Octagon?

"Mike McDonald" wrote:

> Anybody have any tricks for cutting an octagon?

Make a sled using the factory corner of a 3/4" sheet of plywood.

See Fred Bingham's book, Practical Yacht Joinery for details.

Makes dead nuts 45 angle.

BTDT

Lew

dadiOH wrote:
> Mike McDonald wrote:
>> Anybody have any tricks for cutting an octagon? I'm trying to make
>> a couple of octagonal tables. I finally tried doing some resawing
>> and veneering. Now I need to cut the table top into an octagon.
>>
>> Thanks,
>
> You mean where to cut? Find the quarter marks from the corners on
> each side and connect the adjacent ones.
>
Actually, you want to mark each side of a perfect square into *thirds*
and connect the adjacent ones for a regular octagon.

~Mark.

On Fri, 25 Jan 2008 17:15:36 GMT, [email protected] (Mike McDonald)
wrote:

>In article <[email protected]>,
> DJ Delorie <[email protected]> writes:
>>
>> "Lew Hodgett" <[email protected]> writes:
>>> Makes dead nuts 45 angle.
>>
>> The problem with octagons is usually where to put that 45 degree angle
>> cut, not how to cut it accurately.
>
> Yes! I can do trig and such. It's the woodworking part that's more
>"problematic". I already have 16 "pie slices" glued to a substrate. The
>slices already form a "rough" octogon. If I was a better woodworker,
>it would be a perfect octogon. That's the difference between theory and
>practice! So I need to clean up the rough octogon into a nice one.
>
> Getting four sides nice and straight, I can do on the tablesaw. It's
>cutting the first two angled (45) at the correct spots that's the hard
>part. Once I have those two, I can again use the TS to cut the opposite
>sides.


Mark the center.
Draw a circle of a known diameter.-
Devide the circle into 8 equal parts (45 degrees)
Mark where the radial lines intersect the circle
Join the marks with lines and cut on the lines.
Make the circle diameter equal to the "point to point" dimension of
the octagon. and "Bob's your uncle"

--
Posted via a free Usenet account from http://www.teranews.com

The message <[email protected]>
from Mark Ohlund <[email protected]> contains these words:

> dadiOH wrote:
> > Mike McDonald wrote:
> >> Anybody have any tricks for cutting an octagon? I'm trying to make
> >> a couple of octagonal tables. I finally tried doing some resawing
> >> and veneering. Now I need to cut the table top into an octagon.
> >>
> >> Thanks,
> >
> > You mean where to cut? Find the quarter marks from the corners on
> > each side and connect the adjacent ones.
> >
> Actually, you want to mark each side of a perfect square into *thirds*
> and connect the adjacent ones for a regular octagon.

> ~Mark.

If you can do it this way by measuring, then from maths, for a perfect
octagon if you draw a square of side length 1, then measure along the
two sides away from a corner a length of 0.314939, joining up the two
points you have marked gives the 45 degree side of the octagon. Repeat
for the other corners. The length between the two marks on one side is
0.314939.

Regards,

Bryan

On Jan 25, 11:00=A0am, [email protected] (Mike McDonald) wrote:
> In article <[email protected].=
com>,
> =A0 =A0 =A0 =A0 DonkeyHody <[email protected]> writes:
>
> > On Jan 24, 4:18<A0>pm, [email protected] (Mike McDonald) wrote:
> >> =A0Anybody have any tricks for cutting an octagon? I'm trying to make
> >> a couple of octagonal tables. I finally tried doing some resawing
> >> and veneering. Now I need to cut the table top into an octagon.
> > Do you want to make "pie slices" which you will glue together to make
> > an octagon, or do you want to simply cut a solid panel into an octagon
> > shape?
>
> =A0 I already made the "pie slices" and have glued them to a MDF panel.
> Now I want to cut that panel into an octogon.
>
> --
>
> =A0 Mike McDonald
> =A0 [email protected]

