My neighbor taught me with a power feeder. He set it up for doing the face and then the edge. He then walked me through what the feeder was doing and why it was positioned where it was. With a power feeder (not that you're likely to have one) you can watch what's happening from different angles. Then he taught how to safely use it. From there I spent days doing about 1000 board feet of a mixture of cherry and maple. The problem is once you get the face flat and the edge straight and perpendicular to the face you can only start over one more time by flipping it when practicing. You can plane a board down to almost nothing making adjustments along the way.
If you have proven to yourself that the outfeed table is level with the blades, then you might be putting too much pressure on the infeed side in the middle of cut, or not enough down pressure on the outfeed side. If your board is thin, say 4/4 or less, you might actually be bowing the board a little with pressure on the infeed side.
Brian
"Any intelligent fool can make things bigger or more complicated...it takes a touch of genius and a lot of courage to move in the opposite direction." - E.F. Schumacher
Use push pads, not blocks. Pads allow you to push the wood 12" past the cutter, then push the wood through by bearing down on the outfeed table. Pressing on the tail end of the board requires you to put weight on the infeed table, resulting in concave wood. Putting the concave side down, and hitting the ends first, allow one to quickly get a flat board.
I learned these techniques from a shop foreman when I was working in a mill room when I was a kid. I had the opportunity to review his instructions by face jointing cart loads of wood for weeks on end, until I was good enough to run the rip saw for a while. He told me that if I was going to feed wood by pressing down on the tail end of lumber, I would be fired. They needed wood flat in a door shop, more than they needed my smiling face.
I use Marshalltown concrete floats from Home Depot. The sponge rubber has a coarse texture that catches well on the wood.
Another choice for a red rubber grout float:
https://www.homedepot.com/p/Red-Rubb...8003/301651136
< $6
-- Andy - Arlington TX
A professional woodworker friend told me about an interesting technique that I wouldn't even consider trying. When he is jointing pieces for a table top (or I assume any flat surface) he purposely makes the boards concave on the edges. When he prepares for glueup, he only needs one clamp in the middle of the table. Both ends are in contact and the clamp pulls all of the inner edges into contact.
For months, I couldn't figure out why my boards were not jointing dead flat. I studied the videos and practiced and practiced, to no avail. One day, I decided to concentrate on adjusting my jointer as close to perfect as possible. I bought a good 4 foot straight edge and a good dial indicator and spent about 8 hours on, knives, tables, everything. When done, I ran a test board and guess what? The adjustment solved all of my technique problems.
Not to say that technique has nothing to do with jointing flat surfaces, but if your jointer is not properly adjusted, all the technique in the world isn't going to produce flat boards. Jointer adjusting is a real give and take operation. A tweak here, produces a tweak everywhere, so there's a lot of back and forth to it. There's also no room for "that's good enough", because it likely isn't. Look at adjusting your jointer as a new project. Take your time and enjoy the process.
I generally make spring joints and as Jim mentions, clamp along the entire joint. The purpose of a spring joint is to compress the ends of the joint to avoid having it open during seasonal humidity changes (boards lose more moisture near their ends).
I like a very tight lamination when possible, so I put a ton of clamps on a glue up.
Bumbling forward into the unknown.