Print speed for first layer of interface material?  

RE: Print speed for first layer of interface material?

I can't make sense of the image.Do you have a sample file? I'd like to take a look at it in PrusaSlicer.

RE: Print speed for first layer of interface material?

Simple answer is no.  There is no setting to configure a different speed for the first layer of support interface.  

RE: Print speed for first layer of interface material?

@joncl the forums are extremely screwed up these days, I suspect on purpose in order to confuse good information for bad, can you provide a working file and better explanation of what exactly your looking for from slicer. It's normal  these days to see persons asking for things using the incorrect terminology for the thing they want, for example, asking for  (information about "Parts"  when they mean "Objects") this can be cause for the wrong information to be provided. If your willing to provide a file exported from prusaslicer the way you have been working it, people may be able to give you better information. Otherwise not.

RE:

I think there definitely should be a setting to control the speed of the first layer of interface material. I made up an example PrusaSlicer file attached.

The use-case is a flat horizontal overhang that  needs support.

As I mentioned, I use silk PLA for interface material which separates cleanly from PETG, but still allows the PETG to "stick" during the print. Problem is, the first layer prints at FULL SPEED across the supporting (spaced out) material (unless set slower globally). Screen grabs below to help illustrate.

Example part:

One layer before the interface (layer 61):

Interface layer (#62). The problem here is that, if left at the default speed (100%), PrusaSlicer does not seem to know that it's printing over spaced-out support material, and it bridge across those gaps at full speed. PrusaSlicer needs to know that it's actually bridging here:

This is just a different view of the same first interface layer (#62) to show the spacing. I set interface spacing to 0 (zero), which leaves a nice bottom PETG surface. However, another useful setting would be to also control the spacing of the first interface layer, because zero spacing is not needed here (perhaps 200% of support spacing would be the default).
 

Also, it seems to print fine at default speed over the primary material (this is the first interface layer over the example part): 

RE:

Attaching step file.

RE: Print speed for first layer of interface material?

I'm updating here because I found a way to slow down the first layer of interface material with one line of G-code, and I found an extra bit of interesting behavior...

Here's a screen cap of my first interface layer I want to slow down. Notice it's layer #62, and the speed is around 44mm/s:

Under Printers > Custom G-code > Before layer change G-code, enter:

{if layer_num == 61 and current_extruder == 1}M220 S30{else}M220 S100{endif}

Note that layer_num and current_extruder is zero-based, so layer #62 in the UI is zero-based 61, and my interface extruder is #2, which is zero-based 1. Also, "M220 S30" changes the interface material speed down to 30% of the support material speed:

However, this had no effect! Just to confirm my code is working, I changed it to the next layer:

{if layer_num == 62 and current_extruder == 1}M220 S30{else}M220 S100{endif}

And here's it looks like after slicing:

The G-code definitely works for 63(62), so why does the code not work for layer 62(61)? Looking closely at the first image above, this layer ONLY uses the one interface extruder, due to how the extruders leap-frog between layers. So I tried this G-code:

{if layer_num == 61}M220 S30{else}M220 S100{endif}

And there we go:

Apparently, having "current_extruder == 1" in the code does not apply if it's the only extruder for this layer. However, if there's more than one extruder in the layer, then "current_extruder" is needed in the G-code to set the speed of just the interface extruder.