Dual fences?

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Is this idea worthwhile?
I was thinking about featherboards and it occurred to me that if a table saw had a pair of fences and the table could
hold the stock, there could be no lateral movement and no sideways force.
Anyone have an opinion?
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wrote:

Have you ever been shot in the belly by a piece of wood that the saw kicked back? Huge risk of increased kickback if you try that. You now have two pieces of wood that you are trying to safely pass by the saw blade. With just one fence the waste can lay on the table or fall off the table with marginal risk of getting tossed back by the blade.
If your wood is not parallel you have chances for even more adventures in kickback and binding.
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Sat, Feb 2, 2008, 2:41pm snipped-for-privacy@doesthisblockpork.mindspring.com (Jim Behning) doth posteth: Have you ever been shot in the belly by a piece of wood that the saw kicked back? Huge risk of increased kickback if you try that. You now have two pieces of wood that you are trying to safely pass by the saw blade. With just one fence the waste can lay on the table or fall off the table with marginal risk of getting tossed back by the blade. If your wood is not parallel you have chances for even more adventures in kickback and binding.
If you stand out of line of the blade you won't get hit by kickback. When I was in high school shop class the teacher showed use what kickback was. He then told us not to do that. And I never hav
I don't see a problem with two fences, if they are parallel to each other and the blade. I also don't see the need.
JOAT - who does not welcome thread question e-mails..
10 Out Of 10 Terrorists Prefer Hillary For President - Bumper Sticker I don't have a problem with a woman president - except for Hillary.
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On Feb 2, 8:03 pm, snipped-for-privacy@webtv.net (J T) wrote:

Here's another idea based on your post.
I have a sled.
Using clamps the board is fixed.
The sled has a stop.
Why not stand on the other side and pull the sled instead of pushing it?
The 'kickback' would go away from you.
Completely safe?
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Sat, Feb 2, 2008, 6:09pm (EST-3) snipped-for-privacy@aaronj.com (BoyntonStu) doth queryeth: <snip> Completely safe?
I do not believe I know of 'anything' that is 'completely' safe.
JOAT - who does not welcome thread question e-mails..
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(BoyntonStu) doth

And if there IS anything that's "completely" safe, I suspect that it wouldn't be much fun.
I'll stick to things that have just a hint or two of "unsafe" to them...let's me know that I'm still alive by getting me to think "If things go bad, where do I need be that will allow me to TALK about it later?" And hoping that nothing DOES go bad.
Mike
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wrote:

Unsafe for other reasons, such as the mechanics of reaching long distances, but safe for other reasons I'll mention below.
The bottom line: You don't understand kickback. The key to safely and successfully using machine tools is a solid understanding of the physics involved in each operation and using them to your advantage. Fear based "safety" workarounds usually have unintended side effects, at the minimum destroying accuracy or speed of work.
Boards clamped to sleds are not the same as boards trapped between a fence and the rising back teeth of a saw blade. You need three conditions for serious kickback:
1. - Rising Teeth 2. - A fence to trap the work against, to provide traction 3. - Enough slop to allow the wood to rotate against the rising teeth, or a board that pinches shut after being cut.
Ripping a board that's short and wide, or using a miter gauge and rip fence together (without extra room to the side of the blade) can also get ugly in a hurry.
You can prevent kickback by eliminating at least one of the conditions above. For example, a splitter prevents the cut wood from pinching or being grabbed by the rising teeth. A properly adjusted fence eliminates the slop. Without traction (as on the clamped sled or the offcut side of a rip), the possible force of kickback is greatly reduced.
Here's a decent demo that looks like it's filmed in a school shop: <http://www.metacafe.com/watch/910584/table_saw_kickback_demonstration/
Some teachers will demonstrate the same thing using foam.
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On Feb 3, 9:39 am, "Bonehenge (B A R R Y)"

Good video.
Comments:
1> The kickback was away from the fence and it flew in rotation like a frisbee..
2> If another fence was on the other side of the board, how could it fly off the table?
3> A hold down near the fence would prevent lift.4> A slide table push fence would not allow the board held against it to frisbee rotate.
Conclusion: Sliding tables are inherently safer than bare table saws. BTW My slide table stops sliding before your hand can reach the blade. Use a hold down next to the fence as close to the lifting blade as possible. Install a splitter if possible (harder on a slide table) A second fence not even touching the board or a feather board would help.
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Sun, Feb 3, 2008, 10:17am (EST-3) snipped-for-privacy@aaronj.com (BoyntonStu) doth sayeth: <snip> BTW My slide table stops sliding before your hand can reach the blade. <snip>
Yeah, sure, right. All it takes is one time of putting your hand in the wrong place, and your friends will be calling you "Stumpy".
JOAT - who does not welcome thread question e-mails..
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wrote:

Good!
Good! They call these "feather boards".

Not necessary with a sliding table, but big time necessary when ripping, unless your ripping with a taper sled.

If it's not touching the board, why is it there? When it DOES touch, it's all over.
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Bonehenge (B A R R Y) wrote:

I like that explanation, and there's another factor to be considered. A kickback "away from you" is still a kickback. Wood flies.
To where?
Wall with window?
Priceless antique that's in the shop for repair?
Your brand new (and priceless) Harbor Freight router that's just been lovingly unwrapped and awaiting its first plunge?
Someone else in the shop who came in to announce supper?(This one may limit your ability to have children, even tho the kick back didn't hit YOU)
-- Tanus
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http://www.home.mycybernet.net/~waugh/shop /
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If you are pulling a sled towards you, the push sled could have a vertical plywood 'safety' shield you could swing into position..
Hold down, push fence, parallel fence, safety shield.
I can't think of kickback happening and if it possibly did occur, I cannot imagine that the board would hit anything but the shield.
Is your sparkling new HF router safe now?
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BoyntonStu wrote: <snip>

I'm not sure if you purposefully missed my point or you really believe that this is safe.
If it's the former, and you're just pulling my leg, consider it pulled.
If it's the latter, then I'm glad we don't work together.
--
Tanus

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Not with much force, unless it's a tiny offcut.
It's the "trap" that creates the traction on any decent sized part.
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You need three

Might one supplement this excellent advice with the suggestion that using a short ripping fence, ie one that guides the wood no further than the gullets of the teeth, is also a good precaution against kickback.
Jeff
--
Jeff Gorman, West Yorkshire, UK
email : Username is amgron
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You want to be reaching across the blade?
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On Sun, 3 Feb 2008 15:33:55 -0800 (PST), Father Haskell

BINGO!
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On Feb 3, 7:42 pm, "Bonehenge (B A R R Y)"

No.
You are standing on the teeth rising side of the table saw.
Your sled has a handle between you and the blade.
The sled has a stop and you cannot pull the sled off the table.
The hold down(s) eliminate the need for hands anywhere near the blade.
You pull the sled towards you.
Any flying wood goes away from you.
The sled could also have a backstop to trap anything flying its way.
How is it possible for anyone or anything to be hit?
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Design it and sell it them!
--
Mike
Watch for the bounce.
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asmurff wrote:

Rube Goldberg Tools <G>
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