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Wood drifts away from table saw fence at end

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Forum topic by bgilb posted 12-18-2018 05:51 AM 2419 views 0 times favorited 27 replies Add to Favorites Watch
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bgilb

101 posts in 3513 days


12-18-2018 05:51 AM

I have an issue that is driving me crazy. No matter how I cut, the wood drifts away from the end of the fence. I’ve tried weatherboards, the gripper. Nothing helps. The only thing that prevents it is if I use my right hand fingers to sort of squeeze the wood towards the fence. I can only do this with the blade guard though and really with only certain size pieces. And I don’t really feel comfortable doing it. The error is about .004 thicker on one end of about an 8” piece. So even larger on a longer piece. Am I expecting too much? I tried removing the riving knife and it didn’t make a difference. The fence is mostly accurate to within about .003”. The blade is also mostly accurate to about 1 to 2 thousandths. All referencing the miter slot. Any ideas?


27 replies so far

View therealSteveN's profile

therealSteveN

3390 posts in 1029 days


#1 posted 12-18-2018 08:21 AM

The answer will be in your saw fence. All have some manner of adjusting the swing of the fence to align it to the miter gauge slot in the saws top. You will want to find out the name of your fence, or post pictures showing it very clearly, and also where it sits on the fence rail. That is the rail running horizontally across the front, and probably back of the saw. Right at the place where it sits on that rail on the operators side of the saw is where you really need clear pics. Look for any bolts that are visible on top of, under, or maybe even below the rail. There are usually 4 of them, and they will adjust the direction the fence points to.

I think you are saying your fence is veering toward the blade???? If so that can be very dangerous as it can pinch the wood between the fence, and the blade. This pinch can cause kick back, where the wood rides up onto the top of the blade, and comes screaming back at you. Or when the board suddenly isn’t there, and your hands have been pushing forward. Well your hands can very quickly find the blade, which isn’t good. .004 doesn’t sound too much from good, but anything toward the blade is not a good thing. If it’s leading away from the blade, many people set theirs 0.002 out just to keep from any possibility of pinching.

If it is veering toward the blade, DO NOT use the saw UNTIL you fix the fence problem.

If your saw has a riving knife, this is great news. That will mean it’s newer, and a manual can be found. With instruction you can set it up properly.

-- Think safe, be safe

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Redman1

13 posts in 1431 days


#2 posted 12-18-2018 10:04 AM

If indeed your fence is misaligned toward the rear of the blade then you need to fix that. As already stated that is dangerous.

I read you post as the wood is pulling away from the fence behind the blade, potentially dangerous also and the reason to use a splitter behind the blade. Two things I know of could cause that. 1. Misaligned fence or 2. Reaction of the wood from stresses being relieved. I see this often when I rip 2X material and attribute it to stresses being relieved as I know my blade and fence are parallel to each other.

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knotscott

8302 posts in 3830 days


#3 posted 12-18-2018 11:31 AM

Is the board face and edge jointed so it has a flat reference face and edge to follow the fence with?

What kind of saw and fence do you have?

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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bgilb

101 posts in 3513 days


#4 posted 12-18-2018 03:38 PM

Yes it is edge jointed. The fence isn’t towards the blade at the end. It’s about 0.003” away from the blade. I can’t really get it perfectly parallel. Depending on what miter slot I reference off of it’s about 0.003” off compared to the other one. Also since it’s extruded aluminum, the fence dips a little in the very center by about 0.003”. The saw is a G0771Z. I don’t have any problems with burn marks or kickback. Although maybe the wood feels like it could go through a little smoother/faster, it is only 1.5HP I think. The main problem is it not ripping equal thickness across the length. I actually thought it was the riving knife forever because it definitely wasn’t aligned. I ended up shimming the blade outwards using dado shims, because it was the only way to have enough play in the riving knife to get it centered behind the blade. But I ended up testing with it removed and still had the issue.

View Bill White's profile

Bill White

5216 posts in 4415 days


#5 posted 12-18-2018 03:55 PM

What blade are ya usin’? Never heard of weather boards. You mean FEATHER BOARDS? What wood are you cutting?

-- [email protected]

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bgilb

101 posts in 3513 days


#6 posted 12-18-2018 04:11 PM

It’s a Diablo combination blade. Very flat (I know because I got an IRWIN from shit lowes that was wobbly when it was in the saw). It’s some small poplar pieces that are about 2.5” x 8” x 0.75”. Just test pieces to try to nail in accuracy. I thought for sure using the Gripper there was no chance it could drift but somehow it does.

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clin

1051 posts in 1451 days


#7 posted 12-18-2018 04:45 PM



...
Also since it s extruded aluminum, the fence dips a little in the very center by about 0.003”.
...

- bgilb

This caught my eye. If the fence is farther away in the middle, maybe what is happening is the wood bridges this dip through most of the cut, but then towards the end of the cut, the end of the board follows into the dip in the fence.

