Acceptable runout for jointer outfeed table

[John Coloccia]

Corner to corner on my Jet JP-12, I'm measuring about a .010" to .012" depression in the middle (i.e. I put a straight edge corner to corner, and I can slip a .010" to .012" feeler under the straight edge). Does this sound excessive? It does to me.

I know I should call Jet, and I have, but it's been nearly 2 weeks and I still don't have an answer from them despite repeated calls (on the other hand, their service was fantastic with replacing my conveyor bed on my drum sander).

What do you think? I don't see how the outfeed will ever work properly like this.

[Frank Martin]

Not sure what is JET's spec on this, but sounds excessive to me. I don't recall my measurements, but when I inspected my Grizzly 12" J/P the tables were nearly perfectly flat. They were a lot better than my US made Unisaw....

[glenn bradley]

Your outfeed becomes your reference surface immediately following the cut so your concerns are valid. That being said I would not be surprised if Jet's published tolerances were .01" across the length of the table. If that is so you are at the outer edge of their tolerance unless that .012 is slipping around under your straight edge pretty freely.

The next question of course is; what you are using for a straight edge? What is the tolerance for that tool. Mine is rated to have a total variation of .0015" or less across its total length. This would do a reasonably acceptable job of finding .01" of deviation over the length of your tables. If my straight edge were rated at .0015" per inch, that's a different story.

At a cost of a couple thousand bucks we would, of course, like the machine to be perfect. Perfect rarely arrives but, within tolerance should be expected. If you are only half the thickness of a piece of typing paper over the outside of their limits, I would say don't really have a leg to stand on. If Jet claims a flatter table, I'd want what I paid for. My Griz tables were freakishly flat but the fence had to go back for a replacement; it happens.

[Jeff Duncan]

First off you want to use the proper terminology, especially when dealing with a manufacturer over the phone. You don't have runout, you (may) have a warped casting. Runout is measured on rotating parts, ie. a drill press spindle can have runout, a jointer table cannot.
Now with that out of the way as the previous poster mentioned first thing is first, what are you using as a base reference? What accuracy does it have and have you checked off another straight surface to ensure it's still straight?
Assuming the straight edge is accurate and you really do have a .012
depression in the center of the table, that's probably going to exceed the manufacturers tolerances which I'm guessing may be in the .008 range. Though again it is an inexpensive import so it may be within their tolerances? As a reference I have an infeed table on my jointer of about 47" and it's within .002. All that said, it may not make too much difference in your work, easy way to tell is run a few test pieces and see what you get.
good luck,
JeffD

[John Coloccia]

Originally Posted by Jeff Duncan

First off you want to use the proper terminology, especially when dealing with a manufacturer over the phone. You don't have runout, you (may) have a warped casting. Runout is measured on rotating parts, ie. a drill press spindle can have runout, a jointer table cannot.
Now with that out of the way as the previous poster mentioned first thing is first, what are you using as a base reference? What accuracy does it have and have you checked off another straight surface to ensure it's still straight?
Assuming the straight edge is accurate and you really do have a .012
depression in the center of the table, that's probably going to exceed the manufacturers tolerances which I'm guessing may be in the .008 range. Though again it is an inexpensive import so it may be within their tolerances? As a reference I have an infeed table on my jointer of about 47" and it's within .002. All that said, it may not make too much difference in your work, easy way to tell is run a few test pieces and see what you get.
good luck,
JeffD

Yes, good call on the "runout". I spent the afternoon measuring the run out on a small engine's crank shaft and didn't speak precisely.

re: straight edges. I've measured it with 3 different straight edges, all of which agree with each other as well as I can measure, and additionally agree with my infeed table and my table saw. The worst one is spec'd at .001" per foot, and I measured it as .001 over the entire length on a Starett surface plate.

The reason I noticed is that I started going down the rabbit hole of eliminating a little bit of snipe at the ends of my cuts after moving my fence over a bit. That's when I noticed that my infeed and outfeed weren't exactly co-planar. After several hours of struggling to get the tables co-planar, and the fence square, and failing, I started looking at the tables themselves and noticed the warp.

If they tell me it's within spec I'll either live with it or have it ground locally. If it's out of spec, I'm sure they'll make it right. I was just curious what the concensus was. For whatever reason, they're taking a really long time to get back to me on this one. I'm guessing the holiday season is upon us and there's just lots of folks on vacation.

[John Coloccia]

So I took a bit of a better measurement with a longer straight edge. Corner to corner on the outfeed leaves a depression in the middle of .015". That's pretty bad.

Anyhow, the rep said that they don't have another outfeed available to send me right this second. Bummer.

"So I'm just going to send out a new jointer. I'll work it out through the local Woodcraft you bought it from".

Nice.

You know, there's just a handful of companies left that I buy with confidence from because they back up their products with real, decisive action. Jet, Clearvue, Grizzly, Woodcraft, SawStop, LMII, StewMac, BluesCreekGuitars (John Hall), Lie-Neilsen. There's probably a couple I'm leaving out, but these guys have distinguished themselves over the years by never leaving me high and dry...EVER.

Thank you, David...wherever you are.