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Ipe and Bamboo

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backgardenbowyer:
Hi,

I've got hold of a really nice piece of ipe decking from my local wood yard - the grain is straight along the length and flat ringed with no swirls or pins.  I'm going to couple this with a backing strip cut from a reasonable piece of bamboo found at a garden centre.

My question is this - unfortunately my metric dimension Ipe blank is a miserly 19mm (0.75") thick and the boo backing is a fraction under 0.25" at the centre (why isn't anything 1" thick any more!). I've cut rough tapers on the ipe but left it 1.25" wide at the centre, the boom is flattened ready to glue but varies a lot in thickness. 

Given a bow length of say 71" what kind of weight might I get out of this combination?  I'm not looking for real war bow proportions here as at present I shoot a triple laminate 50#28" which I made for field archery.  My aim is to make a sort of step up bow to shoot initially at about 65#28", but tillered to draw 29" or 30" as I grow into it.  The bow is to be used for clout and roving marks this summer so needs to yield something like 220yds with a light arrow.

Is this over ambitious for the materials?  I don't want to add a core laminate as a) I've enough trouble getting one good glue line without having to do two, and b) trying to keep it as simple and therefore authentic as possible.

The last time I made a bow from this combination it chrysalled in both limbs very quickly despite being only 51#28 with no obvious tillering faults.  This will be my first attempt to make a true war bow tiller coming full compass.

Any comments - I need to get on with the project as it is a Holiday weekend here and in theory I should have the time.  I'll try to post pics as the project proceeds.

Stan  UK

Justin Snyder:
If your Ipe is good you have plenty of wood and boo there.  I made a Ipe selfbow that was 69" NTN 3/4" wide and 5/8" deep at the handle and 3/8" side at the tips.  It wound up 65#. If you back yours with boo, at 1 1/4" wide you could easily get over 100#. Justin

grantmac:
With similar Ipe sizing to you I hit somewhere in the 110-130 range with only 1.5" of follow and the bow was 75" NTN. I think you are going to have lots of wood to remove.
    Cheers,
           Grant

Rich Saffold:
Stan,

If you want a 71" bow I'd lay it out so you get 1 1/8th+ through the middle after cutting. This isn't for poundage, but to keep the bow laterally stable. You will probably end up around an inch wide and hopefully won't have to shorten it unless you want to. Remember to keep the limb thickness well under the depth.

I'd also floor tiller the belly to where it feels like a 40# bow, or less since often these bows double in poundage with the bamboo glued on. For this one I wouldn't glue it up with more than an inch of reflex..

Keep the boo on the thin side as well, and make sure its even thickness on both sides with the crown going down the middle of the limbs...

When using Ipe, make sure when dry it sinks like a rock in water. Many lesser woods look like Ipe, and get sold as such...To Chrysall good Ipe takes some serious overpowering..

Rich

backgardenbowyer:
Thanks for all you help guys.  There's a whole lot of experience on this site :)

I decided to glue the bow up this evening. It's still about 1.25" wide at the handle but I'll take a bit off with the planer before I start to tiller.  It's in a jig with about 2" reflex, so probably not more than 1" when I release the presure.  Left it about 74" long for now as it always makes sense to start long and then pike it a bit.   I've never been any good at getting boo backings even and am happy if I can just get them flat enough for a good glue line.

I haven't tested this wood in water, but it is hard, dark and dense, the hand plane just bounces off it - looks better than previous pieces I've had.  I suspect "ipe" gets used as a generic trade name for wood of this type rather than for one species.

Here's a thought about bamboo backings - as light tips are an advantage and bamboo much lighter than Ipe woudn't it be a good idea if the backing was kept farily thick at the tips rather than thinner (which is the usual practice).  I've seen a few yew bows where the sap wood just happened to be thicker at the tips and they shot fine.  Any thoughts?

Stan

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