Thread: Table saw tolerances

You’re asking about a table saw, for cutting wood, right?
Considering that most of the time layout and marking off work, in wood, is done with a pencil, or a knife, which could be up to half a millimetre thick line, then that line might get cut up to, or half way through, or cut off, working to thousandths of a mm, in woodwork, is not going to happen.
The only time I work to that degree of accuracy, is when setting up cutters in the spindle moulder, to ensure they are balanced and projecting evenly, to produce a clean cut. I use a dial indicator for this process.

Upon reading your question again, are you talking about squareness of the table and fences with the blade? Most blokes I know simply cut a panel offcut off on three sides, and measure the diagonals with a tape measure, and if it’s within half a millimetre or less, then that will be good enough for them.

Originally Posted by riverbuilder

You’re asking about a table saw, for cutting wood, right?
Considering that most of the time layout and marking off work, in wood, is done with a pencil, or a knife, which could be up to half a millimetre thick line, then that line might get cut up to, or half way through, or cut off, working to thousandths of a mm, in woodwork, is not going to happen.

He did say 0.003" which is about 0.1mm (0.076mm) but I still agree with you.
It depends on the type of wood, its uniformity and the width cut but even when dry all natural wood products will move slightly over time due to moisture changes so something cut today in a couple in a couple of weeks could have expanded/contracted at one end more than the other by around 0.1 mm.

Originally Posted by SuperM

I’ve been reading up on table saw tolerances and frequently see it should be < 0.003” or less. I like to know how long is the test piece measured on?

I've always used a dial gauge on my table saw. I select a tooth, and mark it with a sharpie. Just behind the actual tooth, I measure from the there to the fence when that tooth is just about to rotate into the table (i.e. as far forward as it can go). I than compare that the the same spot on the blade when that point is as far back as it can go (i.e. just having emerged from the table).

This is the distance I base my measurement from, and I think I currently have mine dialled in to 0.03mm, but I'd have to check that.

Here's a video that might make this more visual and clear: YouTube

Originally Posted by Midnight Man

I've always used a dial gauge on my table saw. I select a tooth, and mark it with a sharpie. Just behind the actual tooth, I measure from the there to the fence when that tooth is just about to rotate into the table (i.e. as far forward as it can go). I than compare that the the same spot on the blade when that point is as far back as it can go (i.e. just having emerged from the table).

This is the distance I base my measurement from, and I think I currently have mine dialled in to 0.03mm, but I'd have to check that.

Here's a video that might make this more visual and clear: YouTube

That isn’t correct. You’re only measuring from one spot on the blade. If the trunions are worn, If the shaft has runout, or end play, or the collars aren’t ground perfectly, if the inner collar is not against the shoulder of the shaft, or there’s dust between the collar snd the body of the blade, or indeed, the blade could be buckled or you’ve picked a deformed tooth, all of these things will influence the running of the blade, at speed. Even the feed rate of the material can change the blade balance. Setting up is only one part, albeit an important one, but making actual cuts with the blade spinning is the only way to check.

Originally Posted by Midnight Man

I've always used a dial gauge on my table saw.

What is the purpose of checking that? Is it to see if the blade spins straight?
Must I always need to use a dial gauge? Any other options?

Originally Posted by riverbuilder

but making actual cuts with the blade spinning is the only way to check.

I said earlier the best way was to make actual cuts.
I can cut a short piece (eg 100 mm), measure at opposite ends and the error is very minimum.
I can cut a log piece (eg 1000 mm), measure at opposite ends and I get a much bigger error.

I've squared the blade and fence as much as I can already to the edge, but still notice differences when I rip a long board.

Originally Posted by SuperM

I said earlier the best way was to make actual cuts.
I can cut a short piece (eg 100 mm), measure at opposite ends and the error is very minimum.
I can cut a log piece (eg 1000 mm), measure at opposite ends and I get a much bigger error.

I've squared the blade and fence as much as I can already to the edge, but still notice differences when I rip a long board.

Actually, that doesn't really make a lot of sense. Can you be explicit about this rip and where you're measuring? Perhaps the problem isn't in your saw, but in your timber. If the board is even to start, and you have your rip fence set at a constant dimension X (mm), then with the correct procedure for ripping and no twisting in the timber, the resulting piece that is cut should be at X mm, at the front, rear, and anywhere along it, whether it was 200mm long to start with, or 2000mm. If the dimensions are different, then the problem is more likely to be the timber is twisting or is able to spring away from the fence, or the starting reference edge wasn't straight to start. I've also seen this on my saw when the piece is able to slightly move on the exit from the blade and take another shave off that the leading edge of the blade didn't create.

There's a good series of YT vids that came up when I looked at Tamar's adjustment vid; Vic's, James', Dan's, and Mark's. All worth watching for tips and techniques on adjustments.

Originally Posted by SuperM

Not sure if I had explained it correctly.

No, you didn't, that's why people are having trouble helping you. Is the piece always wider at the end of the cut? If that is the case the fence is moving away from the blade as you push the material through the cut. What saw is it and does it have the original fence?

As poundy has said, barring other mechanical problems with the saw or blade, if the fence is of some quality and locked down properly there should be no variation in the width of the cut stock.

oh yeah, of course, or the fence moves from the saw.... Which reminds me, must start a thread about adjusting my fence