CrazyIvan2

Sorry to keep banging on about this but everybody appears to be missing the point: skirts may be for priming the nozzle, but it is listed under "build plate adhesion"! I can accept that raft, brim, and skirt are mutually exclusive and therefore skirt has to be an 'adhesion' option, but not even the hover tips mention skirt is for priming the nozzle, so I'm sure you can understand why I don't find it intuitive.

I don't think screwdrivers were designed for levering the lids off tins of paint, but...

What I'm hearing is what the skirt setting can be used for. I'm still hoping for a convincing explanation what was in the designer's mind when skirts were invented. "What we need is a gash print to start off, so that if the user is really quick they can get in and tweak the manual bed levelling on the fly before the real print starts instead of doing a proper levelling before starting the print." "Tell you what, instead of extruding some filament in space or as a blob to ensure the nozzle is primed, let's draw a perimeter around the actual print." Those are printer-specific things, which are normally confined to the printer config rather than the slicer settings.

Fair enough, so calling it "bed adhesion" is something of a confusing misnomer!

OK, basic question and the answer must be here somewhere (I did look)... what is a skirt for? Here's my understanding (corrections welcome): Raft: sets up a buffer between the print bed and the first layer of the model, which can be optimised for bed adhesion. Also eliminates any unevenness in the bed. Brim: increases the surface area of layer 1 in order to improve adhesion, without getting between the model and the print bed (improving layer 1 surface quality and reducing filament waste). But skirt? It's like a brim but does not contact the actual layer 1 print, so how is that supposed to increase adhesion? And if it's not intended to increase adhesion, then what is it for?

I grew up with BASIC and procedural languages. Writing add-ons to existing software (such as an extension for Cura) is a step too far for me. My idea of a "post-processor" is an edit script or perhaps something in AWK... or even a spreadsheet. I sure recognise that one!

...however I've just realised there is a problem with absolute z coordinates. I (accidentally) worked around that, because I orientated my model in Cura with the plinth at the top, so I only had to delete the final layers. It turns out that was a good choice! Nonetheless, I see no reason z coordinates could not be dealt with using global edits.

Not that hard, once I had identified the relevant layers, because I specifically arranged the supporting plinth to be in layers which were dedicated to the plinth only. I now realise what I should/could have done is leave the plinth in the print and inset an air gap layer between (although consideration would need to be applied to the slicer settings so that there was actually solid print below and above the post-slicer insertion of the air gap). The air gap could (maybe?) be achieved simply by modifying the z movement at the start of the layer.

So this isn't a bug but intentional? Thanks.

Okay, so it's not critical, but I was viewing a Cura-generated .gcode file with the intention of editing it manually*, and I couldn't make the number of layers add up. According to the preview, the slider on the right went from layer 1 to layer 13. When I looked in the gcode, the ";LAYER:" comment lines went from -5 through 0 to 8. That's 14 layers. I couldn't figure out what was going on for a while. Then I discovered there was no ";LAYER: -1"! It goes -5, -4, -3, -2, 0, 1, 2...!! So, what is the intention of this layer numbering? Why not keep it the same as the layer numbers when previewing? I can see the negative numbered layers might be intended to represent the raft or other support, but is 0 the first actual layer or is 1? I know, you're going to ask which version of Cura, but I don't have that info accessible right now. It's not the recent release, it's whatever was current back in June. * Why would I want to edit gcode? FreeCAD won't pad disconnected parts of a sketch without them being on some kind of support, because they produce disconnected solids. The easiest way forward was to put them on a plinth and then delete the plinth from the gcode.

That looks like a hard job, even for a skilled worker. First, what's the access like, it looks like it's down a hole. Can the area be disassembled for free access? The next thing is that electrical solder is very soft and we don't rely on it for mechanical strength – that's a sprung contact so when mated the solder joint will be under stress. I'm sure the original part retained the contacts in the plastic moulding, and it has now broken out. That wouldn't stop me trying to make a repair (nothing to lose by trying), but I would also be trying to source a replacement connector. Don't be tempted to glue the contact in before soldering, the heat of soldering can break down the glue and release toxic fumes in the process (eg superglue releases cyanide when heated).

🙄 The above gave me exactly the preview I wanted. Unfortunately the resulting GCode upset my printer (Tina2) to the extent that it tried to print the adhesion raft below the level of the bed! UPDATE: False alarm! I spent ages looking at the GCode and comparing it with a previous run (without the model's Z offset), and couldn't find any significant differences. So I prepared to re-run the same print file. By a strange coincidence, the Tina2's z offset calibration had gone awry. I recalibrated it, and the print is now proceeding correctly (apparently).

Aha! https://github.com/Ultimaker/Cura/issues/15505

It's interesting you mention that, because I found it too. However, although it's ticked to be displayed in the menus in Preferences, I can't actually find it in Print Settings! Why would that be?

I'm using Cura 5.3.0 on Linux, with an Entina Tina2 printer. I want to improve the clean-up of the undersides of prints by raising the model off the z=0 plane, and thus have support structure under the entire model. I've turned off snapping to zero and set z=10mm (say), but although the Prepare view shows the model off the bed, when I slice and view Preview the model is back on the base (with a "ghost" of the model shown where it should be). Scanning through the layers in Preview shows the build at z=0. Some Google results say that's what to do, but others indicate the z offset is to make the printer start on top of an object placed on the print bed. What to do please? I don't want to just "suck it and see" without some advice. Thanks.