Support removal and cleanup
The moment a print comes off the bed, it isn't finished — it's raw. There are little towers of support to snap away, a rough scar where they were touching, maybe a flared skirt of plastic squished out along the bottom edge, and a faint seam running up one side where the nozzle stitched each layer closed. Everything that happens next — sanding, smoothing, painting, gluing — starts from how good or bad that raw part is. And most of how good it is was decided long before you pressed print, back when you chose which way the part faced on the plate. This section is about what happens after the bed, and the first lever you have is the one that stops you needing half of it.
Why support exists, and why it scars
FDM lays plastic in horizontal layers, each one printed on top of the last. That works beautifully until a layer has nothing beneath it — an overhang jutting into thin air, or the underside of a bridge. Beyond roughly 45° from vertical, each new layer overhangs the one below by enough that the fresh bead has nowhere to sit and droops. Support is scaffolding the slicer builds under those regions so the plastic has something to land on. It's meant to peel away afterwards.
The trouble is that support has to touch the part to hold it up, and wherever it touches, it fuses a little. Pull it off and you're left with a stippled, rough patch — a scar. The slicer leaves a tiny gap between support and part to make removal possible, but that same gap is why a supported face never comes out as clean as one printed into open air. Normal (grid) support is dense and strong but clings hard; tree support grows thin branches up to just the overhanging spots, using less plastic and scarring less, but it can't hold up broad flat undersides as well. Dissolvable support — a second material like PVA printed on a two-nozzle machine — washes away in water and leaves almost no scar, at the cost of a more complex print.
The real lever: design so you don't need it
Here's the shift in thinking. You don't have to accept where support lands — you choose it, in the model and in how you orient the part. The roughest face on the finished print should be a face you picked to be rough, ideally one nobody sees.
Orientation is the biggest control. Tip the part so its overhangs come in under 45° and the slicer won't add support at all. A hole printed as a vertical bore needs no support; the same hole printed horizontally sags at the top unless you turn its ceiling into a self-supporting teardrop shape in the sketch. A sharp overhanging shelf can be replaced with a chamfer shallower than 45°, which prints in mid-air with no scaffolding. These aren't tricks — they're consequences of the 45° rule, and they live in your model as chamfers, drafts and teardrops you draw deliberately.
Cleaning up what's left
Whatever support you do use, remove it with flush cutters and a scraper, working from the edges. Two other blemishes are worth a pass. An elephant's foot is the slightly bulged, flared first layer where the hot base squished under pressure and heat; it makes a part sit proud or refuse to seat in a slot, and a quick chamfer with a knife or a deburring tool brings the edge back to size. The seam — the vertical line where each layer's perimeter started and stopped — can be scraped flat, and in the model you can often steer it to a hidden corner rather than the show face.
The theme for everything that follows: decide the finish while you're still modelling. Where support lands, where the seam runs, which face you'll sand — all of it is yours to place. Pick the right route with the diagram below, then start where most parts start.
Orientation and support are decided upstream, in From model to print. Once the part is clean and in hand, the most common next step is knocking down the layer lines — that's Sanding and smoothing.