Thread: Table saw not cutting in a straight line (cuts square, not straight)

Originally Posted by rrich

OK, let me toss a few things out here.

The riving knife needs to be aligned with the arbor flange. But we never do it that way because there is no tool or jig to allow us to do so.
What we do is to align the riving knife with the outside side of the blade. That is cool until the blade is changed. When the blade is changed, the thickness of the blade disk is probably different and our riving knife alignment is off.

With a narrow kerf blade the alignment is even further off AND in most cases the riving knife is too thick to pass through the kerf in the timber being cut. This makes for a very difficult cut as the riving knife is trying to split the timber and misalign the cut.

The suggestion here is to avoid narrow kerf saw blades on the table saw.
I know the arguments, saves timber, less work for the table saw.
Saves wood at about 0.8 MM per cut. (You do the math.) How wide does the timber have to be to save a few MM to get that extra piece?
Less work for the table saw motor. I've never noticed and have no clue how to measure it.

Actually thin kerf blades do reduce load on the motor (& batteries) and thus current draw, & is why the manufacturers have developed a range of thin kerf blades for "cordless" power & table saws. DeWalt's Xtreme series are a typical example. Or is it just another clever marketing / advertising guru's latest gimmick?

Unless I've missed something I have seen no mention of what type of "blade" is in use, other than the OP's comment about changing blades "I put in a brand new high quality blade (CMT chrome)".

Blade design and suitability definitely affects the performance of the saw and quality of the end result. A "general purpose" blade will produce "acceptable" quality in rip and crosscut modes, however a good quality "specialist" blade suited to the task and material will offer far superior quality, far less stress on the saw and require less effort / exertion by the operator.

I have had excellent results with a range of manufacturers "specialist" blades in cross cut mode, on a wide range of tasks from cutting a stack of veneers, thin stock, thick stock, and in cutting very small components to high precision and accuracy on a quite basic Woodfast TS250 "panel saw."

No luck involved, its all in the table saw setup, adjustment, blade selection, sled design, stock hold down, holding your mouth right. All bets are off though, if a saw has unacceptable "arbor float."

i think this is going to be an arbor or something lose in the tilting mechanism problem.

what did the sawstop people say to do to test it?

Thanks for all the advice till now, guys...I spoke to SawStop this AM and they were a bit boggled by the whole thing, too...So I've since done a few things they recommended:

- Clean around grub screws that adjust the arbor tilt, and generally try to get rid of any dust build up
- Try ripping a bevel, as well as x-cut (so, I did that, same thing)
- Try lower angle...did that, too...Tried x-cut and rip at 30, same issue
- Then I adjusted back to zero and ripped...all fine...feels like something in the tilt is causing this

Blade: CMT Chrome 60T finishing blade, not a thin kerf blade.

- I'm also wondering if maybe there's something in the mitre slot or fence that might be pushing the work piece over and causing this...all seems to be running freely, but I might be missing something...

With the thin kerf blade, what I said was that I've never noticed the extra load on the saw and I don't know how to measure it. I've used thin kerf blades on a 1½ HP (820 Watts) contractor model table saw and did not notice any advantage.

I do have a suggestion for a quick test on how to possibly define the problem. Remove the riving knife as if you are going to cut a dado. I don't know if Australia follows the EU rules in not allowing dado blades on a table saw. Even if the arbor is shortened to prevent the use of a dado blade, the riving knife should be easily removable. If that does not solve the problem, I'm at a loss.

At what height do you have the blade? Fully up? Or just cutting through the stock? Like I see on so many amateurs videos?

Originally Posted by riverbuilder

At what height do you have the blade? Fully up? Or just cutting through the stock? Like I see on so many amateurs videos?

shouldn't matter. whats its doing is not going to be fixed by raising the blade up a bit more. what if cutting a groove, it defeats the purpose if he has to raise the whole blade up.

it sucks to say but something isn't right with the saw, if you bought it new its going to be a warranty job or replacing of parts.

Originally Posted by riverbuilder

At what height do you have the blade? Fully up? Or just cutting through the stock? Like I see on so many amateurs videos?