You might try clamping a board to the fence, much like you might attach a sacrificial fence. Shim the dip if needed. The idea is to have something that provides a straighter fence than what you have. See if that helps. You’ll at least know where your problem comes from.

-- Clin

View Rich's profile

Rich

4701 posts in 1044 days


#8 posted 12-18-2018 05:44 PM

First of all, I would ignore the hysteria about danger in earlier posts. It should be pretty obvious that if the board is away from the fence at the back that the fence isn’t angled in towards the blade.

Those don’t seem like awful numbers. I honestly never measure thousandths except when I’m doing the 5-cut square check.

What fence are you using?

-- My grandfather always said that when one door closes, another one opens. He was a wonderful man, but a lousy cabinet maker

View Dustin's profile

Dustin

689 posts in 1195 days


#9 posted 12-18-2018 05:49 PM


...
Also since it s extruded aluminum, the fence dips a little in the very center by about 0.003”.
...

- bgilb

This caught my eye. If the fence is farther away in the middle, maybe what is happening is the wood bridges this dip through most of the cut, but then towards the end of the cut, the end of the board follows into the dip in the fence.

You might try clamping a board to the fence, much like you might attach a sacrificial fence. Shim the dip if needed. The idea is to have something that provides a straighter fence than what you have. See if that helps. You ll at least know where your problem comes from.

- clin

+1 I thought the same thing. I have the Delta 36-725, and the aluminum faces were slightly out of flat, causing the same issues. I replaced them with melamine and haven’t had a problem since.

-- "Ladies, if your husband says he'll get to it, he'll get to it. No need to remind him about it every 6 months."

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bgilb

101 posts in 3513 days


#10 posted 12-18-2018 05:53 PM

It’s the default fence with the g0771z. It’s a normal tsquare style fence. I’ve actually already shimmed the center because it was off by like. 015” originally. But I’ll try to home it in more playing with the bolts or try like melamine. How do I attach that. Recessed bolt holes?

View HokieKen's profile

HokieKen

10437 posts in 1593 days


#11 posted 12-18-2018 06:19 PM

So, what if you take a board that’s longer than the fence with a known-flat reference edge and rip it but stop the cut before the back of the board goes past the front of the fence then carefully turn the saw off while holding the board in place. If you do that and get an equal width cut all the way, it’ll tell you that what’s happening is the trailing corner is riding the dip in the fence. If not, then it’s something else.

-- Kenny, SW VA, Go Hokies!!!

View Jack Lewis's profile

Jack Lewis

474 posts in 1533 days


#12 posted 12-18-2018 08:52 PM

Align the blade to the table miter slot, then align the fence to the blade. You Tube Videos on both

-- "PLUMBER'S BUTT! Get over it, everybody has one"

View AlaskaGuy's profile

AlaskaGuy

5332 posts in 2764 days


#13 posted 12-18-2018 10:04 PM

Does it do the same (pull away) if you completely remove the riving knife?

Does it do the same (pull away) if you use a different saw blade.?

-- Alaskan's for Global warming!

View bgilb's profile

bgilb

101 posts in 3513 days


#14 posted 12-19-2018 05:22 AM

Yes it’s the same with the riving knife. I haven’t tried another blade. Tonight I played with the fence a lot basically reset everything and using finish washers to allow some adjustability while tightening the aluminum fence down I managed to get it about within .001 all around as far as bumps and rises.

This led to about a .005 error over an 8” rip in the wood. Is that within acceptable? That’s about 1mm over 80 inches unless my math is off

View BertL's profile

BertL

3 posts in 1190 days


#15 posted 12-19-2018 06:42 AM



Align the blade to the table miter slot, then align the fence to the blade. You Tube Videos on both

- Jack Lewis

I had some similar pulling away issues, though the pinching/burning is more common. When tilting my blade to 45, the motor support hit something. Not realizing it, I cranked hard and ended up shifting the whole blade/arbor/tilt mechanism, so the arbor was no longer in line with the slots or fence. I had to loosen the bolts holding all of it to the underside of the table to re-allign it, and tighten it all back up. If your miter slots don’t align with each other, you have to choose one to be the true reference, then align both blade and fence to the reference slot. I aligned my fence to the slot, then the blade to the fence. This is a fairly easy tune up, whenever you notice any drifting or pinching. Sounds like you probably already knew that though…

Seems like if the blade is angled away from the fence, running a piece through, while cutting off only half a blade thickness (no cutoff on the other side of the blade to pull it away) should come out parallel, and not pull away from the fence. But you should see a gap between the back of the blade and the piece while cutting, as the teeth will only contact in the front.

If neither of these, then I suspect either the table top, fence, or wood being cut would seem to be warped. Another thought would be flex in the arbor mount, but that seems unlikely.

Could an aligned blade, with an unequal ATB sharpening pull a board one way or another, like a band saw does with unequally set teeth?

BertL

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