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brian
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 Posted: Sat Sep 18, 2004 1:15 am Post subject: Figuring out angle of a cut using "rise over run"? |
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Hi all,
I'm really new to woodworking. In fact, I haven't really done any yet.
However, I am laying my own wood floor (5"x3/4" plank cherry, nailed),
and I've bought just about every tool under the sun by now, so I'll be
doing more after this project ;-)
The key, though, is finishing this project, which requires that I get
around obstruction #1, which is a brick half-wall. The wall is roughly
48" wide, and the flooring runs parallel to that wide side of the
wall. My problem is basically that I'm not wonderful at math, so I'm
hoping someone here can help me figure this out:
According to all the measurements I've taken, my flooring is parallel
with both an exterior wall, and the interior wall which runs parallel
to it. If the brick half-wall was also straight, I'd need to rip a
board to be about 2" in thickness. However, it isn't perfectly
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
Thanks.
brian. |
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Australopithecus scobis
Guest
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| Posted: Sat Sep 18, 2004 1:15 am Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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On Fri, 17 Sep 2004 15:41:25 -0700, brian wrote:
| Quote: |
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
|
tan(theta) = opposite/adjacent
sin(theta) = opposite/hypoteneuse
cos(theta) = adjacent/hypoteneuse
theta = arctan(opposite/adjacent) = 0.25/48 = 0.3 degrees ~= 18 arcminutes.
That's the math. One or more of the tablesaur guys will tell you how to
set up the saw without the math.
--
"Keep your ass behind you" |
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Paul Franklin
Guest
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| Posted: Sat Sep 18, 2004 1:15 am Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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On 17 Sep 2004 15:41:25 -0700, bkjones@gmail.com (brian) wrote:
| Quote: |
Hi all,
I'm really new to woodworking. In fact, I haven't really done any yet.
However, I am laying my own wood floor (5"x3/4" plank cherry, nailed),
and I've bought just about every tool under the sun by now, so I'll be
doing more after this project ;-)
The key, though, is finishing this project, which requires that I get
around obstruction #1, which is a brick half-wall. The wall is roughly
48" wide, and the flooring runs parallel to that wide side of the
wall. My problem is basically that I'm not wonderful at math, so I'm
hoping someone here can help me figure this out:
According to all the measurements I've taken, my flooring is parallel
with both an exterior wall, and the interior wall which runs parallel
to it. If the brick half-wall was also straight, I'd need to rip a
board to be about 2" in thickness. However, it isn't perfectly
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
Thanks.
brian.
|
I *think* this is right...
tan (X) = .25/48
Solving that X=about 0.3 degrees.
If it were me and I had one to do, I'd cut it freehand with a circ saw
or jigsaw and clean it up with a sander.
HTH,
Paul |
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Charles Spitzer
Guest
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| Posted: Sat Sep 18, 2004 1:15 am Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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measure how wide at one end of the wall where the board needs to be. measure
at the other end of the wall. transfer measurements to board. draw line. cut
on line.
"brian" <bkjones@gmail.com> wrote in message
news:6e5927ff.0409171441.58be7f52@posting.google.com...
| Quote: |
Hi all,
I'm really new to woodworking. In fact, I haven't really done any yet.
However, I am laying my own wood floor (5"x3/4" plank cherry, nailed),
and I've bought just about every tool under the sun by now, so I'll be
doing more after this project ;-)
The key, though, is finishing this project, which requires that I get
around obstruction #1, which is a brick half-wall. The wall is roughly
48" wide, and the flooring runs parallel to that wide side of the
wall. My problem is basically that I'm not wonderful at math, so I'm
hoping someone here can help me figure this out:
According to all the measurements I've taken, my flooring is parallel
with both an exterior wall, and the interior wall which runs parallel
to it. If the brick half-wall was also straight, I'd need to rip a
board to be about 2" in thickness. However, it isn't perfectly
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
Thanks.
brian. |
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patriarch
Guest
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| Posted: Sat Sep 18, 2004 1:15 am Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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Australopithecus scobis <nospam@die.spammer.die> wrote in
news:pan.2004.09.17.22.51.35.657774@die.spammer.die:
| Quote: |
On Fri, 17 Sep 2004 15:41:25 -0700, brian wrote:
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
tan(theta) = opposite/adjacent
sin(theta) = opposite/hypoteneuse
cos(theta) = adjacent/hypoteneuse
theta = arctan(opposite/adjacent) = 0.25/48 = 0.3 degrees ~= 18
arcminutes.
