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Riving Knife

3K views 30 replies 14 participants last post by  dakremer 
#1 · (Edited by Moderator)
I dont know why I havent questioned this before - maybe its because its not my saw (I use my bro-in-law's wood shop), but I always wondered if I could add a riving knife to his Jet saw. It should have been obvious to me, especially since there is an opening in the plate for a riving knife, but it didnt click until I actually saw the flange and bolt/washers for the riving knife (while changing the blade)

My question - Do I need to order this from Jet? Is there a cheaper (possibly homemade) alternative? What are my options?

I've been using his saw for a while now, with one kickback, and would like to bump up my safety precautions, and hopefully make that my last and only kickback.

Thanks in advance!
 
#3 ·
Given the saw has the mount for it, I would guess that it came with a riving knife. Maybe its kicking around in the dusty recesses of your b-i-l's shop?

If you can't find it, DIY is certainly an option. You need to find steel sheet of the right thickness (-just- narrower than the blade), and be picky about how it fits onto the mount, about blade clearance, and make sure it does not sit higher than the blade. I made my own for my old saw and it took three tries to get it right, but definitely improved the saw's safety.
 
#9 ·
If a true riving knife doesn't work, you can add a splitter to your zero clearance insert.
I have made several splitters from hardwood, and glued them in a kerf in the ZCI. Make the splitter about 1/2" high, and it will work for most cuts except for miter cuts. 99% of my TS cuts are just straight square cuts, so it works for me.
 
#12 ·
What looks like a mount for a riving knife may instead be for the splitter/blade guard. Like on my older Unisaw. Depends on the age of the saw. I'm studying whether I can make my own, but if not, I'll go for the B.O.R.K.
 
#13 · (Edited by Moderator)
I made a second riving knife easily myself from an old dud sawblade.Needed a larger one for a bigger blade. Just draw out yourshape then cut holding it in a strong vise with a angle grinder with ( my preference) a diamond blade.Careful to remove the teeth section when cutting the saw blank is thinner than the width with teeth attached and poses no width problems.Wear eye glases and gloves too when grinding. I always set my riving knife just a mm or two lower than the height of the blade in question you intend to eventually use this allows for thru and non thru cuts.
Have fun Alistair
 
#15 · (Edited by Moderator)
"why does the knife have to rise and fall with the blade? If you arent cutting through the wood entirely, like dados??"

By definition, that's what separates a true riving knife from a traditional splitter. There are a lot of options available for a splitter….very few for a riving knife.
 
#17 ·
I didn't make it to the shop today. But I'm pretty sure the flange is not for a riving knife as it didn't move with the blade. Maybe it is for a splitter? But then again, it might be the flange to attach the blade guard to… I'm confused now. Haha. I will stop out there tomorrow and try to post some pics
 
#18 ·
So you care about safety but you dont have a guard on your saw ?? even a old style splitter guard like on old jet saws prevent kickback as well as safe operation of the saw but it looks like you had a close call and while your waiting for the other companies to build a safe saw you will likely have another close call unless you get serious about safety.
 
#19 ·
As knotscott said, a riving knife by definition rises and falls with the blade.

The reason for this, and why it is better, has not been explained, I don't think.

A true riving knife is curved to fit very close to the blade, like less than 1/4" clearance.
If it was stationary, you lose three things.
- 1. the gap between the knife and blade would open up and close as the blade height gets changed.
- 2. the farther from the top of the blade the knife gets, the less effective it is at preventing kickback.
- 3. if the knife is fixed, like a splitter, and the blade gets lowered by itself, then the knife will interfere with a non-through cut, as you suggested.

So, the real advantage of the riving knife is that it is less likely to be in the way of making non-through cuts or with miter jigs, tennoning jigs, etc., and therefore it is more likely to remain on the saw. A safety device sitting on a shelf is not providing much safety.
 
#20 · (Edited by Moderator)
I never said I had a close call. Obviously I'm safety conscious because I'm asking question to see what my options are for my brother-in-law's saw. U dont even know if I've used this saw. U have no idea of my safety habits. Take ur "life saving" nursing "skills" somewhere else. I won't block u, so feel free to leave ur contribution to the topic, otherwise take ur crap elsewhere. Looks like we got a new HM

Crank - thanks for the info. That makes sense. Ill have to get under the saw and see if he's got a place for a riving knife or just a splitter. Either way I want to get something on there! Need my fingers so i can save my patients from needing to see "healthcare" providers like TheDude
 
#21 ·
You said you were using the saw and that you had a kick back so are you making stuff up your kind of medicine does not come close to Trauma have you ever stuck you hand into someones gun shot heart to stop the bleeding your a child little buddy you know nothing of real medicine Oh ya I have saved lots of lives something you will never be able to say or do im your work
 
#24 ·
I'd just make one that sits even with the top of the blade and goes up and down with it. It helps with binding on the blade when ripping . Mine is a pain to take on and off so I don't use it. If I see the kerf closing up, I stop the saw and tap in a thin wedge and it holds the kerf open and the wood never binds.
 
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