[darsunt]

I want to cut boards very straight for door casements, and for beams to straighten out walls. But the boards from the lumber yard are all warped and crooked to some degree. When I run the boards along the fence on my table saw, I'm guessing the imperfections are reflected in the cuts.
Is there a trick to using a table saw to get really straight cuts? Or is my table saw too small? I have a DW745 dewalt.

 

[Larryh86GT]

One way is using a table saw ripping sled which is a piece of plywood with a straight edge that slides along the fence, attaching the board you are ripping with either clamps or screws to the sled.

 

[DannyT]

larry is talking about something similar to this

http://www.prowoodworkingtips.com/Table_Saw_Rip_Sled_Plan.html

 

[woodworkbykirk]

sight your lumber before you buy it.. pick out straight lumber and set aside crooked ones

 

[carpdad]

There is cheap way to go which is a clamp that looks like H. You get a straight board (but may warp quickly) or get a 3/4 better grade and flat plywood and cut a 4-5" rip piece to use as a straight edge. You clamp the straight edge and warped board together to cut the warp out on a table saw. Wood working stores should have it in the catalog.
But buying the straightest boards will be cheaper. Cutting the warp out means you waste a lot of wood. For 1x casing, pine, 1/8" warp in the middle of side jambs can be easily worked out by working the board as you nail into the jack stud.

 

[kaschmid3]

If its paint grade try clear poplar over pine generally straighter