New plugin suggestion - cutting corners for bottom layer

[shurik 87]

Hi,

Not sure if the issue was discussed previously, so here are my 5c suggestion/question.

When we print on the glass, the first layer is naturally squashed against the glass and it stands out a bit on the finished parts, giving them sharp edges and also effectively closing small holes and other openings on the first layer.

Is it possible to develop a plugin/feature that will negate this effect by reducing the perimeter of the 1st layer by about 0.1mm, like here:

I do that sometimes for simple geometry for the outer perimeter, but for more complex forms we would need something more sophisticated.

It that something feasible?

[Labern 774]

I have raised a request to be able to use horizontal expansion for the first layer so you can set it to -0.1 to remove the sharp edge

[shurik 87]

That would be lovely!

Is the plugin available?

[ahoeben 1,948]

Though the Cura 2 frontend was built from the ground up to be extensible with plugins, the backend CuraEngine that does the actual slicing was not. This feature needs to be implemented in the backend, so it is not possible to do that as a plugin.

[geert_2 557]

I try to simulate that in the design by adding a small rounding. This works somewhat, but is not optimal. The problem is that this approach is not compatible with desired roundings at the bottom. And it gives a bit of deformation of the first two or three layers.

So indeed a solution in the slicer to reduce only the outer edge (but not the infill, so we still get good bonding) of the first layer with a user-selectable distance would be very nice. Good idea.

[shurik 87]

Reducing just one layer by the tiny 0.1 or 0.2mm perimeter size should not really affect the roundings, IMHO. Or, it will even make them more smooth due to the proper size of that first layer.

But, as @ahoeben says, that should probably be done in Cura proper.

Would someone in UM listen?

[bagel-orb 61]

Lower your bed a little. That should solve the problem.

[lance-greene 7]

ya you dont actually need to squash the first layer, tune the bed while its printing the skirt for the lightest squish you can get and it should be uniform. we do buildplates of 100 spinner caps on our UM2 and there is no squish on the outer first layer of them because ive lowered the bed just a hair while the skirt prints.

[Labern 774]

Some materials require squish and ones with sharp corners. Also the bigger the item the more shrinkage so the more likely the corners will lift.

Having more squish is more reliable. CURA has brim on by default but if you were able to have more squish and an option in CURA to remove the elephants foot then you wouldn't need brim.

[mastory 44]

For me, reducing the bottom layer alone isn't enough.

Take into account that I am printing ABS almost exclusively thru a .8mm nozzle and .2mm layers.  This on top of heated glass with hairspray.  I don't use extreme squish.

With that in mind...   I cut a 7deg wide by 1.5mm tall chamfer around the bottom of my models that have bases square to the build plate.  On top of that I put a 10mm radius on the top of the chamfer to blend it with the side wall.  (Top of the radius ends up about 2mm up)  I do this to all holes and geometry that run square into the build plate.

This treatment just about negates the elephants foot.  There is just enough extra material left that the part can be quickly dressed to size (and square).   Without it, I end up doing a load of sanding and filing.  I am aiming for high dimensional precision and this is a big help to reduce secondary operations.

Edited April 15, 2017 by Guest

[Labern 774]

I always put a chamfer on my models also. But a lot of users on thingiverse and youmagine don't. This is were we need something to remove the elephants foot as it's not so easy to edit stl's

[shurik 87]

it's not so easy to edit stl's

Ditto.

Some models have rather complex internal geometry including small screwholes etc., making the post-processing really difficult.

And yes, normally I do want my smaller prints stick to the glass, so increasing the distance to the nozzle isn't really an option.