Shooting Board

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ruby@magpage.com
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Joined: Thu May 24, 2012 8:03 am
Location: Chestertown Maryland

Re: Shooting Board

Post by ruby@magpage.com »

Jim 72

The 20° skew of the blade is enough to have an effect, where the couple degree skew of tipping the bed up or down does not. The reason to tip the bed is so that a larger portion of the edge gets used.

They did have some interesting math on the site:

"Combined with the 12° bed angle and 25° blade bevel, this yields an effective cutting angle of 35°"


Ed
Ed M
Jim72
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Joined: Sat Sep 21, 2013 4:54 pm

Re: Shooting Board

Post by Jim72 »

ruby@magpage.com wrote:Jim 72

The 20° skew of the blade is enough to have an effect, where the couple degree skew of tipping the bed up or down does not. The reason to tip the bed is so that a larger portion of the edge gets used.

They did have some interesting math on the site:

"Combined with the 12° bed angle and 25° blade bevel, this yields an effective cutting angle of 35°"


Ed
I can see where a larger amount of the blade gets used by going with a slope, maybe wouldn't have to sharpen as often if you were doing a lot of squaring up. I had never seen that approach before and was curious as to why, and yes their math is a little off. :lol:

Paul Sellers has a nice video on a little different shooting board. I have not built any guitars yet, I am early into checking things out and this site is the best I've found so far. I don't know that having the ability to shoot 45 degree angles would be that necessary with building guitars, I would imagine there would be a lot more 90 degree angles . The OP shooting board looks to be well built, and I am sure it will work great!


Thanks,
Jim
Mitch
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Joined: Wed Dec 26, 2012 1:10 pm

Re: Shooting Board

Post by Mitch »

"Combined with the 12° bed angle and 25° blade bevel, this yields an effective cutting angle of 35°"
Funny math for sure until you consider that the blade is skewed, which lowers the effective bevel a bit. Not sure by how much, but maybe that's what LV was thinking.

Mitch
Jim72
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Joined: Sat Sep 21, 2013 4:54 pm

Re: Shooting Board

Post by Jim72 »

Mitch wrote:
"Combined with the 12° bed angle and 25° blade bevel, this yields an effective cutting angle of 35°"
Funny math for sure until you consider that the blade is skewed, which lowers the effective bevel a bit. Not sure by how much, but maybe that's what LV was thinking.

Mitch
Now that is an interesting twist (pun not intentional, but it's there). Is there a sweet spot or most effective skew angle? In theory as the skew increases you will continue to drop the cutting angle towards zero until you suddenly orient the skew parallel to the path of the plane in relation to the work at which point you are suddenly throwing up a wall (scraper?) In real life is that the case or does it fall apart before that (when the width of the cutter becomes less than the thickness of the wood being planed?). Someone must have figured it out. The math is beyond me.

Jim
ruby@magpage.com
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Joined: Thu May 24, 2012 8:03 am
Location: Chestertown Maryland

Re: Shooting Board

Post by ruby@magpage.com »

Jim

I don't know what that optimal angle would be - it probably varies with the wood your are working on. Try this: Clamp a piece of 1 X wood in your vice, edge up, then take a few strokes with your block plane. Start with the plane going straight down the length of the board, then gradually skew it a few degrees at a time and you will see that it get a little easier as the blade does more slicing. Seems that for most boards 45° is about the easiest and cleanest cut, but the effect is not great. The trade-off is that as you skew the plane, the effective length of the bed gets shorter and shorter and it gets harder to make a flat surface. However, if you are smoothing a wider board, you can readily see the effect.

Ed
Ed M
turnertj
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Re: Shooting Board

Post by turnertj »

Hey Jim...

Somehow I missed this entire discussion! Sorry, didn't mean to be a absent. I can g measure the angle I chose, I forget what it was off the top of my head, but I used it in order to use the entire blade when Shooting top and backs. So that way I say a bit sharper, need to sharpen a little less (maybe)...it wasn't scientific. I looked at the average of the tops and backs, in terms of dimensions, and then angled the board so that I was using most of the blade.

Tj
Tj Turner
Author, Scientist, bumbling Luthier
Author of Lincoln's Bodyguard
www.tjturnerauthor.com
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