Assume you mean the cut is making the workpiece a bit thinner in the middle of the cut. What type of push stick are you using? Does the "belly" extend for the same length, regardless of the length of the workpiece? What tooth count are you ripping with? Thin kerf or regular kerf blade? I'm wondering if it's an operator caused movement of the workpiece while repositioning the push stick?

 

Yes and the end of the board that is already cut and passed the blade moves away from the fence though it is straight

 

Without being there and seeing what's happening, to fix it simply saw in from each and to the center until the kerfs meet and separate it into 2 pieces.
A 40 tooth blade will give a nice smooth surface and still rip reasonably well.
A 50 tooth will do about the same, so either one.
I wouldn't use a 60 tooth for ripping.
I would recheck the distance from a marked tooth to the miter slot and verify the fence is spot on parallel to the same miter slot.

 

Even though my fence and blade is parallel on my table saw, I get a small belly in the middle of the cut. How can I fix this

Without being there and seeing what's happening, to fix it simply saw in from each and to the center until the kerfs meet and separate it into 2 pieces.
A 40 tooth blade will give a nice smooth surface and still rip reasonably well.
A 50 tooth will do about the same, so either one.
I wouldn't use a 60 tooth for ripping.
I would recheck the distance from a marked tooth to the miter slot and verify the fence is spot on parallel to the same miter slot.

I got a 80 tooth blade, it cuts smooth edges. I'm currently making beekeeping frames and after straightening the side of the wood that will be on the fence after 2 or three passes you can see the wood moving away from the fence ever so slightly till it become a wide opening after it passes the blade

 

Speaking of straight , is the board edge against the fence straight . Does the fence have a bow checked with a accurate straight edge ?

Rather than the fence parallel to the blade , do miter slot to fence for parallel . Check for run-out of the blade to the miter slot . If no -- 0.000" - measuring tool is available use a combination square and or a long straight edge and a feeler gauge for accuracy . There's no reason 0.002 " can't be obtained .

And last , where is the push stick placed on the board ? if not as close to the blade as possible , like one inch on boards of like 2 inch wide and above , place it there and that will tend to push the far end of the board to the fence . ie don't place the push stick as close to the fence as possible . Push stick placement can be checked close to blade or the fence without the saw even running . Watch what the leading end of the board does with these 2 choices .

Wood moving away from the fence after the cut is looking for a kickback eventually .

 

An 80 tooth blade isn't very suited to cut solid wood, it's intended for plywood. Then if it's a thin keft blade it may be following the soft portions of the wood. A saw blade can bend. If you are needing better saw cuts a full kerf glue line saw blade would work better. https://www.rockler.com/freud-lm74r...ignid=18220912686&gclid=EAIaIQobChMI2MO1ifSFkAMVbjbUAR3mmhnCEAQYASABEgJUI_D_BwE

 

So that could be an issue when trying to cut straight lines?

 

What saw and fence..

 

 

Buy another blade. 24 tpi is what I use. One other thing , if using the proper blade and the board still moves away from the fence, you may be sawing reaction wood.

 

Could be

 

Sure sounds to me like it could be internal stress. What kind of wood is it, and where did it come from? Kiln dried lumber, especially pine, tends to have more internal stress.

Tip: When ripping to width, take a little off each side, then a skim cut for the final width. Exaggerated, but we all know what can happen when you rip a few inches off a wide board.

Yes, it’s the wrong blade, but I can’t see this being the blade.

Check the alignment, then rip some plywood or MDF and see what happens. Otherwise, you could be chasing your tail.

 

It is western cedar that I cut myself about 2 or 3 months ago.

 

If the fence is adjusted correctly then it may be the operator technique, try using a feather board to hold material to fence.

 

I really think that is the case

 

From what I see the lack of a splitter can have a lot to do with it. As the wood passes the back of the blade it can move into the cut just a little and make the bow. A proper splitter can restrain that. My saw doesnt have a splitter so I mounted a 1/8” pin in the mdf throat plate behind and in line with the blade to serve the same purpose. I see the gap in your throat plate for the safety cover, do you have that part? The frame when mounted can serve in a similar manner if its aligned right.

 

I didn't get a splitter or safety cover for this saw but I have an harbor freight table saw I will try to see if it is compatible. I never thought of this. Thanks

 

I make a adjustable splitter . Cut a section from an old blade and adjust to any blade i use by tweeking 2 teeth .