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How effective are riving knives at preventing kickback?

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Forum topic by Ed posted 10-02-2012 05:17 PM 4130 views 0 times favorited 41 replies Add to Favorites Watch
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Ed

28 posts in 799 days


10-02-2012 05:17 PM

Topic tags/keywords: tablesaw question

Safety is important to me. Yet, unfortuantly, there is usually a dollar price tag associated with safety.

I have not found many (none actually as yet) used table saws with riving knives (that ride up and down in a fixed relationship with the saw blade). I wanted to buy a used TS to get more bang for my buck and save some money. But I am having second thoughts given that I will give up this safety feature.

How effective are riving knives? Are there any studies that attempt to quanitifty how much kickback is reduced by thier use?

How do you justify giving up added safety compared to the potential of your injury. Losing a finger(s) would hurt or eliminate my playing of guitar. A high price for saving some money by giving up safety features.

-- Ed


41 replies so far

View Tennessee's profile

Tennessee

1527 posts in 1239 days


#1 posted 10-02-2012 05:27 PM

I ran two different table saws for years without riving knives. Maybe one or two kickbacks in over 20 years. One put a hole in the wall. I learned to stand off to the side when cutting.
That being said, now that I have a decent riving knife on my Rigid 4512, I cannot imagine running wood through a table saw without one again save for blind cuts. I probably am very lucky.

-- Paul, Tennessee, http://www.tsunamiguitars.com

View teejk's profile

teejk

1215 posts in 1409 days


#2 posted 10-02-2012 05:38 PM

Tennessee…you aren’t lucky, just typical. I think I’ve had one kickback on a TS in 20 years (on a board where I ignored the signs that “it wasn’t happy”). But if the riving knife works then by all means use it. 10,000 boards without incident get erased by the exception.

View Loren's profile

Loren

7809 posts in 2372 days


#3 posted 10-02-2012 06:04 PM

Generally it is tension in the board that causes problems
when ripping. If you rip your solid woods on the band saw
the problem goes away. A decent and properly set up
band saw can rip very straight and wood loss is minimized.
After that you can joint the edge or skim it straight on the
table saw safely.

In terms of crosscutting and breaking up sheet goods the
riving knife is not needed, imo.

Do I rip solid woods on the table saw? yes… and I do it
with a retracted (short) fence like they do in Europe. The
short fence gives the wood somewhere to go if it wants
to distort away from the blade coming out of the cut. With
a long fence then the wood is forced sideways into the
blade in such circumstances. The riving knife is useful
but not a panacea for safe ripping.

-- http://lawoodworking.com

View Tennessee's profile

Tennessee

1527 posts in 1239 days


#4 posted 10-02-2012 06:20 PM

Loren: I’d agree with that, no guard is 100% safe. I also have a rather rugged set of kickback teeth on the back end of my guard which mount to the riving knife, something I actually consider more worthy.

-- Paul, Tennessee, http://www.tsunamiguitars.com

View crank49's profile

crank49

3481 posts in 1695 days


#5 posted 10-02-2012 06:31 PM

I like my riving knife and it would sway my decision in buying a table saw of comparable values otherwise.
But, a choice between a 10 year old big iron cabinet saw, without a riving knife and a modern cheap hybrid like what I have now, if they were the same price, I be all over the big iron.
I would come up with a way to at least add a splitter to the big saw.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View OggieOglethorpe's profile

OggieOglethorpe

904 posts in 834 days


#6 posted 10-02-2012 07:09 PM

In my experience, they’re very effective.

Along with eliminating the obvious danger of released stress in solid wood allowing the kerf to close on rising teeth, I find it helpful on sheet goods. The knife helps keep the cut stock against the fence, which I find useful with larger sheets, especially when bevel ripping.

I have never liked anti-kickback pawls. They totally interfere with sleds, jigs, and zero clearance backup fences. I’ve also had them scratch the work. This can be repairable with solid wood, but can be a real issue with plywoods.

The beauty of a properly set up riving knife, which ends a hair below the blade, is that you can leave it in place all the time, regardless of through, non-though, sleds, jigs, whatever… To protect you, a safety device needs to be installed, not on the shelf or floor.

View Swyftfeet's profile

Swyftfeet

169 posts in 896 days


#7 posted 10-02-2012 08:20 PM

I picked up an old Griz 0690 off Craigslist, right tilt, no riving knife. I do use a feather board, a push stick, and a Micro-Jig to keep my self as safe as possible given the circumstances. One thing I noticed when working on my current project is that when ripping 4/4 black walnut the boards seem to be rubbing the blade (Brand new Freud Fusion ATB) and I am getting a little burn randomly through the rip, mostly the first third of the cut. I have jointed the one edge that rides along the fence, and I have checked(several times) the parallelism of the blade and the fence and it seems to be within about .002” But still seems to be pinching in some cases. This does not occur when ripping stable stock, like plywood or mdf. Is this normal? Would a riving knife fix this?

