Jointer Technique??

[Jason Yeager]

I have a Jet jointer/planer, and have had a hard time getting a true edge joint. I consistently get a crown in the joint, more material is being removed from the center of a board than the ends. Seems to be something like a 32nd in 60 inches pretty consistently.

I have checked and rechecked and fiddled and reset the infeed table and have it to within 3 thou front to back and side to side. Any more fiddling and I get it worse, not better. I surmise that is plenty acceptable, so I must be the problem.

Does anyone have any idea what I am doing wrong? I feed the stock into the cutter smoothly with pressure on the infeed table, and after about half the board moves through the cutterhead I shift pressure to the outfeed side.

Thanks

[Dan Friedrichs]

0.003" is fine, you're correct.

There are a few possibilities:
-I assume you're talking about edge jointing, so this is less likely, but make sure you aren't pressing too hard down on the wood, as you may be flexing it, and it springs back when you remove the pressure.

-More likely is that your outfeed table is not coplaner with your infeed table. Do you have a long straight edge you can place across both tables (infeed table fully "up"), and check that they are coplaner? The outfeed table may be tipping downwards.

-Finally, you want to be putting pressure on the stock on the outfeed side as soon as possible. Waiting until it's half-way across is probably waiting too long.

[Myk Rian]

The most important adjustment is having the knives co-planer with the outfeed table. Then, make sure the outfeed and knives are at the same height with a straight edge.
As you move the wood across the knives, put pressure on the outfeed side.

[Scott T Smith]

Does anyone have any idea what I am doing wrong? I feed the stock into the cutter smoothly with pressure on the infeed table, and after about half the board moves through the cutterhead I shift pressure to the outfeed side.

Thanks


Jason, I think that your problem is your techinique. Once the board is started past the cutterhead, you should apply downward pressure to the board only on the outfeed table - not the infeed table. Your objective is to keep the board perfectly flush to the outfeed table over the entire length of the board.

[Darnell Hagen]

Dan's got it, your outfeed table is low on the end away from the cutterhead.

[Rye Crane]

Let's make it three for the outfeed table/cutterhead problem.

Rye Crane

[Dino Makropoulos]

Does anyone have any idea what I am doing wrong?
I feed the stock...

Thanks

If you keep the stock from moving and make a quick pass with
another tool in a control manner ( like a machinist )
you have better results.

[Jason Yeager]

Thanks fellas,

Dino, I am not pickin' up what you are putting down. Could you explain it another way?

Thanks

[Vince Shriver]

If you keep the stock from moving and make a quick pass with
another tool in a control manner ( like a machinist )
you have better results.

huh, say what?

[Dino Makropoulos]

Thanks fellas,

Dino, I am not pickin' up what you are putting down. Could you explain it another way?

Thanks

Jason,
You're moving ( pushing) a piece of wood against a fence
and spinning knifes.

IF you have a perfectly flat face you may get a perfect edge.
Fence and outfeeed table must be perfectly aligned.
Then we have the technique to push and apply just the right pressure
at the right place.
Not impossible but not an easy task.


On the other hand, why not secure the wood and slide another tool,
saw, router, hand held planer, in a control manner.
A homemade shooting board works better for edge jointing.

[Prashun Patel]

How thick is your stock?

With thinner stock, the front and trailing ends can flex and basically flap against the cutting knives instead of riding into them properly. This has happened to me.

I ain't no jointing 'xpert, but if the tables are not coplanar, then wouldn't you only experience probs with one end - in this case the trailing end - of the piece?

[johnny means]

Not impossible but not an easy task.

A homemade shooting board works better for edge jointing.

I don't know about that, any monkey can be taught to straighten a board on a jointer. Good technique is really not that complex. I think a big part of the problem is not having someone there to visually explain how it's done. These types of skills usually don't translate well into text. It really is probably the easiest way to flatten any face or edge.

[Chip Lindley]

I must disagree Dino! This is the work jointers were made for! Other methods you mention are for those who do not have access to a jointer, OR have a jointer which is misaligned, OR have not mastered good jointing technique. Accurate jointing takes a bit of *finesse* and *feel* above and beyond just shoving a board across the tables.

In fact, the OP is getting a *sprung joint*. At times this is desirable when preparing stock for panels, as the ends are assured of closing rather than gapping when clamps are applied. Sprung joints can be made by loosening the infeed table of old-style jointers with dovetailed ways, so as to allow it to droop slightly. Parallelogram jointers will require a different technique.

[Glen Butler]

I haven't seen your jointing technique but I doubt that is the problem. It is difficult to have bad technique on the jointer. You don't need excessive pressure or grip.