Actually, blade fully up is not always the best practise; you will get the least backwards pressure, but not necessarily the best cut quality, as evidenced by the fact that CNC beam saws will adjust the blade projection according to the material thickness. I remember reading ages ago from one of the big blade manufacturers (either Leitz or Leuco) that their blades are optimised for 15mm projection above the material being cut to minimise breakout.

Furthermore, if this is an alignment issue, a lower blade should REDUCE the effects of misalignment because there is less surface pushing the material being cut away.

Originally Posted by elanjacobs

Actually, blade fully up is not always the best practise; you will get the least backwards pressure, but not necessarily the best cut quality, as evidenced by the fact that CNC beam saws will adjust the blade projection according to the material thickness. I remember reading ages ago from one of the big blade manufacturers (either Leitz or Leuco) that their blades are optimised for 15mm projection above the material being cut to minimise breakout.

Furthermore, if this is an alignment issue, a lower blade should REDUCE the effects of misalignment because there is less surface pushing the material being cut away.

incorrect, the angle of attack of the teeth is much more acute, and there is a much greater surface area in contact with the teeth.

Originally Posted by riverbuilder

incorrect, the angle of attack of the teeth is much more acute, and there is a much greater surface area in contact with the teeth.

Irrelevant. Misalignment will be pushing the material away with the side of the blade, not the face of the teeth.

Originally Posted by elanjacobs

Irrelevant. Misalignment will be pushing the material away with the side of the blade, not the face of the teeth.

What misalignment? Have I missed something? The guy says it cuts fine in the 90degree position, then when he rolls it over to 45, it cuts badly, what alignment or misalignment has changed?
Are you referring to the alignment of the blade with the table slots?
Ithought the fellow said it cut badly when ripping also?
How old is this saw?

You must have missed my earlier post where I suggested that perhaps the tilt axis is not parallel to the table; that would have no effect at 90 degrees, but it would at any other angle.

Originally Posted by elanjacobs

You must have missed my earlier post where I suggested that perhaps the tilt axis is not parallel to the table; that would have no effect at 90 degrees, but it would at any other angle.

Yes, that makes sense, maybe loose in the trunions somewhere?

Originally Posted by elanjacobs

You must have missed my earlier post where I suggested that perhaps the tilt axis is not parallel to the table; that would have no effect at 90 degrees, but it would at any other angle.

This is the prime reason that I prefer to use sleds for cutting very small components accurately.

Firstly its much safer, as a sled offers supreme control of work holding and accuracy IF the basic saw alignment is OK.

It is also easier and far more reliable to leave the saw blade "fixed" in the vertical position, or normal (90 degrees) to the saw table, then ensure that the saw blade alignment to mitre slots, fence, sliding table etc are adjusted accordingly. Sure its a PIA to find storage for a number of ramped or "donkeys ear" sleds and you lose a fair cutting depth as a result, but the alternative of spending days in and under a saw table "aligning" trunnions etc is far worse. As we have seen on the recent K3 thread even top name saws have issues.

As a surveyor, I'm far more aware than most about how the angular eccentricities, concentricity, parallel and saw alignment will affect the quality of cuts. It doesn't take much crud on a thread to affect the trunnion action and saw arbour alignment to the saw chassis. On budget saws its a marvel that they are even "close."

Aligning the sled, cutting test components, becomes a relatively simple task compared to fussing about with the saw tilt and then finding hassle's like the OP's conundrum.

So, I’m almost embarrassed to post this but I think I’ve found the issue and it’s me being a stupid idiot. I guess sometimes when we’re working, we don’t see the forest for the wood.

The ash I was cutting was slightly cupped and of course when you tilt the blade that cup is gonna take stock away from the blade, resulting in the arc type cut I was confused by.

I since put in a piece of walnut without any kinks or issues and it cut fine. Not perfect, mind you, mitres always have a way of being a bit fussy, but much much better. On a piece of dead flat ply? Perfect.

Lesson here I guess is, always mill your stock correctly before you do anything. What I was working on didn’t require critical square and flat stock so I didn’t bother and as a result ran into this problem.

Like I say, very embarrassing to admit this, but who among us hasn’t made some silly mistakes working on this wonderful hobby of ours?