I'm looking for some help with a problem I've been having. Through the years I've managed to acquire a planer (ridid 13") and jointer (Delta DJ-20). I've been working with oak lately which I've been buying rough from a good hardwood supplier. To surface the stock I've been cutting it to rough width and legnth. Then I fact joint one surface until it's flat against the jointer bed. The next step, from what I understand is to run the board through the planer, flat side against the bed (down) and plane the board to desired thickness, in this case 3/4". For some reason after I plane it, i put the board down on the jointer bed again and I find that neither surface is flat. For the life of me I can't figure out how this can happen. From what I've read the jointer, and your form, is the biggest source of problems, but once i've found the face to be flat, it should be fine. It doesn't make sense to me how the planer could bow the stock. I've checked the planer and found it to be set up properly (so I think), but even if not, it should only affect the surface being planed, not the other side.
Now, the bow is minor, and with a little pressure i can easily hold the board flat, but I am thinking that it still shouldn't be this way. The only thing I can think of is the board reacting to internal stresses as the supporting wood is planed off, but it keeps on happening across several boards.
I've taken up this hobby to relax me, but at times like this is is anything but. Can anyone shed any light?
Rob