I don't understand jointers!

[wisardd1]

I have a Dw735 planer. I don't understand jointers at all. I know nothing about them. Any education would be appreciated.

dale

Oh yea, I am still very ignorant about all this stuff.

[Beamer]

Ok ... here goes

A jointer:

A rotating cutter head that spins toward the right (usually). There is an infeed table on the right and an outfeed table on the left. There's also a fence that runs parallel here.

The job of the jointer:

To create a flat and straight surface on a piece of wood where none currently exists. Also to use a reference surface to create a second flat and straight surface at a given angle relative to the reference surface.

That's it. That's all a jointer does. And it's the only tool that is designed for that purpose.


Now .. how that differs from a planer:

A planer is a cutter head that rotates above a working surface. They usually have rollers that feed the wood through the machine while the cutter takes wood away from above.

The job of the planer:

To use an EXISTING reference surface to create a 2nd surface that is parallel with that first surface.

That's it. That's all it is designed to do.

You can't put a banana into a planer and expect a flat rectangular shaped board to come out. Banana in, banana out. The feed rollers will press down and flatten out any cupping and a bowed board will just come out a thinner bowed board.

Now - you can get a planer to do some of the job that a jointer does if you put your time and energy into it. You can plane out the cup if you can somehow prevent the rollers from flattening the board out, same with a bowed board - you can put the board on a sled (which is flat) to serve as your existing reference surface and then use wedges and such to support the board where it isn't resting firmly on the sled so the feed rollers don't push it down. Then take light cuts and eventually you'll get a reasonably flat surface with which to run through again without the sled and make a parallel face.

Jointer is step 1 after rough cutting to length. Planer is either step 2 or step 3 depending on your process.

I like to do this:

1. Joint a face flat.
2. Plane the opposite face true
3. Joint an edge square
4. Rip to width

I do this because with grain direction, having two flat faces quadruples my options for feed direction when trying to square up an edge. Others like to reverse steps 2 and 3 to avoid having to leave and return to the jointer.

[rrich]

Dale,

What Jason offered is a good technical explaination, let me try to add something in the context of work.

Ya know that long 24" hand plane that you have in your tool box? Well think of that plane held upside down in a vise and you push wood through it.

A jointer is about the same thing except that it has two real advantages.
First, the in-feed table is adjustable up and down.
Second, there is a fence that is usually at a right angle to the in-feed and out-feed tables.

You use a jointer similar to a hand plane. Usually the first step is to flatten one face of rough cut stock. The stock is placed on the in-feed and held gently down as the stock is moved over the blade. As the stock passes over the blade, the down pressure is gradually transfered to the stock on the out feed table. (The concave side of the stock is always jointed first.) Typically, the in-feed table is about 1/32" lower than the out-feed table. (Sometimes less) This means that you will remove 1/32" of stock per pass.

After the stock is flat on one face but not necessarily smooth, an edge can be squared to the flat face. The squaring operation is done by holding the flat face against the fence and then feeding the edge through the jointer. When the edge is straight, square and smooth the stock can go through the planer. (Jointed face down.)

Your planer is used next to flatten and smooth the opposing face of the stock. When this face is smooth and flat, the stock is flipped over and then planed to the desired thickness.

I realize that I added a few work related steps in the definition but it helps if everything is explained in the context of work.

[Ruffnek]

Dale,

Here's an exaggerated sketch of how a jointer works. The infeed table is set lower than the outeed table. The stock is fed along the infeed table, into the rotating cutters which are set a hair (literally) higher than the outfeed table.



When a portion of the stock is over the outfeed table, downward pressure is then applied to that portion and the remaining stock fed. Depending on the depth of cut and the uneveness of the stock, it may take one or several passes to get the stock flat on the side that is against the tables and cutters.

Once there is a perfectly flat side, it can then be placed against the jointer fence and one edge "jointed." As Jason explained, that edge is now 90° to the jointed face (assuming the fence is set at 90°.

It can now be run through the planer and thicknessed to the desired thickness. The planed face will also be parallel to the jointed face.

Now, rip the stock to width plus 1/16" or so (depending on the jointer depth-of-cut) and then joint the ripped edge to remove any saw marks and bring the stock to final width.

Now you have a four-square board. The two faces are perfectly flat and parallel to each other. In addition, the two edges are
90° to the faces and parallel to each other.

Although there are other ways to "joint" a board, the power jointer is the quickest and easiest to master. It also works in tandem with the planer to produce the four-square stock necessary for accurate woodworking.

Edit In: Here's a link explaing the process... www.wisegeek.com/how-is-a-jointer-used-in-woodworking.htm

[Leo Voisine]

The other posters have said what I would say - so I will ad in just a short point.


Jointer:
The reference platen (bed) is shared with the cutter.
This is why it can "flatten" and "straighten", but cannot thickness(easily).

Planer:
The reference platen (bed) is opposite the cutter.
This is why it cannot "flatten" and "straighten", but can thickness easily.

Jointing must happen first - then thicknessing.

The WORDS really are wrong. A jointer, should be called a planer. A planer should be called a thicknesser.

[sawduster]

My 2 cents. First off, while you do want to use sustained downward pressure on the board while feeding it through the jointer, you don't want to apply so much pressure that it forces any bow out of the board, else it will not remove the bow. Instead, it will continue cutting wood from the concave area leaving the board bowed.

