So I need to cut accurate 30 Degree miters in 2.5 x 12" old growth red cedar
for a hexagon top I'm making. each piece will be 30" long. what's the best
way to set up my tablesaw and ensure that I get accurate miters (off a 1/4
of a degree will mean 3 degrees out on the last cut! My mitering jig isn't
accurate enough for this degree of cutting. thanks
The table saw is best suited for ripping, not crosscutting. I'm not
sayin you can't make an accurate cut with a table saw, you can. You
might have better luck with a chop saw or sliding chop saw or radial
That type of tool is better suited to the task you require. Since
your boards are so wide you may have to flip the board over to
complete the cut. Since it is valuable lumber you might also want to
make test cuts on scrap material first. You could even do a mock-up
of the hexagon with scraps before cutting into such valuable wood.
I must be missing something. This doesn't seem like that challenging a cut
on any table saw. The cut edge will be 13 7/8" long. That's well within the
miter capacity of any table saw. You won't have to flip it over.
I have a large 30-60 degree drafting triangle. That or an adjustable
triangle can be used to set the miter gage.
You didn't ask, but a $60 INCRA Miter V27 with a shop made fence attached is
accurate enough to make the cuts. Mine will make picture frame quality
I've been playing with shooting boards and I would probably fall back on
making fine adjustments with a shooting board.
The Dubby sliding cut off sled sets up accurately to all typical angles.
You have to pivot the fence 1/4" to move 1 degree setting. With that in
mind you can imagine the accuracy you get if you set the fence to exactly
where you want it.
Alternatively make yourself a sled with a fence that attaches to the top of
the sled. Put a screw through the fence end nearest the blade side of the
sled. Pivot the fence on that screw to 30 degrees or close to where you
measure 30 degrees and put in another screw or two to hold the fence in that
position. Make some trial cuts in scraps and check your results. The
larger the scraps the more accurately you see the results.
I would advise using a straight 1x4 for the fence laid wide side down and
make it as long as possible. The longer the fence the less jump it makes in
degree angle as you adjust it on the pivot screw. You can tweak it until it
| So I need to cut accurate 30 Degree miters in 2.5 x 12" old growth
| red cedar for a hexagon top I'm making. each piece will be 30"
| long. what's the best way to set up my tablesaw and ensure that I
| get accurate miters (off a 1/4 of a degree will mean 3 degrees out
| on the last cut! My mitering jig isn't accurate enough for this
| degree of cutting. thanks
You can construct a full-size cutting template using a straightedge
and the largest compass/dividers you can find (I once made a
"use-once" compass to do something similar). Start with an equilateral
triangle and bisect one side - connect the center of the bisected side
to the opposite vertex and you'll have your 30-degree angle.
Use your cutting template to align a straight guide and make the cut
with a hand-held circular saw. Dry fit the parts and make final
adjustments with plane and/or sandpaper on a (long) block.
DeSoto, Iowa USA
Yet another way to add to the confusion.
Take a base of 'X' dimension and run a vertical (Y) (at 90 degrees) of
"X" times the square root of 3 (1.732051), then connect the ends of
the legs, you will have a 30-degree angle on top and a 60 degree angle
on the side and the hypotenuse you have created will have a dimension
(length) of exactly the base(X) times 2.
For all you trig aficionados, a similar situation occurs when you
create a 45 degree angle.
The base is the same as the height but the length of the hypotenuse
is the square root of 2 (1.414214) times the base.
That comes in really handy... to me at least.
~ Buy/borrow/rent an accurate sliding compound miter saw that will allow
cutting 12" wide boards at 30 angle in one pass. Futz with the angle setup
on scrap until the perfect setting is locked in.
~ Buy a better miter jig for your table saw.
~ Make a specialized table saw sled like the one in the link below, only
make the angle 60 degrees by using an accurate 30/60 triangle to setup the
triangle used for reference edges; then make the successive cut for each
joint on the opposite side of the blade, thereby taking advantage of the
principle of complementary angles to insure an accurate 60 degree join.
http://www.e-woodshop.net/Jigs.htm (scroll down to "miter sled")
~ In all cases, use scrap wood to check accuracy of method and to insure
hexagon closes as required.
> So I need to cut accurate 30 Degree miters in 2.5 x 12" old growth
> for a hexagon top I'm making.
As others have suggested, a 30-60 drafting triangle or use trig to lay
out the line the batten line on a sled.
A 30-60 triangle has sides that are 1-2-and sq root of 3.
Tack a batten on a sled at the correct angle and have at it.
Need more help, see F Bingham's book, it's in there.
Mcgyver, you answered your own question.
Set up to as accurate a 30 degree cut as you can with the tools you have and
cut all but the last one. Assemble and clamp the five you've cut and scribe
for the last one. Then hew to the line.
I believe your technique plus the 1/4 degree error the OP mentioned would
lead to a 1/4" mismatch on the inside corner where the 1st and 6th piece
come together. Of course that's pretty easy to "correct" by just marking it
and trimming an angled strip off of board 1 or board 6 to make them meet. If
the angle error is not too bad, they eye will not be able to see it. Same
goes for the outside corner - it will mismatch as well, but can also be
trimmed to match.
Set your TS's miter gauge to 30 deg and cut 2 pieces to the correct length.
Cut 4 more pieces about an inch longer than the desired finished length.
Glue together 2 assemblies of 3 pieces, with a correct length piece in the
center of each assembly. When dry take each assembly and run it thru the
TS with the outside edge of the center piece against the fence. This will true
up the final glue surfaces to be in the same plane and give you the correct
on all pieces. Glue the 2 assemblies together. The eye will never discern
that your joints may be 1 or 2 deg off from each other as all joints will fit
exact at the time you built it.
Be aware that you may experience the joints opening & closing a bit over
time as the humidity changes.
There's a trick here. It is not possible to hold this perfectly.
What you do is cut all six pieces and then assemble three into one
half and three into the other half. If you need the points to meet as
points, make sure the error is slightly on the plus side. At this
stage the edges are about 180 degrees. You can now joint / plane the
mating edges to make them flat and assemble the two halves. The six
pieces will not quite be exactly the same size but they will all look
the same and the joints will all close up perfectly.
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