1st layer on top of supports not attached

Printing this case and the first layer on top of the support is really ugly. And a PITA to remove (not as bad as removing supports from the Ender).


I either end up with unattached filament or a scraped surface. Doesn’t look good.

I’m running 1x now with a .12 top and bottom z distance, but I suspect all this will do is make removal harder.

I’m thinking of using the support filament. I can set it to just be the interface layer, right and not take too much of a performance hit?

??TIA

So does the printer work or not?

sometimes.
sneakernet for now to txfr files. vid is fine. IDK wtf is wrong with it on the network. Bay#2 still dead in ams. support finally decided to replace the ams at MY expense. they will refund when they get my defective one back.

Can’t you flip that over and print it? It looks like it wouldn’t need supports then.

No, there’s a knob on the other side that’s 8mm tall It’d have to be supported and it’s an external surface, wouldn’t look good.

I never really got the hang of snap-off supports. Either bad surfaces in overhangs due to large z-distance, inability to remove supports, PETG warping or (most of the time), all of the above.
But with PLA, using Fiberlogy BVOH (well dried) I got some really nice prints with a 0mm interface.

With PETG, it is more tricky as PETG won’t bond. Ideal for an acceptable surface, but unusable if the support has to hold the part in place. I create extra supports using primitives in that case. Still experimenting with exact nozzle temps though.

Since in your case adhesion may not be an issue, you may want to search the forum for PLA as a support for PETG and vice versa. I have not tried it myself, but it may provide a quick solution for you.

From my experience with BVOH, ensure that filament min/max temps are set to a more or less common value as this setting determines load/unload temps. You do not want a higher melting material to solidify or a lower melting material to decompose in the nozzle. Also temps do vary by ± 4°C on my machine during filament changes. So do not go too closely to the temp edges.

From what I read about the PLA/PETG combination, a lot (!!!) of purging is advised.

PLA with BVOH interface (0mm):

Supported surface:

That looks good.

I found that if I set the Z for the interface to half the layer height it comes off easily. Just got to get under it, is the only issue. It’s a thin walled box basically and getting under it can be difficult, but once I’m under it, comes right off.

Many thanks for the rule of thumb on the z-distance with PLA :grinning: I was not aware of that to date.
With PETG, I tried a large number of different settings but found none to give satisfactory results. Dissimilar material support really helps with the drooping there though.

I don’t think you’ll get a much better surface finish as the layer on top of the support interface is not the same as you will get on say a first layer.
Anyway, for top and bottom support interface try add 0.02 to the end, so for 0.2, change it to 0.22, it works for me.
But if this is something you’re going to be printing a lot of, I’d look at redesigning so you can print it flat and join the bump on separately.

I’ve found that the support interface itself wants to stick to the model often. I’ve recently been changing the top support interface layers to “0” and this has helped a bit, but I can’t seem to find a way to change the bottom support layer interface to “0” so, on middle model supports I still end up with support sticking. Does anyone have any suggestions? @RMB, do you think your suggestion of adding .02 is a better solution?

There’s so many factors that affect supports. How easy they are to remove and how they affect the look of the model after removal. I believe the biggest hurdle for our printers is we are printing with higher filament temperatures and speeds than what we are traditionally used to. The problem is that the support interface may still be still soft when the model part that is being supported is laid on top of it, or the cooling performance for long overhanging runs (or would be if there wasn’t a support holding it up) isn’t quite capable enough, so the filament will still droop down a bit into the support.
Honestly, I don’t play around with support settings enough to make a very informative response. The 0.02 add on was given to me by a much more experienced person as his “go-to” setting, and it works for me most of the time. I don’t do a lot of models with sports though. I would rather redesign something so that it doesn’t use supports or at least minimises using them. I’m not adverse to cutting things up and printing them separately and joining them together afterwards to avoid lots of supports and time.

Just a follow-up on the suggestion from @RMB:

I just finished a print adding the modifier of .x2 distance to the interface layers (top and bottom). I also made the top interface layer solid and set that layer height to one. I can confirm that it did remove rather nicely. I’m pleasantly surprised!

If you’re printing supports with the same plastic as the model, you have to maintain a distance of 1/2 of the nozzle diameter between the interface and supported feature so that the extruded noodle just “rests” on the surface below it. If you don’t maintain that spacing, the plastic gets compressed down in to the support interface below it, just like the plastic gets compressed down over the previous layer in the actual print (though maybe not as much). That “compression” over the support interface layer is what makes it really hard to remove the supports, and it actually makes the surface rattier than if the spacing hadn’t been tweaked. People tend to try and narrow that gap to get better supported surfaces but it’s often counterproductive to do so.

If you’re not happy with your supported surface, and you can’t reorient the model to deal with it, the real solution is an AMS so you can print a filament that won’t stick and use the same layer spacing for the supported surface as for everything else. Or print in two halves that can be joined so that the supports aren’t necessary.

Think of toothpaste squeezing out of a tube. If your height above the toothbrush is 1/2 the diameter of the opening, as you extrude it, it easily bends at a 90º angle and lays across the tips of the bristles. If you bring the tube’s opening closer, the toothpaste has to push down in to the bristles in order to make that 90º bend.

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