where extruder temp is too high - which in context is the point on layer one. Now if the result is due to expansion rather than over extrusion then I stand corrected . But the end result is the same, more filament than you need/want.
.... if you like I am not convinced that elephant's feet are only a result of nozzle to bed distance.
Well, if one maintains bed temperature above glass temperature (Tg) after the first layer, then there are great chances that "elephant foot" will enlarge due to lower layers being slightly pressed under the part weight. That's why, if for adhesion reasons bed temperature is set above Tg for the first layer, it should be reduced to something below Tg for the rest.
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dirkdirk 5
Maybe this will help
http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#elephant
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