I'm working on a Nicholson style workbench which has basically been liften from Mr. Schwarz's book. I don't have a workbench to speak of in my shop, so this seemed like a necessary first project. After letting the wood dry in my shop for several months, it seems that the top pieces have a good amount of twist, bow and cupping in them.

Here is the base (it is 100% rock solid, though not 100% true and square):
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Here is the best way to explain the issue I'm seeing with the top pieces (there are other pictures below but this shows the problem best):
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So, how does a guy with a minimal amount of experience working wood and his sole jack plane go about solving this problem? I've never glued up a top (did I say I was in over my head), so I'm not sure how much twist/bow/cupping I can pull out via simply clamping up a jointed edge.

Here is my thought:
- Rip the worst of the boards down (the bench is 27" wide and I have 3 2x12s so there is some extra I can cut off)
- Add a few more stretchers to the design, and anchor those stretchers to the aprons
- Glue one top piece to the aprons & stretchers and use screws to force the boards flat after I do some hand planing in the worst areas
- Joint the next top piece and glue/clamp/screw to the first piece attached to the top

A few questions:
- How much twist, cup & bow can a guy successfully remove from a 2x12x96 using the process I mentioned above?
- Is it better to have the cup up or down on a workbench?
- Would it be best to rip all the boards in half so I'm only flattening a 6" wide board rather than a 12" wide board?

Note, It would be easy to just give up on this lumber and buy more, but I'm already over budget as it is for this bench so I'd really not like to start over. I also don't need the bench to be an heirloom to my family, if I have to replace it in 5 or 6 years, I'm okay with that. I just need something to help me get started on this hobby.

Thanks in advance for the suggestions...

Here are some more shots of the boards:


IMG_1766.JPGIMG_1767.JPGIMG_1768.JPG