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Bevel Angles on a TS

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Forum topic by sIKE posted 09-23-2009 08:17 PM 982 views 0 times favorited 7 replies Add to Favorites Watch
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sIKE

1271 posts in 3221 days


09-23-2009 08:17 PM

Topic tags/keywords: question bevel

Been pondering this for a bit. When Someone/plan/etc says cut a 29° bevel. I always get things stuck in my head. I use one on those digital bevel boxes so that part is easy. Where I get jumbled up is that 29° from the table which is at 0° from the blade which is at 90°. So should I zero my box on the table, then put it on the blade. Make sure it is at 90° then zero it again so it is at 0°. Then tilt the blade 29° or should I just subtract the 29° from 90° to get where I need? Which would be 61°

I think that both of these are right, I am just trying to learn what others with more experience do.

As an example Larry here says set you blade to 60° which would make the resulting bevel 30° correct?

I love workshop math!

-- //FC - Round Rock, TX - "Experience is what you get just after you need it"


7 replies so far

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SPalm

5257 posts in 3349 days


#1 posted 09-23-2009 08:20 PM

User beware. I have seen it both ways too.
Gotta keep your wits about you.

(At least we don’t have metric angles.)

Steve

-- -- I'm no rocket surgeon

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daltxguy

1373 posts in 3381 days


#2 posted 09-23-2009 11:04 PM

Hi sIKE,

Among other things, I have a degree in mathematics. Not that it makes me any more qualified to answer the question but it sure sounds impressive!

I believe you are correct when you say both are right.(!) This is because when the angle is given in reference to the tool ( set your blade to 60°) rather than the angle relative to the piece of wood then it is ambiguous.

When given in reference to the piece of wood, it should be relatively straightforward to figure it out ( as long as the author was using the same basis for my thinking). Here’s the logic:

I think we can all agree that if someone told you to cut a piece of wood at 90°, you would know what to do. If you were told to cut a piece of wood at 0°, you wouldn’t even need a saw! So instinctively ( or intuitively, as my math professors would say) you know that the basis for the angle is either the length of the board or the face of the board. With this in mind, it should be clear what is a 30° cut across the board, or a 30° angle on the end of the board.

Now consider the tools, in particular a TS vs a RAS which is I think where the confusion began. A 0° cut on a TS (blade vertical and parallel to the fence) is marked as a 90° cut on the RAS ( 0° is the blade vertical but 90° to the fence – that’s how mine is marked). No wonder it gets confusing. The two tools have the blade in different orientations in the normal setting. Now it’s confusing if an angle is meant to be reference off of the blade or the fence.

For bevels I believe there is a similar issue between the two tools though I didn’t check this carefully but something tells me that not all saws are marked the same way. ( Is blade vertical marked as 0 or 90?)

And just be thankful that we do measure angles in degrees because, yes, there are metric equivalents and other units for measuring angles ( radian and steradians :eg 1 radian = 180/pi ~= 57.3 °!)

-- If you can't joint it, bead it!

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TopamaxSurvivor

17674 posts in 3142 days


#3 posted 09-23-2009 11:44 PM

SPalm said what I was going to say, keep your wits about you:-)) Depends on the reference face of the board you are cutting. I was just cutting some compound miters on the table saw to make for dovetails the other day. There are some cuts that don’t work because you are limited by the right or left tilt of the blade. Sometimes you have to do it one weay and sometimes the other ;-)

daltxguy, I’m glad we don’t use radians on the miter gauge :-)) I almost forgot all about them!

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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sIKE

1271 posts in 3221 days


#4 posted 09-23-2009 11:56 PM

daltxguy,

Ouch! My brain just thunked!

-- //FC - Round Rock, TX - "Experience is what you get just after you need it"

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patron

13538 posts in 2808 days


#5 posted 09-24-2009 12:10 AM

the angle you want ,
is the angle formed on the board ,
where the saw blade first cuts into it .

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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daltxguy

1373 posts in 3381 days


#6 posted 09-24-2009 01:19 AM

Sorry to explode any brains.
In the end Spalm said it best.
And when in doubt, hope for pictures
or buy extra wood!

-- If you can't joint it, bead it!

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jussdandy

157 posts in 2674 days


#7 posted 09-24-2009 01:55 AM

uhhhhhhhhhhhhhhh well for me I draw a line forthe angle I want then sight down the side of the blade and hope Im right, I like your method, But well I have to many senior moments for it to work usually

-- Randy I have the right to remain silent, just not the ability ; )

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