First three piece bow! 2nd Gen starts on pg 13

[Apex Predator]

All right folks, I'm in the prototyping phase again. I'm developing a shorter D/R, forward riser, three piece longbow. I'm thinking 58" nock-nock. I drew up a riser that is 14" long. The bow will be built with 1.5" stock. My limb wedges are 8.25" long. I roughed out a pine riser this morning, but forgot to take any photos. I'll get you guys caught up tonight! I've got one of the pirate riser/limb drilling jigs. I plan to lay the mock-up riser on a piece of butcher paper and start drawing limbs until I hit on what I think is right. I'm thinking around 3" deflex, and bring the string nocks back to just above the back of the riser in reflex. I don't know what my limb pad angles are, because I just drew it out until I thought it looked right. I will know more tonight when I start drawing limbs.

1. What kind of limb pad angle are you guys thinking on this? I'd like to be able to make recurve limbs for this model as well.

2. The holes in my drilling jig are spaced 2.5" on centers, but I was thinking of going 2" between the insert and alignment pin, since the longer spacing is crowding my grip area. What are your thoughts on 2" spacing?

3. How short can I go on the limb pads?

4. The riser will be action-wood from Kenny. I plan to lay up the riser with a 3/16" phenolic I-beam. The riser depth will be 1.25" where the limb bolt insert will be. Is this enough depth?

5. Any good tips in general regarding this project?

I should get my riser block, wedges, and take-down hardware today from Kenny, so I will probably answer some of my own questions when playing with the parts. I'll post some photos of my riser tonight.

[BK in Wisconsin]

All right folks, I'm in the prototyping phase again. I'm developing a shorter D/R, forward riser, three piece longbow. I'm thinking 58" nock-nock.

So 61" AMO?

I drew up a riser that is 14" long. .... I've got one of the pirate riser/limb drilling jigs. .... The holes in my drilling jig are spaced 2.5" on centers, but I was thinking of going 2" between the insert and alignment pin, since the longer spacing is crowding my grip area.

If you're talking about the Ibex Garage Ninny Standard Drilling Jig, then yes you're going to have trouble getting a grip on that riser; the holes are too far apart. 1 - 1.5" between bolt & pin is plenty.

1. What kind of limb pad angle are you guys thinking on this? I'd like to be able to make recurve limbs for this model as well.

That's what's cool about prototyping TD's. Just make yourself a few sets of 2˚ wedges you can place between the riser & the limbs and you can test a variety of pad angles with little to no extra work.

3. How short can I go on the limb pads?

The shorter the limb pad, the more the limb acts like a lever on the bolt insert. Mine pads are 4", I don't know how short you can go. Prolly depends on your design.

4. The riser will be action-wood from Kenny. I plan to lay up the riser with a 3/16" phenolic I-beam. The riser depth will be 1.25" where the limb bolt insert will be. Is this enough depth?

Not sure. The inserts are just shy of an inch long and require a 27/64 inch hole. That's a lotta wood. With a riser well reinforced with glass and/or phenolic it should be enough. The more wood the merrier though.

5. Any good tips in general regarding this project?

Yes. Overbuild the riser. These things seem to want to break.
Run an accent through so that the limb bolts screw into some phenolic or glass.
Another accent just behind the throat of the grip helps relieve stress too.
Back the riser with glass.

[Bobmeister]

Marty, sounds kind of like what I did this last winter. Mine is a 16" riser 1.5" wide. Made up three sets of limbs using a-boo and that cheap GI-bow glass. I still need to experiment some more it shoots good but doesn't feel very fast. I will Probably go with a full recurve limb next winter wen I take this project back up.
We need Sixby or Jess on this they have the experience on this belly mount stuff.

[Apex Predator]

58" as measured along the back of the limb and through the riser. I figured that was amo, and would require a 55" or so string.

I had planned to have a piece of glass laminated to the entire back of the riser.

What is the best way to build a 2 degree wedge?

Nice looking bow Bob! I want mine to be a compact, "assault" bow! I may go 56". What kind of limb pad angle is on yours? I think I may need a little more.

[Bobmeister]

It's has 7 degrees limb beds or 14 total , 60 AMO (57" string)

[Apex Predator]

Thanks Bob! I think if I go shorter like 56-58" I'll want some thing around 9 degrees.

[Bobmeister]

Marty, If you look at the top set of limbs the wedge is thinner than the other 2 sets. It was my first try and the wedge flexed away from the riser too much to suit me. So I made the wedges thicker and they taper both directions, that solved the problem. The mounted set are 60@28.

[Apex Predator]

Wow! I didn't think of the wedges bending at the riser. Mine are 3/8", which should be thick enough. I think I will try to build my own wedges, because these only have about 2.5" of flat surface before tapering. Once I get the limb pads sorted out, I will build a set to match. I appreciate your help Bob.

[Bobmeister]

Here is a quick and easy idea for mocking up a riser. Just take a piece of versa-lam and leave it 1.75 wide and do your holes and ruff cut out. I changed pad angels a couple times on this one by just pulling the pins and bandsawing. riser wood is so expensive

[Apex Predator]

I just put a protractor on my design and the limb pads are 12 degrees. I'm sure I will have to shallow them up some. I'll know a lot more tonight after I start playing again. I'm not planing on making my limb butts flush mounted like yours. I will just taper the butts into the grip.