I am planning to build a 3pc takedown longbow. Do you really need a wedge in the limbs or can I just use some parallels and glass? What effect would it have if I did it this way?
You will need the area bolted down to be stiff and rigid, this is most easily accompplished by the addition of a wedge.
If you simply used a stack with no wedge, I expect you would have too much pressure on the stack in the area where the riser would end, creating a hinge there. Additionally, the holes drilled through the butt ends of your limbs may weaken them significantly given they are not appropriately beefed up in that area.
I would recommend you use a wedge...doesnt have to be a big thick wedge, but something at least .250 thick tapered down to a paper thin fade. They are generally about 8" long, but will depend on your bow design.
making a wedge is the least of the problems in making a takedown.
It'll probably take you about 10 minutes. and yes they're necessary.
Yeah, you'll need one.
It would be a lot of work for nothing if you didn't use one.
Necessary.... No.
Kirkll turned me on to what he calls a "double barrel limb wedge". Great way to do it. I've seen several 3 piece t/d with no wedge, too.
The limb bend just needs to be moved far enough away so that it does not bend at the limb pads. Without building several or having a working knowledge of how to do it... stick with a wedge.