Riving Knife Thickness and Kickback

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Forum topic by dgrant posted 11-13-2013 04:18 PM 1605 views 0 times favorited 8 replies Add to Favorites Watch
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47 posts in 2197 days

11-13-2013 04:18 PM

I had my first kickback yesterday which was scary but resulted in no injury. I know why it happened. I was not using the riving knife and got careless about moving a small off cut on a cross cut. I wasn’t using the knife because it has dimensions printed on it giving maximum and minimum blade thicknesses. I have a thin kerf blade installed which is okay on the maximum body thickness at 1.92mm. The knife states a 2mm thickness is the max. The kerf width on the blade is not wide enough though at 2.75mm. The knife requires a 3mm minimum kerf width.

I installed the knife anyway and tried a few scrap cuts. I don’t see any reason not to use the knife. I don’t see or feel any binding and the cut seems nice and straight. The piece just barely grazes the knife on the right so it is snug but not bad. Is there any other reason for the blade dimensions that are printed on the knife? I would rather use it is spite of the thickness issues to avoid a repeat of the issue I had yesterday. I’m making a sled for cross cuts so that will help.

8 replies so far

View Marcus's profile


1165 posts in 2500 days

#1 posted 11-13-2013 04:22 PM

I had a similar issue. My solution was just to go buy a blade that matched the specs of the knife (a knife to match my blade was not available). Small price for piece of mind for me.

View dgrant's profile


47 posts in 2197 days

#2 posted 11-13-2013 04:24 PM

I thought about that but this is a Wood Worker 2 blade and cost me a pretty penny. It was the recommended blade for my saw by the website.

View Marcus's profile


1165 posts in 2500 days

#3 posted 11-13-2013 04:52 PM

Hah, ironically, that’s the blade I bought to match my knife. Have you looked for other Irving knifes? This is the one safety item I will not go without and for me, worth getting right . It all comes down to your comfort level though, and if it feels safe to you, I’m not the one to say don’t do it.

View pintodeluxe's profile


5975 posts in 3294 days

#4 posted 11-13-2013 04:54 PM

Maybe use a magnetic featherboard for the cuts that the riving knife won’t work.
They are one of those safety features that is so easy to use, there’s no excuse not to.
I have had standard featherboards for a long time, but only recently added the magnetic version. I am impressed.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View knotscott's profile


8325 posts in 3856 days

#5 posted 11-13-2013 05:00 PM

How about a $30 alternative to the WWII? The Delta Industrial 35-7657 is $18 plus s/h….I won’t go as far as to say it’s the equal of a WWII (though some do), but it’s darn close for a fraction of the cost….it’s made in the USA too.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View MrRon's profile


5661 posts in 3724 days

#6 posted 11-14-2013 05:17 PM

I have found that setting the blade height low, kickback increases. Using a higher blade height presents a greater attack angle to the wood, thus lessening the kickback effect. With a low blade height, the cutting force is directed parallel to the table top. With a high blade height, the cutting force is directed more downward to the top. This off course is contrary to the belief that the blade should be kept low for safety concerns.

View Woodknack's profile


12891 posts in 2860 days

#7 posted 11-14-2013 06:04 PM

The scenario in the OP is unclear to me. The only (normal) way you get kickback in crosscutting is by twisting the workpiece as you cut so that it binds but the kickback is much less severe than when ripping. I don’t know from experience but braver (or dumber) men than me have done experiments. Kickback should never happen when crosscutting unless you are cutting freehand.

-- Rick M,

View MrRon's profile


5661 posts in 3724 days

#8 posted 11-14-2013 10:39 PM

A riving knife is used primarily for rip cuts, because that is when the kerf has the tendency to close. Kerfs usually don’t close when crosscutting.

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