Cypress bow... now with pics...

[cadet]

Inspired by some others here, I've picked through the racks of 6' cypress pickets at masters and bunnings and found a few which were straight grained enough, with enough of the darker heartwood, and sufficiently knot-free, to try rescuing from picket fence ignominy and turning into double-ended leaf springs...
I seem to be settling on simple, nearly circular tillered, slightly domed bellied, fairly straight tapered self longbows as my thing, and that's what my latest is.
Specs: 63" n-n, 35lbs at 26" so far - a couple more inches draw to scrape out; 18mm thick and 30mm wide on the belly, 10mm thick and 12mm wide at the nocks. Without a string, it weighs 390g.
The grain looks lovely enough to eat, smells gorgeous, and is easy stuff to work, although maybe a little brittle.

[hunterguy1991]

Look forward to seeing this one when you get the technology working again

[bigbob]

yeah! Keen to see the outcome!

[cadet]

Looks like the card reader in my 'puter is broken; have now used another machine and put them on an email to self; next step is to get away from the heavily filtered work system so I can actually put 'em in photobucket - tomorrow night job.
It was good to get the pics on the screen and see tiller at least. It's better than I thought. Has only taken 1 3/8" of set so far, too.

[cadet]

Now with pics of pretty woodgrain, unbraced, braced and nearly full drawn:

[bigbob]

tiller looks pretty good, perhaps a slight hinge about 6 - 8'' from left tip.

[cadet]

I've looked at that area a lot: I think it's more that there's a bit of a weird optical illusion caused by the background, or by the heart/sapwood transition there - but I'm keeping an eye on it.

[hunterguy1991]

Looks pretty nice mate,

Bob I don't think there is a hinge in that left tip, but there is a stiff spot in the left limb from about the centreline down the door in the back ground to the left edge of the door frame... Only slight but noticeable.

Looking at the string to tip angle of the right limb id say that where this bow is drawn to in the photo is as far as it should ever go... any further and you will start inducing a stretch along the right limb which could make it fail with no increase in draw weight.

If you want more draw length, I think the only option would be to get the handle bending a bit more, however, that may result in less weight.

Colin

[greybeard]

Cypress Tiller.jpg (58.28 KiB) Viewed 5847 times

Daryl.

[Nezwin]

Is this the back or the belly? If it's the back, I'm amazed that it's held up this well! For wood bows I was of the understanding that straight (or as close to) grain or a single growth ring was essential on the back (with exception, but the general rule being that a single, longitudinally-uniform grain structure is required for the tension side of the bow). I had also thought that 63"ntn would be too short for a straight bow but you seem to be having remarkable success with no backing at this length. I can only assume that getting the handle bending as you have has allowed for the shorter ntn length, much like cmoore and his plains-style bows.

Looking at the string to tip angle of the right limb id say that where this bow is drawn to in the photo is as far as it should ever go... any further and you will start inducing a stretch along the right limb which could make it fail with no increase in draw weight.

Agreed with that. The string angle isn't far off 90 degrees, much more draw won't be just over-straining the material but would also stack the draw weight, which would not produce a smooth shooting experience.

[cadet]

Thanks for the feedback so far gents. Yet again I've learned a few things in building this.
The photos of the grain were 2 of the belly, one of the back. The one looking along the length is the belly; the pale oval patches are in the back. Generally I tried to put heartwood on the belly, sapwood on the back. It's a board, so I haven't really tried to follow a ring on the back other than getting one without too horrendous a lot of runout. It may yet fail in tension, but hopefully I'll see a splinter rising and be able to bind or back it before it lets go.
Yes, the length of the picket has limited the n-n length, and hence draw length, more than I'd like. There'll just be a tad more scraping on that L limb to bring the very tip about a tiny bit more (I've been conservative on it, because it's all sapwood out there) and on that flattish spot Colin identified. There might be another 1/2" draw in it.
The whole thing was an experiment on one of the lesser quality of the suitable pickets I found. After a couple of hours I've got a light working bow out of a $3.39 plank to play with, and learned a bit more, so I'll call it a qualified success!
Next one I'll go a little wider and try and retain a little more of the decorative picket end to use and place the nocks a further 1/2" out to try and gain an inch or two more n-n length.

[Gringa Bows]

Looking good

[hunterguy1991]

Definitely a success mate, did very well to push that board to id say bloody close to its absolute limit!! and its quite a striking bow with so much grain and colour.

Definitely going to shoot into a big cypress supplier near home and get a big board for a BIG bow to see what this stuff can really do!

Colin

[bigbob]

I still feel there is a stiff spot at the left tip from about 6 -8'' back If you follow the arc greybeard drew and look at the right side limb you will see it diverges away on a slightly different radius to the arc, whereas the left side actually intersects the arc at the tip. all this is probably being a bit pedantic as i feel it is a great result in any case.

[cmoore]

Excellent result!, did you use a grid behind your tiller or just eye ball it?

[greybeard]

I would not be too concerned as to how the drawn profile of the bow fits into the overlay that I posted.

With the change in the ratio of early and late growth in the limbs of your bow it is very difficult to achieve symmetry and sometimes not totally desirable.

Limb timing is paramount and loosing arrows is the best way to monitor limb timing. Generally it can take dozens of arrows for the tiller to settle.

As the bow bends through the handle, tiller [timing] can be fine tuned by hand placement.


Daryl.

[cadet]

Yes, it's bloody near its limits (and that was part of the fun - to see how hard it could go!), and there are some ever so slightly iffy spots that a few more scrapings may yet improve, but I'm generally pleased with it. It shouldn't even be alive still!

Excellent result!, did you use a grid behind your tiller or just eye ball it?

No grid, but that might be another trick to add! Mostly eyeball, but one of my tricks is to use an old CD: draw the bow, and hold an old CD between eye and bow to superimpose the CD's round shape over the drawn bow's tiller. The other trick I use is to use a short block of wood with a couple of matchsticks glued at each end to run along the back to show the gap - and any changes in it - between the block and the drawn bow's back; the other side without the matchsticks can be run along the belly to observe the same effect.

[perry]

Just as I imagined it from your description cadet, this is my favourite Bow design and one I feel is a great all round design for Australian Timber. - well done !

regards Jacko

[cadet]

Post script:
I made a string for this one, and left it strung for a day. It didn't like that, and took a further inch or two of set, so now out to 2 1/2"-3" or so. Maybe not such a great timber after all?

[Nezwin]

left it strung for a day

I understand that, as a general rule, the softer a wood is, the more set it will take (or perhaps, the more susceptible to set).

Unless it's being shot, I wouldn't leave a wooden bow strung for more than an hour, maybe less. Glass bows can be left strung.

You can remove set by use of heat treatment, which this timber should be responsive to.