Hickory Board Bow - Newbie

[passion for knowledge]

I would have to agree with takefive regarding going slow at this point. I got caught out going too fast with my second bow.
On the bright side, it was light enough to get my daughter into shooting a bow.
Macbow's advice regarding a cabinet maker's scraper is definitely worth thinking about. I made a couple out of old recip saw blades that are fairly flexible and work pretty well. They need sharpening a bit more often than the real thing, but they do work.

[tsorenson]

I'm out to 19" on the long string. Planning on getting one more inch before I put a low brace on it as per Greg's advice. I've got a couple small flat spots on the left side...and does it look like a hinge coming off the left side about 10" off the riser? I didn't notice that downstairs, but the picture makes it look like something going on there. I've also got extremely stiff tips still as it seems people had been saying to stay away from them till I get it braced - should I continue with that plan, or should I take some wood off the tips? I'm using a short block of wood to help with finding flat spots and hinges and I thought it was helping a lot, but looking at this picture...I'm not so sure.
 

[mikkekeswick]

First rule of tillering wood bows is to always pull it to the draw weight you intend it to be when finished. If you want 50# then always pull it to 50#. If you pull less during tillering you will almost certainly end up under weight. As you remove wood the bow will obviously bend further until you get to full draw.
The only exception to this rule is if you see a weak or stiff spot show up....then you don't pull any further until you have it fixed. Once it's fixed work slowly back up to pulling your intended finished weight.
You can usea luggage scale (cheap nowadays) or a set of bathrooom scales - onto which you put your tillering sticks base as you pull down.
So onto your bow as it is 0 there is a weak spot about 10 inch or so from the left fade. The right limb is looking the same but not as bad.
I don't agree with tillering this part of the limb then that part as you progress. My aim when making a bow is to get the tiller perfect from the outset and then try to maintain that the whole way through tillering. Perfect tiller could also be described as having a perfect taper. Get used to sliding your fingers up and down the limb after removing any wood - use them as a set of thickness calipers! Your fingers (when trained to it!) can detect tiny imperfections that your eye or measuring will find hard to detect. If you get say the inner limbs working  with stiff tips then even at a short drawlength you are overstressing the wood on the inner limbs. Why would you want to do that? Bear in mind that the long string will make the tips look a look a little stiff compared to the same bow braced but that is easy enough to factor in because it's only a little difference.
So for now stay well away from those inner limbs and get the outer limbs bending. Then post another picture. Also shorten yout string until you have to bend the bow a tiny bit to get it in the nocks.

[tsorenson]

Awesome information - thank you kindly! I thought I was being cautious in pulling under my intended draw weight, but what you said makes complete sense. I will change that up going forward.
I do have a scale I've been using - I think it's even advertised as a bow scale...regardless it seems to do a nice job so long as I remember to set it to lbs. instead of kg!
So are you thinking starting about mid-limb and working down to the tips? Possibly an inch or two to the middle from mid-limb? That's the area it looks like to me that the bend needs to start increasing, but my eyes are new to this. I'll also try shortening the string.

[mikkekeswick]

Yep that's it. Just remember now that to drop your bows weight by half you only need to take off an 1/8th of the thickness......slowly, slowly wins the race  
Post plenty of pics and we'll help you get to full draw without any problems  

[takefive]

If your outer limbs are that stiff, by all means do some careful scraping on them.  A 6 inch block is a good length to check for weak or stiff spots.  Someone on here told me to mark the weak areas in pencil and write NO NO there and that works for me.  On the stiff areas I scribble pencil lines and then take them off with my scraper.  And repeat.  It's just a good way for me to focus on where to scrape and where not to.
Are you close to bracing it on a taut string?

[tsorenson]

Thanks to everyone who has been so kind and patient with their advice! I think I need to do a better job of roughing out next time because I was having to take so much wood off for so long that I was starting to wonder why everyone said I needed to go slow at this point...well, the last few days I'm starting to see that it isn't taking much wood removal to make a big difference. I've been using a block of wood about 3" long - should I try and get a longer piece to check weak/stiff spots, Greg?

So here is the progress from tonight. On the left side, I stayed away from the handle by about 12-14". On the right side, I did the same for most of the work, but did work all the way up to the handle for a few strokes. I abandoned the rasp and went back to the surform - I seem to be much more consistent with the surform. To my untrained eye, I think the right side looks pretty decent? The left side needs a bit of work from about mid limb on out to the tip? I put a tight string on it (just had to bend the tips a very small amount)and this is pulling 48# at 20".

