Why is a table saw fence so long?

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Forum topic by KnickKnack posted 02-15-2011 07:11 PM 1896 views 0 times favorited 10 replies Add to Favorites Watch
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1062 posts in 2985 days

02-15-2011 07:11 PM

First up – I don’t really own a table saw and haven’t really ever used one. But I’ve been looking into buying one – it’s on the list.
Part of my “due diligence” has been to look into the safety aspects of table saws – sharp teeth flying ‘round at a gazzillion miles an hour scare me – not enough to stop me getting one and using it, but enough to make me want to find out everything and anything that can go wrong before I push a green button.
“Kick back” seems to be one of the serious possible issues. I’ve watched the various videos. I’ve read the reviews and blogs. I’ve analysed the analyses.

As I understand it, kick back happens basically when the back side of the blade (going upwards) manages to catch hold of the wood that’s already gone through, usually on the fence side. Riving knives help since they keep the wood away from the back of the blade. Kick back can easily be caused if your wood is “pinched” going through – ie, if the fence isn’t perfectly parallel to the blade and points towards it rather than, if anything, slightly away from it.
And this is where I get confused, and I’ve finally got around to the question – why does the fence extend beyond the blade’s half way point at all? I’ve looked at a lot of pictures from lots of manufacturers, and the fence always extends well beyond the back of the blade. Surely it serves no useful purpose beyond the blade, and creates the potential to pinch the wood and cause kick back.

Thanks in advance for any enlightenment.

-- "Do not speak – unless it improves on silence." --- "Following the rules and protecting the regulations is binding oneself without rope."

10 replies so far

View StumpyNubs's profile


6830 posts in 2220 days

#1 posted 02-15-2011 07:21 PM

The only way to avoid kickback is to keep the piece moving straight all the way through the cut. The fence is what keeps the piece frow twisting away from the blade, and the splitter keeps the piece from twisting toward the blade. If the fence ended at the center of the blade the wood could easily pivot off the end of the fence and twist into the blade. In fact, the longer the fence the better, especially when working with heavy sheet goods that can easily twist as you push them through.

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View RetiredCoastie's profile


999 posts in 2602 days

#2 posted 02-15-2011 07:25 PM

As you rip a piece of stock it needs to be supported by the fence beyond the blade in order to maintain a straight cut which in turn prevents the stock from traveling off line which would cause the blade to bind and resulting in kickback.

-- Proud Supporter of Homes For Our Troops

View CharlieM1958's profile


16229 posts in 3637 days

#3 posted 02-15-2011 07:41 PM

KnickKnack, your point would be valid if one could assume that the pushing force on the material would always be coming from dead center behind the blade. If that were the case, there would be no need for the fence to extend past the blade. As others have pointed out, though, there will always be some lateral force encouraging the workpiece to move off line, and the long fence helps keep it in parallel to the blade.

-- Charlie M. "Woodworking - patience = firewood"

View ajosephg's profile


1878 posts in 2980 days

#4 posted 02-15-2011 08:08 PM

I believe that European TS’s do have fences that only extend past the blade to prevent wood getting pinched after it is cut. As I recall this may be the law over there as is riving knives.

You might be interested in looking at the late Niki’s reply here to learn more about the beneifits of such a fence. Notice that the fence is still about the same length, but it moved so the front of the face extends past the front of the saw.

-- Joe

View whit's profile


246 posts in 3396 days

#5 posted 02-15-2011 08:14 PM

Some of the lateral force comes from the blade, itself. The tooth set has a lot to do with the direction the force is applied. I don’t understand the physics of how it works at the micro level but the blade does impart a bit of misdirection if it’s not tuned properly. That’s just one of the many lessons I’ve learned on the path to becoming an old man. And yes, that was from experience. A really, really, bad experience.


-- Even if to be nothing more than a bad example, everything serves a purpose. cippotus

View Loren's profile


8158 posts in 3067 days

#6 posted 02-15-2011 08:21 PM

Many American cabinetmakers use the tablesaw fence to square panels. You
might suppose, from reading, that everybody uses cutoff sleds but in
pro shops the fence is used often using a factory edge as a reference

European fences, as noted by other posters, have a better design for ripping
solid wood but a short fence is not as easy to use for squaring panels.

View Cosmicsniper's profile


2202 posts in 2578 days

#7 posted 02-15-2011 10:29 PM

If the fence isn’t there, the workpiece isn’t supported. About the time the push stick gets to the blade, you’ll have maybe two inches of support…you won’t be able to push the workpiece straight through.

-- jay,

View KnickKnack's profile


1062 posts in 2985 days

#8 posted 02-16-2011 11:12 AM

Thanks everyone for the answers – truly LJ is a great resource and I’ve learnt a lot from reading and re-reading these replies.
Thanks to ajosephg for the late Niki’s link with more informed and experienced discussion and pictures.

When/if I get the table saw I’ll experiment (carefully), and see how it feels.

-- "Do not speak – unless it improves on silence." --- "Following the rules and protecting the regulations is binding oneself without rope."

View Greedo's profile


470 posts in 2379 days

#9 posted 02-16-2011 01:59 PM

i have been tought (in europe) that when ripping solid wood the fence may not go beyond the back of the blade..
this is in order to let the wood “work” as it is being cut, you know wood with alot of tension in it will start warping when it passes the blade.

when crosscutting with a sliding wagon on european saws, you can use the fence as a stop to make repeated cuts, but then the fence must stop where the blade begins. otherwise the piece you cut off will get jammed between blade and fence and thats extremely dangerous.

and at last when cutting panels it is good to have a certain extra length of fence past the riving knife, to guide the panel some more so that you have nice straight cuts.

on my saw i can slide the fence forward and backwards with two knobs.

View Rick's profile


8287 posts in 2452 days

#10 posted 02-18-2011 02:17 AM

You might be interested in having a look at this “Safety, Anti Kick Back, Etc.” Post that is Happening at the same time yours is.

-- Hope Everyone Is Doing Well! .... Best Regards: Rick

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