Why not a 96" Biesmeyer ??

[Edwin Santos]

I did read that.. I look at all posts multiple times.


Could we forget for the moment aALL my previous posts.. and let me just ask..

WHY did the "old days" saws mentioned above w the 8 or even 10' fence go out of style ?

Was it SAFETY reasons ?

OR.... the fact that more efficient and practical saw configurations were developed and marketed ?

Marc

I've never heard of a table saw with a fence capacity of more than 50" right of blade. If there was an "old days" saw that had a wider capacity, I cannot fathom why, unless it was designed for sheet goods that came in a considerably larger sizes than are typical today.
If there was such a saw, then I would surmise it was discontinued for safety reasons, not because of slider saws appearing on the market. To have such a large fence capacity is inviting someone to do what you are proposing which is inherently unsafe due to the laws of physics. I think Mark Bolton summed it up in his post - the cardinal rule is to never cut anything on a table saw AGAINST THE FENCE that is wider than it is long. Doing so increases the risk of kickback dramatically.

Illustrate this principle by taking your two hands and placing them on the desk in front of you about 6" apart. Push your right hand forward away from you representing the workpiece pushed along the fence. Simultaneously pull your left hand back toward you slowly representing the blade's forward motion which is pushing the work piece in the operator direction. Imagine these two opposing forces working against each other. Now do the same exercise with your hands two feet apart. Do you see the levering occurring? Now you could overcome this levering and the opposing forces by pushing against your rock solid fence and rails really really hard, but you are being advised not to do this because physics is not on your side and the people responding don't want to see you get hurt.

Footnote: drag on the surface of your table saw makes this equation much worse. Even if you waxed the heck out of your table saw's surface, the sheer area of the work pieces you are contemplating will create enough drag to encourage the work to lever. Another footnote: part of the challenge is pushing the workpiece evenly across it's width. If you push too hard, far way from the blade - lever city. If you push too hard near the blade, you could lose your bearing against the fence - lever city.

On a personal note, I have never been cut at the table saw, but I have had one kickback incident. It involved a piece of 1/4" ply that was about 30" square. It dragged on the table just a wee bit, enough to create a slight levering, such that one of the back teeth on the blade caught it, rotated it around, and smacked me in the abdomen.

I hope the above example makes some constructive sense.

Edwin

[Frederick Skelly]

"If there was such a saw, then I would surmise it was discontinued for safety reasons, not because of slider saws appearing on the market."

+1. I had the very same thought Edwin.

[Marc Jeske]

Why the snarky stuff Matt? There's no value in it. The man said he is trying to understand.
Fred

Actually, I am the guilty one who generally started the snarkiness.

It's all good, no problem.

But I do get very frustrated when folks don't seem to be reading.. thinking I am cutting within a glass microparticle Silicosis storm.. after I clearly explained it is 1/8 tsp FAR from the blade on the extension tables.

I probably should have made that last point clearer.

In person give and take Socratic is way easier than texting back and forth.

Marc

[Matt Day]

Why the snarky stuff Matt? There's no value in it. The man said he is trying to understand.
Fred

Why the snarky stuff? How many more times does it need to be said that there’s risk of the stock shifting and therefore kickback? What more is there to understand?

What about using two incra type miter gauges, one in the standard right miter slot, and install another miter bar 5’ to the right, and tie them together. I have a 52” long bar , for instance, that would work. Push from the middle.

[Phillip Mitchell]

If efficiency and accuracy with this one particular cut is what you're concerned with, which seems to be why you're asking the questions to begin with (maybe not? pardon me if I'm wrong here) you should get a track saw and cut 2 (or 3 with a TS75) sheets simultaneously without having to move them to the table saw and feed a full sheet across a table. Cutting a small amount off one edge or end of a full sheet of plywood is certainly easier, less fatiguing in the long term, potentially faster if you stage your material properly and way safer than what you keep proposing on a table saw.

If you really just want a 96" fence and massive side feed support on your table saw, go to town and do it...but thinking that it's an overall better way to accomplish the particular task you've outlined is misguided in my (and many others') opinions.

Track saws are new fangled and cost money, yes, but there's a reason they are popular and it's because they are fantastic at breaking down full sheet goods and solving solving some of the issues inherent with dealing with full sheets of ply on a traditional table saw.

[johnny means]

Same reason you don't put a ladder rack and tool box on a Porsche. Sure it could be done and used, but the utility and results would be poor. They make vans for a reason.

[Andrew Seemann]

I never quite understood why Biesemeyer made a 96" fence for a table saw. I have seen pictures of saws with them, but only maybe a half dozen in 30 years. I could maybe see a 60" fence for 5x5 baltic birch sheets, but nothing really comes wider than 5x5, so any more than that doesn't really have a purpose.

The safety issue is that the blade wants to push the material back at you. To prevent this you push diagonally to against the fence to simultaneously move the material forward and counteract the pushback from the blade, while the fence keeps the material aligned with the blade and kerf. On a board wider than long, the blade has more leverage to push back at you and overcome your diagonal pushing. If it does overcome your diagonal pushing, the blade stops cutting the wood fibers and starts pushing(throwing) the wood at you, known as kickback. It gets really dangerous when you get to the end of the cut and don't have much purchase against the fence and you have little mechanical advantage in your diagonal pushing. That is when it is easy to loose control of the material and have the blade grab it and throw it back at you. On a piece of plywood where you would be cutting 2 feet off of a 4x8 sheet with your fence set at 6 feet, it would be nearly impossible to push against the fence enough to overcome the push of the blade back at you, especially at the end of the cut. Ergo, what could possibly be the use of a 96" rip fence? There really isn't any safe way to use that extra capacity.

I had a similar experience to Edwin, except that the cause of the kickback was stupidity on my part (we'll skip the details). When the plywood flipped up, I caught it right as it hit me in the stomach, but since it knocked the wind out of me, I dropped it back into the blade, and it kicked back and hit me again in the exact same spot. That time my knees buckled and I mercifully dropped to the floor before it happened a third time. After an experience like that, you get really conscious about anticipating and avoiding kickback.

[Mike Kees]

There is a 96'' Biesemeyer fence on a General cabinet saw at the Windsor plywood location in Lethbridge Ab. They use it to ..you guessed it cut plywood sheets to shorter lengths. I too would say this is not very safe. I like the 'do not cut a piece that is wider than the length of the cut' rule. Have had a kickback with a piece of plywood that was about 24'' square,drilled me in the midsection.That was 26 years ago,I have not forgotten how fast it happened or how much it hurt.Marc just listen to any of the advice guys have posted in both of your threads. Where you started with crosscut sleds is a much better option than a 96'' fence. In fact I would say every other option given to you is hands down better than this 96''fence idea. At the end of the day,it is your life and money do with it what you will.