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TS flatness fanatics?

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  • TS flatness fanatics?

    Many years ago I did a lot of work as a machinist where very close tolerances were the norm in a day's work. Like +/- .0001. Now I'm hearing all this dialogue about TS tables that need to be within .001" of true flat. I'm reading in this forum that one should never use a grinder to remove rust from an iron machine table because it will compromise the flatness of the table.

    So here's one for the experts: Just how important is +/- 001" tolerance when we're working with wood that will shrink/grow more than that with a shift in the weather? I build furniture in which close (for woodworking) tolerance is essential, but +/- .001"?

    Also, not every having been exposed before to the importance of maintainingg a TS table to that of a precision milling machine, I've been using a 7" grinder and 180 grit (on a foam-backed wheel) on my old TS for some 40 years now. Today, I checked it with a machinist's straightedge (18") and I could not see even a hiint of daylight under the straightedge anywhere. Granted, I've been careful to use even pressure and never use the edge of the wheel, but even so, I did use a grinder. That poor old TS has lived a few blocks from the ocean for the last 20 years, and I occasionally forget to spray on the WD-40 when I'm not going to use it for a few days. That's all it takes for another ugly accumulation of rust.

    So anyway, just how important are these tolerances? I can understand the need for close tolerances on parallelism of components and in the flatness of the rip fence, but please give us some Real Wisdom on this table-surface thing.
    Unanswered Questions
    are far less dangerous
    than Unquestioned Answers.

  • #2
    0.001" tolerance for flatness seems extreme. I'll bet that's tighter than any manufacturer's specs....maybe even tenfold tighter. It's far more important to get the blade aligned correctly than have a flat table IMO.


    • #3
      I agree that .001" is way too close. I think one person said he called the company (Ridgid) and they had a .016" tolerance (approx 1/64" for non-machinists). I personally think that is reasonable for a maximum deviation, but depending on where it is, 1/64" can mean extra work and tools. 1/64" off on the flatness of a glue line for edge jointing hardwood can mean a bad joint, and the deviation could be up to double that combining the two edges to be glued. If someone is spending $100 for a fine blade on his "cabinet-grade" saw not to have to go those steps or buy those tools, I think he has a right to be upset if the saw won't deliver a cabinet-grade cut.
      One area where the 1/64 can cause major problems is at the front/rear corner of the main table where it mates with the wings. That edge can gouge a piece of veneer ply past the point of recovery.
      But, lets face it: I doubt anyone (except maybe Lorax, Badger Dave, etc) on this forum meets that tolerance all the way around their inserts, especially if its homemade. And we all have these big 3/4" grooves running down the table called miter slots. Its not the depth as much as it is the surface area of the deviation that will cause a problem, and then it has to be in a critical location.
      In summary, I agree with you. If someone is using their table for flattening hand plane soles, or to "scary sharpen" plane irons and chisels, that really isn't its intended purpose. IMHO, I think .016" (not .001) is reasonable for small defects in a saw under $1000, but I also am VERY glad that mine has none close to that. I guess that's why I'm so happy with my TS3650, because it has exceeded my expectations.
      my $.002 worth
      Practicing at practical wood working


      • #4
        I've never checked the flatness of my table. Never had a reason to.
        "Did you put the yellow key in the switch?" TOD 01/09/06