Jointer Question

[Eldon]

Greetings to the group.

I have a Gizzly 8" jointer and have recently discovered a problem of which I need help with. While edge jointing some cherry I was thinking about something else while preforming the task. I suddenly realized that I was making a real nice wedge, rather than smoothing the edge of the rough sawn wood. I was taking off about 1/4" at a pass. The fence is dead on at 90 degrees. I placed a 4" level across the bed and things seem to be in order there. What the heck am I doing wrong? After finding this problem I then tried to edge joint a piece of red oak and again the same problem. I haven't used the jointer all that much, but when I got it I edge jointed some poplar so that I could do a glue up and it seemed OK.

What am I missing here?

Thanks in advance

Dave

[nailshooter41]

My guess would be technique if you are confident that the machine is set up correctly. Even pressure is the key to good technique. The longer the board is, the harder that is to accomplish. And the more times you run the board through the jointer, you may wind up magnifying the problem.

Probably anyone that has used a jointer has made their share of "tapered legs" before getting it correct.

This page says it all better than I could in respect to diagnosing jointer problems. Scroll down to "techniques":

[Leon]

Well, 1/4" per pass seems awfully steep and wasteful. Why are you using a

4" level to check your jointer? A jointer does not have to be level to work properly, you need a strait edge. Even properly set up jointers do not insure against a tapered board. After jointing one edge or side use a TS or thickness planer to make the opposite edge or side parallel to the one straightened or flattened on the jointer.

I suggest taking lighter passes, much lighter, maybe 1/16" Use a long straight edge to determine if the in feed and out feed tables are co planer and insure that the cutting depth is no higher than the out feed table. Make passes only until that edge is straight or flat. Do not try to take the resulting taper out in the jointer.

[Phisherman]

Do a complete jointer tuneup and don't skip any steps. After the tuneup you will know that the blades are 90-degrees to the fence, plus there are dozens of other things that could be wrong. The 1/4" is excessive--1/16" is better. Review the proper technique to using a jointer--keeping the stock tightly against the fence and body posture/weight shift during the cut.

[StephenM]

My preference is to take less than 1/16... more like 1/32. I always expect to take at least 2-3 passes on relatively straight rough-cut lumber. Jointing is an iterative process.

More technique hints:

1. Make sure you rough-cut to length before jointing . It is much easier to accurately joint a 3' piece and than an 8' piece, and it wastes less wood too.
2. Almost all boards have one concave edge and one convex edge. Always joint the concave edge. If you must joint the convex edge, take a pass or three in the middle of the board (don't cut into the first or last six inches) This will cause the board to ride in firmly on the ends rather than rocking on a center point when making a final full-length pass.

Also:

At the risk of sounding anal, jointing is intended to straighten/flatten stock, not smooth it. Smooth and flat are very different things. Some folks "smooth" a less a coarse TS cut with a light pass on the jointer. A jointer can leave a very nice surface if the grain is all going the right way. I seldom see stock without some grain reversal. I prefer to do smoothing with a card scraper.

-Steve

[Jim Weisgram]

[...snip...]

You need something more accurate. Metal straightedges of sufficient length for your purpose are very expensive. I just saw a tip at Fine Woodworking about making a "straightedge" out of MDF, for this purpose.

It showed how to get 3 screws along the edge of the MDF piece set to an accurate line.

It is an adaptation of a well-known method of creating a metal straightedge without an accurate reference surface, from 3 non-reference but straight lengths of material (usually metal).

It requires 3 boards to make 1 straightedge; you have to adjust the screws between all 3 boards to ensure you have an accurately straight edge.

[Frank Howell]

A 4" level? Did the jointer deplete all your funds? If you read the manual, you will find that you need a straight edge to determine if the infeed and outfeed are coplaner. The level will tell you if your jointer is level with the floor. When you say "wedge," do you mean that leading edge is narrower then the trailing edge? If so, then this is an indication that the knives are set to low. If knives are set to high, you will get snip on trailing edge. A quarter inch! That must be some very rough lumber.

[George]

Pssst, Frank, he's jointing, not planing a surface. Makes a 4" level pretty good for checking a 8" dimension. Though that's not the problem. If the knives are square to the fence all the way across, and the outfeed ditto, things should work.

That is IF he's using a flat enough for long enough face against that fence and maintaining proper pressure against it. One should, of course, sight for high spots on the edge of the board and remove them first or spend a lot of time trying to straighten a board. I'm assuming that 1/4" refers to the diference between the end and the middle of a bowed board, as anything else would demand something so loose as to be immediately noticeable even on a Grizz jointer.

Had one at the school in those grant tools that had nearly a 1/8 difference between the L side of the head and the table. Made the knives a joy to set, but we did get a replacement eventually where the difference was much less.