jointer flatness

[Casey Carr]

In the slow moving process of getting my jointer up and running, I checked the flatness on the tables last night. Infeed was dead flat, couldn't get a .0015" feeler gauge under the bar anywhere, figure no need in trying the .001". On the outfeed table however, there is a valley right in the middle of the table. I measured about .004 towards the back and about .003" towards the front end. So it seems the ends are a bit high.

Is this close enough, or do I try knocking the ends down a little? I have one of these: http://www.drillspot.com/products/59158/Norton_61463687570_Machine_Knife_Stone and it seems to work pretty good with mineral spirits as a lubricant. So I could hit one end or the other to try and bring it a little closer to flat, but it's definitely not an exact science. I wouldn't worry too much about it if it were on the infeed and the outfeed was flat, but it's not.

So how do I fix this or do I just leave it alone? Wood Whisperer seems to think the jointer is one of the more important machines to have really tight tolerances on, but he doesn't go over flatness of the tables, just co-planarity. But he references the infeed off the outfeed, and if my outfeed is dished, seems like it'd throw the co-planarity off when checking the knife edge of the infeed vs the opposite end.

I've also read I can shim the gibs somehow to bring the middle up? Not sure how that works though.

I guess I could also reference the outfeed off the infeed, but that seems a little backwards.

It's a Northfield 12" medium duty if that helps.

Any thoughts would be greatly appreciated!

[David Kumm]

That's pretty close Casey. How wide is the hollow? Seems like you will be bridging it most of the time anyway. Is the lip hollowed as well? .003 is generally going to be irrelevant. I would use the jointer and see if it matters. Most new jointers are not specd that close anymore, only the old ones. Dave

[Chuck Wintle]

in my opinion .004 is not very much and likely won't affect too much.

[Jeff Monson]

I'd echo what David said, I dont think .004 is enough to worry about, you could try your stone and see if it helps. You have nothing to really loose by trying it though. I'd be making flat boards and not worrying about it, if it was in my shop.

[Phil Thien]

.003 and .004 are not bad at all. Consider that your straight edge may be out .001 or .002 over its length.

Have you edge jointed some boards to see if they make a nice tight joint?

Have you face jointed some boards to see if those mate nicely?

If the jointer is making nice joints, I'd stop there.

[glenn bradley]

As others have said, we many times get hung up on specs as opposed to usability (I catch myself at this often enough). Face joint and edge joint two boards, place them face down on a known flat surface and push the edges together (if you have no known flat surface large enough, just hold the edges together and look towards a light source); any gaps? If it is acceptable, relax and enjoy a wonderful tool.

[David Thompson 27577]

This is a woodworking tool. It will be used to joint one face and one edge (generally) of workpieces.

Workpieces that are wood. Which moves with changes in humidity.

By more (in most cases) than 3 or 4 thousandths.


So long as the un-flatness does not cause un-squareness at the corner of face and edge, you're good to go.

[Garth Thompson]

It is my guess that the manufacturer specification is .015 so .004 is not something I would worry about.

Garth

[Andrew Hughes]

I feel so bad about your out feed table being so wavey.If you bring it down here i'll trade you my oliver its only a 8inch but its flat.:rolleyes:

[Casey Carr]

All right! I'll use it and see what happens. Listening to the Wood Whisperer, he was saying he's heard so many stories where people were questioning their methods on how they use the jointer when it's usually the setup of the machine that's making them struggle. I've still never jointed anything and I don't want something like this to drive me crazy when things aren't working like I think they should. I'm not in a huge rush to get it operational, as evidenced to how long it's taken me to even get this far. I would rather take the time to get it set up right rather than struggle later.

The hollow is probably 90% of the length of the table, which is why I thought I might possibly knock one end down. The straight edge pretty much rests on either end, with the gap only in the middle of the table, nothing on the lip or back edge. So I won't be spanning the hollow, it'll hit the lip then dip down into the hollow. I know .004 isn't bad, but to me it seems like it's in the worst spot.

And sorry Andrew, I'm not taking this jointer anywhere. That 55 mph when pulling a trailer kills me! :)

[Andrew Hughes]

Okay,I guess, if your ever down around claremont your welcome to stop by here.If you need any pointers using a jointer.Send me a PM and i'll give you my 20. Andrew

[David Kumm]

casey, If the lip is level across the width the valley in the middle of the table won't affect anything. The cutterhead references off the outfeed lip and the cut will be within the .002 or so you can set the knives. A slight dip after the cut has been made won't matter, particularly since the board is pushed from the infeed side until the end anyway. Your technique will create more inconsistency. The jointer is still light years ahead of the new ones in quality. Dave

[Casey Carr]

Thanks Andrew, I will keep that in mind. May just take you up on that at some point. When I fly personally, I typically go to Ontario, so you're not too far away. Of course haven't flown anywhere personally in over a year, but I do occassionally get down to Ontario for other reasons.

[dave toney]

David, I believe that the outfeed table is where you should hold the piece as soon as enough wood has passed the cutter head to safely make the transition. If you think I am wrong imagine jointing a bowed piece that has the crown down, the piece on the out feed has to be held down on the table or it will rise and not be straight.
Dave

[David Kumm]

Dave, I tend to think in terms of large stock as that is more of what I use and forget that others use the jointer for smaller stuff. I agree that pulling on the outfeed side, particularly with shorter pieces is preferable. I joint a lot of wide-16"- long stock and it has to be pushed from the infeed end just to move it through the cutterhead. If I had a feeder it would pull from the outfeed. Either way a hollow after the lip won't affect the board. I always joint concave down and chew off the ends rather than cutting on the convex side. Again bigger stock needs a little different approach than smaller. Dave

[dave toney]

Dave, I tend to think in terms of large stock as that is more of what I use and forget that others use the jointer for smaller stuff. I agree that pulling on the outfeed side, particularly with shorter pieces is preferable. I joint a lot of wide-16"- long stock and it has to be pushed from the infeed end just to move it through the cutterhead. If I had a feeder it would pull from the outfeed. Either way a hollow after the lip won't affect the board. I always joint concave down and chew off the ends rather than cutting on the convex side. Again bigger stock needs a little different approach than smaller. Dave
I understand what you are saying.
I have an Oliver 16" jointer myself, but I use a push block on the infeed to move the boards forward and apply pressure with my left hand to keep the stock flat on the outfeed table, I try to not put any down pressure on the infeed.
Of course, if the board is very long ( more than 4')I have to wait until this is possible.
When edge joining I always push on the outfeed table as soon as possible, regardless of length.
Dave

[David Kumm]

Dave, Sounds like we are doing the same thing in practice. I use the little padded gripper with a piece of wood glued to the end so as not to put pressure downward. Do you have the old 166cd or the newer Oliver? I went from a 12" 166 to a Porter 300cm that I like slightly better although both are at the top of the food chain. Dave

[Myk Rian]

I've also read I can shim the gibs somehow to bring the middle up? Not sure how that works though.
Ain't not true. Think about it. How would shims bend the middle of the table?
Use the jointer as is, and don't worry about it. This is wood you're working with. Not metal.