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Kickback and setting the table saw blade and fence

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Forum topic by Planeman posted 11-28-2008 02:13 AM 6157 views 2 times favorited 20 replies Add to Favorites Watch
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Planeman

97 posts in 2235 days


11-28-2008 02:13 AM

Years ago, and I mean like in the 1960s, I read somewhere that setting the rear of the saw blade just a smidgin – like five or ten thousandths – farther away from the fence than the front of the saw blade will virtually eliminate kickback. I have always done this with excellent results and can cut thin strips without problems. As it was described in the article the wood between the fence and the saw blade gets pinched should the wood bow a little as the stresses are relieved during the sawing. As the saw is usually set with the top of the blade just a touch higher than the wood passing through the saw the motion of the blade rim throws the wood backwards towards the operator.

I thought I would pass this tip along to others and to get responses.

Rufus

-- Always remember half of the people in this country are below average.


20 replies so far

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ChuckM

501 posts in 2324 days


#1 posted 11-28-2008 02:40 AM

I use a similar fence setting as Rufus said in the above. But kickbacks are still possible under that setting in the absence of a splitter / riving knife.

Anyone who wants to read an in-depth discussion of the topic can go to here: http://www.woodcentral.com/cgi-bin/messages3.pl?read=368017

The post by kickback expert Rick Christopherson there also explained how that particular kickback happened!

-- The time I enjoy wasting is not time wasted

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Planeman

97 posts in 2235 days


#2 posted 11-28-2008 03:35 AM

As most of us make about 98 percent of our cuts with the saw blade at 90 degrees to the table it is easy enough to make a wood auxiliary zero clearance blade insert for the saw and place a vertical wooden “splitter” rising vertically from the back of the insert behind and in line with the saw. For those who have a saw not equipped with a splitter this is a good solution. Of course it will not tilt with the blade so when tilting the blade the auxiliary insert will have to be removed and the old insert without the splitter will have to be used. But used most of the time and setting the blade as I suggest should spare most of us from a “gut shot” from some lumber. Fortunately most of the newer saws have a splitter that tilts with the blade. Unfortunately, many of them are incorporated with the clear plastic blade guard which most of us remove for convenience. Anyway, I’ll take a touch of chipping of a melamine surface on the outer portion of the cut to avoid kickback. I don’t cut melamine much anyway and certainly not for high end work.

Rufus

-- Always remember half of the people in this country are below average.

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ajosephg

1854 posts in 2219 days


#3 posted 11-28-2008 06:14 AM

I propose that keeping the blade dead on parallel to the fence is best for all cuts including ripping thin pieces. When cutting narrow pieces put the thin piece on the left side of the blade (opposite the fence) Make or buy a jig for making repetitive cuts i.e. – move the fence using the jig after every cut. This way the thin piece never gets pinched, the wood never gets burned. etc. etc.

-- Joe

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Loren

7571 posts in 2305 days


#4 posted 11-28-2008 07:29 AM

I’ve used this method before but it throws off the accuracy of
the cut and causes burning.

When ripping solid wood I prefer to use a short fence that
doesn’t even go to the back of the blade… this goes a long
way towards preventing jamming and kickback.

A riving knife if the best thing you can have, other than safe
and clear-headed work habits. It’s pretty easy to fashion one
into a table insert… though it won’t tilt for you.

Board Buddies work well too… as do featherboards clamped to
the fence.

As a one-time pro I work fast and take some risks to shave set-up
times… but I also know the machine very well and can tell by
hearing and feel when something is wrong with the cut. I’ve
been hit in the stomach a couple of times by thrown boards. I
was never more than a little bruised. Small pieces are much more
likely to be launched at your face and that’s the real danger in
kickback with a saw under 3 HP. Big 5 HP saws can really hurt you.

-- http://lawoodworking.com

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ajosephg

1854 posts in 2219 days


#5 posted 11-28-2008 09:15 AM

Loren -
Are you talking about Planeman’s method or my method?

If mine, what is going to cause burning or loss of accuracy? Burning is caused by the board coming into contact with the “side” of the blade. If the blade is parallel with the fence only the teeth on the blade touch the wood. therefore no burning.

