What am I missing on Supports  

RE:

I will answer my own question. It appears that the "interface spacing" creates additional space between the part and the actual supports. I am not sure why you would want this as it looks terrible and is not removable so what's the point of turning this on? It says it creates more uniformed surface for the supports but it seems to me you giving up good finish for this small bit of uniformity? I might see this working if you could cool the nozzle temp down for this specific layer but that cant happen that I see? Anyone?

RE: What am I missing on Supports

I do not have the XL, but I've printed with supports for several years on the Prusa and various other printers.

With break-away supports, realistically, it's often said that the bottom side of the supported item will turn out butt-ugly at best.  It's best, if you can, to draft and position your model for 'greasy side down' orientation, as in to try to get things so that the supported surfaces are not prominently presented.

Having said that, the parameter that usually makes the most difference in appearance of surfaces supported by break-away supports is the 'Contact Z distance' or 'Support Z distance' depending on your slicer.  This will usually default to a value between 0.2mm and 0.4mm, again, depending on the slicer, printer profile, filament profiles, etc.

I've found that 0.2mm will give you supports that are difficult to break away and a nasty looking supported surface.  0.25 is a value that has been recommended on this forum for some time as a good starting value for Z distance.  If you get too much space, yes, the supports will break away quite easily, but the supported surface will be even more ugly in appearance.

There's also the 'X-Y separation' or 'Support X-Y distance', depending on your slicer's terminology.  This is how much 'breathing room' there will be between the supports and the printed object in the X-Y plane.  My experience is that tweaking this makes minimal improvement in the appearance of supported and adjacent surfaces.

There's also the 'number of interface layers', and one number for that I've heard here has been 3.

However, as you are finding out, break-away supported surface appearance can be a function of (among other things) the particular printer.

I would suggest making test prints, using portions of your production print, and tweak things for the particular printer/slicer/filament combination, first starting with the Contact Z Distance, and then tweaking other parameters if you wish.

One thing that I've found makes quite a bit of difference is the slicer, both slicer type/brand and version.  The developers love to tweak things, and I've seen where a newer version of a slicer can indeed result in uglier supported surfaces.

My opinion is, in general, that Cura will do a better job, overall, with break-away supports than PS.  I know some other folks agree to disagree with me on that.  😉  You might try another slicer, or even a different version of your favorite slicer and see if there's a significant difference.

For a good cosmetic appearance of a supported surface, it's almost imperative to use soluble supports.

RE: What am I missing on Supports

This is what it looks like to me:

Interface spacing is the space between the top of the supports and the actual 'first' layer of your printed model. You should only do zero if using adverse materials (ex: petg/pla), 0.1 is useful for 'pointy' organic supports, 0.2 is ugly but more easily removable.

I don't know what your full model looks like but kinda seems like you'd be better off only having supports at the edges as a structure for bridging; this amount of supports seems unnecessary/hard to remove/ugly.

There are also things to help make support structures easier to remove 'as one piece' like using rect.grid instead of just rect for support structure pattern and upping the top interface layers to 5.

Best option, since this is the multi-head XL section, print supports in an adverse material to your model's material, snug settings, and set interface layer to zero.

RE: What am I missing on Supports

THank you for your help. It has been extremely helpful to learn this as it has really never been an issue on my M3+. Can you please tell me what causes this first layer looseness or is there a way to skip this first interface layer altogether? I did have it turned to off for top and bottom on this print but wow does it look terrible. The supports remove very well but this is what is left. 

I have not issues with soluble supports although I have not tried it yet but that is pretty expensive the way I see it? Could be out in left field but ouch.  

RE: What am I missing on Supports

Can you please tell me what causes this first layer looseness or is there a way to skip this first interface layer altogether?

The first layer of the actual model when supported is more or less like bridging. Only difference is there's a layer of support interface at a small set distance below it compared to normal bridging where its nothing but air underneath. And like normal bridging, more distance makes it look worse. You can't just 'skip' a first layer. 

The only way to fully eliminate the 'sag' is to have the "Top contact Z distance" set to zero so the model's first layer can get 'the squish' as if it was printed directly on the bed itself. Obvious problem with that is if your support-material and model-material is the same then they will just be fused together as one piece. To get around that you could use 'adverse materials:' things like having your model made of PLA and the support made of PETG, or vice versa; or the more expensive, model of PLA and supports made of soluble PVA/BVOH. Problem with that is they dont stick to each other (thats why they're adverse materials), so you're going to have a bad time trying to get the start of a layer to print directly on it since the material would rather stick to the nozzle than the adverse material.

So now you get the issue where you want the start and end of bridging support to be the same as your model, so they stick, but you want everything in between to be an adverse material. That currently takes manual supports designed in CAD to do.

So most just use 0.1 or 1.5 or .2mm of "Top contact Z distance" and put up with some ugly. Or design/print things in a way to reduce the amounts of support/large bridging needed.

Maybe your models when printing on the MK3 were much smaller so it never got super ugly. Maybe you had customized support settings that you didn't bring over. Too many unknowns to do a good comparison.

... and set interface layer to zero.

I mistyped this. "[Top] Interface layers" should be 5, but "Top contact Z distance" should be zero. Effectively making it like the default "soluble support" setting.

"Top contact Z distance" is the distance between the top of your support's interface layer and the first layer of your model printed on top of that interface layer.

And just to muddy things up some more, know that not all PLAs are just PLAs, and same for other materials. So you might luck out and find brands or materials that do work well as 'adverse support materials'; maybe a brand of PLA+ adheres nicely to a different brand PETG, so you'd be able to use either as a 'soluble support' for the other. Case in point, I found out the couple rolls of PLA-F I've had sitting around works perfectly as a zero z-distance support material for regular PLA. Sticks just enough for perimeters to lay out, but not so much that I can't literally peel off supports for perfectly squished overhangs.