Printing a dovetail / can't get support to do what I want

[kaltorak]

I’m building some pieces to hold my laptop and docking station and other computery things vertically. (Same project I posted on a week or two ago.)

It’s basically two parallel rectangular walls with some rectangular “beams” running between them. I printed some test objects this afternoon, and am confident my internal “beams” can bridge the gap between the walls - no supports required(!!!)

I modified the outside walls to receive dovetail rails on both walls. I’ll use those to connect units later.

Problem is, I can’t get the slicer to give me supports which make sense. I’m using an AMS and I have support filament available.
Ideally, I think I could get by with a thin vertical wall of support filament where I drew the red line, then start building up real filament to form the downward-pointing triangle of the dovetail rail receiver. Failing that, I’d imagine it should work to simply fill in the entire channel of the dovetail rail receiver with support filament.

As it is, the best slice I can get looks like this.

No matter what slicing knobs I’ve tried, I can’t seem to get the slicer to simply infill the channel with support filament, rather than building an entire scaffolding wrapped around the print.

Is the slicer working around a problem I can’t see?
Or if my idea’s a good one, does anyone have ideas for how to better configure the slicer knobs? Am currently doing this:

Thanks!

[user_3026326371]

Try the ‘snug’ option
This usually forces the supports to be as flimsy as possible to not waste too much material.
Usually it just starts from the model where needed.

Another option with these angles is to just include a single wall thick area in your cad program.
If your outer walls are set to 0.42mm “fill” the edges between the rails with a 0.42mm section.
Assuming you print in 0.2mm layers you could include a gap of 0.1 or 0.15mm between rail edges and this filler wall = makes removal easier but even without it is not a problem to cut off a 0.42mm slim strip with a sharp blade.
I actually prefer this way when printing long dovetails as is saves a ton of filament and gives good results - won’t work well with tail angles below 50º in my test …
Here I sometimes get some wavy outer wall lines that require a bit of sanding for a good fit.
No issues though is the dove tails are rather loose fitting to just hold things together with no real structual needs…