How do you support a spike or tooth so it prints clean?
A spike or a tooth that points down is the worst kind of overhang. It starts as one tiny dot in mid-air. A 3D print support pin, which Slant 3D calls a support thumbtack, gives that dot something solid to grow from and holds it in place the whole way up.
Applies to
- Process
- FDM / filament
- When
- Teeth, horns, spikes, claws: any tip that starts in mid-air
- Goal
- A tip that’s held still and stays clean
Why it matters
Slicer support around a tip usually doesn’t touch it. The tip starts as a little cone with nothing holding it upright, so it rotates, leans into the support nest around it, and you get weird blobs on the side of the part.
The thumbtack fixes that. A single little spike runs from the tip down to a broad lower surface. Support grows up under the flat head, which is the easiest thing in the world to support, and the tooth grows out of the pin.
The tip is held the whole time. It can’t settle into anything.
What good looks like
- One slim pin per tip, lined up with the tip’s axis
- A broad, flat head on the bottom of the pin, facing the bed
- The pin is the narrowest point, so it snaps there and not in the tooth
- The column under the head is short or braced, not a tall, skinny tower
How to apply it
- Find each tip that points down and starts in mid-air.
- Model a thin pin straight down from the tip. Keep it narrowest where it meets the tip so it breaks right there.
- End the pin in a broad, flat disc. That’s the thumbtack head.
- Either draw it in CAD, or position a thumbtack STL in a program like 3D Builder and merge the two.
- Let the slicer support the flat head, or better, hold the head up with a designed support tied to the main part.
- After printing, snap or snip the pin at the tip and clean the nub flush.
Exceptions & tradeoffs
The thumbtack still needs support underneath it, and that support is a tall, thin column. Slant 3D had one fall over and fail the print while filming this video. For tall drops, hold the head up with a designed support comb tied to the main part instead of a lone slicer tower.
If a rotation puts the tip pointing up or sideways, it doesn’t need a thumbtack at all. Check orientation first.
Common mistakes
- Trusting slicer support around a tooth tip, then sanding blobs off the side of itGive the tip a thumbtack pin so it’s held from the first layer
- Making the pin as thick as the tooth, so it snaps inside the toothNeck the pin down where it meets the tip
- Standing the thumbtack on a long, thin slicer tower that gets knocked overKeep the drop short, or tie the support to the main part
Frequently asked questions
- How do you 3D print a spike or tooth pointing down?Model a thin pin from the tip down to a broad, flat head. Support lands on the flat head, and the pin holds the tip in place so it can’t lean into the support.
- What is a support thumbtack?Slant 3D’s name for a modeled support pin: a slim spike from an overhanging tip down to a wide, flat base, shaped like an upside-down thumbtack.
- Why do tips get blobs on them with tree supports?The support often doesn’t actually touch the tip. With nothing holding it, the tip leans and settles into the support around it.
- Can I add a support pin without CAD?Yes. Position a ready-made pin STL against the tip in a program like 3D Builder and merge the two models.
The support thumbtack for a tooth: a spike from the tip to a broad lower surface, placed in 3D Builder or CAD — Stop Using Slicer Supports | Design for 3D Printing ↗ at 02:25.
Thumbtacks still need tall, thin support that can fall over; a designed support comb is more reliable — Stop Using Slicer Supports | Design for 3D Printing ↗ at 04:48.
The thumbtack, and the honest note that one fell over on them mid-video, are Slant 3D’s. They don’t give pin dimensions, so we don’t either. Our breakaway-waist numbers on Designed supports are a sane place to start the pin.