I use alot of exoitc woods, burl and curl,
Babinga,Zebra,Cocobolo,ect., in many of my projects. The stock is
1&1/2" thick ( band sawed to with in 1/8" of the template ) and the
template 3/4" plywood. Useing a flush trimming bit ( ball bareing on
top or bottom ), on a router table, I always end up ruineing the piece
with tare out especially on curved and round end grain projects.I mean
it's scarey, the piece kicks, jumps and huncks tare out of the wood.
Please help, what am I doing wrong???
Your cut is too deep for the diameter of the bit. As the cut gets
deeper, the forces exerted by the bit on the wood get more angled
toward the grain direction. If possible, use a larger diameter bit.
I have one that's about an inch in diameter. And / or, bansaw closer
to the final pattern line on the ends so the bit is taking a shallower
cut there. Slow down the feed rate on end grain if you can do that
and still avoid burning. A good sharp bit helps too, but the problem
never really goes away.
"In theory, theory and practice are the same, but in practice they are
Everything DH said. Also, if you get really close to your line (<1/16")
while bandsawing, you could try a climb cut. The bit needs to be sharp for
this. NOTE: Only do what you're comfortable or feel safe with. Many
people do not feel safe with climb cuts. If you don't, don't do it.
Take the cut in shallow (north/south) stages.
If the cut is shallow enough you can climb or anticlimb cut, choosing
the least tearout direction.
How? With plunger; that's what they do, cut in stages.
More on tearout:
You should trim the piece as close to the final cut before using a flush
trim bit. Additionally when you near a thin spot where the bit is likely to
grab the grain and tear it out or near the corner when going cross grain it
is best using caution to route in the reverse direction, this creates the
situation where the cutter is pressing against the grain rather than wanting
to tear it out.
I didn't see a reply to your question. that was my thought exactly. All
the technique in the world will not cure a low quality bit. I got rid of
all my burning problems doing roundover edges on end grain by replacing one
of my bits with a new quality bit.
Been there. Straight-flute bits are more likely to grab than spiral
bits, and if
you have endgrain to deal with, you WANT to do the cut with a good
jigsaw or bandsaw instead, because those cut pulling the wood to the
rather than flinging it across the shop.
Either a spiral bit (will help, but not eliminate the problem) or a
in your router table can do the endgrain trimming. If you need to use
bearing, it MIGHT help to glue the workpiece to a more massive chunk
of wood; inertia is your friend.
I had this problem while routing tenons. I like to take the depth all
in one plunge to ensure uniformity. To prevent tear-out I use sharp
bit and I tape the work piece with masking tape. After the plunge, I
move the router around the work piece very s-l-o-w-l-y. The tears stop
splitting out right at the point where the router stops cutting. It
still tears out, but the tape serves as damage control. I work mostly
with maple and black walnut so I can't ensure this technique will work
with your "exotics."
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