That's the math. One or more of the tablesaur guys will tell you how
to set up the saw without the math.
|
Rip it straight, and get out yer trusty hand plane. This won't take an #8,
willit? ;)
Patriarch |
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Doug Miller
Guest
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| Posted: Sat Sep 18, 2004 5:23 am Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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In article <6e5927ff.0409171441.58be7f52@posting.google.com>, bkjones@gmail.com (brian) wrote:
[snip]
| Quote: |
According to all the measurements I've taken, my flooring is parallel
with both an exterior wall, and the interior wall which runs parallel
to it. If the brick half-wall was also straight, I'd need to rip a
board to be about 2" in thickness. However, it isn't perfectly
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
|
Here's the math:
angle = atan (rise / run)
where atan is the "inverse tangent" function (shown as Tan -1 on some handheld
calculators, or accomplished by using the Inv and Tan buttons on others; in
the Windows calculator, check the Inv box, and click the "tan" button).
In this case:
angle = atan ( 0.25 / 48 ) = atan ( 0.0052 ) = approx 0.3 degrees
You may have a tough time setting up a taper jig to cut a taper that shallow
on a table saw.
Here's how I'd do it:
1) mark the cut line on the board
2) trim the board close to the line; preferred tool is a bandsaw, but a saber
saw will work
3) finish up with a hand plane
--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter
by sending email to autoresponder at filterinfo-at-milmac-dot-com
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Larry Kraus
Guest
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| Posted: Sat Sep 18, 2004 6:07 am Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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I'm thinking the variance is not exactly constant over the length of
the brick wall. If you want the edge of the board to match the wall
exactly, rip to the widest dimension, scribe to the wall and fit with
jig saw, coping saw and/or belt sander.
bkjones@gmail.com (brian) wrote:
| Quote: |
According to all the measurements I've taken, my flooring is parallel
with both an exterior wall, and the interior wall which runs parallel
to it. If the brick half-wall was also straight, I'd need to rip a
board to be about 2" in thickness. However, it isn't perfectly
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
Thanks.
brian. |
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Mike Marlow
Guest
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| Posted: Mon Sep 20, 2004 7:41 am Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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"brian" <bkjones@gmail.com> wrote in message
news:6e5927ff.0409171441.58be7f52@posting.google.com...
| Quote: |
Hi all,
I'm really new to woodworking. In fact, I haven't really done any yet.
However, I am laying my own wood floor (5"x3/4" plank cherry, nailed),
and I've bought just about every tool under the sun by now, so I'll be
doing more after this project ;-)
The key, though, is finishing this project, which requires that I get
around obstruction #1, which is a brick half-wall. The wall is roughly
48" wide, and the flooring runs parallel to that wide side of the
wall. My problem is basically that I'm not wonderful at math, so I'm
hoping someone here can help me figure this out:
According to all the measurements I've taken, my flooring is parallel
with both an exterior wall, and the interior wall which runs parallel
to it. If the brick half-wall was also straight, I'd need to rip a
board to be about 2" in thickness. However, it isn't perfectly
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
Thanks.
brian.
|
If your brick wall runs true, so that the runout is fairly straight from 0
to 1/4in, then I'd just strike a chalk line or a pencil line from 0 to 1/4in
on the floor board and freehand it on the table saw.
