Help! Problem with Face Jointing

[Joe Adams]

I'm trying to flatten one face of some 6/4 hardwood that is 5" wide and 48" long on a Powermatic 54HH 6-inch jointer.

The stock was fairly flat to start with and I'm taking 1/32" per pass.

I am feeding it with downward pressure on the outfeed side and only feed pressure from the infeed side.

My problem is the board is ending up thicker on the ends than the middle which I believe is defined as concave. I am NOT talking about cupping across the width.

When I place a straight edge from one end to the other along the freshly jointed face, there is a gap in the middle large enough to fit one to two pieces of paper. (I even checked my straight edge against two Stabila levels to confirm it is flat.)

Am I being too picky to expect the jointed face board to be dead flat?

Am I doing something wrong?

Is there something I should adjust on the machine?

I'm at my wit's end and would greatly appreciate your help.

Thanks!

Joe

[Bill Orbine]

First off....jointer is not designed to give you consistent thickness though out the length of the board. It only flattens the faces you run. Two pieces of paper is about .006" to .008". Say .007" over 4' is pretty good, I think. If you want better.....hand pressure on the wood should be only over the areas where the board touches the table. Any where else, the board is deflected towards the knives and you are wasting your effort. Any snipes?

[Mel Fulks]

remove wood from the side that is convex along the length. Be careful to avoid dangerous instability and rocking ,by
allowing end to fly over cutters a little ,then holding down on outfeed table. Cutting on the convex side often makes the board move in the right direction as well as being cut. Try this before deciding to start adjusting. Directions to face on concave side are mainly driven by liability concerns ,not good results. If you have any nicks in the knives try to avoid them, they can make the machine actually "out of adjustment ", even if it is perfect .

[Danny Hamsley]

Your knives are not set flush to the outfeed table. If you lay a straight edge over the outfeed table and over the cutterhead, when you rotate the cutterhead manually, the knives should just kiss the straight edge. Just very barely kiss. If there is no kiss, the knives are set too low. If the straight edge is raised slightly when you rotate the cutterhead, the knives are set too high. Once you get it right, the board will come off the jointer dead flat.

[Robert Engel]

Short answer: yes, you're being too picky.

If you could possibly joint that board perfectly flat, it wouldn't be that way tomorrow!

Its woodworking!!

[Mel Fulks]

Agree that by measurment you gave, tables might not need any adjustment.

[John Lankers]

I think you're ok with 6 - 8 thou over 4'.
Before you make adjustments to the machine pay attention where and how much down pressure you apply, even when jointing a 6/4" board.

[Don Jarvie]

Let the board sit a day and do it again then run it through the planet a few times and let it sit for a day. Sometimes you need to let the board adjust a bit.

Also take a pencil and mark the whole pick then joint it. The pencil will show what's not being cut. If it's the middle showing the pencil then the ends need to come down a bit. If the ends are clear but the middle is showing on one side you might want to check the jointer. Follow the manual on how to set it up if that's the case.

[Andrew Hughes]

I think it should be flat.The only light you should see between the straight edge and the wood is from the surface the Bryd head leaves.
If your technique is good then it's your jointer .

Aj

[johnny means]

Wait, your board is ending up ticket at both ends. This is what is supposed to happen when you joint the a bowed board. Your paper thin variance sounds negligible to me.

[Joe Adams]

Your knives are not set flush to the outfeed table. If you lay a straight edge over the outfeed table and over the cutterhead, when you rotate the cutterhead manually, the knives should just kiss the straight edge. Just very barely kiss. If there is no kiss, the knives are set too low. If the straight edge is raised slightly when you rotate the cutterhead, the knives are set too high. Once you get it right, the board will come off the jointer dead flat.

Danny, you're the man! I checked with a straight edge and the helical cutters are just barely above the outfeed table. Maybe a few thousandths at most. I'll readjust the outfeed table tomorrow.

The gap in the middle of the jointed face over 48" is 0.008 to 0.010 at worst so again, maybe I'm being too picky.

This is kiln dried wood stored in a climate controlled environment so I don't think it's moving around too much. This particular piece appears to be quartersawn as well.

Erich and I will make a point to see you the next time we visit our relatives in Georgia. We're still using the wood we bought from you last time.

Thank you Danny and thanks to all who responded. I truly value everyone's input and will take all the advice to heart.

[larry senen]

If the out feed table is low, he should get a snipe at the end of the cut. If his technique is bad, that is, he keeps pressure on the infeed table then switches to the outfield table half way through I suppose you would get a concave surface.

