I'm confused, please set me straight!

[John Jussel]

So, I recently bought my first table saw (Bosch 4100-9). I plan on building some jigs first such as a crosscut and miter sled. I've been searching the web for different ideas on these sleds. A lot of good info and designs out there. One thing I am confused about though. Most people who are using sleds (on Youtube for example) do not use their riving knife while using the sled. Is there a valid reason not to keep the riving knife installed while using the crosscut/miter sleds? I would think you would want to always have it on unless obviously, you have a dado blade set installed. Also, I took it off to cut through my zero insert plate, but other than that wouldn't it be safer to keep it on when using a crosscut sled?

John

[Bradley Gray]

I have an old PM66, and the riving knife I use is attached to the insert, which I generally remove when using a sled. So I don't use a riving knife with a sled but I don't see a down side for you using one.

[Rod Sheridan]

Hi John, you want to have the riving and guard on the saw at all times.

The riving knife prevents kick backs and the guard also does that by preventing contact with the top of the blade.........Regards, Rod.

[Doug Garson]

I have an old PM66, and the riving knife I use is attached to the insert, which I generally remove when using a sled. So I don't use a riving knife with a sled but I don't see a down side for you using one.
Are you sure you have a riving knife? Sounds like you have a splitter. A riving knife moves up and down and tilts with the blade, can't see how one attached to the insert could do that. Why do you remove the insert when using a sled? I've thought about doing that also. Does it improve dust collection?


To the OP's original question the riving knife or splitter is primarily to prevent kickback when the piece between the blade and the fence catches on the back of the blade and is lifted and thrown toward the front of the saw. Most don't think it can happen when the fence is not there and that's probably why they don't use it. However it can happen without the fence and the riving knife can prevent it. The attached YouTube video by Laney Shaughnessy illustrates how it can happen. . https://www.youtube.com/watch?v=GPEfykBtNhg. (https://www.youtube.com/watch?v=GPEfykBtNhg.)So the answer to your question is yes it would be safer to leave it in place when using a sled.

[Brian Henderson]

So, I recently bought my first table saw (Bosch 4100-9). I plan on building some jigs first such as a crosscut and miter sled. I've been searching the web for different ideas on these sleds. A lot of good info and designs out there. One thing I am confused about though. Most people who are using sleds (on Youtube for example) do not use their riving knife while using the sled. Is there a valid reason not to keep the riving knife installed while using the crosscut/miter sleds? I would think you would want to always have it on unless obviously, you have a dado blade set installed. Also, I took it off to cut through my zero insert plate, but other than that wouldn't it be safer to keep it on when using a crosscut sled?

John

You're going to find that YouTube is a really awful place to learn about safety, everyone takes all of their safety devices off, even if it makes no sense. I think the whole thing is idiotic, but what can you do?

[glenn bradley]

Rule of thumb; use your safety devices whenever it is safe to do so. I generally remove my throat plate and use the RK with my sleds.

[Michael Zerance]

I leave my splitter on whenever possible. I can't see why using a sled would require the riving knife or splitter to be removed.

[Justin Ludwig]

I own that saw and take it with me for installations and the occasional closet build. The run-out on the blade is enough that I wouldn't rely on a sled for accurate cuts closer than 1/64 and sometimes 1/32 (wood dependent.) I'm not knocking the saw, it's every bit worth <$600. Not sure why you'd need a RK for a CC sled as tensions that pinch a blade are released during rips. I've made 1 or 2 cuts in my day and have never had a blade pinched in a crosscut.

This is my preference and I don't recommend it to anyone, nor do I allow my help to operate my TSs in this manner, but I removed my RKs when I run the saw.

Blade selection for that TS - Freud Diablos thin kerf work great. Don't put a full kerf on that saw, you'll burn it up prematurely.

[Ken Fitzgerald]

I leave my splitter on whenever possible. I can't see why using a sled would require the riving knife or splitter to be removed.

Michael....It depends on the design of the saw. I am one of those who leaves the guard and splitter on if at all possible. However, to use a sled, I have to remove both as the splitter is part of the guard. Without removing the guard/splitter, I could not use a sled.

[Michael Zerance]

Michael....It depends on the design of the saw. I am one of those who leaves the guard and splitter on if at all possible. However, to use a sled, I have to remove both as the splitter is part of the guard. Without removing the guard/splitter, I could not use a sled.

I see. I don't think I've come across one like that before.

[Brian Henderson]

I leave my splitter on whenever possible. I can't see why using a sled would require the riving knife or splitter to be removed.

A splitter I can see, since they might be too tall to fit through the kerf on the sled, but a riving knife? If the blade fits, the riving knife fits too.

[Pat Barry]

Its called a crosscut sled. I really don't think you need a riving knife.

