Table saw issue - Woodworking Talk - Woodworkers Forum
 
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post #1 of 12 Old 11-17-2019, 10:59 AM Thread Starter
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So, I'm still new to woodworking. Wondering if someone here could help. I'm trying to tune my tablesaw. It's not a top dollar saw by any means. Older craftsman. It's not great but it gets the job done. The issue I have is that when making rip cuts, it will start off cutting straight but about half way through the blade will deflect off the line to one side (usually the left) and then come back center near the end of the cut. Essentially it cuts an ever so slight arc. Maybe 1/32" difference between the center and each end. And each end ends up dead on with each other. By marking a line all the way down the cut you can watch it happen.

I've checked the trunion or whatever it's called. The part the blade mounts in. It's all tight and square. The fence is perfectly square to the blade. Riving knife is perfectly in line with the blade. Blade is at a perfect 90 to the table. Blade is brand new and true. Am I missing something?

Last edited by Pistol; 11-17-2019 at 11:02 AM.
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post #2 of 12 Old 11-17-2019, 11:25 AM
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Is the wood jointed properly? If youve legitimately checked everything on the saw, then blade deflection, fence deflection, or improperly jointed wood can cause skewed cuts.

Did you actually check the blade for flatness? Reason i ask is one of my blades recently warped out cutting some super hard exotic woods and threw everything out of whack. Blade "looked ok" until i fully raised it and checked with a square. Was basically cupped forward into the fence.

A good dummy check is to not use your current fence and clamp a straight guide on the left of the blade and attempt a cut that way. Should help narrow things down. Also check the width of the actual saw cut to the kerf of the blade, can also tell some good stories.
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post #3 of 12 Old 11-17-2019, 12:36 PM
where's my table saw?
 
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Is the board's edge curved .....?

IF, and that's a big IF the saw is properly set up blade and fence parallel to a miter slot so they end up being parallel to one another and the new blade is flat, not warped there shouldn't be any issues except .....

A slight curve on the edge against the fence "may" result in duplicating that same curve on the saw cut side. Feed pressure must be even or the blade will try to stall. Overheating from force feeding will warp the blade also.

Try this. Take your freshly cut board and insert it back against the fence and "recut it" without changing the fence. See if any more material gets removed. Then move the fence over 1/32" and make another pass and see how much material gets removed.


Let us know what happens.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 11-17-2019 at 12:39 PM.
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post #4 of 12 Old 11-18-2019, 01:31 AM
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I am also wondering if the edges of the boards that are against the fence are straight?

Wise men speak because they have something to say; fools because they have to say something -Plato

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post #5 of 12 Old 11-18-2019, 08:40 AM Thread Starter
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Yes, fence edge is jointed properly. I always start by jointing one face then one edge. Then run through my planer for the other face. Other edge is trimmed on the table saw. I'm a bit OCD about square and flat so I'm constantly checking. Crazy the way wood moves. Had a board actually pop apart once because of grain tension as I was cutting. Got to the last 8 inches or so and it popped right apart without touching the blade.
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post #6 of 12 Old 11-18-2019, 10:02 AM
where's my table saw?
 
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Wood tension ....

When some woods are ripped, they either contract or open at the kerf. This may be the cause of your issue. Try a different species or a different piece and see what you get. Another cause may be that your are allowing the saw to remove slightly more material by varying your feed rate in the center...? Does the curve look like ) or like ( after the cut?


How straight is the fence itself?


If all else fails, which would be unfortunate and quite mysterious, your only alternative would be a few strokes with a hand plane in on the ends. If these pieces are to be glued into a wider panel then a 1/32" gap in 3 ft or 4 ft wouldn't be a big deal. In fact some woodworkers purposely joint a curve in the pieces, creating a "spring" joint when clamped together:
https://www.popularwoodworking.com/f...spring-joints/


The video:

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 11-18-2019 at 12:04 PM.
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post #7 of 12 Old 11-18-2019, 10:53 AM
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Check the fence for straightness, and whether it might be flexing. Many of those older C'man saws had pretty horrible fences.



Another thing to consider is the wood itself. Internal stresses in kiln dried lumber can often cause something like this.


Try running some plywood and if it goes straight you have your answer.



Let us see a pic of your set up and maybe a pic 1/2 way through the cut.
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post #8 of 12 Old 11-19-2019, 02:19 PM Thread Starter
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I'm thinking it's the fence. Its straight as an arrow, but may be flexing. It happens with all wood species. With plywood it just seems to bind as I get near the center.

Out of curiosity I built a sled basically like you would use to joint on a table saw. Or a single miter crosscut sled. Not sure how to explain it. 4ft long and only sits on one side of the blade. I used it to rip a board. Slid right through the cut without binding or deviation. Cut was perfectly straight and square. So I guess I need to replace the fence. Or build one. Any economical suggestions?
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post #9 of 12 Old 11-19-2019, 04:10 PM
where's my table saw?
 
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Just add an 3/4" wood face to your fence .....

Or use Melamine, UHM plastic, aluminum what ever you have that's straight and won't flex. No need to "build" a new fence. Try that first before buying a new one.


Having said that, I seriously doubt a typical aluminum section of 1.5" X 2.5" is flexing enough to give this issue, so I'll be curious how you deal with it. My older Craftsman fence was a cast aluminum section and very stout. I still have it with it's modified head and rail, but no longer in use.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 11-19-2019 at 05:43 PM.
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post #10 of 12 Old 11-19-2019, 04:18 PM Thread Starter
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It's the Align a RIP that I believe came with craftsman saws. Not sure if it's original to the table or not. Its hollow aluminum rail. Not sure necessarily that its flexing. But something if wonky with it. Maybe its twisting. Not sure but I did notice as I'm cutting, when I get to midway of my cut where it begins to deviate, the front edge of my board will be off the fence. Then as the cut straightens out it comes back to the fence. I'm keeping solid and even pressure down and against the fence the whole pass. So it would have to be the fence. Maybe a slight bow that I'm missing? Idk.
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post #11 of 12 Old 11-19-2019, 04:34 PM
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Have you tried a cut using a feather board?

Wise men speak because they have something to say; fools because they have to say something -Plato

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post #12 of 12 Old 11-19-2019, 05:26 PM
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Its the fence. My align a crap fence did the exact same thing. Get rid of it asap. In the interim, theres a screw on the far side that lets you adjust the tension, tighten that dkwn a bit to help keep the flex off.
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