I think a short fence is dangerous because in effect your are freehanding for at least part of the cut.

-- Joe

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Loren

7571 posts in 2305 days


#6 posted 11-28-2008 09:35 AM

Short fences are standard in Europe where safety laws
are more rigorous. I’ve tested the approach. For
Plywood a long fence is easier to work with. For ripping
solid stock a short fence is safer and reduces scratching and
binding as tension is released in the stock as it exits the
cut. This is my experience.

I meant Planeman’s method. As a pro who wanted clean
cuts and fast setups offsetting the fence didn’t work for
me.

-- http://lawoodworking.com

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miles125

2179 posts in 2663 days


#7 posted 11-28-2008 11:15 AM

I contend theres a conspiracy behind saw tables being at or near crotch level. Likely brought to us by the same culprits who put that poorly placed bar on boys bicycles.

-- "The way to make a small fortune in woodworking- start with a large one"

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niki

426 posts in 2737 days


#8 posted 11-28-2008 11:16 AM

Loren
You are very correct…the European are “safety fanatics” and if they recommend (and teach in schools) to use the “Short fence” for ripping solid wood, probably it is very safe.

Here is a PDF file of the UK HSE (Health & Safety Execution = USA OSHA) that shows it…
http://www.hse.gov.uk/pubns/wis16.pdf

I know that it’s very difficult to accept the short fence idea (even I was very doubtful) but even a few American authors are recommending it…

Jim Tolpin (Table saw magic) recommends it (page 79)
http://books.google.com/books?id=BYW4RSLPT40C&pg=PA79&lpg=PA79&dq=Table+saw+short+fence&source=web&ots=iTKa01i1kD&sig=Wj2kV6mVQtK9JIAg0RPGRRrntKY&hl=en&sa=X&oi=book_result&resnum=9&ct=result

Ian Kirbi (The Accurate Table Saw)
http://www.rockler.com/blog/index.cfm?commentID=215

Mark Duginske “Mastering Woodworking Machines”
http://books.google.com/books?id=z-pzOU6R_xoC&pg=PA40&lpg=PA40&dq=Table+saw+short+fence&source=web&ots=lUe38tGRYy&sig=ZIRwVZKajam1rAIqhSW2kOW6oqQ&hl=en&sa=X&oi=book_result&resnum=1&ct=result

Most of the new generation TS’s in EU are coming with short fence (my TS is 2001 model) and I don’t have any problems…

As for my method to set the “Blade / Miter slot / rip fence”, (and short fence) you can see it here (I call it “Dynamic test”)
http://lumberjocks.com/topics/4128

And just a few pics to show my confidence with short fence…the board is 67” long and 1¼” thick (please note that I’m using not only “short fence” but also “Low fence”

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View ajosephg's profile

ajosephg

1854 posts in 2219 days


#9 posted 11-28-2008 04:36 PM

Niki:

You have provided some very good information and resource material.

However, I didn’t see that ripping thin pieces was addressed. I occasionally rip thin (0.050 thick or less) strips from solid stock to use as facing on plywood edges. (This is what I think Planeman was also talking about.)

While the short fence as described works well and is safe when working with stock as wide or wider than the push stick I see a problem if the objective is to rip a very thin strip to the right of the blade because when the cut is completed there is no way to push the thin strip past the blade – (the push stick being much wider than the stock to the right of the blade) unless you have a helper who can pull it through. But, let’s face it, most of us work alone much or all of the time.

Therefore, I still maintain that the safest method for ripping thin strips is for the thin part to be left of the blade, and readjust the fence after every cut using a jig. When the stock gets reduced to the point a push stick can’t be used, then it is time to put it in the scrap bin and get another piece.

This is not to say that the short fence concept should not be used for this, just that when fabricating thin strips, the strip should be left of the blade.

-- Joe

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niki

426 posts in 2737 days


#10 posted 11-28-2008 07:33 PM

Hi Joe

Sorry, I referred to Loren’s post and in general about the kickback and using short fence for ripping.

As for thin strips…I use a sled with a pusher (as on the pics below) but, if the strips are thinner than 1/8”, I’m using the “Vacuum sled” that also holds the strip tight to the sled after passing the front teeth to avoid flattering.

