maker2
Posts: 113
Joined: Sun Jul 19, 2015 9:05 am

auto layer height to get perfect top layer height each time

Thu Jun 06, 2019 12:52 pm

Currently printing a 2mm high model. Only with Simplify it's going to be 1.9mm high.

Why? I'm printing at 0.2mm but my first layer is set to 150% (yes, I really do like to do that and it guarantees perfect prints over the whole bed area).

So why not have a checkbox in the Layers tab for "auto adjust layer height to achieve perfect Z final layer"?

Basically the slicer would adjust by a tiny amount the height of each layer so the final extrusion height would be achieved.

In this case the layers might be 0.2125, for example, so that with 8 of them + the 0.3mm first layer we achieve 2mm exactly.

Of course S3d already can do this sort of thing horizontally (adjusting track width on the fly) so not only makes perfect sense but is entirely coherent with Slicer function


gearsawe
Posts: 142
Joined: Sun Sep 10, 2017 11:06 pm

Re: auto layer height to get perfect top layer height each time

Fri Jun 21, 2019 9:54 pm

This would be a pretty difficult thing to implement. even the +$100,000 printers don't do this.
I would love the feature. But lets say a face was purposely put at 1 degree. How would that be implemented?
Or you have a part with multiple levels. There would mixed layer heights on a single layer.

rexipus
Posts: 8
Joined: Mon Aug 05, 2019 9:12 pm

Re: auto layer height to get perfect top layer height each time

Tue Aug 06, 2019 12:41 am

Depending on the steps of the stepper motor or whether it's geared and its gear ratio, the feed rate of the Z axis screw, etc. this could prove problematic for people. For instance, it's always been my custom to use as my layer height some integer multiple of native base layer height that depends on the Z-axis screw turn rate and the number of steps of the stepper motor that turns it. It used to be .04mm before I modified my Z-axis setup. This means I set all my layer heights to multiples of .04mm, so .12mm, .16mm, .20mm, .28mm, etc. Any layer height in between these would work less well because at some point the controller either changes from rounding down to the next step of the stepper motor to rounding up, or vice versa, and then you get a layer that's different than the ones that preceded it. This could leave visual artifacts such as repeated patterns of individual layers that look different than the other ones (sticks out more, or sticks out less).

S3D-Jake
Posts: 657
Joined: Wed Jun 20, 2018 12:45 pm

Re: auto layer height to get perfect top layer height each time

Mon Aug 26, 2019 2:30 pm

Awesome idea! Also, great feedback on the challenges it presents. I'll keep an eye on your thread to see if anyone with more free time can come up with a clean way to handle these potential issues.

Thanks again for your feature request!
"A bird does not sing because it has an answer. It sings because it has a song."

maker2
Posts: 113
Joined: Sun Jul 19, 2015 9:05 am

Re: auto layer height to get perfect top layer height each time

Mon Aug 26, 2019 3:05 pm

On my Duet Wifi my steps / mm are set as follows:

M92 X200 Y200 Z1600 E822

Looks as though there would be no issue making fine adjustments to the Z layer height.

maker2
Posts: 113
Joined: Sun Jul 19, 2015 9:05 am

Re: auto layer height to get perfect top layer height each time

Tue Aug 27, 2019 10:27 am

I guess if it's a problem for some people there could be a parameter "Fine adjustment Quantum" which @rexipus could set to 0.04mm (and I'd leave empty).

S3D-Jake
Posts: 657
Joined: Wed Jun 20, 2018 12:45 pm

Re: auto layer height to get perfect top layer height each time

Tue Aug 27, 2019 10:52 am

That is one way of handling it. The question then becomes do a majority of users know their Z axis stepping values for their printer? And if they do, would they feel comfortable inputting those values manually? I envision a solution that has less user input needed to setup holding way more weight with our developers.
"A bird does not sing because it has an answer. It sings because it has a song."

maker2
Posts: 113
Joined: Sun Jul 19, 2015 9:05 am

Re: auto layer height to get perfect top layer height each time

Tue Aug 27, 2019 10:59 am

I know nothing but 0.04mm sounds like a bit of a worst case scenario on a modern FFF printer where 0.05mm is a typical minimum layer height.

My other printer has: M92 X160 Y360 Z1600 - also a very high level of resolution for Z. Don't know about other people.

The solution would surely be to put in a default parameter that is very conservative and then knowledgeable users can modify it.

If the mouseover help tip /documentation is properly written we can all do that.

The only types of people I know that use S3d do so because they want to play with parameters to make better prints. But maybe you have lots of purchases from schools / corporations where end users don't care?

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