Acceptable "tolerances" for Jointer

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Forum topic by Rockne posted 10-22-2014 08:59 PM 1416 views 0 times favorited 3 replies Add to Favorites Watch
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48 posts in 2840 days

10-22-2014 08:59 PM

Topic tags/keywords: jointer planer flat table tolerances setup

I recently purchased a new jointer/planer that, for the most part, I really like. By “for the most part” i mean the overall design, functionality, footprint, ease of use, etc. I should specify that the jointer/planer was pretty expensive (it is made in Austria, so that will probably tip you off as to which manufactuerer it is). The jointer tables are not perfectly flat, having at .007 and .008 “twist” (infeed, outfeed respectively) when measuring the diagonals with a precision straight edge and Starrett feeler gauges. The manufacturer said that these tolerances were within their limits, and that I should see how it worked in practice before we undertook any efforts to fix it (on my nickel, which seems laughable). Well, on 8/4 8” wide piece of cherry, the piece is about .010 out of flat (the piece is .010 narrower (when starting with a perfectly square piece) on one side than the other). In your opinion , is this within acceptable tolerances (let’s assume that you had $4,000 in the machine including shipping)?

3 replies so far

View bigblockyeti's profile


5282 posts in 1917 days

#1 posted 10-22-2014 09:22 PM

This seems within tolerance for a $1000 – $1500 machine. For $4000 my requirement would be < 0.002 for table flatness. I have an ancient 12” Crescent jointer and I had to lap the tables to get them perfectly flat, they were close when I got it, just not close enough to me. I do know which brand you’re referring to and those numbers seem unacceptably high.

-- "Lack of effort will result in failure with amazing predictability" - Me

View runswithscissors's profile


2890 posts in 2221 days

#2 posted 10-22-2014 09:43 PM

When you say the piece is narrower, are you referring to twist, or thickness? A jointer doesn’t work very well for thicknessing, so I wouldn’t use that kind of discrepancy as a determiner of accuracy.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View Rockne's profile


48 posts in 2840 days

#3 posted 10-22-2014 09:54 PM

Runswithscissors, I should have stated that better. The net result of the inherent “twist” of the tables is that, on my perfectly square test pieces, after jointing, the one side is .010 narrower than the other. In other words, the effect of the twist on the table is to cause (at least on my test boards which were not the full width of the table, 8” vs. 12”) is to cause one side to be “thinner” than the other (again, starting with a perfectly square piece). So far as I can tell, the “thicknesser” (planer) on this works well.

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