Is it more difficult to joint longer boards?

[Nick2cd]

I got some scrap 2x4s from the Home Depot the other day to play around with some new woodworking tools I got for Christmas. One of the boards had a pretty big bow in the edge of it. I had some difficulty getting it completely flat with my jointer. The piece I was working with was only about 4 feet long but I felt like it exceeded the effective length of my tables. Is this thought process plausible or am I just making excuses for poor technique?

[thewoodwhisperer]

I personally find it more difficult to joint longer boards. There is definitely a point where the curvature of the board might exceed the table's ability to establish a proper reference surface. If the board is fairly flat, you shouldn't have too much trouble even on jointers with shorter beds. On really long boards, I try to analyze the board by sighting down from one edge. My goal is find the peak of the cup. I put that part facing down and that's where I apply my pressure in the first pass. Orientation should look like a smiley face. After the first pass alone, you should have a significantly larger "flat" from with to reference the remaining cuts.

Now unless you have a really small table top jointer, 4' should probably not be an issue. If you're having significant problems, it would very well be a calibration issue or user error.

[Morton]

I agree with everything Marc said. You can do some removing-of-material by hand too for longer boards with significant warping, to make it easier at the jointer to start with something a little more flat -- just rough out some of the really high spots. Or as Marc said - try to catch just those spots at the jointer first. I'll often do that with twist too - try to carefully hold the board for the first pass to make a nice flat spot to reference for the next passes.

However, I don't think 4' should be too much trouble - depending on the length of the jointer bed. I was having trouble and actually found my jointer to be not calibrated, so had to spend some time getting it back in shape - then things actually worked. So, check your jointer also.

[Screamer777]

I have an board that is not straight. It's a Australian Blackwood (Acacia melanoxylon) board and is about 2.3 meters long. It bows from the one end to the other end. Something like this: ) . It's is about an half inch that it bow from the one end to the other.

My question now is is it OK to cut the board in the middle on than joint it. I compromise length for thickness of the board if I do it.

Any suggestions?

[Nick2cd]

I personally find it more difficult to joint longer boards. There is definitely a point where the curvature of the board might exceed the table's ability to establish a proper reference surface. If the board is fairly flat, you shouldn't have too much trouble even on jointers with shorter beds. On really long boards, I try to analyze the board by sighting down from one edge. My goal is find the peak of the cup. I put that part facing down and that's where I apply my pressure in the first pass. Orientation should look like a smiley face. After the first pass alone, you should have a significantly larger "flat" from with to reference the remaining cuts.

Now unless you have a really small table top jointer, 4' should probably not be an issue. If you're having significant problems, it would very well be a calibration issue or user error.

i think i've isolated the problem thanks to your post, Marc. i was running the boards as a frown instead of a smile. by the time the first point of contact of the frown came off the end of the outfeed table, the tailing end would be referencing off the middle of the board instead of the first point of contact. the smile makes more sense to effectively create a larger and larger flat spot. don't know why i didn't see this before. regardless, thanks to all who helped me out here.

[Vic]

Nick, when I was jointing my 12ft timbers, I was using two outfeed and two infeed rollers. The key is to get the infeed positioned at the tail, so you're compensating for why you're trying to accomplish. A few had pretty good twist and I managed to waste very little.

(null)

[Morton]

Johan - that's the choice -- either take that 1/2" off both ends and loose that much thickness -- or cut the board in half and loose less thickness, but obviously end up with two shorter boards. Hard to join them back up again (depending on the project). A lot of times for major cupping (across the width) you can rip a board down the middle, joint both halves (now much less cup to each) and then glue them back together. That works since it's a long grain- to - long grain glue-up