--
-Mike-
mmarlowREMOVE@sprintmail.com |
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Doug Miller
Guest
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| Posted: Mon Sep 20, 2004 4:39 pm Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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In article <7ks3d.7316$mb6.2986@newsread3.news.atl.earthlink.net>, "Mike Marlow" <mmarlowREMOVE@sprintmail.com> wrote:
| Quote: |
If your brick wall runs true, so that the runout is fairly straight from 0
to 1/4in, then I'd just strike a chalk line or a pencil line from 0 to 1/4in
on the floor board and freehand it on the table saw.
|
Either (a) you misspelled "band saw" or (b) you're an idiot. Freehanding
*anything* on a table saw is *very* dangerous, and advising other people to do
it is both dangerous and stupid.
--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter
by sending email to autoresponder at filterinfo-at-milmac-dot-com
You must use your REAL email address to get a response. |
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U-CDK_CHARLES\\Charles
Guest
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| Posted: Mon Sep 20, 2004 5:42 pm Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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On 17 Sep 2004 15:41:25 -0700, brian <bkjones@gmail.com> wrote:
| Quote: |
Hi all,
I'm really new to woodworking. In fact, I haven't really done any yet.
However, I am laying my own wood floor (5"x3/4" plank cherry, nailed),
and I've bought just about every tool under the sun by now, so I'll be
doing more after this project ;-)
|
You probably spent too much on tools . . .
You don't want to calculate anything.
What you want to do is take a compass and use it to scribe the profile
of the wall onto your plank. You probably want to leave a 1/4" gap at
the edge, which you'll cover with your baseboard.
Once your plank is scribed, cut it with a sabre saw or a band saw.
You might want to get one of the many books on the uses of a steel
square. There are very few things that you need to do in the shop that
can't be done with a square.
An adage from higher math comes to mind: Numbers are the enemy. Avoid
using them. In math, that means you simplify first, then plug in the
numbers. In the shop, I'd turn that around: Mark your measurements on
a story stick and never use numbers until the next project. |
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Mike Marlow
Guest
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| Posted: Mon Sep 20, 2004 5:49 pm Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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"Doug Miller" <spambait@milmac.com> wrote in message
news:gcA3d.10950$ck.4500@newssvr31.news.prodigy.com...
| Quote: |
In article <7ks3d.7316$mb6.2986@newsread3.news.atl.earthlink.net>, "Mike
Marlow" <mmarlowREMOVE@sprintmail.com> wrote:
If your brick wall runs true, so that the runout is fairly straight from
0
to 1/4in, then I'd just strike a chalk line or a pencil line from 0 to
1/4in
on the floor board and freehand it on the table saw.
Either (a) you misspelled "band saw" or (b) you're an idiot. Freehanding
*anything* on a table saw is *very* dangerous, and advising other people
to do
it is both dangerous and stupid.
|
Well, I did mean table saw but that may or may not make me an idiot. I have
free handed a great number of things on a table saw over the years without a
problem and more importantly, without the suggestion of a problem in the
making. If you can rip a board with a fence in place then why would it be
dangerous to guide a like board without that same fence in place? Slow and
easy is the key to a good cut. I disagree that freehanding "anything" on a
tablesaw is *very* dangerous.
--
-Mike-
mmarlowREMOVE@sprintmail.com |
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Doug Miller
Guest
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| Posted: Mon Sep 20, 2004 6:31 pm Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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In article <JdB3d.7480$mb6.3692@newsread3.news.atl.earthlink.net>, "Mike Marlow" <mmarlowREMOVE@sprintmail.com> wrote:
| Quote: |
"Doug Miller" <spambait@milmac.com> wrote in message
news:gcA3d.10950$ck.4500@newssvr31.news.prodigy.com...
In article <7ks3d.7316$mb6.2986@newsread3.news.atl.earthlink.net>, "Mike
Marlow" <mmarlowREMOVE@sprintmail.com> wrote:
If your brick wall runs true, so that the runout is fairly straight from
0
to 1/4in, then I'd just strike a chalk line or a pencil line from 0 to
1/4in
on the floor board and freehand it on the table saw.
Either (a) you misspelled "band saw" or (b) you're an idiot. Freehanding
*anything* on a table saw is *very* dangerous, and advising other people
to do
it is both dangerous and stupid.
