Raft Separation Distance and base layer adjustments

[MetalBellows]

1.) The "separation distance" setting is useful to make cleaning up printed parts easier but I've run into the issue several times where the part adheres to the raft but the supports around it do not or do not consistently. The ability to set the separation distances for the part and supports independently would seemingly solve this problem allowing the user to reduce the separation distance for the supports, since they do not need to come off the raft cleanly, while maintaining a more ideal separation distance for the part itself. Alternatively a checkbox that turns on/off the application of the separation distance for the supports would accomplish the same thing, giving the user the option of either applying the same offset to parts and supports or have the offset to the part only and let the supports default to 0 gap/offset.

For reference, the part I've been having a fair bit of trouble with has a round base (where it contacts the raft) that connects to a larger square boss above. The round base attaches firmly enough to the raft to keep it in place during printing but is still easy(ish) to remove afterward. The supports at the cantilevered corners of the square, however, have a tendency to break from the raft and curl. There's usually at least two that break free, not always the same two, and I have had all four break using the same settings. I'm hesitant to remove the separation gap all together because it will make the part difficult, if not impossible, to remove cleanly without a good amount of post-processing, but I don't know any other way to ensure the supports stay put.

2.) Another useful adjustment would be the distance between the raft base layers and the solid layers above it that the part is printed on. I've disabled the base layers (which perform their function very well) because the solid layers almost invariably separated from them. What I would end up with is a part that had the supports firmly attached to them and the raft and a base layer firmly attached to the platform, but a failed print because the raft and base layer separated from each other. Currently the only separation adjustment is between the raft and the part but there is no way to adjust the separation of the raft components to address this problem.

[jdurand]

I have a terrible time with #2, prints good raft base, then prints "raft layers" that are not attached to the base. Model falls over with "raft layers" still attached to the model and the raft base stuck to the platform.

The raft should NOT be the weak link. Those "raft layers" should be very firmly attached to the base. They should also cross-hatch so you don't wind up with lose strings.

If I turn the base layers off the raft layers are printed on, not attached to the platform and fall off before it's even done printing. I can see from the Z height display that the first raft layer is being printed way too high.

If I turn off the raft completely the part is properly stuck to the platform, but these parts need the raft for surface finish and extra support (tall polycarbonate).

[brian442]

So for #2, are you saying that the bottom layers of the raft actually separate from the top layers of the raft? I haven't seen that myself, so I wonder if it's related to the layer height or the material/temperatures being used..

[MetalBellows]

Yes, the printer puts down the slow, broad, fairly widely spaced base layers of the raft directly on the print bed. Then it prints several solid layers alternating direction on top of that to create a flat solid platform to build the part on. My issue is that the solid layers separate from the base layers so I have those first 2 or 3 layers on the bed and the surface the part is actually printed on either curls up or shifts or otherwise causes problems with the print.

[jdurand]

I've settled on making my own rafts for polycarbonate printing on BuildTak. The raft is simply a rectangle under the part 3 layers thick. I set first layer to be a bit fat but not a lot, set the table and nozzle hotter for the first layer and it seems to be working ok.

For PLA I just print on the glass with glue stick.

[CAM-Source3D]

I'm glad to see I'm not the only one who has experienced this situation with the top raft layers not being bonded well at all with the base raft layers.
For me this issue has been very strange as we've got about 20 printers here and Simplify3D can be used with over half of them, yet I haven't seen this issue on all of the printers I've run it on.

As a previous response shared, When printing without rafts, the printer(s) in question print with a perfect first layer. If choosing to print with a Raft, the base layers go down fine, then when the print begins to do the solid top layers of the rafts, they're just not bonded well with the base layers. Tall parts easily knock over as OP has stated.

When I print with other printers using raft through Simply3D, this does not happen at all.

The printer(s) that do exhibit this issue, exhibit no other issues such as under extrusion, leveling, etc...

This is not a new issue for us, as we've seen this issue for as long as 2 years or so...

Since it is an issue not plaguing every printer using Simplify3D, but surely enough systems that otherwise exhibit and hardware, electronic or any other reason for it or to solve the issue, then it would be nice if Simplify3D could add a setting for users to adjust the "gapping" between base raft layers and top raft layers, although there shouldn't be any gapping there anyway....