I don't use a straight edge to make my jointer tables coplanar. I use the resulting joint to decide what to do with the table. Ok I get it close with a straight edge. Then I joint two boards and oppose them. This tells me if the tables have to go up or down. Spread in the middle means the tables are sagging. Spread at the ends means the opposite obviously. So I adjust. Joint again and see how the joint looks. Readjust if necessary.

[glenn bradley]

Plus yet another one for outfeed table as a possibility. Technique could also play here for sure. Once your stock is a few inches past the cutter head most of your downward pressure is focused past the cutterhead as described. Pressure feeding into the cutterhead should just be adequate to control the stock and feed it.

[Jason Yeager]

thanks for all the information.

One thing I did not mention is that I was using a Lee Valley 50" straight edge, which is able to span nearly all the outfeed and infeed tables, so that I can see if they are coplanar. the 3 thousandths difference is over the entire length of the tables. The infeed is sagging 3 thou, which I didn't think was a problem, which is why I was thinking technique.

[Chip Lindley]

Jason, you might want to check your Lee Valley straight edge against another known flat surface to insure it is indeed accurate. Issues with certain Lee Valley tools have been brought to light in other threads.

[Ken Shoemaker]

When I bought my Delta X5 joiner, it came out of the box perfect. I decided to shapen the knives after a coupler years and the wheels came off. It never worked right since. Itr was causing the boards to taper and I was getting scalloping. It just wasn't what it should be.

Last week I stopped by a glass shop across town and got them to cut me a 12 X 4 X 3/8 inch peice of tempered glass.

I checked the tables with a known straight edge and was satisfied the tables were coplaner. I then set the glass on the outfeed table, letting it hang over the knives. I placed several rare earth magnets on the glass over the knives and loosened the screws. I made sure the cutter head was at Top Dead Center and I could hear the knives click against the glass as they were pulled up by the magnets. I tightened the screws and continued to the next knife. After all three knives were adjusted, and rechecked for tightness, I gave it a try.

PERFECT!!!!!!! It makes ALL the difference in the world....

I want to say this; I am not so smart that I figured this procedure out. I saw it here at SMC on someone elses post. They glued the magnets on. I wish I could remember who it was so I could give them proper credit.

At very least THIS IS WHY one should become a contributor. That $6.00 just made my woodworking experience a whole lot better.

Sorry for the long post...... Ken

[Thomas Pender]

I vote for technique. I tend to doubt the LV straight edge is off enough to cause what Jason has described. I have noticed that if I do not properly apply pressure to the board after it crosses the cutterhead I get the problem you describe. In other words, while we do, at first, apply force into the cutterhead, once the board goes over the cutterhead, if I push down on it as I draw the board accross the cutterhead (and against the fence), I tend to get good results (sometimes I use one of those magnet featherboards to push the board against the fence). Another thing, even with edge joining, if it is a little tiny bit off, it is darn hard to spot on the glue up. Modern clamps 12" a part really push the boards together well.

BTW-I love Ken's idea of using glass. It never occurred to me. However, with most modern jointers now having indexed heads, I think technique will be become more of an issue as time progresses.

[Prashun Patel]

One more point about technique:

You want to apply pressure on the outfeed, but as close to the cutterhead as is safe. This will minimize flex on the infeed side.

[Jerome Hanby]

I've never set up a tall aux fence or other extension to try it, but would a feather board on the outboard side just past the cutter head help make this a more foolproof operation?

[Don Morris]

I disagree with Glen, it is easy to get bad results from a jointer from technique alone. Thus, I wouldn't discount technique for your problem. I've tested this numerous times with different techniques and achieved different results. I bought a 36" machinist straight edge which cost me $$$, but I can test for straight. Depending on how much pressure I put on a piece on my jointer and at which phase, beginning, middle or end, I can get different results. This caused me no end of grief until I realized it was the technique and not the jointer. Once I developed a pretty even technique, or pressure on the piece throughout the process, the boards got much better. This assumes you've done your job on getting the jointer beds coplaner and the blades at the right height. There are several tests to determine if you've done that.

I had read all the jointer manuals, did all the tests and got the blades in the right position and was still getting boards that weren't flat. Someone suggested I analyze my technique critically. When I did, technique was the factor that when I changed it in accordance with the error I was getting, the error disappeared. Wow, technique in my case was the single factor. Again, make sure the mechanical factors are in sinc: coplaner beds, blades at the right height, etc. Then analyze your technique according to the error your getting. Then change your technique in a way that might positively effect a change in the result. Worked for me, worth a shot. The old timers developed it (that sense of touch) over years and years of doing it. It's called practice makes perfect. Just can't replace it.

[Richard Dragin]

Another vote for downward pressure only on the out feed side might be all you need to solve the problem.

It's must not be easy for the OP to figure out the problem when there is so much B.S. in this thread. If you are not sure what B.S. I am talking about it is probably yours.