I want to cut a symetrical 12 sided shape that is about 9" at widest.
Im using a miter set at 30 degrees.
I set a stop, so each cut is the same
I experimented (luckily) and I cannot figure out how to cut this shape out
and get all sides even.
Some sides are much to short, others much to long etc.
any clues on how to do this properly?
thank you
geetarplyr wrote:
>
> I want to cut a symetrical 12 sided shape that is about 9" at widest.
> Im using a miter set at 30 degrees.
> I set a stop, so each cut is the same
> I experimented (luckily) and I cannot figure out how to cut this shape out
> and get all sides even.
> Some sides are much to short, others much to long etc.
>
> any clues on how to do this properly?
>
> thank you
start with a circle (you have 360 degrees) and then mark it off to 12
sections... then you have each at a 30 deg. cut.....
i bet when you cut it that you have some ends closer to the center than
others... this is why some ends are longer than others and not even....
On Sun, 1 Aug 2004 17:18:58 -0700, "geetarplyr" <[email protected]>
wrote:
>thanks for that.....I wonder what the shape was called!
>
>the thing is, I dont want to just cust against a pattern and line up cut
>lines on the saw. I want to cut in a jig so that I can exactly replicate
>may pieces. Id did draw up a cardboard template and the saw angle is 30
>degrees for this. I tried starting to cut from a 9.25 square to get to 9
>with this cut. I set a stop on the fence of the miter saw, to push the
>piece against so the first cut is exactly right per the template. When I go
>around and cut, turning it over to get all the sides, It ends up being
>lopsided...not all sides the same length. Driving me nuts. Had to put it
>down for a while and came here to ask for help.
Now you are talking about accuracy:
For every human operation there is an inherent error. You can't help
that. If you do a series of similar operations, the error will
compound. That's life. You *will not* get a jig to repeat the same
cut that many times without some form of error [except for those who
claim to be able to set up their table saw to make cuts within ten
thou..] So, you must put in the human "bugger factor", and eyeball
each cut as it is being made. That's the "art" of woodworking; that
and patience.
Bill.
Are you asking about the unequal sides or about how to achieve a width
of 9 inches? It sounds to me that you are asking about the variation in
the sides? You did not say what you are using for making the cuts but
it really does not matter. The angle you are using is correct. The
trouble is the angle is not truly 30 degrees. Any variation from 30
will give you fits. You can "true" up your cuts by setting the mitre
stop for 45 degrees and then make a cut. Put the two cuts together to
make a right angle and check it with your best and most accurate square.
If you don't have 90 degrees you will need to adjust a wee bit until
you do get it.
This, of course, has nothing to do with the cuts you need for your
12-sided project. But, if you can get this far you are now much closer
to achieving a 30 degree cut with your miter gauge setting, all else
being equal. You may have to fuss a bit one side or the other of the 30
setting on the miter gauge, even if you are able to achieve a true right
angle as mentioned above. This is because there is often some variation
in the accuracy achieved in production settings of mass produced miter
gauges. Of course, you could always pick up one of those fancy after
market mitre gauges ....
geetarplyr wrote:
> I want to cut a symetrical 12 sided shape that is about 9" at widest.
> Im using a miter set at 30 degrees.
> I set a stop, so each cut is the same
> I experimented (luckily) and I cannot figure out how to cut this shape out
> and get all sides even.
> Some sides are much to short, others much to long etc.
>
> any clues on how to do this properly?
>
> thank you
>
>
You are right it would only be 15 degrees
To figure out the miter for any number sided item you take the number of
sides divided in to 360 and then divide it by 2 to find out what degree you
set your miter saw to.
Chris
"Harvey Levin" <[email protected]> wrote in message
news:H8FFc.27305$WI2.8915@lakeread05...
> Maybe it's me, but if you cut all the mitres at 30 degrees, you get an
> effective angle of 60 degrees when you put the pieces together. Cut all
> your pieces at 15 degrees and you'll get the 30 that you're looking for in
> each corner.
>
> "geetarplyr" <[email protected]> wrote in message
> news:vqiFc.43433$rh.7623@okepread02...
> > I want to cut a symetrical 12 sided shape that is about 9" at widest.
> > Im using a miter set at 30 degrees.
> > I set a stop, so each cut is the same
> > I experimented (luckily) and I cannot figure out how to cut this shape
out
> > and get all sides even.
> > Some sides are much to short, others much to long etc.
> >
> > any clues on how to do this properly?
> >
> > thank you
> >
> >
>
>
Maybe it's me, but if you cut all the mitres at 30 degrees, you get an
effective angle of 60 degrees when you put the pieces together. Cut all
your pieces at 15 degrees and you'll get the 30 that you're looking for in
each corner.
"geetarplyr" <[email protected]> wrote in message
news:vqiFc.43433$rh.7623@okepread02...
> I want to cut a symetrical 12 sided shape that is about 9" at widest.
> Im using a miter set at 30 degrees.
> I set a stop, so each cut is the same
> I experimented (luckily) and I cannot figure out how to cut this shape out
> and get all sides even.
> Some sides are much to short, others much to long etc.
>
> any clues on how to do this properly?
>
> thank you
>
>
A miter of 15 degrees should do the trick, I believe.
"f/256" <[email protected]> wrote in message
news:[email protected]...
>
> "Upscale" <[email protected]> wrote in message
> news:[email protected]...
> >
> > "geetarplyr" <[email protected]> wrote in message
> > news:vqiFc.43433$rh.7623@okepread02...