I feel your pain. Getting the angles cut perfectly enough that the
pie slices all match up without any gaps is indeed a challenge. The
problem is that your joint is so long that any minute error is
magnified. I've tried it a couple of times and came close, but not
close enough. Here's how I did it:
1. Forget trying to get all the pie slices to meet at a single point
in the center. Cut 1/4" or so off the tip of each slice so you have a
hole in the center.
2. Clamp ONE pie slice so that the edge to be glued is perfectly
horizontal. Spread some glue on this piece. Slide its mate around on
top of it until the glue begins to grab just a bit. Carefully
position the second piece on top of the first by feeling the joint
between your fingers. WALK AWAY for 30 minutes or more. Carefully
set the glue-up aside to cure overnight.
3. Repeat step two until you have two "half octagons".
4. Put your two half octagons together dry and check the gap between
them. It will need cleaning up.
5. With a tablesaw, jointer or hand plane, carefully work the joint
between the two halves until it matches along its entire length. I
had success by carefully shaving the edge with my tablesaw, with the
outside edge of the octagon against the fence.
6. When you have the two edges mating well enough, glue them
together.
7. Drill a nice round hole in the center of the octagon.
8. Plug the nice round hole with contrasting wood and sand flush.
9. You will probably have to clean up the outside edges to get
everything flush.

Good Luck.

DonkeyHody
"Every man is my superior in that I can learn from him." - Thomas
Carlyle

"Mike McDonald" <[email protected]> wrote in message
news:[email protected]...
> Anybody have any tricks for cutting an octagon? I'm trying to make
> a couple of octagonal tables. I finally tried doing some resawing
> and veneering. Now I need to cut the table top into an octagon.

A while ago I posted a similar question for a 6 sided table, got some good
replies that can help you;

http://groups.google.com/group/rec.woodworking/browse_thread/thread/75e0858843fea35c/366f34d81b78c5d0?lnk=st&q=#366f34d81b78c5d0

DJ Delorie wrote:
> Mark Ohlund <[email protected]> writes:
>>> You mean where to cut? Find the quarter marks from the corners on
>>> each side and connect the adjacent ones.
>>>
>> Actually, you want to mark each side of a perfect square into *thirds*
>> and connect the adjacent ones for a regular octagon.
>
> Actually, it's 0.292893 of the width, in from each corner.

Precisely. That's why I could never get this right ;-)

On Fri, 25 Jan 2008 13:51:47 -0500, Mark Ohlund
<[email protected]> wrote:

>dadiOH wrote:
>> Mike McDonald wrote:
>>> Anybody have any tricks for cutting an octagon? I'm trying to make
>>> a couple of octagonal tables. I finally tried doing some resawing
>>> and veneering. Now I need to cut the table top into an octagon.
>>>
>>> Thanks,
>>
>> You mean where to cut? Find the quarter marks from the corners on
>> each side and connect the adjacent ones.
>>
>Actually, you want to mark each side of a perfect square into *thirds*
>and connect the adjacent ones for a regular octagon.
>
>~Mark.
That's a HEXagon. 6 sides
OCTAgone is 8 sides.

--
Posted via a free Usenet account from http://www.teranews.com

On Jan 24, 5:18 pm, [email protected] (Mike McDonald) wrote:
> Anybody have any tricks for cutting an octagon? I'm trying to make
> a couple of octagonal tables. I finally tried doing some resawing
> and veneering. Now I need to cut the table top into an octagon.
>
> Thanks,
>
> --
>
> Mike McDonald
> [email protected]

Here is a table I made with some advice

http://www.woodweb.com/knowledge_base/Solid_Wood_Octagon_Table_Top_Failure.html

http://www.woodweb.com/galleries/project/posts/392.html

In article <e478b307-9b68-40d5-bf80-36d9a8a2fbcd@s19g2000prg.googlegroups.com>,
DonkeyHody <[email protected]> writes:
> On Jan 24, 4:18<A0>pm, [email protected] (Mike McDonald) wrote:
>> Anybody have any tricks for cutting an octagon? I'm trying to make
>> a couple of octagonal tables. I finally tried doing some resawing
>> and veneering. Now I need to cut the table top into an octagon.