[Myk Rian]

its called a crosscut sled. I really don't think you need a riving knife.
^^^^this^^^^

[Mark W Pugh]

So, I recently bought my first table saw (Bosch 4100-9). I plan on building some jigs first such as a crosscut and miter sled. I've been searching the web for different ideas on these sleds. A lot of good info and designs out there. One thing I am confused about though. Most people who are using sleds (on Youtube for example) do not use their riving knife while using the sled. Is there a valid reason not to keep the riving knife installed while using the crosscut/miter sleds? I would think you would want to always have it on unless obviously, you have a dado blade set installed. Also, I took it off to cut through my zero insert plate, but other than that wouldn't it be safer to keep it on when using a crosscut sled?

John

I don't think either device provides any protection while using a crosscut sled. There is nothing to "pinch" or force back on the blade. What am I missing here?

[Doug Garson]

For all those who think a kickback can't occur in a crosscut operation please watch the Laney Shaughnessy video I linked to and tell me it didn't happen.

[Michael Zerance]

I don't think either device provides any protection while using a crosscut sled. There is nothing to "pinch" or force back on the blade. What am I missing here?

You may be right and I don't think you are missing anything. I just don't see the point in removing a safety device that is not impeding the cut.

[Pat Barry]

For all those who think a kickback can't occur in a crosscut operation please watch the Laney Shaughnessy video I linked to and tell me it didn't happen.
He wasn't using a cross-cut sled but its a good reminder of what can go wrong when poor procedures are followed

[Rod Sheridan]

Its called a crosscut sled. I really don't think you need a riving knife.

Hi Pat, depending upon the type of sled, you could have offcuts contact the rear of the blade, which gets exciting all of a sudden............regards, Rod.

[Art Mann]

There is no protection against lack of training or outright stupidity. The guy experienced a kickback because he tried to remove the cutoff while the blade was still powered. I did that once about 40 years ago and learned my lesson. If you do stuff like that all the time, you are going to get hurt whether your riving knife is installed or not. While he is at it, he needs to replace his saw with a Sawstop if he is going to reach over the top of the blade like that because he will eventually go off balance or lose his footing and an accident is almost inevitable.


For all those who think a kickback can't occur in a crosscut operation please watch the Laney Shaughnessy video I linked to and tell me it didn't happen.

[John Lankers]

I don't think a riving knife is a guarantee against kickback, I experienced a few kickbacks with or without riving knife that left a lasting expression, but a riving knife will reduce the risk tremendously. A sled, same as a slider lets you clamp workpieces down, first to keep your hands out of the danger zone and second to prevent it from shifting during the cut, a push block is no guarantee either. Here is a link to a post from Tom Hintz where he gets caught of guard trying to recreate a kickback situation: http://www.newwoodworker.com/basic/kickback2012.html
My advice is to use a r. k. or splitter whenever possible and don't let time or inconvenience stand in your way, it will hurt you eventually in one way or another.

[Rod Sheridan]

I don't think either device provides any protection while using a crosscut sled. There is nothing to "pinch" or force back on the blade. What am I missing here?

Mark, kickback occurs when the wood contacts the rear or top of the blade.

This can occur when ripping, crosscutting or making non through cuts.

regards, Rod.

[Ben Rivel]

Yea thinking about how kickback occurs it doesnt seem like a splitter or riving knife would be needed when using a crosscut sled. That aside it also doesnt seem like it would hurt or cause any problems to use at the least a riving knife with a crosscut sled. Its just another layer of protection.

[David Kumm]

If you crosscut ( not rip using a sled ) wood it is much less likely to close up behind the blade because you are severing the straws that form the wood rather than splitting them. Doesn't mean you should take off the knife, just that offcuts are a more likely danger, as is too much cfm at the guard if it pulls the offcut into the blade. For a riving knife to be most effective, it needs to be as thick as the plate of the blade but less than the kerf. If less than the plate, the kerf may still be able to close enough to contact the back teeth. Dave

[John Lankers]

David, you're making some excellent points. For controlling the offcut Felder (and maybe others) are offering a very simple device to guide the offcut away from the saw blade.
Balancing cfm and static pressure at the blade guard is (at least for me) much more challenging.

[John Gornall]

A table saw is at the center of so many different cuts. And as woodworkers usually only do a few of each cut they don't take adequate time for safety. Working in a shop that makes wood parts for a manufacturer we have a different point of view which may be useful to you. For example we might be making those little triangle pieces shown above and we need produce 20,000 of them. So we take the time to setup safely. For these there would be a piece of plywood about 1/16th inch thicker than the wood stock 6 inches wide clamped across the saw table from front to back and a suitable distance to the right of the blade. Another piece of plywood would be screwed to this one which bridges out over the blade. Clamped, screwed and strong. The blade would be raised into this bridge. Can't reach the blade with your hand, the pieces can't get to the dangerous part of the blade. And finally a tube connected to an air hose is placed to blow the pieces (or off cuts) clear and out the back of the saw. The sled is designed for this setup and is left of the blade.

When using a sled you can work up suitable guards with a little thought. Plexi guards can be seen through. The stock guard isn't likely to work and sometimes may make things more dangerous. Push the sled under the guard and with the spinning blade in the middle of it all find you can't move the sled because it's caught on the guard. And don't forget your blade coming out the back of the sled at the end of the cut.

Be safe out there!