Raft separation distance and next layer height problem

[dunginhawk]

.5 separation distance w/ fan on from layers 3-7 did nothing to help it detach.

[dkightley]

Do you have your extrusion multiplier set correctly?

If you're not sure, print a cube with 0 top solid layers, 0 bottom solid layers and 1 perimeter....and measure the wall thickness, which should match the extrusion width (auto or manual). If it doesn't adjust the extrusion multiplier so it prints the correct width. This will make sure you're not pushing too much plastic out as you're extruding - which might be what is causing the first layer to stick too firm to the raft.

[krouviere]

In version 2.2, this worked correctly.
For example, setting to a .014mm gap yields the result in the first picture below.
Setting to 1mm gap yields the result in the 2nd picture below.

This is exactly what I would expect. I have control over what the machine is doing. I can also easily see the result of changing a value in the user interface and validate that the control is changing the parameter I want to change. And as odd as it may seem, I may actually want this if I am doing something creative with multiple processes and overlapping models.

I don't see any downside at all to making it work like it used to. In fact the way it is now, I don't think there is good control between 1st layer after separation and the layer after that. The way it worked prior to 3.0, the 2nd layer after separation would have a fixed relationship with the 1st layer after separation.

Sure, I can goof up and set the gap too large, but that's my fault. I want the control.

[jomireyn3]

Thanks. I'm the original poster of this question. This is exactly what I expected to see when I tried this feature. I bought Simplify3D just after version 3 came out, so I didn't have the earlier version to compare to, but this is what the documentation seemed to be describing.

I have tried all the suggestions from this thread with no success. I've essentially stopped using the software because of this problem, and have delayed any projects that depend on the more accurate printing for small parts and tight tolerances that it provides because the bottom surfaces are essentially ruined by the raft.

Seeing these results from the earlier version leads me to believe that this is a bug, not a feature.

Does anyone who's had poor results with the new version still have access to the old and can you compare them with a few test prints?
PLA would be preferred. I'm doing some projects that require the ability to sterilize the model to take into an operating room, and only PLA has those properties.

[dunginhawk]

i do have access... its installed on my laptop at home... i wont be home to test it until wednesday or thursday, but ill test it then

[krouviere]

FWIW, I do most of my printing with ABS and have generally found that I have a hard time with PLA if any PLA raft or PLA support is involved.
If you have a dual extrusion machine you might be able to print the raft out of another material, or print without a raft on glass or something.
Someone may have suggested that before.

I do think this is a bug. I have contacted support. Their initial response was disappointing. I pointed out that prior to 3.0 it worked as expected and asked that their engineers take another look at this. Maybe they can be persuaded to change it back especially if other people complain. It's hard to believe it was intentional given the great track record they've had with providing lots of control over the process.

[jomireyn3]

Thanks, I think I will contact support, too. We have a Makerbot 5th Gen, and it's native rafts work great with PLA, but Simplify3D does a better job for the small parts and holes. I tried duplicating the Makerbot Desktop settings in S3D, without any luck.

[dunginhawk]

first test with old software netted the same results. .2 separation, 85% infill and it was impossible to remove.
testing at .4mm and 220c nozzle temp

[bapro]

The raft is going the opposite direction as it did in version 2. This results in worse bottom surface, higher bounding and less accurate prints because you have to add more space between the raft and your print. Since we also lost the possibility to change solid infill angle in V3 it´s not much to do other than to lower the temprature and increase the distance.

I hope this will be corrected in the next update.

[dkightley]

In version 2.2, this worked correctly.
For example, setting to a .014mm gap yields the result in the first picture below.
Setting to 1mm gap yields the result in the 2nd picture below.

This is exactly what I would expect. I have control over what the machine is doing. I can also easily see the result of changing a value in the user interface and validate that the control is changing the parameter I want to change. And as odd as it may seem, I may actually want this if I am doing something creative with multiple processes and overlapping models.

I don't see any downside at all to making it work like it used to. In fact the way it is now, I don't think there is good control between 1st layer after separation and the layer after that. The way it worked prior to 3.0, the 2nd layer after separation would have a fixed relationship with the 1st layer after separation.

Sure, I can goof up and set the gap too large, but that's my fault. I want the control.

I'm at a loss as to how changing how this is represented in the preview will have an effect on the printed model. The v2,x preview showed the second and subsequent layers printing above where the first layer was printed....showing the model "levitating" above the raft. This graphical representation looks as if has been changed in v3 to show the first layer printed at the elevated height and then the second and subsequent layers being printed at approximately the height where they actually is printed in real life. The effect looks equally strange. The model no longer "hovers", but looks as its been mis-drawn. Both can be said to be either right or wrong....but how can this be correctly represented to satisfy everyone??

Surely the real issue is the first layer of the model is for some reason sticking too hard to the raft after being printed in fresh air and dropping under the effect of gravity. To me, this is probably caused by other factors...and not how high the layer is printed! Or how it is represented in the preview!