Primitive Archer
Main Discussion Area => Bows => Topic started by: stuckinthemud on April 23, 2020, 03:03:37 pm
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So, I am making a D-bow and at 1" tip movement the bow is at target weight and bending fairly evenly. I normally chase the draw-weight from here but it is sooo tempting to pick up a big rasp and hog off a mm or so all over. What approach do you take from here: slowly scrape a little and chase the draw weight or rasp off a mm all over and then re-commence tillering?
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If it was me I would keep scraping small amounts , weight can drop quick when you start stretching it out ,slow & steady usauly wins the race !
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Remove wood evenly and re-evaluate as it draws back further. You can't really judge the tiller very well at 1" movement.
The question is, of course how much to remove.. only trying it and experience can tell you that, but at this stage you can be fairly bold,, then gradually slow down.
The mistake beginners make is to start off too tentative, get frustrated at the lack of progres... they then get too bold and over do it.
I often do some arithmetic to work out an approximate draw weight at full draw... that lets me know how much draw weight I have to take off... I have a reasonable idea how much wood that is 'cos I've had to reduce bows for people in the past.
Del
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I floor tiller to a good bit lighter than that :) but I've done a few so can go pretty close to final thickness at rough out.
Del gives good advice.
Probably best to measure drawlength over tip movement.
Trace the profile before it takes any set.
Compare the bow to the original profile as soon as you unstring it after exercising it. Set tells you most things.
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From the get go, I start gauging limb balance. If it was as heavy as you said, I'd rasp it, but rasp the stronger acting limb more... assuming you're drawing the string from where the string hand fulcrum will be.
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tempting to pick up a big rasp and hog off a mm or so all over.
is there going to be a thickness taper?
a "mm all over" or removing evenly might be a mistake if the tips are going to be 1/2 the thickness of the handle. If you remove some percentage of thickness at the handle, try for the same percentage at the tip.
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tempting to pick up a big rasp and hog off a mm or so all over.
is there going to be a thickness taper?
a "mm all over" or removing evenly might be a mistake if the tips are going to be 1/2 the thickness of the handle. If you remove some percentage of thickness at the handle, try for the same percentage at the tip.
Well said... I was about to add a caveat to my post pointing out the same thing. :)
Del
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There is a thickness taper and I would percentage the amount cut, I guess what I'm asking is how hard you guys chase the draw weight. I usually go very slow to get to brace but as I gain experience and I have a reasonably good idea what needs to come off I am questioning my usual approach
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I think it was badger that once said. Don’t think of it as taking off weight. Think of it as perfecting the tiller. Whenever I’m removing wood. I’m working at perfecting the tiller.
Bjrogg
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Taking short cuts can and will put a person's bow below their projected draw weight,but a person can get really familiar with a certain type of wood too.It's up to the bowyer.
Getting the limbs' resting profile to look balanced from the get go helps a lot.Starting out with a proud or rounded belly.
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Getting familiar with a certain wood was a good point I have had well seasoned pristine osage that refused to drop poundage after multiple scrapings and exercise but drop 3-4 lb in the next couple of scrapes I usually pre ruff taper my limbs to the front profile and small removal from there tell as close to perfect tiller as I can get but I'm never in a hurry any more when it comes to tiller so I enjoy the slow pace and usually get a decent hunting bow ! being in a hurry has bit me more then once when I first started !
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If you are looking at tip movement and judging target weight you are looking at the wrong thing. How far is your string hanging down? If you are at 24" and pulling target weight with 1/2" tip movement your bow is still pulling about target weight at 24". Weight is not a function of limb stiffness as much as it is a function of leverage.
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I like to keep rhe string short, its about 2 inch hanging down
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Once I string it I use a scraper-like tool. Jawge
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Starting out with a proud or rounded belly.
Ed, you advise doing the bulk of the reduction with the belly more rounded than what one intends to finish with? (so that stock removal is easier?)
Then flattening the belly to final crossection as you get closer to the finished thickness?
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If you are looking at tip movement and judging target weight you are looking at the wrong thing. How far is your string hanging down? If you are at 24" and pulling target weight with 1/2" tip movement your bow is still pulling about target weight at 24". Weight is not a function of limb stiffness as much as it is a function of leverage.
That's what I meant but put better :)
Your string shouldn't 'hang down' it should be tight to the belly. The way the force is applied to the limbs changes a lot with a dangly string - not good. More down than in - this will give you the impression your outer limbs are stiff. Hard to tiller when you aren't seeing the picture correctly. Tiller should be perfect from the outset.