[Phillip Mitchell]

Some folks (myself included) prefer for the cutters to be a few thousandths above the out feed. It seems to perform better than dead on flush, in my experience. I don't know if I'd mess with the out feed, but that's just me.

[lowell holmes]

This problem is why I have always had a thickness planer.

[Jim Becker]

This problem is why I have always had a thickness planer.
It's kinda a requirement to have a thickness planer as the second step here...face jointing a board flat only deals with the first side. ;)

[Robin Frierson]

Yes, I prefer the cutters to be about 3 thous above the outfeed. I use this method to set the outfeed.

"Tip: Some advanced woodworkers have found
that they can virtually eliminate snipe by setting
the outfeed table in the following manner:
Repeat Steps 1-4 using a freshly exposed
insert. Then lower the outfeed table slightly so
the insert lifts the straightedge off the table.
Place a ruler next to the straightedge and rotate
the cutterhead, watching how far the carbide
insert pulls the straightedge. Adjust the outfeed
table and recheck until the straightedge only
moves 5
⁄32"

[Alan Schwabacher]

The knives should be a little above the outfeed table, though how much depends on feed rate and knives. If you look carefully at a jointed board, you will see very subtle scallops where each knife has cut. As the board rides on your outfeed table on the points between scallops, the knives rise a little above to make the scallops.

Think of it this way. If the board were not moving, the cutters would make one cylindrical cut into it. As the board moves along, each cutter moves up into the board and then down out of it, one after another. The faster the board moves along, the bigger the difference in position of the cut from each knife, so the lower the point between a pair of curved cuts. The outfeed table height should be set so as to support these points to allow the board to move past in a straight line. Consequently, the outfeed table should be set just a little below the top of the knives, but how much below depends on knives, cutterhead speed, and feed rate. A height that allows a knife to move a straightedge a small amount (5/32" suggested above) is a good amount.

Use your jointer more before making changes to settings. It may be set just fine. If it does turn out that your observed curve is due to knives being too high (and it may not be the case) a faster feed rate could take care of the problem.

[Joe Adams]

I used a Starrett dial indicator and determined that the knives are at most 0.004 above the outfeed table. These are individual carbide cutters on a helical head and there is some variance. I don't think the individual cutters can be adjusted.

[John Lankers]

It probably just boils down to technique. As far as planing a board to thickness a flat jointed face provides a flat reference for the planer... banana in banana out.

[Andrew Hughes]

Joe I would like to suggest my method of setting up a jointer after changing knives.It should work the same on your Bryd head.
Take two pieces of hard maple that are thick and tall enough so that when you handle them on the machine you cannot change their shape with pressure.Face joint them then pass the edges separately across the head.
When they are held together with your hands they should look like one board.
Since they are white you should be able to see any snipe or gaps in the middle or ends.
A darker wood will hide a gap.
A good length would be about 3 ft +

Aj

[larry senen]

I used a Starrett dial indicator and determined that the knives are at most 0.004 above the outfeed table. These are individual carbide cutters on a helical head and there is some variance. I don't think the individual cutters can be adjusted.

Shouldn't be any variances. Remove the inserts, clean the head below them and use an inch torque wrench to set them all the same.

[Andrew Hughes]

Yes there should be a variance the inserts have a slight radius edge.

Aj

[glenn bradley]

Your material is longer than your infeed table. Since we joint concave side down (when present) it is possible that with the board in the starting positions, the end of the board is hanging lower than the eight of the infeed table. The table is true, your material is not. This means that during material feed, the portion of the material that is not supported will try to follow the irresistible plane of the table once encountered. In the case of a concave board the arch will climb the leading edge of the infeed. This usually results in thinner ends but, the point is that a fouled feed path on a jointer can provide sub-optimal results.

[Joe Adams]

The height adjustment correction seems to have done the trick. I used the Starrett dial indicator to adjust the outfeed table to top dead center of the carbide cutters.

Afterwards, I face jointed the same two boards that were giving me problems along with a half dozen others with no issue. All dead flat. I also edge jointed them without issue.

Then on to the planer for thicknessing and the table saw to rip parallel edges. Lots of sawdust went into the dust collector today.

Once again, I really appreciate everyone's help!

Joe

[Danny Hamsley]

Joe,

Look forward to seeing you and Erich again. Since you were here last, I added a 12" jointer to the planer room, and I absolutely love that thing.