Sparse infill help

[dennisjm]

So I have these large objects that need printed. They take along time and I want to save time on infill.
Hoping someone can suggest something better than what I'm thinking.

If need at least a small bit of infill because the top is solid and flat so it needs something to print on. So I can do like 1% or .5% infill and just get a couple support walls basically and that's plenty.

The problem if I choose two infill angles then the walls don't work so well since they don't have solid material to print on every layer.
But then when it gets to the top layer the layer still runs the same direction so only the 1% has support to print on and there are big sags.

What I really want is the 1% infill with just one layer but then when it gets to the top to switch to +90 degress so it can print across the infill bridges instead of lined with.

So I know I can of course use multiple processes and switch the infill direction for the 2nd process at the top... but you all know how annoying and time consuming that is when I have a bunch of models to print and have to slice them all, figure out the correct heights then go back and adjust the processes and reslice etc.

Anyone have a better idea? This almost makes me need to use a different slicer that can do hex or triangle or anything else infill.

[KeyboardWarrior]

If you post the STL files, a factory file, or a screenshot I think that would help to. Just so people have a better understanding of what you're trying to print. Also, I think that turning off random infill placement, and using 45/-45 at 5 or 10% should work just fine in 90% of cases.

[dennisjm]

What I'd really like is to print this with pretty much 0 infill, yet find a good way to do the top surfaces nice.

base1.STL

(216.1 KiB) Downloaded 189 times

[jimc]

you need some type of infill. as said prior be sure to turn off the random infill placement and just set it to atleast 10-15% infill and let it run. to have no infill then slice the tops off the model, print them separately then solvent bond them on when its all done.

[dennisjm]

My current process is 1% infill for all but the last little bit then up to 30% infill a bit before the top starts.
Will see if it works I guess. It certainly saves a bunch of time.

[KeyboardWarrior]

My current process is 1% infill for all but the last little bit then up to 30% infill a bit before the top starts.
Will see if it works I guess. It certainly saves a bunch of time.

I personally don't think 1% is enough in any-case to build 30% infill on-top of, it's a ton of bridging for each strand of infill but that's an interesting test.

[dennisjm]

I tested a small piece with the concept and it seemed to work. I don't think it would work with PLA but this is an ABS part. There is enough layers of 30% that it seems to build up fine by the time the real top surface needs to start printing.

That said, I haven't actually finished the actual part yet. Time will tell I guess.