Dazed and Confused about jointer operation on crowned board

[scott vroom]

OK, I'm getting all wrapped around the axle on operating my new 8" jointer. Here's the problem: I have a crowned board that I want to face joint flat. I place the board on the jointer in the "frown" position then feed into the jointer blades. Where do I apply downward pressure to the board as it first makes contact with the blades, and where do I apply downward pressure on the board as it passes over the blades until the pass is completed? It seems that downward pressure can be applied at the very front and very rear edges of the board only; applying downward pressure at any time over the middle of the board will defeat the effort to flatten the board (and will leave me with a thinner and still crowned board. If only applying pressure on front and rear edges, I'm going to find myself in an awkward (and dangerous) stance on longer boards.

Help!!!!

[Leo Graywacz]

If your goal is to make a flat, true, straight board then you have the right idea. You can't put any pressure on the board that will change its shape otherwise it won't become true.

Most of the time I will put the board in the smile position to flatten a board. But if you have a bow that is larger than what you can take off the board to make it true you have two choices. Use another board or put pressure on the board and make it closer to true.

[Rod Sheridan]

Hi Scott, first visualize a line connecting the two lowest points on your board, then look at the gap from this line to the bottom of the middle arch.

That's the amount of wood that would have to come off the ends to begin making the board flat.

As you can imagine, if you have more than say 1/4" of gap, you probably can't use that board. Cut it into shorter boards for other uses.

So, if you decide that you can flatten your board, you put it arch up and feed it into the cutter, once you have some board on the outfeed table, you transfer your feed pressure to the outfeed table.

This is where the "feel" of operating a jointer comes into play, if you push down hard, you deflect the board so you just push down a bit, and pull the trailing edge forward with a hooked push block.

(No downward pressure on the infeed table, just pull forward with the hooked push block).

Hopefully I have understood your question correctly.......regards, Rod.

[Barry Vabeach]

Scott, I usually flip in the other position, and take down the middle hump and find that is easier for me. When you do it the frown way, you get an aggressive cut at first ( because the board is curving down ) - when you do the hump it is a much more gradual increase in the depth of cut. You are on the money with the idea with very light pressure.

[Willard Foster]

How much are your boards warped?

One thing that I find helpful is to rough cut the length, especially if there is a lot of warp. The shorter the board, the easier it will be to get it flat. Also, you will be taking less material off your board.

You can put pressure on just the ends to get started. Taking very light cuts of course.

Sometimes I start with a hand plane to take some of the material off near the ends.

Good Luck,

Bill

[harry strasil]

the best way to get the most board out of a wide cupped board is to rip it in half and do each piece then glue it back together so the grain matches.

[johnny means]

Here we go with the frown vs. smile argument.

I personally am a smile guy. I would place the board crown down on the infeed table. I would apply pressure right in the middle of the board so that both ends were level with each other. I would then start to feed the stock through the cutter. Depending on the severity of the bow I would know that I might not actually begin cutting until some of the board is actually already past the cutter head. As soon as I heard the blades begin to cut I would transfer my downward pressure to the outfeed side of the board and continue feeding. After this first pass I would have a reference surface in the middle of the board. I would also notice that when I placed this jointed surface down on a flat surface both ends of the bow would be approximately the same distance from said flat surface.

Others might do it differently, there morons.

[Leo Graywacz]

Others might do it differently, there morons.

They're.........

[harry strasil]

add me to the moron club.

[Leo Graywacz]

I do it both ways depending on the situation, grain direction, length of board and a few other things that you will know when you see the particular board.

Mostly I try to do it smiling.

[scott vroom]

Very helpful responses, thanks. I can see where it makes sense to cut boards shorter to minimize the amount of crown. Rod's comment about having a "feel" for jointing makes sense also. Because it's a power tool I tend to think that "feel" isn't important. There's definately an art to power tool woorworking and it's gonna take time and LOTS of practice.

Scott

[Joseph Tarantino]

there was an article in wood magazine about using a jointer and a planer to prepare material for building. the jointer discussion addressed exactly the situation you are confronting. i believe it was the june, 2008 issue. the article covered where to position your hands and feet and how and where to shift your weight to effectively prepare the material. HTH.

[Walter Plummer]

I will second what Willard said. Try to cross cut and rip your stock as close to
size as you can + 3 to 4 inches and then face and plane. I used to work with a guy who would take the whole board, 10' or more and joint till it was flat. Of course it was only 1/4" thick on each end but he "won"

[Jim Becker]

Scott, if it hasn't also been mentioned already, shorten the board so it's only slightly longer than components coming out of it. This will insure you can take the least material off the face while flattening, preserving more thickness for final dimensioning. It's also easier to process that way. Any board that is really bowed should only be used for very short components and secondary stock, anyway, for this reason.

[Chip Lindley]

Others might do it differently, there morons.

Yeah, I'mma MORON TOO. Makes perfect sense to have two points of contact rather than a board that rocks in the center. I will use all the help I can get! If that SMILE is really broad, I have no plex about ripping the board in half to obtain more usable stock.