 

[Jomohr84]

Yeah work on that left limb, don't touch the right. Get em bending evenly before pulling it further. I try to keep my tiller as even as possible, if I see an imbalance I correct it before pulling further. I strongly recommend making a tillering gizmo. Set it for the weakest spot on the weaker limb, then use it on both limbs until they even out. DO go slowly, it's easy to take wood off, pretty hard to put it back on. It may take a while on that left limb, but it will be worth it. Then try to keep them bending evenly as the draw length progresses. I hope this makes sense, this is what has worked for me.

[takefive]

I'm seeing what you're seeing; the right limb looks pretty good and the left could come around a little more.  Think I'd stay away from  mid limb on the right one, esp. until you get the left bending more.  A 6" long block is the way to go.  If you drill a hole in the center of it and twist a pencil into it, you've got the tillering gizmo.  Run it along the limbs and the pencil marks will show the stiff areas.  Personally, once the bow is at low brace I use a scraper or very fine rasp.  To each their own, though.  Go easy with the surform now that you're getting close.  

[Jomohr84]

Once they start bending more evenly, always readjust the gizmo as hinges may start to bend less. You will notice the gizmo start to mark the entire limb, then it is time to readjust or reset it to the weakest spot. The goal is to get it so the gizmo doesn't mark at all, then your tiller is perfect.

[mikkekeswick]

I wholeheartedly agree with using a gizmo. Great tool! However if you keep tillering for an 'even bend' or another way of putting it is that the gizmo touches along the entire limb then you would have have perfect tiller for a pyramid bow....not this bow. If you guys look back on page one where the OP shows the bows width profile you will see that the limbs are parallel width for a good chunk of their length then taper into the tips.
This width profile needs what is called an elliptical tiller. Eg. as you progress along the limb from handle to tip the bend should increase with the last 8 - 10 inches being stiffer.
The reason behind this is that with your width taper you will notice that the limb tapers in thickness too. The amount of bend and therefore the overall tiller should be determined by the woods thickness at any given point. Thicker wood can't bend as far as thinner wood. With a bow we are aiming to bend the wood to the point where it starts to show a little set so these limits are important.
A pyramid bow which tapers in straight lines from the fades to the tips doesn't need any real thickness taper (because it does it's tapering in width)so it's 'perfect tiller' is an arc of a circle with all parts of the limb bending the same amount. Tillering so that a gizmo touches the whole limb equally will give you this.
So onto your last photo! The right limb is looking better now but still has the same problem - it is weak about 6 -8 inches out from the handle to mid limb. You still need to get the mid to outer limbs bending more. The left limb is still the same too but not as bad as the right limb and it is stiffer overall than the right.
So you need to correct these weak spots or else you will start getting set there and nowhere else. Now is the time that going slowly will make or break this bow!
When you remove wood you are exposiong wood that hasn't felt much compression and will act stiffer than it actually is. You need to pull the bow to it's tillered to length about 20 - 30 times before your changes will show the bows true new shape. So plenty of exercising it between wood removals is very important.
You have very little wood to play with now so be very careful and make sure you have a 'plan' before removing anymore!
Also another tip now is to keep taking the string off and looking at where in the limbs any set is showing up. If it's all in one area then sure as eggs is eggs that area is weak! The wood will tell you how to tiller from now on if you watch carefully.  
Good luck.

[takefive]

Yes, the gizmo has its limitations so I've provided a link that discusses them.  What I mean by an "even bend" is a smooth arc without hinges or obvious weak areas whether the tiller is elliptical or arc of circle.  Using the gizmo with some thought regarding the bow's profile will give you that.
You're doing great on your first bow, Tom.  Go easy with that surform     When I get to the final tillering, it's a scraper and 60 grit sandpaper for me.  Tillering your first bow is tough enough without the added distraction of a chorus of well meaning guys telling how they think you should do it.  "Too many cooks..." so I'm l leaving the kitchen.  

 http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=125;t=001047;p=1

[tsorenson]

Awesome guys. I'm sitting on the bow project for a while as I am needing a longbow stringer - it's on order from Amazon right now. So in the meantime I have a question for you all:

Since I've been using a surform plane I've got scrape marks all over the belly. I know I don't want to take wood off the entire belly anymore, but I'm wondering if I should sand all the marks off the belly now before advancing any further as I imagine sanding those marks out will weaken the limbs. My thinking is that if I wait to sand them out, I'll end up under weight for sure...I might end up under anyway, but this seems like it gives me the best chance? Once I sand the marks out, I would just keep using sandpaper to finish the tiller. Does that sound like an okay plan? Or do I need to correct the tiller before doing anything more at all?

