Riving knife vs splitter

[Prashun Patel]

I thought I understood the difference, but after looking at my (stealth gloat alert) brand new Jet Proshop tsaw I'm not sure anymore.

I thought that a riving knife sits closer to the blade than a splitter and tilts as the blade tilts.

The proshop splitter goes through the insert, so it's pretty closer to the blade except when the blade is in a very low position. How'd a riving knife be better here?

Also, the Proshop's splitter - even the previous Delta Shopmaster one I had - tilted with the blade just fine.

So what's the real difference in safety btn a rk and a splitter?

[Jim Becker]

I was under the impression that the ProShop has a splitter, not a riving knife, based on previous posts on this subject. My understanding is that Jet will introduce a new saw with the riving knife, but it will not be the same machine as the ProShop...due late 2008.

What you describe is not a riving knife if it does not stay tight to the back of the blade and raise up and down with the blade.

[Prashun Patel]

I revised my post to be clearer. My saw definitely has a splitter - not a riving knife. BUT, the splitter it has tilts well with the blade and is mounted very close to the blade for cuts 3/4" and deeper. It's also mounted through the insert to the blade mechanism with good sized bolts so it's plenty stable.

So, I'm not seeing why a riving knife is so much better than a well-designed splitter - except perhaps when cutting very thin stock...

[Jason Beam]

True riving knives raise and lower with the blade. They always stay within about 1/4" of the blade at any given height. This is better because it gives the leaste possible chance of anything twisting and catching those back teeth. Don't think of just a kerf closing up on a board with tension. Also think of the loose piece that may get hung up somehow and rotate into the back of the blade.

Kickback is almost always caused by those back teeth getting ahold of something and shooting it at you. The closer the knife gets to the blade, the smaller the window of opportunity can be. It's not perfect and if you really tried you could still cause a kickback on a saw with a riving knife.

Secondly, a TRUE riving knife never sits above the top of the blade. This is my favorite detail. This means you don't have to take the riving knife off for nearly all of the cuts you make on a TS. If you rarely take it off, it's more likely to stay there and do it's job. Dados, rabbets, tenons, etc almost always require you to take the splitter/guard off because they're 'non-through' cuts and it'd get in the way. With a true riving knife, about the only time you have to take it off is for a smaller blade like a dado blade. Personally, I cut my rabbets and dados with my router table, so I don't think I'd ever have to take my RK off (as soon as I get a saw with one, that is).

As a side note on RK's, some of the UL rules also mention ease of removal/replacement. I think there is something about being able to put take it off and put it on in under 10 or 15 seconds. I don't know exactly how long, but the intention is that they need to be easy to replace or they won't go back on.

[Jim Becker]

A riving knife is always the same distance from the blade no matter what the height and also can be set (with the proper knife installed) so that the top of it just just below the blade height. That means you can use it for non-through cuts, too, since it travels up and down with the blade as you adjust the cutting height. In effect, it can stay on the saw virtually all the time. That, in itself, is a major increase in safety, IMHO. Even a "well designed splitter" cannot do these things.

[Prashun Patel]

I see now. Thanks.

[Nissim Avrahami]

Hi Shawn

Riving knife sits 1/8"~5/16" (3~8mm) behind the blade, lower by 1/8" than the blade and moves together with the blade like they are "welded" as one unit (up, down and tilt).

On the pics, you can see it at full blade height but it will keep the same reference position at any height and it will disappear with the blade below the table top when fully down (yes, I must remove the blade guard first :) )

This is the "Euro version" of riving knife without any "kickback pawls" that are not mandatory in EU...

The blade guard "clicks" into a slot in the riving knife and tight by a wing nut.

http://i208.photobucket.com/albums/bb151/matsukawa/Rivingknife.jpg

Regards
niki