Jointer problem

[Sean Troy]

Seems I've had one problem after another today of some sort or another so I'm just trying to work through them one at a time. This problem is with my jointer. I have an older 6" Jet. I'm getting a nice 90 degree cut (outfeed and infeed at a 90 with the fence) but a slope with my cutting. It's like I'm cutting down hill? If I switch the board by going from one side and then reverse it to go from the other side, I end up with a wide V shape on the jointed edge. What the heck? I put a level on the beds and they seem equally level in feed and out feed. I have the out feed the exact same height as the blades at there highest point. Any ideas? thanks, Sean

[Don Alexander]

if i read your post right you make the firstpass and are getting a 90 degree cut but when you flip the board end for end the result is a wide V

sounds like you either have a cupped board or you need to double check the 90 degree of your fence in relation to the cutter

[Anthony Whitesell]

I'm not sure using a bubble level will be accurate enough to ensure the beds are parallel. If the level is long enough, just try to use it as a straight edge.

[Sean Troy]

I'm not sure using a bubble level will be accurate enough to ensure the beds are parallel. If the level is long enough, just try to use it as a straight edge.
Iwas just trying to see if the outfeed table sloped down hill.

[Sean Troy]

if i read your post right you make the firstpass and are getting a 90 degree cut but when you flip the board end for end the result is a wide V

sounds like you either have a cupped board or you need to double check the 90 degree of your fence in relation to the cutter
I may not have described the problem correctly. The 90 degree is fine no matter what end of the board i enter into the cutter first. The cut only seems to go to the midway point of the bard so when i reverse the board and do that cut, the jointed edge is sloped towards the middle of the board from both ends.

[Bob Vallaster]

Post removed.

Bob V

[Steve Kohn]

It sounds like the cutterhead is set incorrectly in relationship to the outfeed table.

Do you have a manual with the jointer?

[Sean Troy]

If you're double-darn sure that the fence and table are square...sounds like one knife (or more) is creeping out of adjustment. If a knife rides high on one side, your cutter is effectively a cone, rather than a cylinder when it rotates.
Remove power and check knife height on each blade.

Bob V
The jointed edge is 90 degrees, it's the whole length of the board that ends up in the V shape. If your looking at the face of the board, the left and right side end up higher than the middle.

[Sean Troy]

It sounds like the cutterhead is set incorrectly in relationship to the outfeed table.

Do you have a manual with the jointer?
It's set according to the manual. The blades all the way across are level with the out feed table.

[Robert foster]

Sean: I had a similar problem and I thought the tables were set up right but found that the rear table was not quite at the correct height. It wasn't off much but when I reset it it fixed it.
Good Luck
Bob

[Phil Thien]

I might not understand your problem, but a refresher course just in case... :D

(1) Jointers don't guarantee parallel sides. A board coming out with a taper isn't unexpected. As long as the face it gives you is flat and perpendicular to the fence, then that is all you can expect. Once you have flat references, you use a planer for opposing faces, and a table saw for opposing edges.

(2) Why are you turning boards around while jointing? You want to consistently orient the board so you aren't lifting the grain.

(3) If you don't turn boards end for end, and joint two boards for a glue joint, does the wood come together, or is there a gap? And if there is a gap, where is it?

[Dave Cav]

If I am reading your post correctly, it sounds like you are getting a concave edge along the length of the board. Your outfeed table might be a little low; it won't hurt to experiment.

[Sean Troy]

If I am reading your post correctly, it sounds like you are getting a concave edge along the length of the board. Your outfeed table might be a little low; it won't hurt to experiment.
Convex not concave

[Sean Troy]

I might not understand your problem, but a refresher course just in case... :D

(1) Jointers don't guarantee parallel sides. A board coming out with a taper isn't unexpected. As long as the face it gives you is flat and perpendicular to the fence, then that is all you can expect. Once you have flat references, you use a planer for opposing faces, and a table saw for opposing edges.

(2) Why are you turning boards around while jointing? You want to consistently orient the board so you aren't lifting the grain.

(3) If you don't turn boards end for end, and joint two boards for a glue joint, does the wood come together, or is there a gap? And if there is a gap, where is it?
I was switching end for end because the jointer wouldn't cut past the half way point on the board. It would keep cutting the first half no matter how many times i passed it through but not past half way.

[Elijah Fontenot]

Sean: I had a similar problem and I thought the tables were set up right but found that the rear table was not quite at the correct height. It wasn't off much but when I reset it it fixed it.
Good Luck
Bob


I have to agree with Robert on this one. I feel that i understand what you are talking about b/c I too had this problem with my jointer. My problem was that my outfeed table on my G0490X was out of whack by a little (the end of the OF table was lower and needed to be raised a little) and once I read the manual and adjusted it....It corrected my problem.

