New here with a laminate question

[Aaron H]

Hello everyone,  I am new here to this website and new to laminate bow building.  I recognize some of the names I see as I am a member over at one of the other primitive bow building sites.

I am building my first laminate, it is a 66" bamboo backed ipe, with a 16-18" padauk power lam (.250" tapered to .000").  I already have a z splice, clean, straight grained piece of ipe that measures .250" across.  Already cleaned up the bamboo to .125" at center. It will me a D/R design, pyramid bow, 1 1/2" at the fades straight tapered to 1/2" at the nocks.

My question is this,  I am shooting for a #45-#50 draw weight, and I am hoping to get my numbers right and have little tillering to fine tune.  Do I have enough ipe belly wood to hit that draw weight, or should I consider adding a core laminate to bring that weight up.   If so, what thickness should I be thinning it to, and should it also be tapered.  I was considering maple for the core wood if I need it.

Thanks everyone,
A a ron

[LittleBen]

I think you're going to come in under weight personally, although I've never used a powerlam that long but once.

I think you need to be somewhere Around .500" stack to get what you want. You could obviously go a bit thicker, but i think that would do it pretty dang close unless you're planning some ungodly amount of reflex, which I assume you're not given the pyramid profile and relatively narrow limb.

I would probably add a core lam maybe .125" ... You should have enough belly material that you don't need to taper the core, but you certainly could. I would probably just use a parallel cause it's simple and a pyramid should end up with relatively uniform limb thickness.

I just caliperred a recent hickory hickory ipe tri-lam. It's 66" maybe 39-40# @ 28" with a 12" riser. The stack is .435" at the fades. Have a nearly identical one that's about .460" and nearer to 55#@ 28". That doesn't say much except that the .375" Youve got is going to be wayyyyy under. And that .500" with a .250" belly slat should give you room to tiller from more weight than you want to a lot less than you want.

I'm also assuming you're going to glue on a built up handle in addition to the powerlam, and the handle being around 12".

If it's a semi bendy handle bow, you might need slightly more thickness.

Cheers!

[Aaron H]

Do you think a 16-18" power lam is too long, I haven't spliced those together yet, so I could shorten them a bit still.
A .125" maple core is what I was thinking, but you bring up a good point as to the thickness should be nearly parallel with a pyramid design.  And yes, I do plan to add a 12" maple handle as well.

Thank you LittleBen

[LittleBen]

Aaron I dont think a 16"-18" powerlam is too long. It's not very thick at the ends so it will bend some anyway.
 We're talking total length of the powerlam is 16-18"? or are you splicing two together to get to 32-36"? I've never seen that done .... I just want to make sure I understand clearly.

I was gonna suggest maple for the core if for no other reason than I like the looks.

[Aaron H]

Yea, 16-18" total length.

[mikkekeswick]

I think it'll be too heavy if you add another 1/8th....but if you left it at 3/ths you'll be under weight more than likely.
Also a pyramid design isn't the best for a r/d side profile. It's much better to keep your fade width for around half the limb then taper into 3/8ths nocks. this will provide extra stability for the mid/outer limbs and also wityh this design you will have thickness taper - therefore a wider thinner mid/outer limb which will hold relfex better than a thicker narrower limb.