Primitive Archer
Main Discussion Area => Bows => Topic started by: Ippus on September 02, 2015, 02:15:06 pm
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I'm really just getting started - looking forward to selecting my first staves in the next week or two, probably Siberian elm, but something I haven't quite understood yet from my reading is this:
How do you get to a target draw weight?
I mean, does the wood kind of decide for you? Does stave selection have a lot to do with it, or is it pretty negotiable (downward at least) in the tillering phase?
If I overshoot with a self-bow, particularly ELB, can I just continue removing wood until it's down to where it's as light as I want it? In that case, is it better to try removing width? If I remove thickness, am I restricted to removing wood mostly from the belly, or is that going to make it collapse under compression - do I dare mess with the back at all?
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well, its a complicated question,, but to over simplify ,, yes remove wood till desired weight is achieved,,there are fairly standard processes to tiller the bow without over straining the bow, and there are different opinions on where to remove wood for best results,, it really depends on the design,,start with something simple and ask questions and learn as you go,, reading will only get you so far,, hands on is the only way :)
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Thanks! I'm pretty sure my wife and several friends think I've gone off the deep end at this point, but I'll show them. I'll show them all! Muahahahaaah! >:D
Seriously, though. Really excited to get started! Just got the notification that my local library got TBB 1 in (they had the other volumes, but not the first!), and work seems exceptionally long today.
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Follow some of the builds on my blog.
Bottom line... always pull to your target draw weight (unless you see the tiller isn't right as you are applying weight, in which case you stop and remove a litte wood to correct the tiller), that way you'll either end up at your target or with a pile of broken wood.
It is nonsense to think Ooooh I want a 50# bow, but I don't want to overstrain the wood so I'll go gentle and pull it to 30#
If you pull to 30# you'll end up with a 30# bow
Del
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What I do while tillering so I get to the weight I want is to check tiller to the max weight. So if I want a 50# bow at 26" I make my long string pull to 50# and check to be sure everything is good them remove more wood, pull to 50# and check tiller, and so on. I get off the long string and to low brace as soon as possible, usually when I get about 8" of tip movement.
If you come in over, remove wood until you get the weight you want. Remember to exercise the wood often as you tiller.
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What I do while tillering so I get to the weight I want is to check tiller to the max weight. So if I want a 50# bow at 26" I make my long string pull to 50# and check to be sure everything is good them remove more wood, pull to 50# and check tiller, and so on. I get off the long string and to low brace as soon as possible, usually when I get about 8" of tip movement.
If you come in over, remove wood until you get the weight you want. Remember to exercise the wood often as you tiller.
+1
Doing it like this you'll get results that go like this:-
50# at 6" long string (and by long string, we mean only just long enough to get onto the bow)
50# at 10" long string
50# at 16" long string
50# at 20" braced
50# at 22" braced
50# at 24" braced
50# at 26" target weight at target drawlength.
If you keep pulling 50# you end up at 50#!
The main adjustments of tiller are in the first 4 readings, after that it's very fine tuning and removing wood v carefully to ease it back.
If you are not heartilly sick of putting it up and down on the tiller and exercising it, then you aren't doing it enough! >:D ;)
The hard thing is getting your eye in to seeing problems before they are too obvious... also knowing how much wood to remove to achieve the desired result.
The whole process is one of successive approximation and prevention rather than cure.
When in doubt, stop, take pictures and video, look at how the bow actually flexes, not just the static curves.
Del
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First make a tillering gizmo, it will put you over target weight so you have a lot of room to work down to your target weight.
Get your limbs bending evenly with no stiff or weak spots. When you get to this stage you take full length scrapes on each limb 10 at a time. Somewhere between ten and twenty depending on the wood will drop your bow a pound or so. Do a couple of scrape sessions, check poundage, check the tiller with your gizmo and correct any stiff or weak spots that show up and repeat until you are at your target weight.
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When I started I went back about 2 or 3 years in the "Bows" section and read every post. Pay attention to all the full draw pictures and especially the "tiller check" posts. Try to get the shape of a bow burned into your retina.
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Thanks! I'm pretty sure my wife and several friends think I've gone off the deep end at this point, but I'll show them. I'll show them all! Muahahahaaah! >:D
If you are reading and posting on this site, there is a good chance you are off the deep end like the rest of us. My wife knew I had lost it the day I came home from the game processor with six elk legs and began stripping sinew. Enjoy the addiction. Tell your wife it is safer than drugs and cheaper than a girlfriend.
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Thanks! I'm pretty sure my wife and several friends think I've gone off the deep end at this point, but I'll show them. I'll show them all! Muahahahaaah! >:D
If you are reading and posting on this site, there is a good chance you are off the deep end like the rest of us. My wife knew I had lost it the day I came home from the game processor with six elk legs and began stripping sinew. Enjoy the addiction. Tell your wife it is safer than drugs and cheaper than a girlfriend.
Amen Jeff I had a good laugh at that one. My wife said, when I started my 3rd bow, "exactly how many bows do you need?" Now she comes out and visits with me while I'm working and let's me know when it's time to eat!
