[Bug] Layer by layer printing

[maddaFreak]

Hello there,

under my first thread you'll find a short discussion about printing models with and without raft.

But until now i discussed this problem even in the german reprap forum and a user thinks that this must be a sort of bug.
Because, when i'm telling S3D to print my two process "layer by layer", the gcode generates first the complete raft and than is trying to print the
modell without raft, but we think, that the firmware is making trouble stepping down the z axes because the twin extruder could get in the way.

So, even the raft should get printed "layer by layer" and everything would work fine again, or what do you think about?

best regards

madda

[horst.w]

Hi neighbor,

you are right, the raft will be printed first and completely, than the 2nd object start to be printed. The PrintPreview shows it, there is no doubt about it. But when you check on the raft box for both objects in both processes it is the same !!! First the one raft and than the 2nd and than alternating the two objects.

When you are using only one (base)process and the raft box is checked on, than both objects are concerned and the raft for both objects will be printed, but now alternated layer by layer !

Thats really strange and normal I would say it is a bug and not a feature!
Otherwise when raft is printed with 3 layers, it needs in reality 6 layers (without a base layer!) and a high of ~ 2 mm (layer high = 0,2) while an object without raft needs for the first 2 mm round about 10 layers.
Therefore you can not join the two conditions together!

Best regards
horst.w, GER

[dkightley]

All

We have here a problem to which there is no answer...or at least a foolproof solution. We do , however, have a scenario that must be avoided if you have a dual extruder!

Set up two models to be printed by different processes. The one on the left with a raft...and the one on the right with no raft. And by pure coincidence, both processes are set to use the right extruder.

The print starts......the raft for the model on the left is printed...all four or five layers..and then the first few layers of the right model need to be printed. CRASH!!! The left extruder hits the raft! Print fails. So we have the bug as reported in this thread! The whole of the raft for the left model is printed before the first layer of the right model.

Okay....let's pretend the bug has been fixed so the first layer of the model on the right is printed after the first layer of the raft for the model on the left. CRASH!! The first layer of the raft is printed at 200%...a nice 0.4mm thick...and when the head moves to print the first layer of the model on the right, the head is lowered to print a 0.2mm layer!!!...and the head strikes the raft just printed.

So.....with or without this "bug", the stated scenario will fail. What we have is as I stated in my first line.....a problem to which there is no answer......other than to be aware of the likelihood of it happening....and don't set it up to fail! And to set this scenario up so it won't fail....

Set the model needing the raft to print on the left from the first of the two processes....and use the left extruder. Set the model on the right to print from the second process...and also print from the left extruder. Now when the print runs, the raft for the model on the left is printed, then the first few layers of the model on the right, then alternating two layers on the left and two layers on the right....and the right extruder head will not crash into anything!

If you need to use the right extruder, swap the left and right models around..and the order in which they will print. The left extruder head will then be okay. What you may not be able to do is to use the left extruder for one model...and the right extruder for the other.

I've said this somewhere on this forum before......just because the software will not do what you want it to do doesn't mean its a bug!!!!!!

[maddaFreak]

Hello everyone,

sure not everything is a bug. But when the software is offering a "layer by layer" option, but the print isn't build layer by layer ... i think this is a bug ^^

That raft thickness is different from a normal model is correct, but than the software should step the none raft model until it gets on a high for laying the
raft layer. So it should first print 2 layers from the none raft model, than get on the raft z stepping printing the first raft layer. I think this would be
the better definition for a "layer by layer" option with different process. And when getting an option for adjusting these layers so that there is no intermediate step, it would be perfect
Could be like "fit in one Raft layer into 2 none raft layer".

best regards

madda

[horst.w]

Doug, ".....just because the software will not do what you want it to do doesn't mean its a bug!!!!!! "

you have pointed it !


@ MADDA

The problem is to solve! Why you want to use raft for one object and for the next you didn't ?

I imagine you want to print a sphere and a cube. The sphere needs something around to make a best contact to the printtable, the cube doesn't need it. Ok!

Use Skirt/ Brim , 2 or 3 layers, Distance: 0,05 mm and 20 perimeters. That will be printed always in the right way, is very strong and also would avoid warping the cube (not needed imperatively >>> 2nd process and check off or give it only 1 or 2 layer, 5 to 10 perimeters are enough), but always useful for some other reasons).



H.

[horst.w]

Hello everyone,

sure not everything is a bug. But when the software is offering a "layer by layer" option, but the print isn't build layer by layer ... i think this is a bug ^^

That raft thickness is different from a normal model is correct, but than the software should step the none raft model until it gets on a high for laying the
raft layer. So it should first print 2 layers from the none raft model, than get on the raft z stepping printing the first raft layer. I think this would be
the better definition for a "layer by layer" option with different process. And when getting an option for adjusting these layers so that there is no intermediate step, it would be perfect
Could be like "fit in one Raft layer into 2 none raft layer".

best regards

madda

You ignore that the FirstLayer is always the FirstLayer for all objects. Printing the given layers for the non-raft-model has priority to that what you wish to do. The lowest common factor when using a layer high of 0.20 mm and raft with 3 given layers for it, comes up to 2.0 mm
Raft is not only a setting, raft is also a program / function because it use min 3 layers which cannot be influanced by the user.

Use skirt / brim as I wrote and all will be well.

H.

[wirlybird]

I would agree with Horst. It really doesn't seem fair to call something a "bug" when you are trying to force to dissimilar printing methods at the same time.
A raft is a process and the print is a process. The happen in a prescribed sequence.
Don't get me wrong , I am a critic of S3D and its issues, especially lately but I think in printing you have to group multiple prints in a way that makes sense for quality and efficiency.

[maddaFreak]

Hello everyone,

ok, for this realy special problem in the background (raft / none raft) it's perhaps not realy a bug, more of some kind of special problem.
I'm using this software for 4 weeks now and sure i don't get everything correctly.
But in the first way when i'm adding different process and tell him he should print it layer by layer and the result is something different,
for newbies it looks like a bug ^^

And on the other way, it could be done by the slicer. He could say, hey, this will not be printed layer by layer because raft is something different,
or he could calculate the layer by layer thing correctly, including the more than one first layer problem. I don't want to tell it would be simple,
but i'm no fan of "it's not possible" ;D

For your question "why you want use":

I'm getting very different models for printing and for saving time i want to fill my printing bed. But some parts does have enough ground that
they don't need to be rafted and ... when directly printed on bed, the baselayer quality is finest you can get.
The other parts are often realy made delicate, sometimes my wallthickness is just 0,5mm. The x400CE is doing'em fine, but they need a raft
otherwise this parts are getting off from the bed and destroying everything.
Thats why i thought it would be nice to use Raft/non-raft at once.

But thanks for your idea with the skirt / brim idea. It looks more like the cura antiwarping layer and could be in the moment the best
answer for my problem.

Just a shorty ... S3D offers options for raft ... so i could use just 1 raft layer. So the raft is adjustable

Thanks for answering you all, keep on printing

best regards

madda

[wirlybird]

Completely understand your need and you have a valid point for what you are wanting to do.

[maddaFreak]

Hello again,

i've started a print without raft, trying out your skirt/brim layer.
I'm realy curious about the result ^^

best regards

madda