Table saw binding

[ralitaco]

Disclaimer: I am new to table saws.

I have the Ridgid R4518T table saw. I followed the instructions on how to square up the blade and the riving knife, but when I lock the fence in place the boards seem to bind at the the riving knife. I measured and it is the same distance at the front of the blade and the back of the blade to the fence. What am I missing here?

I discovered this while cutting off the rounded edge of some 2x's.

 

[Oka]

Two issues I see. The Riving and blade are not in exactly in line. Likely there is a small deviation between the 2. You need to set a straight edge off the blade and match the riving knife accordingly.
Another possible issue is when you lock the fence it move ever so slightly.
One solution is to belt sand the riving knife and take off about 1/1000 or so e.g. Blade .125 and riving knife= .11. Hope that helps.

 

[gmakra]

Another thing is are you using a thin kerf blade?
Most standard blades are 90 though and ripping blades can be 120 though. Thin kerf blades are 70 thou.
Also does this happen occasionally or all the though. It could be there are stresses in the board which can give you a workout trying to get the lumber through the saw.
Forrest saw recommends setting the back side of your fence 4 or 5 thou wider than the front of your fence to allow for thermal expansion from the wood.

 

[tvrgeek]

Is it binding between the fence and the knife? Or is it pinching the knife? The first is setup. Portable saws are notorious for sloppy fences.

The second is the wood or a miss-match between a full kerf knife and a thin kerf blade. Verify your setup with more stable material, like MDF or plywood. Some wood has a lot of internal stress and will pinch. You need to keep shims handy to stuff in the kerf after the blade to keep it from binding.

Blades come in all kinds of thicknesses. "Full kerf" are 1/8 or 125 thou. Thin kerf can be many different thicknesses. No standard. There are several specifications on riving knife to kerf dimensions, but basically, if it is as thin as the blade plate, it is fine as that is smaller than the kerf. Most portable saws the knife is thin enough for "thin kerf" blades. My cabinet saw was not, so I had to buy a thinner knife.

FWIW, my fence is about .001 out.

 

[mpeele]

I looked at the manual for your saw and it has adjustments for horizontal and vertical adjustment for the knife and I'll assume the knife and blade are in the same plane.
I'll also assume the blade is parallel to the miter slot and the fence is also. And the blade kerf is wider that the splitter. Manual has instructions for doing all of that.

So with all that said and done I think you last comment "I discovered this while cutting off the rounded edge of some 2x's" is where you problem is.
Your 2X4 probably has some bend or twist or booth and that is causing your problem.

There are several ways to deal with the twisty bendy wood.

 

[Berta]

Just in case! Did you measure using the blade body or the blade tooth? It matters.
Filed under Lessons I have learned.

 

[ralitaco]

Thank you everyone for your input. I think I may start over and recheck everything. I have a small square that I am using to verify the blade and knife are "in the same plane" but it is not a fancy or expensive square. Also, I think I will purchase a metal ruler and use that instead of a tape measure. Even better, I may try to find a gauge (don't know what they are called but has a round dial and spring loaded pin...saw it in a video) that I can run in the miter track to make sure the fence is not the issue. And I do have some squares of MDF so that may work too.

 

[patlaw]

The Harbor Freight dial indicator is cheap. I don't know how accurate it really is, but it's good for checking variations.

1 In. Travel Machinists Dial Indicator

Amazing deals on this 1In Travel Machinists Dial Indicator at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[ralitaco]

The Harbor Freight dial indicator is cheap. I don't know how accurate it really is, but it's good for checking variations.

1 In. Travel Machinists Dial Indicator

Amazing deals on this 1In Travel Machinists Dial Indicator at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

View attachment 204403

Thank you sir...Dial Indicator...never would had guessed that

 

[mpeele]

Thank you everyone for your input. I think I may start over and recheck everything. I have a small square that I am using to verify the blade and knife are "in the same plane" but it is not a fancy or expensive square. Also, I think I will purchase a metal ruler and use that instead of a tape measure. Even better, I may try to find a gauge (don't know what they are called but has a round dial and spring loaded pin...saw it in a video) that I can run in the miter track to make sure the fence is not the issue. And I do have some squares of MDF so that may work too.

You can check the fence without a gauge using the miter track slot. Just align one end of the fence flush with the edge of the slot and then check the other end. Use a block of wood thinner than the miter slot to gauge flushness at each end of the fence.

To align it clamp the blocks( 1/2" X 3/4" X height of fence) to each end of the fence such that they extend into the slot.
Losen 2 fence adjustment screws at top of fence just enough to wiggle fence and push fence with block to side of slot (block side of fence to side of slot) with locking mech unlocked.
Lock fence lock to rail and then tighten fence adjustment .
Check the other slot.

I have a dial indicator and find using the blocks is easier and faster than using an indicator.

 

[Oka]

Do not get that Harbor freight one, it is only good to one-hundreth you need one-thousandths tolerance dial indicator amazon or other places have them for 15-100 bucks depends on you brand and q.c.

 

[tvrgeek]

Actually, the HF one is just fine. You are looking to see the needle move, not the actual number. I welded a tab to a bit of 1 1/2 tube so it would sit in the T-slot and ride along. The one pictured above the hash marks are .001. As in one thousands. You can interpolate more as they are surprisingly consistent even if the actual number is off. Mine was binding a little so I bought a little better one. $30 or something. Smoother, but no better in actual function.

But, you don't need to. You can stick a sharpened bolt through a bit of MDF that fits the slot and slide it along. It is relative. Actual numbers don't matter. I use foil tape to shim some 3/4 MDF for a snug fit. Of course, I now use a dial indicator, but more convenient than accuracy. Mark the blade so you always make a measurement from the same point on the blade. Don't let a couple thou in blade wobble fool you.

E-bay has several nice ss ruler sets. Be sure one of them the scale goes to the edge, Many start in some. I think I got a 6, 8 and 12 for like $12 that are very nice.

You are too far away, otherwise I would say toss it in the car and drop by. Maybe someone on the shore can jump in.

 

[bob vaughan]

I discovered this while cutting off the rounded edge of some 2x's.

There is a possibility that the saw is in fine shape and the 2x4s are some knotty spongewood from the big box store that will twist and warp when ripped. Most construction softwoods will do this to some degree unless less than 10% of the width is being ripped off.

 

[bainin]

Things that have happened to me :

1. Saw is capable of making a deeper cut than the pawls on the riving knife are able to raise above- binding on the pawls rather than the knife.
2. Tiny deflection on the board that hooks on something for instance -board deflects a tiny bit beyond the cut and gets hooked on the opening of the table saw insert.

b