Is tapering the core absolutly necessary. I see the cores come with tapers like .065 to .001, etc. If I do an all wood laminated bow must I taper the laminates, or maybe just one of them, the core? Reason for asking is I have some Walnut and Osage wood and plan on the Osage being in the center with the Walnut on the outsides and the same combination in the riser. Of course I don't want it to break, its to be my own personal showpiece but I want it to be shootable.

The amount of taper you use changes where the limb bends towards the tip. I use as much as .003 on a longbow and .002 on a recurve. With the recurve I'll probable stick with .001 or zero in the future- with the longbow I'm building currently- .003 works. Many bows have all parallels and work fine- alot depends on your design.

Tapers are used to get all of the limbs bending.  If you bend a stick that has the same thickness and width throughout, most of the bend will be in the middle (handle area).  If you taper the width of the limbs it will bend more towards the tips.  The same is also true if you taper the thickness and keep the width the same throughout.  If you taper both the width and the thickness it bends even more towards the tips.

Bows that bend more towards the tips are more efficient than those that don't but may not store as much energy and stack.  It's a balance.

No you don't have to taper the mid lam on an all wood bow. You will more than likely however end up tapering though the belly lam to the mid lam.
Here is an osage lam I did without tapers, you can see the Urac where it goes into the middle lam.
The Yew lams has a taper in the center and therefor has one continuous lam on the belly.
Hope this helps.
Mark

Thanks Trux, Jason,and Mark. Mark, I appreciate the photos. You guys gave me a lot of information, thanks again.