Ippus, you have received a lot of good info so far. Also go back a few pages in "bows" there was some great videos posted recently. Then check out YouTube. Look for, boarrior bows and Clay hays. Both are really good information guys. They have build a longs and how to's. Get the Traditional Bowyer's Bible's volume 1 and 2. Read them. Take pictures of your progress and post them here and let some of the best Bowyer's in the world walk you through your builds. Don't be afraid to ask questions. The only dumb question is the one you don't ask.
Oh and welcome to the obsession! Patrick
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My wife said... "exactly how many bows do you need?"
Same number as shoes and handbags? >:D
Del
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My wife said... "exactly how many bows do you need?"
Same number as shoes and handbags? >:D
Del
At least the hand bag part Del! Patrick
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Hey guys, not trying to hijack, but hopefully this continues this great conversation-
When tillering at your desired weight, what is the method you use to pull, see the scale, and step back to view and work the bow? Seems like a lot to manage and I cant picture it.
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I'm using my tiller tree and a digital scale. When you hit the weight and let it down it shows the max weight it went to.
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Hey guys, not trying to hijack, but hopefully this continues this great conversation-
When tillering at your desired weight, what is the method you use to pull, see the scale, and step back to view and work the bow? Seems like a lot to manage and I cant picture it.
Yeah it's a lot to do, 'cos you are looking at the bow, the weight and the length.
Which is why we all occasionally screw up by pulling too hard or too far or being too busy looking at the draw length and missing the hinge starting to bend... >:(
But if you have the rope from the scale going down to a pulley near the floor, you can stand back six foot and pull and watch evrything at once.
I can't get back very far in my workshop, so I have a camera mount on the wall opposite the tiller tree. That way I can video it and the watch at my leisure.
Like this :)
https://youtu.be/Yni817qcUDs (https://youtu.be/Yni817qcUDs)
Del
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And a 2:1 purchase makes it so much easier, especially for the exercising part.
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Just remember that for a beginner getting a good tiller is paramount.
You may not get the weight you want on your first few but that's ok.
You may not get a bow LOL.
There are some buildalongs on my site.
Jawge
http://georgeandjoni.home.comcast.net/~georgeandjoni/index.html
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When tillering at your desired weight, what is the method you use to pull, see the scale, and step back to view and work the bow? Seems like a lot to manage and I cant picture it.
Since I can't attach a pully where I have space for my tree, I have a scale, a camera, and a gizmo all close to hand. Because I don't want to leave the bow drawn for long, I do the following steps: 1. exersize twenty pulls or so just under weight.
2. Pull with scale to draw weight minus an inch or so, noting how far that is.
3. Draw again to that length and secure on the tree-quickly snap a picture. Release.
4. Pull again and mark with gizmo.
5. Look at pictures and see if I can see hinges or stiff spots.
6. Compare what I think I see with what the gizmo marks say. Believe the gizmo-at least at first.
Some can tiller with a mirror and avoid all this. I haven't managed that yet. Go slow and check occasionally for twisting caused by uneven wood removal.
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Hey Jeff, why do you need to exercise it first? (maybe this is a stupid question?)
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Snowplow, you exercise after removing wood to register that wood removal and to help educate the wood to bend and recover. I think exercising also help to break in the bow so when you hit your target weight it stays there.
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It's a good question. Exersizing also allows the tiller to settle in so you get a clear idea of what it will be.
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This is a GREAT video series. This is the one on tillering. It really helped me as a beginner to get whole picture.
https://www.youtube.com/watch?v=UXrcV4iVq74
My take and I am a newbie. Sometimes I think the masters just don't explain the obvious to them things. Masters, PLEASE correct me, if I am wrong!
You have a stick.
You shape the stick to your bow type that you have chosen but it is too thick to bend.
You thin it to the point that you can bent it a little bit.
You put it on a rack and pull down on the string with the number of lbs that you want your bow to have. It will not bend much and it will not bend in a nice curve like you want so ..
You remove wood from the belly until both sides bend the same way but don't increase the amount they bend, just make them the same.
Now you start removing wood. As you do so it will bend more and more. Make sure that it bends the way you want by removing wood from the right places. Keep it symmetrical (unless that is not your goal tiller)!
NEVER pull with more lbs than you want you bow to be! This will over stress the wood resulting in all sorts of different problems.
Once it bends as many inches as your desired draw length, you are done.
I think a pyramid bow is a good place to start but that might be wrong.
Read the the bowyer's bibles, all four, cover to cover before you start!
What is the rule? Double the width and you increase the bows power 2 times. Increase the thickness and you increase the bows power 8 times?
There seem to be two basic tiller types, D and circle.
Forget recurves and such until you have done a few bows.
English longbows have a special shape that is not like the rest of the world's bow because they had special needs at the time it was invented.
Hope this helps.
Douglas E Knapp
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Thank you, everyone! I'm home sick today, and doing a good bit of reading (local library had all four volumes of TBB!)
Thanks for the video links, too.
This is all immensely helpful!
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You are wrong, magick.crow. Us masters know all and tell all. ;D ;)
Your info is basically correct. A slightly overbuilt flat bow or bendy handled bow is a good place to start. These designs can take a bit more oops and still give you a good bow.
The width and thickness depends on the wood used and the design bow you are wanting to build.