Page 110 - Robot Builder's Bonanza

THE WOODCUTTER’S ART 79

Coarse Filing and Shaping
You can shape wood using rasps. A rasp is the same as a file— both are covered with a surface
of sharp teeth to grind down the wood— but the teeth of a rasp are much more coarse. You
can also shape wood using a heavy- duty drum or disc sander, outfitted with very coarse sand-
paper (see the section immediately following, on sandpapers).

Sanding
Sandpapers are used to smooth wood, removing saw marks, chips, and other imperfections.
Sandpapers are available in a variety of grits— the lower the grit number, the coarser the
paper. With a higher coarseness you remove more wood at a time as you use the paper.
The recommended approach is to start with a coarse grit to remove splinters and other
rough spots, then finish off with a moderate- or fine- grit paper. For wood, you can select
between aluminum oxide and garnet grits. Aluminum oxide lasts a bit longer. Sandpapers for
wood are used dry. For hand sanding, wrap the paper around a wood or plastic block to pro-
vide even pressure.

Grit
Use F M C EC
Heavy sanding • •
Moderate sanding •
Finish sanding •

Grit Key Name Grit
EC Extra coarse 30-40
C Coarse 50-60
M Medium 80-100
F Fine 120-150

Painting
Wood can be painted with a brush or spray. Brush painting with acrylic paints (available at
craft stores) takes longer but produces excellent results with little or no waste. One coat may
be sufficient, but two may be necessary. Woods with an open grain may need to be sealed first
using a varnish, primer, or sealer, or else the paint will “soak” into the wood. You may also
opt to skip the painting step altogether and apply only the sealant.
Spray paints are an alternative to brush painting. Be sure to use the spray can according
to the directions on the label. Use only outdoors or in a well- ventilated area.

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