Well, I did mean table saw but that may or may not make me an idiot. I have
free handed a great number of things on a table saw over the years without a
problem and more importantly, without the suggestion of a problem in the
making.
|
And so you conclude that it's safe. I conclude that you've been lucky.
| Quote: |
If you can rip a board with a fence in place then why would it be
dangerous to guide a like board without that same fence in place?
|
Because without the fence, you have nothing to guide it with, and the board
can easily become skewed. It takes only a very slight degree of skew to cause
a kickback.
| Quote: |
Slow and easy is the key to a good cut. I disagree that freehanding "anything" on a
tablesaw is *very* dangerous.
|
You might be the only person to hold that opinion.
"Never cut freehand under any circumstances!" -- Kelly Mehler, "The Table Saw
Book"
"Never freehand on a table saw! ... I've watched some old-timers do this and
get away with it -- at least while I was watching. But I've also noticed that
many of them can't count to ten on their fingers..." -- Jim Tolpin, "Table Saw
Magic"
"Never crosscut freehand on a table saw! If you inadvertently twist the stock
even a tiny bit, the blade will jam in the kerf and throw the piece off the
table with tremendous force." -- Tolpin
Suture self... it's your fingers. You've been lucky so far. But don't advise
other people to adopt practices that are universally recognized as unsafe just
because you haven't gotten hurt -- yet.
--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter
by sending email to autoresponder at filterinfo-at-milmac-dot-com
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JAW
Guest
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| Posted: Mon Sep 20, 2004 6:32 pm Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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Find a short marking piece for each side of the cut out, mark it and transfer to the real piece. Draw a straight line
from each cut out side and cut.
Tools needed - pencil.
brian wrote:
| Quote: |
Hi all,
I'm really new to woodworking. In fact, I haven't really done any yet.
However, I am laying my own wood floor (5"x3/4" plank cherry, nailed),
and I've bought just about every tool under the sun by now, so I'll be
doing more after this project ;-)
The key, though, is finishing this project, which requires that I get
around obstruction #1, which is a brick half-wall. The wall is roughly
48" wide, and the flooring runs parallel to that wide side of the
wall. My problem is basically that I'm not wonderful at math, so I'm
hoping someone here can help me figure this out:
According to all the measurements I've taken, my flooring is parallel
with both an exterior wall, and the interior wall which runs parallel
to it. If the brick half-wall was also straight, I'd need to rip a
board to be about 2" in thickness. However, it isn't perfectly
straight. The variance is roughly 1/4" over the 48". So I need to rip
my board with that in mind. Does anyone know the calculation for
figuring out the angle to set my board as it goes over the table saw
blade?
Thanks.
brian. |
|
|
| Back to top |
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Doug Miller
Guest
|
| Posted: Mon Sep 20, 2004 6:42 pm Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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In article <FRB3d.23380$_z4.11578@fe1.columbus.rr.com>, JAW <youwish@noserver.com> wrote:
| Quote: |
Find a short marking piece for each side of the cut out, mark it and transfer
to the real piece. Draw a straight line
from each cut out side and cut.
Tools needed - pencil.
|
And a bandsaw. :-)
--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)
Get a copy of my NEW AND IMPROVED TrollFilter for NewsProxy/Nfilter
by sending email to autoresponder at filterinfo-at-milmac-dot-com
You must use your REAL email address to get a response. |
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Swingman
Guest
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| Posted: Mon Sep 20, 2004 8:15 pm Post subject: Re: Figuring out angle of a cut using "rise over run"? |
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"Mike Marlow" wrote in message
| Quote: |
I disagree that freehanding "anything" on a
tablesaw is *very* dangerous.
|
Although I see freehand table saw use done all the time on job sites by
modern day "carpenters", it is usually done with an underpowered saw that
would easily bog down before it bit back at you.
While you might get away with it over time, it is definitely not the safest
practice on any table saw ... do it on a cabinet saw and you're just asking
for trouble.
Just my tuppence ....
--
www.e-woodshop.net
Last update: 7/10/04 |
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