Ozbow

Well I'm ready to give this a go but want some suggestions for a starting point!
I will be grinding my own lams from Bamboo poles not the laminated flooring.
Suggestions wanted on, number of lams, lam thickness, parallel or tapered, glass thickness, length etc to end up with a flat laid longbow around 50lb.
I realise theres a lot of other variables but all I want is a starting point not the perfect formula
Any ideas guys? I'm leaning towards parallel lams because they just seem so much easier to grind and have full length without splicing tapered lams.
Cheers,
Mike

Hi Mike, Due to the work involved and expense of grinding lams from bamboo poles may I suggest you use them as the outer lams only and use laminated bamboo in the core, assuming you are after the look of the nodes under clear glass.
If you go for a wide bow tapering to fine tips you may be able to get away with parallel cores but it is my experience that some core taper is generally necessary to avoid hand shock.
As you are grinding your own there is no reason to have spliced tapers .
Figure out your bow length, riser length, preferrable width of limb tapering to what tip width and I will give you a formula that should get you close and deliver a sweet shooting bow. Steve

Hi Steve,
The main reason I had for staying away from Tapered lams initially was ease of glue up and not really having to worry about the postion of a tapered lamon the riser. I am planning on around 66-68 inches with fairly fine tips, not too concerned about how the first one turns out, after all its going to be a learning expierence anyway. The bamboo will be under coloured glass not clear.

Cheers,
Mike

Hi Mike, Well it looks like you will have to make one up and go from there , somewhere around 8-10 mm of core stack at the centre with 40 thou or 50 thou glass or a combo. Taper from 35-40mm down as fine as you can go, the shooting will dictate what you will have to do.
Steve

Thanks Steve

Hi Mike,

If you are going for parallels only, you are really looking at a pyramid bow as Steve is suggesting. My recommendation is to keep the bamboo for when you wish to put it under clear glass and use anything else you can get your hands on for this one.

A 68" bow with 18" riser with 50thou glass on both back and belly has a stack at mid point of the active limb of 6.7mm

Have fun mate.

Steve

Hi Mike,

It may be beneficial to purchase a copy of John Clark’s manual ‘Design and Construction of Composite Longbows’. Ausbow Industries; http://www.ausbow.com.au email; sales@ausbow.com.au

For the first time [laminated bowyer] there is a lot of information which will help fill in the gaps.

Daryl.

I agree with Daryl. Before you do anything else I think you should buy a copy of Clark's book. When you have read it and built a few bows to a formula, then you can start to experiment.

I would not try to build a bow from parallel lams only. You will probably find that it will fail in compression at the end of the fade. I tried building my hybrids using parallel lams, as are used in recurves. I built two and they both failed. I did not bother pursuing that line of development.

I also think you will find that building a pyramid bow using glass and parallel bamboo lams is a different kettle of fish from making a pyramid bow from a single piece of timber.

But hey, half the fun of building bows is learning from your mistakes!