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Wood drifts away from table saw fence at end

by bgilb
posted 12-18-2018 05:51 AM


27 replies so far

View therealSteveN's profile

therealSteveN

2812 posts in 962 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

View Redman1's profile

Redman1

13 posts in 1364 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.

View knotscott's profile

knotscott

8289 posts in 3763 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....

View bgilb's profile

bgilb

101 posts in 3447 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

5205 posts in 4348 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]

View bgilb's profile

bgilb

101 posts in 3447 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.

View clin's profile

clin

1030 posts in 1384 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

4478 posts in 977 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?

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

View Dustin's profile

Dustin

689 posts in 1128 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."

View bgilb's profile

bgilb

101 posts in 3447 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

9496 posts in 1526 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

440 posts in 1466 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

5278 posts in 2697 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 3447 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 1123 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

View bgilb's profile

bgilb

101 posts in 3447 days


#16 posted 12-19-2018 06:49 AM

How much accuracy should I expect? I like your idea of running it through but only taking off a smidge. I think the only thing that can be out of alignment now is the blade to the miter slot so I’ll check that tomorrow. Seems unlikely the miter slots would be off by .005 over 8 inches.

View therealSteveN's profile

therealSteveN

2812 posts in 962 days


#17 posted 12-19-2018 12:14 PM


The only thing that prevents it is if I use my right hand fingers to sort of squeeze the wood towards the fence.

- bgilb

I must apologize to the Lumber God who feels I created hysteria panic. The only way I can make any sense of the words the OP wrote is that the wood was indeed moving toward the blade, or how could he possibly squeeze the wood TOWARD the fence, if it was already passed it?

Again my apologies, reading what was typed I took he meant stock was going toward the blade. Even 0.001 toward could cause kickback in the correct situation, and that increases with each additional amount it’s off.

Rich please, so you don’t make a complete fool of yourself publicly, unwad your panties. The rest of your posts do often have an opinion that most would consider learned from some experience. But to be an adult, you need to quit with the childish insults. People come here for information, opinions, and to learn, not be abused like children on a playground by the class bully.

-- Think safe, be safe

View therealSteveN's profile

therealSteveN

2812 posts in 962 days


#18 posted 12-19-2018 12:17 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.

- HokieKen

I didn’t note this. I’ll admit the thought that stock was running into the blade was what caught my eye.

Seeing the OP saying this isn’t the case. I would say this is a smart move going forward.

-- Think safe, be safe

View therealSteveN's profile

therealSteveN

2812 posts in 962 days


#19 posted 12-19-2018 12:24 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

I agree a sac fence is a smart move to see if this is the cause of the problem, cheap, easy to do, and it wouldn’t be the first time a piece of wood saved a TS.

-- Think safe, be safe

View therealSteveN's profile

therealSteveN

2812 posts in 962 days


#20 posted 12-19-2018 12:24 PM

wrong line quoted above Hokie Ken, and it won’t let me blank it out. I meant to quote – clin

-- Think safe, be safe

View tomsteve's profile

tomsteve

949 posts in 1607 days


#21 posted 12-19-2018 02:41 PM



How much accuracy should I expect? I like your idea of running it through but only taking off a smidge. I think the only thing that can be out of alignment now is the blade to the miter slot so I ll check that tomorrow. Seems unlikely the miter slots would be off by .005 over 8 inches.

- bgilb

thats quite accurate. personally i only use a ruler that goes down to 1/32” increments which is .0313(except in setup of machines and when im working with metal. then i break out the metal workin measuring machines). im building with wood that moves through the season.
1mm over 80” is 0.039370” difference in 80”. splittin atoms here.

i have a 3” thick live edge red oak mantle over my fireplace that can have a 3/16” variation in measurements throughout the year- depending on which season i measure it.

exactly how much is the wood drifting away from the fence?

View 000's profile

000

2859 posts in 1287 days


#22 posted 12-19-2018 02:46 PM

Try testing on a longer piece of wood (maybe 30 – 40”)
Use something soft like mdf so that the saw isn’t fighting the wood.

Only times I have had wood pull away from the fence is,
when the fence is too far out at the back,
or the blade is dull and I’m forcing the wood through.

View jimintx's profile

jimintx

916 posts in 1972 days


#23 posted 12-19-2018 02:56 PM

... 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.
- Rich

I agree with you, Rich. I read the problem statement to say that the stock separates from the fence face at the end of the fence away form the operator, and towed the back of the saw.

-- Jim, Houston, TX

View smitdog's profile

smitdog

430 posts in 2493 days


#24 posted 12-19-2018 03:35 PM

Just for curiosity I’d try ripping a longer piece. It might be too easy for the 8” piece to follow imperfections in the fence face. If a longer board still has the issue then the problem may be elsewhere. Also, does the back of your fence clamp down or is it free to move? It could be slight variation in how much pressure you are putting against the fence depending on your hand position on the table. If the back of the fence can move ever so slightly then that could be accounting for your .005 difference as you push through the cut.

-- Jarrett - Mount Vernon, Ohio

View Robert's profile

Robert

3397 posts in 1868 days


#25 posted 12-19-2018 04:28 PM

The only thing I know of that could cause this is either a misaligned riving knife or fence. From the sound of it, if anything the fence would be doing the opposite of what is happening.

I always assume a machine is set to specs at the factory (but no, I’m not always right).

Take the shims out, reset everything to factory specs and start over. Review, your manual recommendations on alignments.

When check riving knife be sure straight edge is straight ;-) and not contacting any teeth, ie lays along the blade plate.

If that checks OK, the correct procedure for a table saw is:

1. Align blade to miter slot. (Not 100% necessary, but you should still do it).

2. Align fence to the BLADE, not the miter slot. .003-6” wider at rear, reference off same tooth.

When doing test cuts don’t use lumber. Use plywood, MDF, particle board, etc. because cannot distort.

If none of this works, sorry, but I’m at a loss.

How are you measuring the gaps? I prefer feeler gauges. Dial indicators can work too, but any time you move them (as in adjusting fence-to-blade) you introduce error.

I suppose it could be something like a loose trunnion but you would know that by now, right?

-- Everything is a prototype thats why its one of a kind!!

View bgilb's profile

bgilb

101 posts in 3447 days


#26 posted 12-19-2018 06:43 PM

After checking the blade it was off by .005 compared to the right miter slot. The only weird thing is it’s closer to the fence in the back. Would that really make slanted pieces? I tried adjusting it but was having trouble picking a consistent spot on the blade so I’ll get to try again after work.

View ccc118's profile

ccc118

19 posts in 562 days


#27 posted 12-19-2018 11:10 PM

Check to make sure nothing is causing the work piece to tip away from the fence and towards the blade, such as the throat plate not being level, etc. With the saw off, try feeding a work piece through against the fence and see if anything is causing it to rock at the end of the cut.

I have the same saw and had a similar issue where I felt like something was pulling the work piece at the end of the cut. It turned out to be my riving knife alignment, but it sounds like you already checked that. Is the other side of the fence flat? You can remove them and switch them around if the other side is flat. I had to do that on mine.

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