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Extension Table Flatness

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Forum topic by Damian Penney posted 09-24-2008 03:34 PM 984 views 0 times favorited 10 replies Add to Favorites Watch
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Damian Penney

1140 posts in 2677 days


09-24-2008 03:34 PM

What are the typical tolerances for the flatness of an extension wing? Setting up my new tablesaw (blog post to follow) and one wing is crowned .003” which prevents me getting it perfectly flush with the saw.

Also if it is in spec would I be better off having the front and back .003” below the top with the crown level or vice-versa?

I’ve contacted Jet but figured I’d ask here too.

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso


10 replies so far

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coloradoclimber

548 posts in 2754 days


#1 posted 09-24-2008 03:59 PM

Damian, I did some looking into this a few years ago when I was upgrading my table saw. It turns out the manufacturer specs are typically between 0.010 to 0.025 for flatness. This may shock you, it did me. That doesn’t seem very flat to me.

So your wing is well within spec. I suspect if you call and ask about 0.003 they will tell you what a fine table saw you have and how nice and flat it is and how it is well within the manufacturers specification. The flip side of that is that if you call and complain long enough and loud enough they’ll probably send you a replacement wing, which will also be manufactured to somewhere between 0.010 and 0.025 and it’ll be a crap shoot which wing is flatter.

Good luck, maybe things have changed in the last few years but it seemed like the 10-25 mils was pretty typical across manufacturers.

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Damian Penney

1140 posts in 2677 days


#2 posted 09-24-2008 04:31 PM

I figured as much. I’ll see if I can get a replacement out of them all the same, perhaps I’ll get lucky.

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

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GaryK

10262 posts in 2674 days


#3 posted 09-24-2008 05:39 PM

.003” sounds fantastic to me. That less than the thickness of a human hair. You won’t any wood you’ll be cutting that’s that flat.

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

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Damian Penney

1140 posts in 2677 days


#4 posted 09-24-2008 05:45 PM

Not .000” though is it :) I’ll just align the slight crown of the extension with the top of the table, just wanted to make sure that it wasn’t anything I should worry about.

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

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coloradoclimber

548 posts in 2754 days


#5 posted 09-24-2008 06:07 PM

Gary,

Indeed, you are correct, 3 mils is pretty small. In the context of woodworking 3 mils is very small, likely much smaller than the expansion you’ll see across one season. Probably smaller than the run out on your 10 inch blade, probably smaller than the alignment error to your blade, or at least to the fence.

BUT, this is Damian’s BRAND NEW baby (I’m speaking from my emotional response at the time and extrapolating to Damian). This saw is the center of my woodworking world, it’s brand new, it’s shiny, I just spent a LOT of money on it, it MUST BE PERFECT. Or at least that’s what I thought. So I got out my shiny guaranteed straight edge and my feeler gauges and my dial indicator, I checked front to back, side to side, cross angles, alignment, arbor run out, all the little measurements I’d read about in books, magazine articles, and on the internet.

And oh when it wasn’t perfect (or at least in the 1-2 mil range) oh how I cried and wailed. I cursed my gods and all the worlds manufacturers. I promised I’d return to church and give up my life of sin if only my table saw wings were flat.

But apparently either god is not a woodworker or he/she/it has figured out that 1-2 mils is not really a requirement to do excellent woodworking. So my wings didn’t end up flat flat flat, and my arbor has a tiny bit of run out, and my fence has some misalignment, and lo and behold, it still works pretty well.

But I can certainly understand the emotional response.

Of course there is a point where things get so far out of whack they do cause problems, but in reality under 5 mils (or probably more) for a table saw flatness is unlikely to affect the quality of any woodwork.

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Damian Penney

1140 posts in 2677 days


#6 posted 09-24-2008 06:30 PM

Yup, that pretty much sums it up :)

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

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marcb

762 posts in 2359 days


#7 posted 09-24-2008 07:27 PM

A tiny little bit of sanding will flush that up for you…... IF YOU DARE!!!!

Seriously though, it’ll work. Just use a decent sized piece of wood to wrap a large strip of high grit sand paper on, think of this as jointing metal.

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Damian Penney

1140 posts in 2677 days


#8 posted 09-24-2008 07:30 PM

Scratch it! THE HORROR!

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

View RJones's profile

RJones

310 posts in 2841 days


#9 posted 10-07-2008 04:43 AM

Wheeww and I thought it was just me… My new Grizzly is out just a touch more at about .003-.004. Not sure it’s worth calling and replacing the top or is it?

-- http://rjoneswoodworks.com/

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Damian Penney

1140 posts in 2677 days


#10 posted 10-07-2008 02:25 PM

I called Jet about it and they did send me a new one, haven’t checked it for flatness yet; 0.003 is within spec but a call certainly wouldn’t hurt. Enjoy your new saw!

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

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