Riving Knife question, what does it do?
bduffin104
| Posted in General Discussion on
I’ve logged many hours and days behind a various table saws over the past forty years so I’m somewhat embarrased to admit that I’ve never used a riving knife or a splitter. I can see how they might prevent kickback from some action wood pinching the blade. Is that what it’s for? I’ve always used various shop made sliding trays for cutoff and mitering with my table saws. It seems like a riving knife would just interfere with these types of setups. What am I missing?
Replies
I've also logged some time on
I've also logged some time on the tablesaw, and have been using an SCM slider with riving knife for 15 years in a professional shop. If the riving knife is the correct thickness and is set just below the height of the blade, then it will systematically help prevent pinching the blade, especially when ripping. You don't even think about it being there. I've come across only one situation where it is in the way and must be removed - when making a plunge cut, that is, if you lay the stock over the blade and slowly raise the spinning blade through the wood.
Thanks for the info! Nice saw. I did make a couple of plunge cuts just today, so maybe the riving knife won't work for me. A word of caution to those new to plunge cuts: NEVER BACK YOUR WORKPIECE INTO THE BLADE! The result could be quite violent.
Thanks for asking this "basic" question, as I never knew either. My riving knife has 2 positions, thru cut and non thru cut. I admit to forgetting to adjust this when I don't do thru cuts. Do people find this distinction important on the riving knife? (My saw is a new Dewalt 10").
A riving knife has two functions. First is preventing the board being ripped from closing around the back of the blade which can cause a kickback. But. I think a more important function is to minimize or prevent a board or panel from skewing away from the fence and coming into contact with the rising teeth on the back of the blade. This lifts and throws the board or panel back at the operator is a frequent cause of table saw injuries.
You are so right. The worst accident I've ever had with a table saw was while cutting a warped piece of 1/4" plywood, which being light, lifted above the blade and the the blade grabbed it and in a millisecond threw it back into my gut, hard! My fingers were not anywhere near the blade, fortunatley, but also another reason the panel lifted up. I was bruised and bleeding a bit but was lucky not to have sustained more serious inguries. And yes, I think a riving knife would have prevented this acciddent.
bd
there was a similar(to your's) incident down in Texas a few years ago.
A man was cutting a sheet of 3/4 ply and the off cut viberated over the saw blade(no riving knife) and shot back and hit the man in the gut. He was sore but went back to work. Went home that night and went to bed like always, died in his sleep from internal injuries! The projectile coming off a table saw can be very lethal. Take them seriously.
Doug
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