Once you are removing wood from the entire length of the board, you are finished on the jointer. Time to move to the planer. If you continue on the jointer it will continue cutting on the flat surface created and this flat surface is likely not parallel to the other surface so will eventually create a board with a point at one end.

The comparison to hand planes is a good one except that the configuration of traditional hand planes has the bed in front and behind the blade on the same plane where-as the tailed jointer has those on parallel planes, one being about three skidges higher than the other. This is a benefit to tailed jointers because it somewhat automates the process of making a coplanar surface on a board, where-as one must use finesse and discretionary planing to make a planar surface using a hand plane.

[wisardd1]

So I guess since I buy my wood three sided finished typicially, I don't need one. Thanks for all the feedback I appreciate it. ONe more question is this the process of milling or is there some other machine for that?

[lexrex]

If you buy your wood 3 sided milled already and it's dead flat after a week in your house I would be amazed I would take a close look at that wood you buy with a quality square and see how good it is after it acclimates.

[Leo Voisine]

Jan 17, 2010 10:29:13 GMT -6 wisardd1 said:

So I guess since I buy my wood three sided finished typicially, I don't need one. Thanks for all the feedback I appreciate it. ONe more question is this the process of milling or is there some other machine for that?

"Milling" - I would gander is just a word to describe work being done in a place called a milling shop.

In that shop they would first face plane (jointer on the wide face) to make a flat surface.

Second they would edge joint one edge (jointer) - using the newly face planed face as a reference plane - and then make a 90 degree edge.

Thirdly, they would thickness the opposite face (thickness planer). This would make the two faces parallel to each other.

Lastly, they would rip the opposite edge (table saw) - using the jointed edge as a reference plane - that will make the two edges parallel.

The system is called "FEE" Stands for Faces - Edges - Ends.

You get one face flat, then get one edge 90* to that face, then thickness for parallel faces, then opposite edge for parallel edges.

I saw mill might not use "exactly" this same method - but their method will be similar. Sometimes they have machines that will plane both faces and at least one side all at one time.

If you don't have a jointer - and you want the mill to give you a flat face and one square edge, the term for that is S2S, or surface two sides. From that you can finish the job at home. You will run the wood through your planer - with the surfaced face down - than you will rip on the table saw with the surfaced edge against the fence.

[Joe Lyddon]

Same picture as Cody's modified to stress a point...



Now, as soon as you have a straight edge on the OUTFEED, weight should be placed on IT so as to keep it being cut straight... The crappy edge will be cut off taking a straight edge to the outfeed.

[sawduster]

I noted this when I first went through this thread, but neglected to mention it before. Note the grain direction in the drawings posted by Cody and reposted by Joe. That is the direction of feed you want to use if it is possible, so that you are cutting into the falling grain. You might have issues with tear out if you go in the other direction.

[jim@jlazy3]

Well, not to confuse things to much, because I do recognize the benefit to having a jointer, and will likely buy one some day....I do not own or use one.
If I have a particularly twisted board in the pile, and I just have to use it, I'll put it on a planning bed, and shim up the high spots and make the repetitive passes necessary to get it flat. However, the one thing that is never mentioned when there's a discussion about making straight boards out of warped and twisted ones is that warped and twisted boards will return to their previous warped and twisted shape after all of this jointing and planing if said board is not glued, screwed, or someway fastened to or within something permanent ASAP.
I have had to rebuild a couple of flat panel glue ups because the "newly flat" boards didn't stay flat!

Personally, I sort the lumber I'm buying pretty carefully, and I leave the questionable stuff right there. I also buy S2S 13/16 as much as possible. I edge joint at the TS (with a piece of laminate at the outfeed side of the blade) if necessary. A jointer would make edge jointing, when needed, a bit faster, but after all of these years of cabinetry building, I still don't own/use a jointer.

IMHO, a jointer is not at the top of a "must have" budget list.

[Joe Lyddon]

I use my planer like that too... ;D

Also, if you mark the Factory edges & cut accordingly, one can run pieces (several at a time) through the planer (jointer) taped or clamped together, to get all of them basically "jointed".

... and one can always use a router fence, on a router table, to perform the Jointer function too. ;D

[sawduster]

Personally, I sort the lumber I'm buying pretty carefully, and I leave the questionable stuff right there. I also buy S2S 13/16 as much as possible. I edge joint at the TS (with a piece of laminate at the outfeed side of the blade) if necessary. A jointer would make edge jointing, when needed, a bit faster, but after all of these years of cabinetry building, I still don't own/use a jointer.

I seldom use my jointer for flattening faces. It is only a 6" model, and an older Craftsman with a fractional HP motor, so lacks the capacity to joint wide boards. By careful selection of lumber I avoid having to take too much off of faces, and will often glue up panels then use hand planes to flatten them as needed. I even use other methods for edge jointing long pieces that exceed the effective length capacity of the bed of my jointer. I went without a jointer for a long time and got the one I did because it was too good a deal to pass up. I also take a couple of passes with a finish plane over edges that have been jointed by machine that will be glued up to make panels. I find that it takes a couple passes at something less than .002" thick shavings with the finish plane before I'm getting a full length shaving. This removes the little ripples left by the tailed jointer and makes for invisible glue lines if I have matched the grain well.