Acetone vapor finishing for 3D printed ABS – getting there...

3D printed parts always have this rough, structured finish where you can see and feel the printed layers very clearly. Various methods have been tried out to get to a nice polished finish. The most promising so far has been treatment with a SMD hot air desoldering station, but thats a lot of manual work and does not always give really nice results.

So a few days ago at ​http://blog.reprap.org/2013/02/vapor-treating-abs-rp-parts.html came along an interesting description for using acetone vapor to achieve a nice and smooth surface. Initial trials using a small glass and a minor amount of acetone looked promising, so we ordered some labware and raided the Raumfahrtagentur Biolab for a heatplate with precise temperature control.

Safety warning: acetone and especially acetone vapor is combustive and a fire risk. Only work in a well ventilated place and have a fire extinguisher at hand. Do not heat on an gas stove. Read the safety warnings regarding health risks for acetone. Don´t Panic.

This is our current process description, to be changed and updated as we find out more.

  1. Pour about 2-3mm of acetone into the cylinder
  2. Set it onto the electric heatplate, turn temperature to ca. 110°C

Setup for acetone vapor treatment

  1. Watch as the layer of recondensation of the vapor creeps up on the glass wall. Turn down temperature way before the vapor condensation line raises to the rim of the glass cylinder.

Acetone vapor rising

You can see clearly how high the vapor has risen

  1. Insert your objects. We suspended them on metal wire hanging from the aluminium lid by means of an magnet on the outer side. Not sure if that is the optimum method, but it works for now. It is useful to have a second identical glass cylinder to try out placement of objects and see how high the vapor must rise before the objects are covered.

Objects in acetone vapor

  1. Watch carefully how the objects smooth out, remove when you feel it is enough smoothing. Usually it is just a few minutes. You can see the acetone vapor condensing on the objects that are colder then the vapor as well as on the wires. Maybe one optimization is to pre-heat the objects with a warm air, so less condensation occurs.

Apparently the smoothing continues for a while after removal, until the acetone vapor has vanished. Cover acetone cylinder again and wait a couple of hours for your objects to become hard again.

Update:

First series of controlled experiments with test bodies. 5 minutes is sufficient for proper smoothing. Touch-hard after about 30 minutes sitting. Apparently a little bit of shrinking occurs (less then 0.5mm on 20 mm diameter / width). The test bodies were printed with 3 outer layers and 40% infill, the print was rather sloppy and imperfect. Next series with more infill and / or more outer layers.

OpenScad file with the test bodies attached.

  • Posted: 2013-03-07 20:18 (Updated: 2013-03-11 02:33)
  • Author: frank
  • Categories: public

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