Hazel longbow, 100# @ 28"

[FilipT]

My goal is 90# (or maybe even 100#), if it's so unnecessary heavy now, than I still have some shaving off to do, which will hopefully remove excess weight. I even plan to heat treat it as I bought heat gun.

[FilipT]

Took the string we are talking about these few last pages and got it to dangle a bit and than pulled to about 100# like Badger and Del said. Like I said, it is about 100# at 20".

Than I took the pre made FF string which is not exactly suitable for shooting this bow because of its thin loops and braced the bow with it. I did this as LAST RESORT, because that spectra fishing braid wouldn't ever stop stretching. I risked everything just to finish this bow and I dare to say it paid off.
I braced it with ease and looked at the profile. String stretched just a tiny bit and I measured that brace height dropped about 5 mm since initial bracing and then stopped. Nothing severe like the spectra obvious brace height dropping.

When I put the bow on tiller I immediately noticed on left limb (lower limb) hinge that will develop soon if I am not careful. Coincidentally and interestingly, hinge on the lower limb is almost exactly same distance as the kink on the right limb (upper limb). Marked this place to avoid it in future.
Profile was a bit uneven, upper limb was weaker and lower was stronger. I rasped the lower limb to correct this. After not too much rasping and scraping later, I put the bow again on tiller, this time connecting the scale to pulley.

It read 100# at 18". I removed the string and scraped lower limb a bit more and upper a bit less. Now again on the tiller I got 100# at 20". Limbs look very even. I called quits for today as it's so dark outside and in my garage (despite the light bulbs) that eyes are playing tricks on me. I will continue tomorrow.

Question:
Is there a math that will estimate draw weight in current state at 28" / 29"?

[WillS]

If it's braced properly (between 4 and 6") and reading 100lb at 18" you're looking at 166lb if nothing else changes (which it will) at 30", or 155lb at 28".

You're going to lose a lot of weight as you get your eye in, muck about with the tiller, second guess yourself etc.  The reflex will pull out as well.  I'd say you'll be left with pretty much exactly 140lb at 30" if everything goes very well.

[Del the cat]

Sounds like you are on track, but don't rush. 
The moral of the story, is use decent string material....
Del

[FilipT]

Yes, it's 6" brace. Reflex is almost gone too. What do you think how much wood will this bow loose till it gets to 100 at 28". Just so I know the estimate, are we talking about millimeters here or scrapings?

Yes, Del, it's radically different feel when you have non stretchy stringer and non stretchy string. What a feeling to finally see this bow braced! I must now go slowly, tomorrow I will try photographing the bow so I can put it on computer to see better bend and where to scrape.

I learned so much from my errors on this bow. Definitively I am going much wiser to the next longbow projects. But the biggest thing is still estimating at beginning how thick to leave staves so I don't have over excessive wood removal to get to target weight. It's obvious that I underestimated initial thickness of this bow and that is why I have such strong wood. Also there was this "hazel is soft wood" theory at the back of my head during shaping. "Oh, it's hazel, make it much thicker!" Yeah sure, do that and feel pain hahaha.

[joachimM]

What do you think how much wood will this bow loose till it gets to 100 at 28". Just so I know the estimate, are we talking about millimeters here or scrapings?

Go for scrapings rather than rasping.
If the thickness now is about 35 mm and 140# at full draw, you'll end up with roughly 32 mm at 100#. But that's just a silly equation (from the cubic relation between thickness and draw weight).
Tiller slowly. You've been taking your time so far, now is not the time to rush.

[Badger]

   Instead of thinking of it as removing weight think of it as perfecting tiller and the weight will continue to drop as you perfect it. Just keep bringing it to your target weight and keep perfecting. If it continues to take set past the reflex you put in you might want to reconsider your target weight. If you want 90# don't pull it to 100, I would not brace a 90# bow when it is reading 90#@20" still a bit too heavy but it is too late for that now.

[FilipT]

I think I will go for 100# at 28", that is why I am pulling to this weight. Tnx for advice guys, I'll keep you updated.

[DC]

But the biggest thing is still estimating at beginning how thick to leave staves so I don't have over excessive wood removal to get to target weight.

Removing excess wood is good for the soul (and the upper body)

[FilipT]

I tillered bow to 24", where it reads 100#. Now I need help how to proceed further. Here is a picture of bow at 23". Are limbs okay or not, should I remove evenly from both sides?

[Del the cat]

Left limb looks good, right looks a tad stiff.
Take a few even strokes of the rasp all along the right limb and put it on the tiller again.
Del

[FilipT]

How about now? This is 100# at 26". I think right limb needs just a bit more. I am very near end and this here are last opportunities to correct the bend.

[FilipT]

I removed just a bit wood from the right (upper) limb. Scale shows 100# at 27". I will continue tomorrow because it's getting dark and I have some other things to do. But bottom line is that I want to hear your opinion guys. What do you think of this bend, should I correct something or it's basically done and ready for 28" draw?

What is next for me, should I make radius on edges (currently it's small chamfer), scrape the tool marks, etc.?

[WillS]

Personally I'd say the tips are still quite a bit too stiff - especially the left one in the last photo.  You may well find that if you leave it the way it is currently that you start to develop chrysals on the belly around the handle area, out to mid-limb on both sides.  It sort of depends what cross section you've gone for, but I'd be thinking about bringing those tips round quite a bit yet.

You also need to work out where you're going to be holding it and shooting it from - if it's on the tiller in the dead centre of the bow, and the pulley hook is on the dead centre of the string, when you put it in your hand the tiller will be off.  Won't take much to correct it, but it's something you need to consider.  If you're actually mounting the bow on the wall below centre, and the string pulley is just above centre then ignore all of that

Finally - chrysals in hazel are often really hard to see, on account of the timber being so white.  Make sure you give it a really careful check in different lighting from different angles - even the tiniest hairline chrysal can suddenly fold up and become an issue, so before you go any further be 100% certain you've not got any, otherwise you'll have to retiller to account for them.

[FilipT]

It's bad light but if you look closely at center you can notice that bow sits in "saddle" at center but the pulley pulls 1" to the right. That is where I put arrows. I designed tiller setup this way so I don't need to worry about making lower limb stiffer. It simply becomes stiffer when you tiller it and produces balance while holding in hand.

I am looking constantly for this chysals, but I didn't find any. Bow is long 72" tip to tip, how much of length of tips should I correct?