So I recently aquired a new jointer (yay) and was reading the manual when confusion struck in reference to “open vs straight vs splayed joints”. This is in reference to the adjustment of the outfeed table. It reads as follows: Planer table above circle of cut yeilds open joint – planer table even with circle of cut yields stright joint – planer table below circle of cut yields splayed joint.

I’ve always been taught that the outfeed table should be just a hair (I forget actual measurment) below the cutting head. I thought this would yield a stright joint and had something to do with the wood springing back after the cut. Now i’m questioning the actual reason. In the manual’s statement i assume that open or splayed joint is  essentially concave or convex, but which is which i’m not able to figure out. (I mean if the outfeed table was above the cutting head it would hit it anyways wouldn’t it?)

It also says “the reciever side of the planer table is set so that with a workpiece of length 2m, and open joint of approximately 0.2 to 0.5 mm is produced. This makes me think that open must be concave seeing as a convex joint would hardle ever be desirable. Why is the standard for jointers not a straight joint then, i am wondering. I know that for gluing it can be desirable to have slightly concave joints but if i’m using the jointer for a lot of other things including face jointing I don’t nessearily want that… Any thoughts?

thanks,

ty