No sparse layers (beta) - anyone using it?

U1 Toolchanger
1

I’m wondering if others have been using this feature:

No sparse layers (beta):
If enabled, the wipe tower will not be printed on layers with no tool changes.

Of course, I saw this warning:
User is responsible for ensuring there is no collision with the print.

However, as much as I was trying to be careful and keeping the prime tower well away from the parts of my print, so far, I’ve not had luck with it.

I tried to use it a few times.

I’ve had two very obvious collisions! OUCH!

One, I think I left the prime tower in its default position, and when the toolhead was moving from the prime tower, to go and change a toolhead, it collided with the other parked toolheads!

I don’t know why the slicer would have allowed this! There certainly wasn’t any part in the way of the tool head. On a second try I moved the prime tower further forward away from the parked toolheads and it seemed to continue without another collision.

On another attempt, the active toolhead collided with parts of my prints, even though there appeared to be plenty of room.

I would think that the Z would be controlled to stay high enough over the current point of the print, then move to the prime tower, then down to meet it (or the bed), do it’s prime. then go up to the known safe Z level before traveling again. But perhaps it’s not doing this? I didn’t try to analyze the failure!

After this second failure, I just decided that this feature may not be ready for use by us mere mortals yet!

I don’t want to risk any more collisions.

I do see this same setting available in Orca Slicer, so I assume it’s not a SnOrca only feature? I’m not sure what is known about this feature yet.

I’m wondering if anyone else has had luck with this feature, or if you know the ‘rules’ on “ensuring there is no collision with the print”?

2

I would think that feature is just asking for the wipe tower to turn into spaghetti. If you skip printing layers, higher layers won’t have anything to adhere to.

3

Without the collisions, it actually works well. No spaghetti!

It adjusts the Z height as needed during printing. The bed moves up to the required height and seems to track nicely only performing the prime when a tool change happens, instead of at each layer. It’s a nice filament and time savings.

However, the collisions are a different story!

Perhaps I’m the only one that has tried it? I’ll put it on hold until I learn more, unless someone else has a suggestion about it.

4

That might be the problem then. If the head is moving in X, Y, and Z in a single movement, it might not be raised enough to clear the part yet. I’d have to observe a print or examine the GCode to be sure, but it seems likely given your description and the beta status. And more likely to occur the longer the print goes on (the more wipe layers are skipped, causing a larger delta between the tower and the print).

5

I think it needs more work.

If you want to see the g-code, just enable the option, then slice and take a look.