Of course your way is also very good but with my method, I can cut even a 3/8” strip into two 1/8” strips.

I think that everybody should choose the method that he feels good and safe for him.

For strips thicker than 1/8” I’m using the same method but without the “Vacuum chamber” and of course, always feather board (rollers), riving knife and guard.

On the pics below, I was cutting 2mm (0.0787”) strips

Oh, in this ocasion, I would recommend reading Rick’s website…he explains the kickback penomena very professionally (well, he is an Engineer and rights the owners manuals for Festool USA)
http://www.waterfront-woods.com/Articles/Tablesaw/tablesaw.htm

Regards
niki

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niki

426 posts in 2737 days


#11 posted 11-28-2008 11:12 PM

Thank you Bentlyj

As for the Vacuum sled, I have not only side view but a step-by-step….
http://lumberjocks.com/topics/1401

And some improvement…
http://lumberjocks.com/topics/1946

I’m using a normal home-vac with power (speed) control and I adjust the power till I feel that the board is “vacuumed” strong enough (no need full power for that.

Regards
niki

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ajosephg

1854 posts in 2219 days


#12 posted 11-29-2008 04:51 AM

kudos to you niki – you deserve to be the Lumberjock of the day.

-- Joe

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niki

426 posts in 2737 days


#13 posted 11-29-2008 10:20 AM

Thank you so much Bentlyj and Joe

I would like to show you an e-mail reply that I got from the Engineering department of “Metabo” (my table saw manufacturer) about the short fence position.

As you will see, he is using the ward “Minimize” and not the word “Prevent” because a kickback cannot be totally prevented even by using riving knife and short fence…

It looks like the Germans are using different terms…”Reactive wood” – means “Solid wood” and “Dead wood” is what we call “Man made boards”....

—————————————————————————————————-

Dear customer,

thank you for your email regarding the setting possibilities of the rip fence.

Reactive woods (not dead woods) can move to the side just after cutting. That´s why there might be the risk of a kick back if the rip fence is set in the long position.
In order to minimize this it is recommended to set the end of the rip fence to the saw blade centre (short position).

For sawing dead wood like chipboards it is recomended to set the rip fence in the long position in order to achieve the maximum guiding length.

The riving knife is absolutely necessary and the correct position of the rip fence has to be chosen according to the wood!

If you have further questions please feel free to contact me.
Furthermore enjoy woodworking!

With best regards

—————————————————————-
Florian Fischer
Produktmanager Holzbearbeitung
Product Manager Woodworking

Phone: +49 (0) 70 22-72-2529
Fax: +49 (0) 70 22-72-2074
Email: ffischer@metabo.de

metabo
work. don’t play.

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ChuckM

501 posts in 2324 days


#14 posted 11-30-2008 02:03 AM

About: “When ripping solid wood I prefer to use a short fence that
doesn’t even go to the back of the blade… this goes a long
way towards preventing jamming and kickback.”

The photos shown in the thread about using the short fence seem to suggest the short fence – which offers less guiding control past the saw blade – is not to be used alone, especially when cutting long stock, but requires the use of other accessories. So both the long and short fence systems have their pros and cons. Not sure if the grass is greener on the other side the fence, but I had a British woodworker visitor over the summer and he seemed to be more envious of the various tools he saw in a woodworking show I took him to in this part of the world (of course our shops tend to be bigger than our counterparts in the UK).

-- The time I enjoy wasting is not time wasted

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johnpoole

74 posts in 2124 days


#15 posted 12-01-2008 04:08 AM

a lot of discussion on this one.. the way that works for me when repeating very thin cuts is an old trick my grandfather taught me, almost 50 years ago,, a simple jig, 2ft long 4 inches wide, lays flat against the fence. (mine has a handle 90 to keep my hands higher), at the rear of the jig is a small block the thickness you want to end up with,, slide the fence over so the block just clears the blade.. then make your repeat cuts with the bulk of your stock left of the blade.. the jig stops kickback, because the block holds the cutoff,, your hands are safe.. i use this to make repeat cuts for segmented turning.. maybe not euro safe, but almost 60 years and i still have 10 fingers.. and no dents in my belt buckle

-- it's not a sickness, i can stop buying tools anytime i want

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