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User Preferences for Stave Slope confused

Ted Kline

PRO Member
I'm not really sure but can someone explain the setting for slope in User Preferences in reference to where the angle is measured. Is >0 the angle from a horizontal plane to the outside edge of the stave? Is the <90 measured from a 90 degree vertical to the slope. If this is correct, then does it mean I should use the <90 for the angle on a table saw cutting the top and bottom of the stave board.

It would be nice if the program would calculate the "true" length of a board needed meaning the segment length plus the additional length need for the slope angle. I have no idea of how to calculate that and rely on test cuts to figure out the length and my angle confusion above.

Thanks
Ted
 

Lloyd Johnson

Administrator
Staff member
First, the slope for both the Stave and the Compound angle is the number of degrees from the table where zero is flat on the table and 90 degrees points straight up.

It is important to understand the difference between staves and compounds. A stave is a ripping process that means a stave is typically a tall ring where a long segment is cut from a long piece of wood. A compound is a short ring where the segments are crosscut from a board just like you would do if you were cutting ‘flat’ segments.

Aside from the difference in cutting staves (rip cut) and a compound (cross cut), the calculations for the two types solve for different values.

In a stave, you specify the lower outside diameter, the upper outside diameter and the height of the ring and the software solves for the slope.

In a compound, you specify the slope, the lower outside diameter and the height and the software solves for the upper outside diameter.

Now I’ll link you to a thread that goes into a lot more detail regarding Stave and Compound and when and why to use one or the other. Please be advised, though, that the calculations for the board lengths of the two tilted segment types are the only ones that would work for them. Since staves are ripped from individual boards, the board length is the total length of the boards you need for the number of segments you want.

For the Compound, the formula is similar to a Flat where you are going to flip the board after each cut and the Board Length is how long of a board you need to cut your desired number of segments. Any other calculation could be interesting, but it wouldn‘t be the correct board length.

The main thing you should learn from the following link is how to use the ‘wedge’ technique to cut the time it takes to make a ring of tilted segments in a fraction of the time it takes using the traditional method of tilting your blade to a goofy angle and using a non-standard angle for the fence.
Here is the link:

Lloyd
 

Lloyd Johnson

Administrator
Staff member
I'm not really sure but can someone explain the setting for slope in User Preferences in reference to where the angle is measured. Is >0 the angle from a horizontal plane to the outside edge of the stave? Is the <90 measured from a 90 degree vertical to the slope. If this is correct, then does it mean I should use the <90 for the angle on a table saw cutting the top and bottom of the stave board.

It would be nice if the program would calculate the "true" length of a board needed meaning the segment length plus the additional length need for the slope angle. I have no idea of how to calculate that and rely on test cuts to figure out the length and my angle confusion above.

Thanks
Ted
I need to give you a different answer for your first question as I misread it. In the File > Options screen the setting for the slope has nothing to do with staves or compounds. Instead, it recognizes that nearly all table saws calculate the tilt of the blade one way while a small number use a different standard. The default settings (more than zero) is what you use for virtually every saw made in the US. If your blade is perpendicular to the table (pointing straight up), your protractor for the blade tilt is 0. On some international saws, though, the protractor shows 90 degrees which is when you need to select the < 90 option. The miter is similar and the slope allows you to change how you want the slope to appear in the calculations.

Here are the defaults:

If your stave is perpendicular to the table (straight up), the slope is zero and the tilt is x degrees from 0.

For the compound, though, the slope is the number of degrees from the flat surface of the saw’s flat table. If you want this to be different (I don’t recommend this), you can change the Slope value in File > Options.

I hope that helps.
 

Ted Kline

PRO Member
Thanks for your reply. Definitely helps understanding the difference between staves and Compound segments. Now for the next questions. Currently I would like to make a ring with a 4" base (lower diameter) and 10" upper diameter and about a 40 degree slope. The board I will be using is 5.25" x 40" x .875" . So I will be using the Compound segment. I input the numbers for 12 segments and the board height is calculated at 4.96. I also like to Pre-cut the board to a parallelogram. Does the 4.96 board height include the added length needed for the parallelogram?

Just curious, when I try to switch the ring to Stave and use a calculated height from the Compound calculations (bowl height minus base height) it the slope and dimensions do not come out the same. Does not make sense to me.
 

Lloyd Johnson

Administrator
Staff member
Yes, the height shown is after the ring is flattened whether you do that before or after cutting the segments.

You cannot switch between staves and compound and have them be the same because, well, I’m not smart enough to do that, nor do I intend to try. You have to decide which you want to use and then make it ‘to order’.

make sure you use the keyboard shortcuts to change the diameter, height, etc. using the arrow keys. It makes it much faster.
Lloyd
 

Lloyd Johnson

Administrator
Staff member
Thanks for your reply. Definitely helps understanding the difference between staves and Compound segments. Now for the next questions. Currently I would like to make a ring with a 4" base (lower diameter) and 10" upper diameter and about a 40 degree slope. The board I will be using is 5.25" x 40" x .875" . So I will be using the Compound segment. I input the numbers for 12 segments and the board height is calculated at 4.96. I also like to Pre-cut the board to a parallelogram. Does the 4.96 board height include the added length needed for the parallelogram?

Just curious, when I try to switch the ring to Stave and use a calculated height from the Compound calculations (bowl height minus base height) it the slope and dimensions do not come out the same. Does not make sense to me.
Remember that the slope of staves is the number of degrees from vertical and the slope of compounds is the number of degrees from the flat table so you would have to subtract the slope from 90 to switch between the two.
This is not my idea. This is hotter slopes are specified in books.
Lloyd
 
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