3D Printing: Drilling 3D-printed plastic (5 Solutions!)
Channel: Roel Van de Paar
Date: 25/06/2019

3D Printing: Drilling 3D-printed plastic


The Question: I need to do some post processing of my 3D-printed models that includes adding
some holes. For each of PLA, ABS, PETG and other 3D-printing materials:
In what ways is drilling a hole in a model made from that material like or
unlike drilling wood? Is it worth getting special "plastic drilling bits" that
cost tons of money or can I use regular high speed drill bits? Do these
plastics have grain that they will split on when drilled into, and if so, what
are ways to avoid such splitting? Are higher speeds better, or lower speeds, or
should I only use a finger-twirled bit holder?
Are some 3D-printing materials easier to drill than others?
What other methods also work for creating a hole in the different types of
plastics?

Solutions Sample (Please watch the whole video to see all solutions, in order of how many people found them helpful)

== This solution helped 6 people ==
I wouldn't recommend drilling a hole in a 3D printed part in a traditional
sense like with wood. Instead, I would merely ream a 3D printed part.
I've done this quite a bit where I'll print my holes at a slightly smaller than
nominal size and use a standard carbide drill to ream the hole.
Things to consider:
 * Printing the holes smaller than nominal will ensure your hole is not
 printed larger than nominal
 * Printing with a higher shell will ensure you can remove the material
 without exposing the infill
Note that drilling directly into (or thru) an infill area of the part could
lead to cracking of the part later, depending on the hole's functionality. In
general, a printed hole (even if reamed) will be significantly stronger than
one drilled through an infill area.

== This solution helped 12 people ==
Have to get this out of the way... Can you just print the hole into the part
instead of drilling? That's usually best, when possible.
If you need to drill, you'll definitely want to print an undersized hole and
then ream it out with the drill. This both provides alignment for the drill and
adds extra plastic around the region you'll be weakening. If you don't know
where the hole needs to go in advance, fill the model with a hex pattern of
tiny holes in the general region of the future drilling. This is an easy way to
strengthen the area with more plastic without making the entire part solid.
(Using a slicer that allows localized print settings will also work.)
The hole should be aligned more or less vertical or "across the grain" (+/-45
degrees aligned with the Z axis) to ensure there are nice, strong hoops of
plastic around the hole to keep it from splitting. Drilling into a printed part
(particularly PLA) from the side / parallel to the XY plane is highly likely to
split it. It may even be ok at first but crack later under load or due to
creep.
Regular wood drill bits work ok, but you need to go slow and take nibbles,
leaving the plastic time to cool so it doesn't melt and stick to the bit.
(Coolant is an option.) Use a pilot hole, piloted bit, or step drill to remove
less plastic per pass. A really sharp bit will perform dramatically better than
a dull bit.
Put something hard and drillable like wood behind the plastic part to help
avoid breakage and bit-jamming when you break through the opposite side.

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