Sequence One At a Time clearance vs printhead polygon is terrible

[rimbo 0]

Cura extends the collision zones unnecessarily, considering helper blocks as physical objects.

 

 

[Slashee_the_Cow 409]

Could you provide the Cura project file (.3mf, in Cura go to File > Save Project)? That would make it a lot easier to investigate.

 

Also, some information like what Cura version you are running? And what do you mean by "helper blocks"? Did you import those as meshes before turning them into overlap modifiers? For basic shapes like that you should start with a support blocker and resize/move it as needed.

 

Edit: I just did a quick test with a mesh and while it does still have the outline for the print head, it isn't actually blocking anything preventing it from slicing:

 

In your second last picture (the one that shows the "unable to slice" error), your models are too close together.

 

Also, your printhead is set to be pretty damn big - 8cm x 7cm. That will block off a lot of space for each model, since it needs that much clearance in every direction.

 

Also (I need a thesaurus) a model won't be printed if the dark area immediately around it exceeds the bounds of the bed (the lighter area is fine).

Edited December 31, 2023 by Slashee_the_Cow

[rimbo 0]

@Slashee_the_Cow

 

I don't mind the physical limitations. After all my print polygon assumes printing tall models. The head itself is of average size in my opinion. Especially that almost the entire hotend fan fits right under the stepper motor.

 

By helper blocks I mean the non-physical blocks e.g. support blockers. They should not affect the physical size of the printed model. They should shrink it if anything! And yes, I created them as support blockers first.

 

"In your second last picture (the one that shows the "unable to slice" error), your models are too close together. "

There may be some confusion with the stl because it has a pair of earings as one, so they are both printed as one model. To achieve "One At a Time" printing I blocked 1 earing in each pair. The part I underlined is my main gripe here.

 

 

Cura 5.6

 

I've attached the project from the OP, as well as another project I think I did pretty good with as far as packing goes. That said look at the actual printing order, what the hell! 🙂

cardboard_rivet_washer projekt 2.3mf Earring_Honeycomb_noSupports projekt.3mf

[Slashee_the_Cow 409]

In your first example, the modifier meshes don't have any bigger a footprint (comparatively) to the models:

But more to the point: to make sure there's no accidents you need to make sure none of the darker areas overlap, for models. Ignore it for modifiers. Only overlap the areas the head will be if you're 110% sure you've got your measurements right for the head. And even then, you should allow yourself a little wiggle room.

The dark parts are the footprint of what will actually be printed (taking brim or skirt or such into account if necessary. 

The light parts are the area where the print head will be. Make sure you've measured and set your print head size properly, and that the Apply Extruder offsets to GCode setting is correct (it depends on the firmware).

It's entirely possible #10 was hit because the print head size isn't set big enough, since it's squeezed as tight as possible. For the washers it probably doesn't matter due to the height (or lack thereof).

 

Also, like far too many people, you seem to be focusing on speed (in this case fitting as many things as possible onto the bed). It doesn't take that much longer to quickly remove a few items (as in, less than 11) from the bed and restart the print. Something you learn as you do more of this: it's better to do it properly rather than try and cheat the system. Some people try and skimp on support, and then their model falls over and all that filament (more than what the supports would be) is wasted. Sometimes people print too fast and the vibrations from the acceleration and jerk make a print wobble and your layers shift.

 

I've actually tried the exact same thing as you (packing things in as tightly as possible) and it didn't end well. As I said, for flat stuff you might be able to get away with it, but anything with a bit of height is more trouble than it's worth.

[GregValiant 1,342]

There is a bug in the One-at-a-Time mode that a project like that might cause to show up.

It depends on two things to come together:

• The last model printed is shorter than others.
• Particular moves in your Ending Gcode.

It looks like that washer at #11 is printed last so you have that condition covered.

In your Ending Gcode there is a 50mm Z move at the end of the print, so the bug shouldn't show up.

 

The bug is that instead of the final Z move being at the transit height (that clears all models), the last transit is at 5mm above the last model.  If your ending gcode then tells the print head to go to X0 Y0 without that 50mm Z move, then it would go through your screw #10 and screw #8.

 

If you print a lot of One-at-a-Time projects it's something you need to be aware of.

 

 

[rimbo 0]

On 1/1/2024 at 4:10 AM, Slashee_the_Cow said:

Ignore it for modifiers.

You speak wisdom, through and through. But you seem to be missing that part. I do ignore them. Cura doesn't! It will often refuse to slice due to "bed overcrowd" triggered by no other but the damn modifier blocks.

 

@GregValiant

Wow, thanks! Is there a "know workarounds thread" with pieces like that somewhere?!

 

On that note, do we have any means at all to influence the printing order? I've been testing for an hour to only one cocnlusion - it's all random.

[GregValiant 1,342]

I've tried to figure out the print order myself.  It's a computer so random doesn't really happen, but I haven't been able to figure out the order.  It seems to have something to do with the order the models are created or brought in, but I haven't found a hard and fast rule.  Random I think is a good word for what we see with it.

 

A common feature request on Github is to be able to move the models in the list at the bottom-left of the Cura workspace and have that be the print order.  It hasn't happened yet though.

[Slashee_the_Cow 409]

1 hour ago, GregValiant said:

It's a computer so random doesn't really happen, but I haven't been able to figure out the order.  It seems to have something to do with the order the models are created or brought in, but I haven't found a hard and fast rule.  Random I think is a good word for what we see with it.

The technical term is "pseudorandom".

[rimbo 0]

Id gladly mark this thread as solved but it isn't. To quote my previous post:

It will often refuse to slice due to "bed overcrowd" triggered by no other but the damn modifier blocks.