[Roy from Pa]

Damn Mike you are long winded.    LOL but I agree with you.  The gizmo is a great asset for tillering,  however it has limitations with certain bow designs.  Use it wisely and learn from experience.

[takefive]

I would sand 'em out.  I string my bows by putting the bottom limb tip against my instep and pulling the handle toward me while pushing the top limb away.  You'll get the hang of it after a couple of times.

[tsorenson]

mikkekeswick - when you talk about set showing up without the string on, you're talking about areas where the bow bends towards the belly, correct? I have some of that going on at a spot about 10 inches from the tip on the right side, but don't notice it anywhere else. The reason I ask for clarification is because nothing else about this tiller makes me think that spot 10" from the tip is weak - the entire tip seems stiff. Anyway, I will probably sand all the tools marks off the limbs this week and hopefully my stringer will come late in the week so i can start working on stiff spots over the weekend. (that is how I take out hinges, correct? I need to removed the wood from stiff areas around the hinge and/or weak spots?)

[mikkekeswick]

Yep. Set is permanent deformation of the wood or crushed wood cells on the belly.
The key to using this method is to trace the outline  of the back onto something and then use that as a reference as you progress with drawlength.Basically as you tiller some set will show up - that's not a bad thing it's just the way it is  
What matters is that you distribute that set along the bows limbs correctly.
You want little to non in the inner limbs, a little starting to show mid limb and the rest out towards the tips.
Any set in the inner limbs (by overstressing the wood there) will show up as a large deflection at the limb end which in turn has neghative effects on energy storage etc...
But anyway as you progress with your tiller you may miss the startings of weak spots by just concentrating on the bend but if you also keep a close eye on where any set then these areas will become apparent.
Really it's just another 'tool' to use to get your bow bending correctly. It's also never wrong! It took me a while to learn how useful it is but once you get the hang of it then you can tiller any limb shape or profile simply by watching the wood and how it reacts.

[tsorenson]

Picture time...I worked most of the day - I'm either being extra cautious with taking too much wood off or I'm just the world's slowest at tillering. I figure I've spent over 15 hours tillering and today I just hit 22" (it's fully braced now.) Mainly I just worked on getting the left limb bending as much as the right...as you're about to see, I went a little too far. However, I think the bend is looking pretty good? I made a gizmo and it seems o agree with this thought, although the eye test tells me something isn't quite right. Your thoughts are welcome!
 
Start of the day - left limb was still stiff.

 
Midday - both limbs bending about the same amount and according to the gizmo the right limb was bending almost perfectly. I didn't touch it again till just a few minutes ago. Left limb had some flat spots.

 
And the final pic of the day. Left limb is now bending slightly more than the right. According to the gizmo, both limbs are bending pretty well, though. I'm only at 22", so still have another 6" to go.

Oh - tradgedy struck today, too...tillering stick fell off the counter while the bow was in it at full draw. The string came off the stick and I feared the worst, but I didn't notice any chips or crack...hoping I dodged a bullet?

[tsorenson]

Was feeling under the weather again today, so decided to buckle down and crank this thing out. Here it is - 53# @ 28". It took 1-5/8" set on one side and 1-3/8" on the other. It doesn't have a positive tiller - measured 6.5" from belly to string on both sides of the fade, so not sure if that'll be a problem because I shoot split finger? Anyway:

 

Tough to see because of the lack of contrast, I guess. Having never done it before, I guess I don't really know if this is good, bad or otherwise, but it looks serviceable to me. I pulled it to 29" just to be sure there wouldn't be any problems on an overdraw. Unless someone points out a big problem that needs fixed, I'm willing to call it finished. Need to shape the handle, stain it and finish it. Then the fun begins!

[tsorenson]

So I want to cut a rest - Sam's build along says he cut it 1.25" above center...is that about right? I already formed my grip so that the top of my hand is pretty much on center and having the arrow 1.25" above that looks silly. Should I change my grip? And should the arrow shelf be cut 1.25" above center? BTW, I shoot split finger.