How Flat is a Flat Table?

[cincinnati]

Two major woodworking tool manufactures has a spec of 015" to .020" for flatness.

[keakap]

I carefully reread the thread that I linked to in post #xx above and Nick's statement there indicates that the table should be flat to within 010"-012" (two thicknesses of a crisp dollar bill).

I have until now been laboring under the false recollection that he had said .005". He did not.

Actually, a gap equal to two thicknesses of a dollar bill allows some significant light to pass through.

My first reaction to .010 vs .005 is, and had once in the past been, well that sounds more reasonable, and .005 is quite a tight spec. BUT...

Having watched some how-to woodworking with power tools videos with the sensei taking his just-cut workpiece and laying on his TABLE's surface to demonstrate the absolute STRAIGHTness of the cut, and remembering that with my old table I could never do that, I had second reactions.

2nd 'but': but it's Shopsmith's design, and if they say .010-.012 is within design goals, so be it. Pour moi, after beating myself up trying to drill perpn holes, I went to Woodcraft and bought a piece of Baltic Birch ply to make a new drill press table surface. Flat. And a lot of stuff, like Ed said, doesn't need flat.

Now, I wonder what Nick would say about a theoretical .038? ;-)

[keakap]

Two major woodworking tool manufactures has a spec of 015" to .020" for flatness.

TONKA, and who is the other one?

[keakap]

Two major woodworking tool manufactures has a spec of 015" to .020" for flatness.

And yes, that was in fact a joke.
Purely.

[cincinnati]

TONKA, and who is the other one?

JET and Grizzly.
Said to shoot for .010 but the above is acceptable
This is what others reported after talking to customer service with each company.

Bill M. should be able to give us an idea what they should be.
I know metal working tools has a much tighter tolerance than woodworking tools.

[keakap]

JET and Grizzly.
Said to shoot for .010 but the above is acceptable
This is what others reported after talking to customer service with each company.

Bill M. should be able to give us an idea what they should be.
I know metal working tools has a much tighter tolerance than woodworking tools.

I should think that .010 wouldn't cause serious grief on a table saw, especially if the operator were aware.
But can we compare Jet & Grizzly's products in that way? Shopsmith has the extra burden of the drill press mode, which really really needs a flat flat in some (if not most) cases.
I think the dip or sag only caused me trouble in drill press mode- the other was just annoying.

[Ed in Tampa]

Ed in Tampa, I want to thank you from the bottom of my heart.
For one thing you have reassured me that in at least one aspect of my being I am not a complete delusional lunatic, at least in my own opinion.
For now I know that at least one other Shopsmith owner on earth has had 'table' problems that interfere with his workpieces' quality (I used to have a heck of a time trying to drill perpendicular holes in thick pieces, f.e.)
And I absolutely believe that you acquired your tables from Shopsmith and not EBay or the guy on the street selling stuff out of his staionwagon.

But hey Ed, you say you've got only .005" off? You ever think of selling those babies? Oh, dang, never mind. I wouldn't know what to do with something under 40 thou anaway.

Actually 2 were off more than .040". That said one that I later used for a router table self corrected itself, to something under .040" can't tell you the actual but I know front to back it is straight, side to side was a problem but I figured if I was using it as a router table the front to back levelness was all I was really concerned with.

The third table is sitting in my garage and if I get a chance I will retest all three and let you know the exact amount they are off.

[Ed in Tampa]

I should think that .010 wouldn't cause serious grief on a table saw, especially if the operator were aware.
But can we compare Jet & Grizzly's products in that way? Shopsmith has the extra burden of the drill press mode, which really really needs a flat flat in some (if not most) cases.
I think the dip or sag only caused me trouble in drill press mode- the other was just annoying.

You are exactly right for a saw it really doesn't matter. However for the multipurposeness of the SS it sure does.

I think Delta spec is closer to .005" or so I have been told. The new granite tops are suppose to be dead on with no more than .001".

[keakap]

... front to back it is straight, side to side was a problem but I figured if I was using it as a router table the front to back levelness was all I was really concerned with.

An excellent example of how an unflat table can be fine in one use, even if it's a disaster in another.

Strikes me that I'm bugged-- or was-- about finding an anomaly with the equipment (I almost said 'my' equipment, but I can do without the viagra jokes) when it comes after many situations (over years) when I had inaccurate results on workpieces and didn't know why, even though I thought I was being soooooo careful.

Hm, I bet that router table of yours is dy-no-mite! Flat to start with in its new life, no way you're ever going to have to worry about table-top sag, so common with router tables.

(but how did Shopsmith know you needed a good router table top?) ;-)

[keakap]

...I think Delta spec is closer to .005" or so I have been told. The new granite tops are suppose to be dead on with no more than .001".

granite table tops---

"The Family Table Saw".

Togetherness-- you rippin a nice piece of white oak while right by your side is the wife choppin onions and slicin mushrooms...

[and I just realize I haven't had breakfast yet. no wonder...]