> > > and get all sides even.
> > > Some sides are much to short, others much to long etc.
> >
> > > any clues on how to do this properly?
> >
> > Draw a circle with a 9" diameter. Then mark 12 lines one at a time on
the
> > exterior of the circle, but touching the circle, and crossing each other
> by
> > 300 . Cut to the markings and you're done.
>
> The widest in that dodecagon is from one corner to the opposite one, if
that
> needs to be 9", the circle should have a diameter of 96.59% of 9"
>
> 9 x 0.9659 = 8.6931" = 8 11/16" aprox
>
> Guillermo
>
>
thats probably it. If can be sure to always use 2 edges of the piece in the
jig that are the correct spacing to center that might do it.
<[email protected]> wrote in message news:[email protected]...
> geetarplyr wrote:
> >
> > I want to cut a symetrical 12 sided shape that is about 9" at widest.
> > Im using a miter set at 30 degrees.
> > I set a stop, so each cut is the same
> > I experimented (luckily) and I cannot figure out how to cut this shape
out
> > and get all sides even.
> > Some sides are much to short, others much to long etc.
> >
> > any clues on how to do this properly?
> >
> > thank you
> start with a circle (you have 360 degrees) and then mark it off to 12
> sections... then you have each at a 30 deg. cut.....
> i bet when you cut it that you have some ends closer to the center than
> others... this is why some ends are longer than others and not even....
"Upscale" <[email protected]> wrote in message
news:[email protected]...
>
> "geetarplyr" <[email protected]> wrote in message
> news:vqiFc.43433$rh.7623@okepread02...
> > and get all sides even.
> > Some sides are much to short, others much to long etc.
>
> > any clues on how to do this properly?
>
> Draw a circle with a 9" diameter. Then mark 12 lines one at a time on the
> exterior of the circle, but touching the circle, and crossing each other
by
> 300 . Cut to the markings and you're done.
The widest in that dodecagon is from one corner to the opposite one, if that
needs to be 9", the circle should have a diameter of 96.59% of 9"
9 x 0.9659 = 8.6931" = 8 11/16" aprox
Guillermo
thanks for that.....I wonder what the shape was called!
the thing is, I dont want to just cust against a pattern and line up cut
lines on the saw. I want to cut in a jig so that I can exactly replicate
may pieces. Id did draw up a cardboard template and the saw angle is 30
degrees for this. I tried starting to cut from a 9.25 square to get to 9
with this cut. I set a stop on the fence of the miter saw, to push the
piece against so the first cut is exactly right per the template. When I go
around and cut, turning it over to get all the sides, It ends up being
lopsided...not all sides the same length. Driving me nuts. Had to put it
down for a while and came here to ask for help.
thanks for the advise.
"f/256" <[email protected]> wrote in message
news:[email protected]...
>
> "Upscale" <[email protected]> wrote in message
> news:[email protected]...
> >
> > "geetarplyr" <[email protected]> wrote in message
> > news:vqiFc.43433$rh.7623@okepread02...
> > > and get all sides even.
> > > Some sides are much to short, others much to long etc.
> >
> > > any clues on how to do this properly?
> >
> > Draw a circle with a 9" diameter. Then mark 12 lines one at a time on
the
> > exterior of the circle, but touching the circle, and crossing each other
> by
> > 300 . Cut to the markings and you're done.
>
> The widest in that dodecagon is from one corner to the opposite one, if
that
> needs to be 9", the circle should have a diameter of 96.59% of 9"
>
> 9 x 0.9659 = 8.6931" = 8 11/16" aprox
>
> Guillermo
>
>
By the way, your computer clock is about a month fast.....LOL
Todd L
"geetarplyr" <[email protected]> wrote in message
news:vqiFc.43433$rh.7623@okepread02...
> I want to cut a symetrical 12 sided shape that is about 9" at widest.
> Im using a miter set at 30 degrees.
> I set a stop, so each cut is the same
> I experimented (luckily) and I cannot figure out how to cut this shape out
> and get all sides even.
> Some sides are much to short, others much to long etc.
>
> any clues on how to do this properly?
>
> thank you
>
>
On Sun, 1 Aug 2004 12:15:14 -0700, "geetarplyr" <[email protected]>
wrote:
>I want to cut a symetrical 12 sided shape that is about 9" at widest.
>Im using a miter set at 30 degrees.
>I set a stop, so each cut is the same
>I experimented (luckily) and I cannot figure out how to cut this shape out
>and get all sides even.
>Some sides are much to short, others much to long etc.
>
>any clues on how to do this properly?
>
>thank you
>
After drawing you still have to cut, but can eyeball along the cut as
it is being done.
Method 1.
First draw points for a hexagon (6 sides). This is simple with the
compass set to the radius of the circle, just go from point to point
around the circle, those distances being equal to the radius. Don't
draw the hexagon, just the points.
Now you need points inbetween those. The easy way is to find one,
then go around the circle as above for all the middle points.
To find one bisecting point, put your compasses onto one point and
draw an arc above and below the two points in question. Do the same
from the other point on the circle to intersect the first two arcs you
had just drawn. These intersections, above and below if joined will
bisect the arc between the points [and so give one other point on the
circle.] No need to join, just line up with a ruler and mark the
point on the circle.
Now work around the circle as before, and you have 12 points evenly
spaced.
Method 2. use a simple, neat drafting program like DeltaCad, and do
it in one step.
Bill.