Jointing Opposite Faces
George VondriskaDescription
I get asked, all the time, about using a jointer to face joint opposing faces of a rough sawn lumber. Will this work? Can it be done? If not, why not? The answer; a jointer will do a great job of getting two opposing faces smooth and straight, but it WON’T guarantee that the two faces are parallel to each other. The problem is that, if the two faces aren’t parallel to start with (and from a sawmill, they won’t be) you can’t make them parallel on a jointer. This is a bad start to a woodworking project.
The right approach
This is a great application for a jointer and planer working together. Once you have one face of the board flat, take it to the planer and you’ll be guaranteed flat faces, parallel faces, and uniform thickness.
When SHOULD I use a jointer?
Although the jointer isn’t the right tool for face jointing opposing faces of rough sawn lumber, it’s great for lots of other jobs, and a must-have tool for getting your lumber true. We’ve got lots of great info if you’re wondering “what is a jointer used for?”
Jointer techniques
Jointers aren’t the toughest tools to master, but there are subtleties that will help your work come out better. Be sure you’re confident about how to use a jointer before diving in on your first project.
For more info
Learn more about how to machine your rough sawn lumber perfectly square by watching Post Haste Project: How to Square a Board.
Question I've had asked of me a bunch of times is, I buy my lumber rough sawn, I own a jointer, can I resurface my faces using nothing but the jointer? And the answer is no, don't do it!! So that's what we're gonna talk about here. We're actually gonna joint two faces here, and I'm gonna show you why it doesn't work. So, let me talk you through the procedure first. One might, one face down on the jointer, make a pass, get that nice and smooth. Flip it, other face down, make a pass. Here's where this goes wrong. What we don't know in the result is, are we getting those two faces parallel to each other? So let me start by jointing a face. We'll move on from there. We've got one face nice and flat. That's what face jointing is all about. Now, let's go ahead and flip this over and we'll see what happens, and then we'll talk about why this doesn't work so well. All right. Well, here's where we've got. Smooth, flat face, smooth, flat face. Jointers excel at that. What we don't know is when we flip this over and we make that second pass, is a giving us two faces that are parallel to each other? Well, let's see if we did or not. I've got a set of digital calipers here. So I'm zeroing 'em out. And then we'll take a reading. On this end of the board .9285. On this end of the board, what we can already tell it's kerflooey. 0.9835. This end is thicker. So the deal is that, when we're taking that face from the sawmill, resting that on the jointer and making a pass, we're making that sawmill face straight and flat, but we don't know if we're getting parallelism. And obviously, in this case, we didn't. So at the end of the day, the real answer to this is, you have to joint one face flat. Then you have to go to a planer, and with the face you just completed down, plane the other face. And a planer will succeed in getting the two faces parallel to each other. And it also gives you the benefit of, every piece that we plane at a given setting is gonna come out exactly the same thickness. Because the other thing we run into here is, a couple of passes on this board, a couple of passes of the next board, a couple of passes on the next board. Are they all gonna be uniform in thickness? We don't know, the jointer doesn't provide that. So the perfect procedure for this as I outlined is, jointer-planer combination in order to get your material smooth to faces, and the faces parallel, and the thickness of the material uniform.
What about just using a planer on both sides of 14' rough cut lumber then rip one side straight, flip and rip the other side, 14' lumber is kinda big to run over a jointer you can do this on over sized parts then trim the waste off to size. This should give 4 sides squar or will it be out? At what point is wood good enough. Because it moves, metal also moves just not as much. I worked in a machine shop for 7 Years trust me metal moves. Heat and cold will change metal just not as far as wood will. I also use a digital caliper in woodworking but seriously 5thou tolrances in wood is ridiculous. It might work for jigs to set them up but don't count on it staying that way. Aircraft alumian 6061 and plexi glass or HDPE plastic. Most carbide cutting tools will work on this type of materials I'd use a 80 tooth no hook blade ment for this type of material.
I seek to always get wedge shaped boards when face jointing. The jointer removes more material from the infeed end of the board no matter how much pressure, or where the pressure is applied on the board as it is fed over the cutter.
Can you use a thickness planer to accomplish both tasks? I make signs on a CNC. I purchase 2x12 redwood boards. They are air dried, but I let them sit for while and dry out further. Often they are cupped to some degree. I just run them through the thickness planer, alternating sides until pencil lines I've placed upon both sides widths, are gone. It seems to work.