> Do you want to make "pie slices" which you will glue together to make
> an octagon, or do you want to simply cut a solid panel into an octagon
> shape?

I already made the "pie slices" and have glued them to a MDF panel.
Now I want to cut that panel into an octogon.

--

Mike McDonald
[email protected]

Bryan McCormick wrote:

> If you can do it this way by measuring, then from maths, for a perfect
> octagon if you draw a square of side length 1, then measure along the
> two sides away from a corner a length of 0.314939, joining up the two
> points you have marked gives the 45 degree side of the octagon. Repeat
> for the other corners. The length between the two marks on one side is
> 0.314939.
>
> Regards,
>
> Bryan


1. Start with a square "A" x "A"

2. Draw diagonals

3. Measure from their intersection (or use a compass) to mark 1/2 "A"
along the diagonal toward one corner.

4. Repeat for the three remaining corners.

5. Draw a line at a right angle to the diagonal, at the mark, to the
edges of the board.

6. Repeat for the remaining three corners

7. Cut off the corners along the lines drawn in steps 5 & 6

--
Jack Novak
Buffalo, NY - USA
[email protected]

In article <[email protected]>,
DJ Delorie <[email protected]> writes:
>
> "Lew Hodgett" <[email protected]> writes:
>> Makes dead nuts 45 angle.
>
> The problem with octagons is usually where to put that 45 degree angle
> cut, not how to cut it accurately.

Yes! I can do trig and such. It's the woodworking part that's more
"problematic". I already have 16 "pie slices" glued to a substrate. The
slices already form a "rough" octogon. If I was a better woodworker,
it would be a perfect octogon. That's the difference between theory and
practice! So I need to clean up the rough octogon into a nice one.

Getting four sides nice and straight, I can do on the tablesaw. It's
cutting the first two angled (45) at the correct spots that's the hard
part. Once I have those two, I can again use the TS to cut the opposite
sides.

--

Mike McDonald
[email protected]

On Jan 24, 4:18=A0pm, [email protected] (Mike McDonald) wrote:
> =A0 Anybody have any tricks for cutting an octagon? I'm trying to make
> a couple of octagonal tables. I finally tried doing some resawing
> and veneering. Now I need to cut the table top into an octagon.
>
> =A0 Thanks,
>
> --
>
> =A0 Mike McDonald
> =A0 [email protected]

Do you want to make "pie slices" which you will glue together to make
an octagon, or do you want to simply cut a solid panel into an octagon
shape?

On Jan 25, 12:15 pm, [email protected] (Mike McDonald) wrote:
> In article <[email protected]>,
> DJ Delorie <[email protected]> writes:
>
>
>
> > "Lew Hodgett" <[email protected]> writes:
> >> Makes dead nuts 45 angle.
>
> > The problem with octagons is usually where to put that 45 degree angle
> > cut, not how to cut it accurately.
>
> Yes! I can do trig and such. It's the woodworking part that's more
> "problematic". I already have 16 "pie slices" glued to a substrate. The
> slices already form a "rough" octogon. If I was a better woodworker,
> it would be a perfect octogon. That's the difference between theory and
> practice! So I need to clean up the rough octogon into a nice one.
>
> Getting four sides nice and straight, I can do on the tablesaw. It's
> cutting the first two angled (45) at the correct spots that's the hard
> part. Once I have those two, I can again use the TS to cut the opposite
> sides.

Screw the top to a sheet of plywood at 45 degrees. Run both through
the saw. Rotate the top 90 degrees and repeat.

On Thu, 24 Jan 2008 22:18:13 GMT, [email protected] (Mike McDonald) wrote:

> Anybody have any tricks for cutting an octagon? I'm trying to make
>a couple of octagonal tables. I finally tried doing some resawing
>and veneering. Now I need to cut the table top into an octagon.
>
> Thanks,
J.O.A.T. is the Octagon master, ping him and hope he's in a good mood..
Ok, hope he's in a "better than usual" mood..


mac

Please remove splinters before emailing

Mike McDonald wrote:
> Anybody have any tricks for cutting an octagon? I'm trying to make
> a couple of octagonal tables. I finally tried doing some resawing
> and veneering. Now I need to cut the table top into an octagon.
>
> Thanks,

You mean where to cut? Find the quarter marks from the corners on
each side and connect the adjacent ones.

