Video of tablesaw kickback

[Digit]

As you say Martin, no Tungsten tips in those days, and I was pushing a Lime butt that had been squared on the two sides one day when we hit a file that was buried deep within the timber. The teeth passed me like swarm of Bees and went straight down the shop, there wasn't a tooth left on the blade, it was that quick!
The worst thing with a kick back I found was when the timber lifted up, no, no crown guard either, it could either fly straight up in the air, or worst still, drop back onto the spinning blade and fly off in any direction.
Happy days!

Roy.

 

[White House Workshop]

I find hand-held saws can be just as dangerous. How many of us push in the 'lock' button when making a long cut? I know I have, even doing it accidentally sometimes. I always stand to the side of a handheld c/saw in case of kick-out (the saw kicks out of the cut).

I tend disagree about kickback being more common in thin ply or sheet materials. The worst cases I've ever heard of are people trying to rip a piece that is too thin and not using pressure clamps to help feed the wood into the blade, or crosscutting against the fence (aaarrrgghhh!).

 

[dedee]

For quite some time now I have been using by tablesaw with just a half fence ie the fence only goes as far the centre of the blade which surely reduces the changes of kick back considerably. I also always use the riving knife.

Andy

edit this article explains in detail the half fence
http://www.woodcentral.com/articles/pow ... _108.shtml

But it was Tony who showed how simple it was to convert the Kity


And

 

[OllyK]

I find hand-held saws can be just as dangerous. How many of us push in the 'lock' button when making a long cut? I know I have, even doing it accidentally sometimes. I always stand to the side of a handheld c/saw in case of kick-out (the saw kicks out of the cut).

I tend disagree about kickback being more common in thin ply or sheet materials. The worst cases I've ever heard of are people trying to rip a piece that is too thin and not using pressure clamps to help feed the wood into the blade, or crosscutting against the fence (aaarrrgghhh!).

Mine doesn't have a power lock, thankfully.

Worst kick back I had from a hand held was cutting wet floor joists.

 

[OPJ]

Martin, that is frightening! How many home or professional woodworkers do you see using a metal detector today, let alone fifty-years-ago?!? :?
I've only see someone go through a nail in some ash, in my short time. The circular saw made a very slight complaint but still cut straight through it and didn't kickback or anything.

Circular saws (handheld) can be quite dangerous but generally you do stand to one-side, and so should be okay. If you're cutting MDF with one and the saws not fully supported and sags a little, the blade can bind and jump (DAMHIKT)... Even still, with two hands on the tool, it's not as bad as a table saw.

The other point with a handheld saw is to NEVER tie back the guard. I saw a program a few years back where one idiot did just that, put the saw done when he'd finished cutting and, with the blade still spinning, the teeth hit the floor, it bounced up and chopped off his, er... I don't even want to think about it!

I've also heard of a guy getting his knackers caught in the sliding carriage of a large dimension saw - but, I think we'll leave it at that for today!

I think plywoods are only dangerous when ripping against a full-length fence. :shock:

 

[Slim]

The other point with a handheld saw is to NEVER tie back the guard. I saw a program a few years back where one idiot did just that, put the saw done when he'd finished cutting and, with the blade still spinning, the teeth hit the floor, it bounced up and chopped off his, er... I don't even want to think about it!

I've also heard of a guy getting his knackers caught in the sliding carriage of a large dimension saw - but, I think we'll leave it at that for today!

:shock: (Crosses legs and cringes)

 

[Digit]

You're quite correct deedee, a short fence should IMO be standard. The full fence has basically only come to the fore as it is much easier, (cheaper) to produce a non moving full fence than a short one.
My table saw has a full fence and the first thing I did to it was to fit a short false fence, they are much less likely to cause trouble I find.

Roy

 

[head clansman]

Hi Olly

Yes it was frightening, when i think back to those day the machinery in the dockyards were old and outdated well past there sell by date considering most of it was manufactured just after the first world war. And most of it still in use till the place closed in April 1997. know wonder were all deaf.

When you consider the diameter of a nail today compared to yrs ago let alone the size of a bullet and lets be honest some of the weapons use in the wars some of those bullet were massive i forgot to mention the joiner that i mentioned after he came out of shock said he actually felt the blade swiz pass by the side of his face it was that close all in the blink of an eye , that's what i call splitting a hair . To dam close for my comfort .

I was only an apprentice my self at the time I suppose i was lucky really to have a really good master in those day taught me never never never use a machine without guards and never never never mess about in the machine shop , from his teaching i still have all my finger in tack and wish to keep them that way .

When you see how well the machinery were made and see the thickness of the steel in those day and that sort of thing could still happen, it make you mind boggle when you see how flimsy machinery is to day , it don't bear thinking about if that situation were to happen in today time heavens forbid. stay safe everyone keep those guards one at all time.

