[a1Jim]

See knotscott's first drawing that's how wood is face planed Or flattened on one side.

 

[a1Jim]

 

[Holbs]

let me take another shot at this.

as i have learned the hard way, when you start any project, you need a starting reference for everything that follows. think of a project that you have 10 1"x1"x1" square blocks stacked ontop of each other. If just one of them is not "referenced" to the first, you will have a leaning tower. all measurements, angles, reference points start with the first flat reference face you did on the first block. you base the entire tower on that first block. this is the purpose of a jointer. to give you that first flat face as a reference for everything else.

you run a 2×4 across a jointer. great, you have your reference point. you flip it over and run the 2×4 across the jointer again. you would think the top and bottom are now perfect. they are not. the top face could be 1degree, 2degrees, etc from the bottom face. and those degrees stack up for every inch.

this is what the planer does. by leaving the first 2×4 jointed face on the bottom, as the 2×4 feeds into the planer cutter heads hitting the top of the 2×4… it is always constantly being referenced against the perfect bottom. end result, perfect parallel top and bottom to EACH other.

plus, with a planer… you can say i just need 1/32" off the top to make the board exactly the size i want. or 1/8th, or 1/4th, etc. Hence the name Thickness planer as you can whittle away at the thickness of a board.

 

[knotscott]

"Another question springs to mind: given the twisted in/twisted out issue on a planer, what is the method for flattening boards? "

The knives on the jointer head are positioned precisely at the same height as the outfeed table. The infeed table is slightly lower, and can be adjusted to take a larger or smaller amount off. The difference between the height of the infeed and outfeed tables basically causes the cutterhead to remove all the high spots, until there is no difference between the high spots and the low points. Any deviation in the board that's higher than the height difference of the tables just gets skipped. It often requires multiple passes, depending on how large that difference is, until it's removing the same amount the length of the board. It can be a difficult concept to grasp (and describe) in theory…..eventually a light goes on, and you'll get it.

Here's a pic I plucked from Wood Mag's website:

Here's a series of pics from Stephan Woodworking:

1st pass:

2nd pass:

3rd pass:

And yet another from Happywoodworking.com:

 

[FeralVermonter]

Holbs, Jim, knotscott, all of you, thank you, the light just went on.

I get it.

So let's say I have a table saw and a planer (I don't) and let's say I'd like to get a board perfectly straight and square on both faces and both edges. I joint one edge. I make a parallel edge with the table saw. Then, in the jointer, I flatten one face. Then, using that flat face as my reference, I flatten the other face in the planer. Right?

 

[knotscott]

Without a jointer, the steps should be to flatten a reference face first with a handplane or planer sled first, then place the opposite side with the planer. Then edge joint an edge with a TS sled or router, then use that edge as a reference against your TS fence to trim to final width.

If you have a jointer, you flatten a face first, put the flat face against the jointer fence and edge joint a 90° square edge, then use the planer on the opposite face, and rip to width on the TS using the jointed edge against the TS fence.

A TS ripping sled for edge jointing without a jointer:

 

[LeChuck]

I would venture to say that the term "jointer-planer" would come from the fact that you generally "plane" one face, and you "joint" one edge. It doesn't have anything to do with the functionality of what we now call a "planer", which is really the misnomer in my opinion, and should probably be called a thicknesser.

 

[FeralVermonter]

I think you probably got it, LeChuck. Makes good sense.

Sorry, in the example I posted earlier, I meant "if I have a TS and planer" and the jointer that I do actually have. I suspect, knotscott, that you thought I was talking about squaring up a board with only a saw and planer. But I do have the jointer (or will, when it's finally fully reassembled) and I also have a radial arm saw that's in pretty good shape. Seems like I should be able to square up fairly small boards, between the two-let's say no more than 1 3/4" to a side. Might not be perfect… but it's what I have, now, and moreover I think I might actually be able to pull it off, and I've been meaning to make some cutting boards…

Next up on the tool-restoration list, though: the ancient rockwell table saw tucked away up in the barn… and then we'll be cooking with gas…

I want to thank you all again. It's really, really cool of you all. Heading out now to tune up the jointer (or go inspect the tablesaw… or get distracted by that cool old bit brace…)