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Difference Between a Splitter and Riving Knife

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Forum topic by iSawitfirst posted 08-10-2009 09:34 PM 2906 views 0 times favorited 2 replies Add to Favorites Watch
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iSawitfirst

34 posts in 3273 days


08-10-2009 09:34 PM

Can anyone tell me if there is a difference other than shape?

Thanks in advance.

-- The aim of art is to represent not the outward appearance of things, but their inward significance. Aristotle


2 replies so far

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BTKS

1984 posts in 2926 days


#1 posted 08-10-2009 11:53 PM

There is a difference. The splitter is in a fixed location and stays in place. When you lower and raise the blade, the gap between the two opens allowing a greater chance of kickback and stays above the table eliminating its use for rabbet cuts, etc. The riving knife moves with the blade and maintains a tight tolerance to the rear of the blade. This does require different thickness knives depending on blade kerf. The knife actually sits just below the top of the blade arc thus allowing it to be used for non-thru cuts. The riving knife will be mandatory on all new saws sold in the U.S. in 2014 I believe, could be wrong on date. There is also a difference in timing for current designs in the market place. I have been lead to believe, most manufactures are working on retrofits for current designs and adding them to all new designs. The riving knife is much safer and greatly reduces chances of kickback. Always follow good tuning and safety practices regardless of splitter or riving knife. Seems like I’m leaving something out. Oh yea, most riving knife saws have to change the trunion to slide up and down as a unit instead of swing to allow the riving knife to follow the blade. Most use four dovetail ways. I know Steel City’s saws use dovetails and the ways are adjustable for wear. It would take thousands upon thousands of trips up and down to open any tolerance but hey you never know. I’d rather adjust than replace. That’s most of what I know about them, hope it helps. BTKS

-- "Man's ingenuity has outrun his intelligence" (Joseph Wood Krutch)

View Jason Beam's profile

Jason Beam

2 posts in 2678 days


#2 posted 08-11-2009 01:01 AM

About all I can add to the above is this:

The UL has made them mandatory as of this year on all NEW models. By 2014 all models must be equipped with them in order to get underwritten by the UL. It’s not a law, but dang close, eh? :)

Also – the mandate does NOT specify having the riving knife below the top of the blade, though I believe they should. Part of the whole reason splitters are tossed is because they get in the way on non-through cuts. A riving knife that sits above the blade is just about as troublesome as a splitter in this regard.

Finally – a true riving knife that sits just below the blade’s biggest benefit is that it will more likely STAY on the saw. Most people pop their splitter off and it never makes it back on the saw, or rarely does. So, anything that reduces the need for removal is a very big advantage.

Oh, and … I’m not sure if it’s spelled out in the UL mandate, but a true riving knife is even better if it can be quickly removed and replaced. The easier it is to get that thing back on the saw without having to futz with aligning or spacing or finding the right size wrench or anything like that will dramatically increase its effectiveness just by merely increasing the time it spends actually in place.

My current saw doesn’t have one … but my next one absolutely will. And it won’t be one of those silly half-measures that has all the mounting bits above the blade for the guard and pawls. I’m excited to see the new innovation this UL mandate has brought, but there are some real eggs out there, too. There are a handful of folks who have it pretty close to right – the PM 2000 and I think SawStop’s got a real riving knife that either has no mounting spots or they’re below the blade. I use an over-arm blade guard anyway, but I’d still be on the lookout for a model which has a true knife with the ability to mount the guard (then I’d only have to pop the guard off instead of the whole thing, for example). :)

-- Jason Beam - Sacramento, CA

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