Rate my prints - How are these?

Feek · 12 Dec 2021 at 12:18

My Prusa MINI+ was delivered on Friday and of course, it's been running almost continually since.

How do these look?

Is that what I should expect from first and last layers?

Remember these pictures are close up and with the light angled to show most detail.

First layer

Last layer

Sides are pretty good

This is the clip, I printed at 0.15 and 40%.

Printed using Prusament PLA

andy_mk3 · 12 Dec 2021 at 12:25

First layer showing nozzle is too far away from the bed. You'll need to adjust the Z offset to lower the nozzle down a touch, I'm not familiar with the Prusia printers but there's usually an option in the menu for Z offset. The best way to adjust it is have the option open on the menu as the first layer is going down, and lower it gradually until the filament has a nice squash on it, lines of filament on the bed next to each other should merge together.

Once dialled in the bottom layer should look as good as the top layer.

Feek · 12 Dec 2021 at 12:34

That’s interesting, thanks. There is a very easy adjustment for the z axis. I’m already at -1.685 so I’ll wind it a bit closer.

andy_mk3 · 12 Dec 2021 at 13:14

Yup that's the one you want. If you find your first layer starts getting lumpy at all then it's probably too close. It's one of those things you just get an eye for with experience.

Scougar · 12 Dec 2021 at 17:40

Is the red meant to be joined?

Feek · 12 Dec 2021 at 17:46

Scougar said:
Is the red meant to be joined?

At the clip end? No, neither of them are joined there, the clip can open.

andy_mk3 said:
Yup that's the one you want. If you find your first layer starts getting lumpy at all then it's probably too close. It's one of those things you just get an eye for with experience.

Have dropped it a fraction further and it's looking better, thanks.

Scougar · 12 Dec 2021 at 18:44

Also make first layer slightly thicker. E.g. 2.4 first layer height (If using .4 nozzle).

Have you calibrated e steps? (Amount of filament commanded vs what actually comes out the extruder).

Feek · 17 Dec 2021 at 15:09

Actually just lowering it a fraction further made a huge difference, thanks. I've not calibrated e steps - The printer instructions say it shouldn't be needed out of the box and I don't really have any way to accurately measure it anyway.

andy_mk3 · 17 Dec 2021 at 16:06

The e-steps should be fairly close out the box on the Prusia.

It's a very fine balance getting the z-offset right, the smallest change can transform a print in how well it goes down

Dr Who · 25 Dec 2021 at 14:56

As per everyone else you need a bit of Z-Offset in your slicer or physically adjust your Z-Offset. If you're using superslicer (Pretty much the best and free) run the calibration tests and you can get it dialled in.

Diagro · 13 Jan 2022 at 22:07

Generally z layer heights are done in 0.04 intervals.

0.04, 0.08, 0.12, 0.16, 0.2mm

So on so fourth.

It's to do with the stepper motor.

If you do it in 0.05 increments you will get layers that are bigger or small at various times.

Feek · 13 Jan 2022 at 22:20

Diagro said:
Generally z layer heights are done in 0.04 intervals.

Oh, that's interesting. I had no idea, thanks.

Prusa slicer only lists these, should I add some manual ones?

Feek · 13 Jan 2022 at 22:21

Dr Who said:
physically adjust your Z-Offset.

Sorry, I missed your reply. I've done this and it's much, much better now. It's very easy to tune it on the printer itself.

andy_mk3 · 13 Jan 2022 at 22:30

That's not true for all printers needing to be 0.04mm intervals. It's calculated by the the steps in the stepper motor and the thread pitch of the lead screw. The idea is that you don't want to be printing at a height which is between steps. But in reality, the majority of printers are perfectly capable of microstepping which divides full steps into a smaller steps, therefore is a non issue really. I'd imagine a company like Prusia that build the hardware and software are full aware of this and the presets are set knowing that it's not an issue

Diagro · 13 Jan 2022 at 22:32

andy_mk3 said:
That's not true for all printers needing to be 0.04mm intervals. It's calculated by the the steps in the stepper motor and the thread pitch of the lead screw. The idea is that you don't want to be printing at a height which is between steps. But in reality, the majority of printers are perfectly capable of microstepping which divides full steps into a smaller steps, therefore is a non issue really. I'd imagine a company like Prusia that build the hardware and software are full aware of this and the presets are set knowing that it's not an issue

Micro stepping doesn't fix the physical limitation of a 1.8 degree stepper motor.

Dr Who · 14 Jan 2022 at 12:53

Diagro said:
Micro stepping doesn't fix the physical limitation of a 1.8 degree stepper motor.

Doesn't fix the physical limitation but allows it to have up to 256 steps per 1.8 degree although 16 steps is seen to be the best balance of resolution and holding torque. In reality it is mostly used for smoothing rather than resolution. The best way to improve resolution is with gearing as this increases resolution and holding torque