--

dadiOH
____________________________

dadiOH's dandies v3.06...
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On 25 Jan 2008 13:50:49 -0500, DJ Delorie <[email protected]> wrote:

>
>[email protected] (Mike McDonald) writes:
>> Yes! I can do trig and such. It's the woodworking part that's more
>> "problematic". I already have 16 "pie slices" glued to a substrate. The
>> slices already form a "rough" octogon. If I was a better woodworker,
>> it would be a perfect octogon. That's the difference between theory and
>> practice! So I need to clean up the rough octogon into a nice one.
>
>Mark your center.
>
>Draw a circle, diameter = width of table.
>
>Draw line through center.
>
>Draw line at 90 degrees to other line, also through center.
>
>Two ways to draw 45s:
>
> * use a 45 degree drafting square (bigger is better)
>
> * bisect one 90 degree angle
> - same circle-making setup
> - two arcs centered at the intersection of the straight lines and the circle
> - the arcs intersect each other at two points
> - draw line between those two points and the centerline
>
>Now that you have all eight lines and the big circle, draw lines
>perpendicular to each line and tangent to the circle. This is your
>octagon outline.
Easier yet, draw the 2 lines at 90 degrees. Draw a line between the
intersection of these lines and the circle. Measure that line. Mark
the middle of the line. draw a line through that mark and the centre
of the board.

--
Posted via a free Usenet account from http://www.teranews.com

Mark Ohlund <[email protected]> writes:
> > You mean where to cut? Find the quarter marks from the corners on
> > each side and connect the adjacent ones.
> >
> Actually, you want to mark each side of a perfect square into *thirds*
> and connect the adjacent ones for a regular octagon.

Actually, it's 0.292893 of the width, in from each corner.

[email protected] (Mike McDonald) writes:
> Yes! I can do trig and such. It's the woodworking part that's more
> "problematic". I already have 16 "pie slices" glued to a substrate. The
> slices already form a "rough" octogon. If I was a better woodworker,
> it would be a perfect octogon. That's the difference between theory and
> practice! So I need to clean up the rough octogon into a nice one.

Mark your center.

Draw a circle, diameter = width of table.

Draw line through center.

Draw line at 90 degrees to other line, also through center.

Two ways to draw 45s:

* use a 45 degree drafting square (bigger is better)

* bisect one 90 degree angle
- same circle-making setup
- two arcs centered at the intersection of the straight lines and the circle
- the arcs intersect each other at two points
- draw line between those two points and the centerline

Now that you have all eight lines and the big circle, draw lines
perpendicular to each line and tangent to the circle. This is your
octagon outline.

"Lew Hodgett" <[email protected]> writes:
> Makes dead nuts 45 angle.

The problem with octagons is usually where to put that 45 degree angle
cut, not how to cut it accurately.

[email protected] (Mike McDonald) writes:
> Anybody have any tricks for cutting an octagon? I'm trying to make
> a couple of octagonal tables. I finally tried doing some resawing
> and veneering. Now I need to cut the table top into an octagon.

There's some handy math here:
http://www.delorie.com/quake3/octatrap/

Mark Ohlund wrote:
> DJ Delorie wrote:
>> Mark Ohlund <[email protected]> writes:
>>>> You mean where to cut? Find the quarter marks from the corners
>>>> on each side and connect the adjacent ones.
>>>>
>>> Actually, you want to mark each side of a perfect square into
>>> *thirds* and connect the adjacent ones for a regular octagon.
>>
>> Actually, it's 0.292893 of the width, in from each corner.
>
> Precisely. That's why I could never get this right ;-)

Don't feel bad...thirds will make an octagon too as will quarters.
After all, the OP didn't specify an octagon with *equal* sides :)

--

dadiOH
____________________________

dadiOH's dandies v3.06...
...a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico