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Tablesaw Kickback - What Did I Do Wrong?

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Forum topic by WoodGoogan posted 04-18-2020 05:47 PM 959 views 0 times favorited 37 replies Add to Favorites Watch
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WoodGoogan

3 posts in 319 days


04-18-2020 05:47 PM

Topic tags/keywords: kickback safety dado

Newbie woodworker here…

Was trying to make a box for a wireless speaker kit and forgot to cut the grooves in the piece before cutting the four sides. Using a Freud box joint blade set a 1/4”, I proceeded to cut grooves on each of sides individually holding it down and against the fence (also at 1/4”) with a short push block. I got through a few, but one of the pieces just kicked back and I don’t want to do any more since I’m not sure what I did wrong.

Is it because the piece is square and equivalent to a cross cut against the fence?


37 replies so far

View Kelly's profile

Kelly

3383 posts in 3956 days


#1 posted 04-18-2020 06:07 PM

Let’s start with the dimensions of the wood. If, for example, you are talking pieces that are only six inches long, that’s a recipe by itself.

Second, if the fence veers a tiny bit, it’s another ingredient.

The push block, probably helped, up to THE point.

Obviously, once the back of the blade starts the grab process, it’s over in a half second from there. IF you could have both pushed with the block and from the side (up against the fence), you might have pulled it off.

Anyway, wasn’t that exciting? If nothing else, you, now, have an even greater appreciation for push blocks.

View Madmark2's profile

Madmark2

2316 posts in 1600 days


#2 posted 04-18-2020 06:08 PM

Looks like you pressed down too hard on the heel. This pivoted the workpiece up into the blade and BANG!

Work slower. Plan your steps, this groove should have been made before cross cutting. Thing your cut thru. Know if, when & how you will change your grip. Don’t stand between the fence and blade. THINK

You should have had the dado away from the fence and not close. This amplified the twist and let it get away.

By the location of the damage on your push block I can tell the block was tight to the fence. This prevented you from pushing the stock into the fence, thus allowing the stock to twist. The push block should really only contact the stock.

The dado at 1/4” fights the push 2X. Your push block doesn’t have a heel to prevent the piece from slipping.

I use a push shoe with a heel and a tapered side stick. The tapered side stick ends at the center of the blade. The shoe block helps push down on the leading edge. The tapered side stick keeps the stock against the fence and prevents the stock from twisting into the blade.


My go-to safety devices.

I count 7 errors:
  1. Workpiece too small
  2. Pressing down too hard on the heel when feeding
  3. Rushing
  4. Dadoing near edge
  5. No heel on push block
  6. No feather board or side stick
  7. Push block was against fence allowing twist into blade

Don’t let the desire to avoid scrap make you take risks.

-- The hump with the stump and the pump!

View BroncoBrian's profile

BroncoBrian

896 posts in 2970 days


#3 posted 04-18-2020 06:09 PM

Hard to tell from that picture… but, most kickbacks are from the same issues.

- Your piece is not properly pushed against the fence, using a stick can slip too easily
- Your material to too small, or much wider then it is deep (which twists in and left easily)
- You are not using a riving knife, or again, too small to engage it

The wood catches the back of the blade and then there is not much you can do but keep your hands away from the spinny sharp bits. So glad you are ok.

Do yourself, your family, and yourself a favor! Build a crosscut sled! Feel free to look at mine in my projects. That tings has saved body parts and is a dream to use! My favorite item in my shop is that sled.

-- A severed foot is the ultimate stocking stuffer.

View BroncoBrian's profile

BroncoBrian

896 posts in 2970 days


#4 posted 04-18-2020 06:11 PM

... and what Kelly said, make sure you are a few thousandths wide on the backside of your fence. Toed in is trouble.

-- A severed foot is the ultimate stocking stuffer.

View pintodeluxe's profile

pintodeluxe

6318 posts in 3825 days


#5 posted 04-18-2020 06:12 PM

If you can’t groove the parts while the board is still extra long, try large push pads. I use the Bench Dog brand. They’re big and orange and really help control the workpiece.

That said, working short pieces on the tablesaw is inherently dangerous. Avoid it when you can.

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

View LesB's profile

LesB

2872 posts in 4455 days


#6 posted 04-18-2020 06:12 PM

Check out this posting about a “safe” push stick. https://www.lumberjocks.com/topics/308922

Another thing Kelly left out above is that your were cutting with a box joint blade which is wider than a normal saw blade and has fewer teeth which only increases the chance of problems developing. It might have been a good idea to make the cut in a couple of passes to get to full depth.

-- Les B, Oregon

View CaptainKlutz's profile

CaptainKlutz

4161 posts in 2506 days


#7 posted 04-18-2020 06:28 PM

Welcome to LumberJocks!

Sorry to read about your kick back event. Never any fun.

Hard to tell what you did wrong? This article might help you figure it out:
https://www.woodcraft.com/blog_entries/preventingtablesaw-kickback-it-s-not-an-acceptable-risk

There are many more articles on WWW about avoiding kick back, if this randomly selected one does not make sense to you.

For me, the two things that stopped 99.99% of kick back were:
1) ALWAYS use a splitter, or riving knive on newer saw
2) Never cut across the wood grain with board wedged between fence and blade.

Best Luck figuring out what happened.

Cheers!

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

View OnhillWW's profile

OnhillWW

296 posts in 2244 days


#8 posted 04-18-2020 06:37 PM

Obviously a riving knife is not applicable to your situation, so ignore that recommendation. That said, everything else everyone has said is good advice. Proper hold down, steady even push through, avoid small pieces when you can. Also check that your throat plate does not wobble, if it moves at all – with small pieces like that it is a recipe for an accident. I would have cut the dados in two passes, shallow followed by at full depth.

-- Cheap is expensive! - my Dad

View Madmark2's profile

Madmark2

2316 posts in 1600 days


#9 posted 04-18-2020 06:40 PM

It was a DADO cut. Splitters and riving knives do not work cutting dados. Thru cuts yes, but dados, no.

Look at the pictures before commenting. He doesn’t need general advice, he needs to know how and what caused this particular accident. Splitters or riving knives (installed or no) had NOTHING to do with THIS!

-- The hump with the stump and the pump!

View BroncoBrian's profile

BroncoBrian

896 posts in 2970 days


#10 posted 04-18-2020 06:50 PM

I’m reminded of what the block button is for…

I don’t think anyone is trying now to help and I bet most people here know what a riving knife does. It is hard to tell from that picture what is happening, looks like a picture of a Bench Dog push block, doesn’t it Willie. Just looking at that again. It looks like the push block was injured! Yikes.

If you look at the bottom of the image, a rabbit was cut, it turned and caught the block on the way back…

True, a riving knife is not relevant to that use case. Not is a crosscut sled. A router table would probably be the best bet or some other jig to hold that thing in place.

Be careful everyone. Hospitals should be avoided right now.

-- A severed foot is the ultimate stocking stuffer.

View bondogaposis's profile

bondogaposis

5953 posts in 3363 days


#11 posted 04-18-2020 07:00 PM

Those work pieces are too short to feed through a table saw, it is very easy for the rear of the piece to tip into the back of the blade, kick back is what you get when that happens. Also now would be the time to tune your saw and make sure that the rip fence is parallel to the miter slots and that the blade is as well. When work pieces are that short you have to look at alternative methods to make your dados, using a router table would have been much safer. Part of safety is considering the proper order to make your cuts, typically one of the last steps should be cutting to final length. I hope you didn’t ruin your box cutting blades but sometimes a kick back will spring a blade out of shape. Don’t ask me how I know that.

-- Bondo Gaposis

View WoodGoogan's profile

WoodGoogan

3 posts in 319 days


#12 posted 04-18-2020 07:07 PM

Thanks everyone! All good advice…

Madmark2: I think you’re right about pushing down on the heel and along with a short, mitered piece of wood which could have (and likely) pivoted the piece…

The push shoe you pictured (“The Hand Guard”) looks like it has an adjustable heel which would be super beneficial. The cheapo one I have has a heel too small and I always feel like it’ll slip while pushing.

bondogaposis: Any way I can tell if my box cutting blades are ruined?

All—it seems the short piece (and my lack of forethought) is the culprit…

Thanks again for all the replies.

View CaptainKlutz's profile

CaptainKlutz

4161 posts in 2506 days


#13 posted 04-18-2020 07:09 PM

Newbie woodworker here… I proceeded to cut grooves on each of sides individually holding it down and against the fence (also at 1/4”) with a short push block.
- WoodGoogan

IMHO – The mistake was simple: cut across the wood grain with board wedged between fence and blade.

With cross grain cuts it only takes the slightest error to push a small piece sideways and get caught by blade, resulting in kick back.

Either use a cross cut sled, or use miter gauge and use a spacer block attached to fence to set the required 1/4” depth, so that as wood is pushed forward it is no longer touching the block or trapped against the fence.

Thanks for reading my 2cents opinion.

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

View Kelly's profile

Kelly

3383 posts in 3956 days


#14 posted 04-18-2020 07:21 PM

I missed the obvious – YES, as Capin noted, the cut should have been near the fence. The thought of doing it on the outside scares me.

View tvrgeek's profile

tvrgeek

1451 posts in 2661 days


#15 posted 04-18-2020 07:27 PM

I have started to use sleds for any small part. Parts secured to the sled.
If not on a sled, feather boards in two directions.

Small parts are just plain scary.

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