Oscillating smoothing device for a three-dimensional printer

A powder-layer three-dimensional printer comprising:

• a build box adapted to contain a plurality of layers of a deposited build powder to form a powder bed;
• an oscillating smoothing device comprising a leading blade, a compaction sled, and an oscillating motor, the leading blade including a leading edge facing a direction of movement of the oscillating smoothing device across the build box and providing an initial contact of the oscillating smoothing device with the deposited powder, and the compaction sled following the leading edge so as to trowel and compact the build powder forming the plurality of layers, wherein the compaction sled includes a powder contacting surface that starts above the powder bed and extends a distance into the powder bed, and wherein the oscillating motor imparts oscillating motion to at least one of the leading blade and compaction sled;
• and
• a smoothing device mount adapted to move the oscillating smoothing device across the build box, the leading blade and the compaction sled being connected via the smoothing device mount.