 

[Digit]

Of course we all know that a band saw is safer than a table saw and that if the band breaks it simply stops moving don't we?
Like Hell. Where I served my time we had, I think, a Wadkin with a 26?ft long band, I was behind the saw as my instructor was trimming the edge of a Hawker Hunter canopy when he allowed it to twist and the band broke, -- and fed all 26ft past me onto the floor at callosal speed.
'Hm, never seen that before' he commented, and we went off to get a cuppa and steady our nerves!

Roy.

 

[steve tighe]

definately twists the wood so that the rear of the blade picks up the piece

No Losos,watch the vid again especially his hands.

He takes his left hand away first (the hand pushing the piece through) & has only light pressure with his right hand,effectively he's let go of the piece going through the saw.

As others have said,it's a demo & it's a good one,what it shows is what can happen if you don't have complete control of what you're doing,the fact that the guard & knife are missing is irrelevant,it just makes it easier to see what's happening on the vid.

If you're running thin sheet material through a saw then it might be an idea to have two pieces of timber handy,one holding the sheet down down on the table to stop it riding up & the other,the push stick,to use to push the sheet the last bit past the sawblade.

Generally it isn't a bad idea with sheet materials (I know that's not what's being used in the vid) to take a 10mm rip off one edge before ripping to whatever size you want just to release any tension in the board.

Again,as others have said,the fence only needs to be as long as the back of the saw blade.

 

[Slim]

Again,as others have said,the fence only needs to be as long as the back of the saw blade.

The fence ending at the back of the blade will have the same effect as a straight through fence. It should stop just behind the front of the blade.

 

[steve tighe]

So what happens to the last knockings of the piece going through the blade then if you don't have the fence at least covering the blade ?

What's to stop the piece twisting,where's the control of the timber while it clears the blade ?

 

[Slim]

Steve, rather than me explain it. Watch this from our very own Steve Maskery.

 

[Digit]

So what happens to the last knockings of the piece going through the blade then if you don't have the fence at least covering the blade ?

The riving knife should keep it on course.

Roy.

 

[steve tighe]

Ok Slim,I appreciate I'll have to tone down my views a bit on here,that's a good vid from Steve but it isn't something I'd necessarily do.

In my opinion (only),no I wouldn't have the fence set that far forward but what I would do (& normally did) if I was ripping down thin material is to have a second stick to hold the piece down to the table.

In Steve's second clip you can see the piece riding up a bit off the table,the second stick would hold the piece down(use it similar to the sprung thingy he had holding the piece to the fence) & flick it away from the blade once it's cut through,the push stick only needs to be a bit of scrap can push the cut piece clean through the blade,not everyone's going to turn the saw off after every cut.

It's a good video & a sensible one in my opinion.

 

[Slim]

The point is that only the front few teeth are cutting the wood. It is not the front teeth that cause kickback as they force the wood down into the table. It is the rear teeth that lift the wood and the top teeth that throw it forward. The benefit of a short fence that finishes behind the front teeth is that there is space for the wood to move into, thus avoiding being trapped between the blade and fence, which is when kickback occurs.

There is also a scenario where cutting solid timber (not sheet goods) with high internal stresses can cause kickback. When the wood is cut, the internal stresses are released. This will result in the saw kerf either closing up or opening out. The riving knife takes care of the problem if the kerf wants to close, but if it wants to open, the wood will jam between the blade and fence (assuming a long through fence is being used). This would obviously result in a kickback scenario. Using a short fence allows the stresses to be relieved because there is space by the blade for the wood to move into.

There is an excellent article by Barb Siddiqui & Richard Jones here

 

[Digit]

Spot on Simon. Anybody with a full length fence on their saw should consider fitting a short sub fence, it's as important as the riving knife for safety.

Roy.

 

[Steve Maskery]

In Steve's second clip you can see the piece riding up a bit off the table

Do you know, I didn't realize that that had happened until quite some time after I'd published the video, I certainly wasn't aware of it at the time, nor during editing, which seems astonishing now.

I think the problem was that I was trying to be a super-good boy and use the push stick too early. Pushing down off the front edge of the table raises the workpiece. I should have used my hands until the workpiece was entirely on the table an only then picked up the pushstick.

Slim, your explanation is spot on.

Cheers
Steve

 

[NeilO]

I believe the short fence should be positoned so the end of the fence is parallel with the last tooth to be cutting the wood, thus allowing the wood to enter free space and "seperate" without being tensioned on the blade,
which is what I believe to be the cause of kickback....the teeth of the saw blade rising and snatching the wood, thus throwing it forward/back towards the user..

 

[Jake]

Useful tips on good working practice here, note where the fences are in the drawings