-- Brian

View HorizontalMike's profile

HorizontalMike

6960 posts in 1638 days


#8 posted 10-02-2012 09:15 PM

All I can say is that the riving knife drove my purchase of the G0690 TS. I hate splitters and kickback pawls, so the way Grizzly integrated the Riving knife sold me. Unlike Crank, I sold out for the riving knife 8-), and I do have to say my newer G0690 can probably be classified as “big iron” since it tops out over 600lb. with the router extension table.

FWIW, I also use the Yellow Board Buddies rollers on the fence as an added measure of safety. They work well and are easy to adjust to the current need/cut.

-- HorizontalMike -- "Woodpeckers understand..."

View Steven Gaffin's profile

Steven Gaffin

31 posts in 980 days


#9 posted 10-02-2012 09:20 PM

In a shop with about 270 college students. The only kickbacks where wen the riving knives were not attached. It does take time to take them off when they are in the way but I don’t think it affected production time as much as some people make it out to be.

View Cole Tallerman's profile

Cole Tallerman

392 posts in 909 days


#10 posted 10-02-2012 09:46 PM

I have pushed a board through the table saw that was pinching on the riving knife so hard that i couldn’t get it through the table saw. Without the riving knife i would be picking bits of wood out of my skin. That being said, It feels alot safer to use a table saw with a riving knife. You can get a used ridgid table saw for $200 with a riving knife.

View klassenl's profile

klassenl

116 posts in 1383 days


#11 posted 10-02-2012 09:57 PM

Another vote for buying a saw with a riving knife. Mine is a General 50-200. Good saw.

-- When questioned about using glue on a garbage bin I responded, "Wood working is about good technique and lots of glue........I have the glue part down."

View teejk's profile

teejk

1215 posts in 1409 days


#12 posted 10-02-2012 10:44 PM

cole…to push that hard tells me the board “wasn’t happy”. I watch those and generally toss them in the scrap pile. I figure if they can’t handle a cut, they won’t like being put in any finished piece either.

and horiz…do those rollers eliminate the need for my home-made feather boards (say e.g. running a board on edge of 3/4” stock for panel dados)?

View HorizontalMike's profile

HorizontalMike

6960 posts in 1638 days


#13 posted 10-03-2012 01:45 AM

teejk: ”...and horiz…do those rollers eliminate the need for my home-made feather boards (say e.g. running a board on edge of 3/4” stock for panel dados)?...”

YES. The “Yellow” Board Buddies only roll ONE way and lock if you try to roll them backwards toward the operator. You want the “YELLOW”.

http://www.grizzly.com/search/search.aspx?q=board%20buddies&cachebuster=1134331692494796.5
Yellow = Table Saws (roll clockwise)
Green = Shapers (roll both directions)
Orange = Radial Arm saws (roll counterclockwise)

The Board Buddy Track allows you to adjust positions of the board buddies. This mounts on your fence.

-- HorizontalMike -- "Woodpeckers understand..."

View Milo's profile

Milo

862 posts in 2043 days


#14 posted 10-03-2012 02:13 AM

Ed,

I am kind of surprised no one said anything about a simple splitter behind the saw blade. For the most of us, 99% of our cuts are vertical cuts against the fence. With this cut, a splitter is no different than a riving knife. A riving knife just moves with the blade when you make an angled cut. And the pressure on the board is different in an angled cut.

Just get a good splitter, adjust your fence, and you’ll see a huge difference in kickback.

And this is from the guy who once sported a perfect diamond shaped bruise for a week from a piece that shot off the table, bounced off my stomach so fast I didn’t feel it (at first!), went through a window in the door, and landed 20 feet from the shop!

-- Beer, Beer, Thank God for Beer. It's my way of keeping my mind fresh and clear...

View Ed's profile

Ed

28 posts in 799 days


#15 posted 10-03-2012 02:45 AM

”Losing a finger(s) would hurt or eliminate my playing of guitar. A high price for saving some money by giving up safety features.”

If this is important to you, then I would save my money and get a SawStop.
A riving knife may help kickback, but it’s not going to help if you accidentally hit your hand on the blade.

Good point, Jonathan. As I think about it, I’d rather pay $50,000 than lose a finger. So a Sawstop is really not much cost as insurance to avoiding that experience. And a riving knife is not much cost to help avoid kickbacks.

I see clearly, that for me, I should take advantage of the safety features that are currently available.

Thanks for all the input.

-- Ed

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