Basic Intarsia Cutting Skills
Use a bandsaw or a scrollsaw?
This question is obviously a very easy one if you only have one
tool or the other. If you are lucky to own both then you will have
more of an issue. Generally I would always use a bandsaw whenever
possible, if only because the travel of the blade pulls the wood
down onto the table as you cut and makes the process less stressful.
You can mount a 1/8" blade in your saw and this will do most of
your cutting (cuts about a ½" diameter).
Scrollsaws on the other hand, run up and down into the wood, pulling
the wood with it. This is particularly evident cutting hardwoods
or very grainy woods. Controlling your direction under these circumstances,
is more difficult and your accuracy suffers.
Scroll saws do have a benefit though, in that they will cut tighter
radii than a bandsaw, and are less aggressive and therefore safer
to use for small pieces. They also remove less wood, so cause less
distortion when cutting two adjoining pieces from one block and
then gluing them back together (like the back of the loon). Scroll
saws are the only tool you can use for internal cuts. Really having
both tools is great.
Squaring Your Saw:
Before beginning to saw a project, always check your saw for squareness
by making a test cut, and checking the result with a good quality
square. The major reason for ill fitting intarsia pieces, aside
from inaccurate cutting, is out of square pieces. They touch at
the top or bottom, but not on the opposite face. The thicker the
wood, the more obvious this problem will be.
Sometimes, out of square cuts can be caused by tear out fibres
on the back of your piece, getting caught between the wood and the
table. Check for this and sand the back to maintain a flat surface
to work from if this seems to be an issue.
Patterns for Sale by site owners
What do you cut first?
If the piece is of a reasonable size (ie.4" round+), I would usually
rough cut it to size first. Then any inside cutouts would be done,
while the piece is large enough to hold onto. Lastly, I would cut
the outside lines.
The advantage is particularly obvious when you have thin cross
grain sections. The inside cut is done on a scrollsaw while the
waste wood is still in tack, the outside can be cut on a bandsaw,
where less vibration is likely to break the thin cross grain sections.Always
deburr the back side of the piece after each cut.
If you are cutting very small pieces, it is important to do all
the fine cutting while the piece is attached to a larger block.
The last cut should be the one that separates it from the waste.
For tight inside cuts, make sure you make a few preliminary cuts
through the waste wood, up to the edge of the cut line, first. Then
as you cut along you're line, if the cut turns out to be too tight,
you will have an escape route.
Predrilling for Inside Cuts:
If the pattern calls for an inside cut (ie. cutting the windows
out of the old car pattern), you must predrill a small hole in one
corner first. Then feed the scrollsaw blade through the hole, reattach
the blade to the upper holder, reset the blade tension, and finally
cut the shape.
To remove your piece, you must release the top of the blade and
reverse this process. Sometimes when doing the original pilot holes
the wood tears out on the back. Be sure to sand this off first,
so that your piece sits flat on the scrollsaw table during cutting.