Put a reliable hard straightedge on the outfeed table and over the cutterhead ,without touching the cutterhead knives, and onto the infeed table and see if the straightedge is at an angle or parallel to the tables. That was how I saw the misalignment of my jointer tables.

I hope you figure out that issue and good luck!

[Bill Orbine]

Other than table alignment, any nicks in the knives can cause the board to ride astray from the outfeed table of your jointer.. something to think about. Or knives could be dull. Or even your feed rate can be too fast.

[John Coloccia]

I was switching end for end because the jointer wouldn't cut past the half way point on the board. It would keep cutting the first half no matter how many times i passed it through but not past half way.

Ah. So it's wide in the middle and narrow on the ends? The first problem is that it's very difficult to put such a board through in the first place without wobbling. That said, this could also be because the outfeed table is angled backwards. As the board moves onto the outfeed, it will tip up in back and you'll not hit the last half of the board. I think you said you checked this, but I'd recheck it just to be sure by setting the infeed and outfeed to the same height (i.e. set the infeed to a 0" cut), and that straightedge should lay dead flat across both tables, or at least shouldn't be wobbling on a high point in the middle.

[Ted Wong]

Sounds like your tables are out of adjustment.

[Sean Troy]

I'll recheck the tables again when I get out in the shop today. It was mentioned that the end of the outfeed table may be lower than the start of the outfeed. Can this be adjusted? I thought the tables moved up and down but no ability to tilt? thanks all for the help, Sean

[Chip Lindley]

I was switching end for end because the jointer wouldn't cut past the half way point on the board. It would keep cutting the first half no matter how many times i passed it through but not past half way.

Ah Ha! Now the truth comes out!

Even with a jointer perfectly aligned, a bowed board, convex in the center will do the same. The center of the board must be cut down first. This is "eyeball" work at the jointer when dealing with rough lumber that is twisted, bowed or warped. But, if you are starting with a straight board and getting taper, there is either a machine or operator problem.

Technique makes a big difference. Shifting weight to the outfeed at about the midway point of the board is normal practice. You may be shifting your weight too soon. Try keeping your weight on the infeed until about 3/4 of the board is by the cutterhead. See if you do not get more "flat" and less "V".

If technique makes no difference, your outfeed table may be sagging at the outer end. Visualize it! You feed the first half of a flat board across the cutter, and that flat portion seesaws "downhill" on the outfeed table. That lifts the trailing edge of the board off the infeed table and the cutterhead will not touch it. On a jointer with inclined ways, thin shims will have to be added to level the outfeed.

If neither of these makes a big difference, lower the outfeed table just a "thou" or two below the knives. Some experimentation is in order to find your jointer's sweet spot. Let us know what happens next.
~Chip~

[Tom Hammond]

It took me a while to understand what the problem is. I think I have it now. Assuming your cutter height is not too low and properly matches your outfeed table, which from your posts I am ASSUMING you have checked... then:

Two things:
1. Your cutters are dull and the board is being pushed up by the cutters as you advance it. You might think the cutters are new, sharp and/or wonderful. I can almost guarantee you they are not. I learned this the hard way on a oak staircase. I ruined two 6-ft long 18 x 5/4 oak treads until I realized the problem. My stock was doing EXACTLY what you are describing. It was not a cheap lesson, and one I remember VERY clearly.
2. You may be jointing the convex edge of a bowed board.


Sharpen/replace your blades, or move your fence so that you are using a sharp section of the cutter. Also, make sure you joint the concave edge of any bowed board, then run it through your table saw to give parallel edges, then back to the jointer for cleanup.

[Sean Troy]

It took me a while to understand what the problem is. I think I have it now. Assuming your cutter height is not too low and properly matches your outfeed table, which from your posts I am ASSUMING you have checked... then:

Two things:
1. Your cutters are dull and the board is being pushed up by the cutters as you advance it. You might think the cutters are new, sharp and/or wonderful. I can almost guarantee you they are not. I learned this the hard way on a oak staircase. I ruined two 6-ft long 18 x 5/4 oak treads until I realized the problem. My stock was doing EXACTLY what you are describing. It was not a cheap lesson, and one I remember VERY clearly.
2. You may be jointing the convex edge of a bowed board.


Sharpen/replace your blades, or move your fence so that you are using a sharp section of the cutter. Also, make sure you joint the concave edge of any bowed board, then run it through your table saw to give parallel edges, then back to the jointer for cleanup.
I hope the blades are not dull, there brand new. I think some people are picturing the board being jointed on the face, it's not, it's the side grain, 3/4 inch thick. thanks, Sean

[Sean Troy]

It was the outfeed table height that seems to have been causing me the problems. I spent a lot of time adjusting by just the smallest amounts and it seems to have a sweet spot that is tiniest amount from one way or the other. Thanks all for the help. Now I can move on to the next tool problem.

[Tom Hammond]

"Outfeed table not matching the cutter height" strikes again.

Your life just got a ton easier. Congrats.