Tillering help

[TheBronzeAge]

I've got this bow at the beginning stages of tillering.  (It's my first bow, and so I'm not really sure what it should look like.)  I've had to do a lot of rasping and sanding to get it even to bend on the tree, even with a double pulley system, and I want to make sure I haven't introduced any fatal flaws.  How's the tillering look so far?
     

If it helps I've added two blue lines to this picture that run exactly parallel to the edge of the one thing I know is actually level in the picture, one above the bow and one below.
   

[George Tsoukalas]

I think you should get mid limb and on bending more. Jawge

[Rain Man]

In my non-professional opinion, it looks like all of your bend is the first half of the limbs.  I don't see any bend at all from mid-limb out to the tips.

[Rain Man]

aw... Jawge beat me to it

[shamus]

+1 to Jawge.

[TheBronzeAge]

Alright, I thinned out the tips some and pulled it again.  I swear it looked like it was bending more before I had to let go with one hand to pick up the camera, but given what I got do I need to thin the tips more?
   

Other questions:
1) I've been pulling the bow to the tillered point about 30 times every time to work out any kinks.  Good, bad, not enough?
2) When to add the notches for the string?
3) When to switch from the long tillering string to the actual bowstring?

Thanks everyone, it's very helpful to be able to ask experts.

[walkabout]

heres a link which might help you out a little, it explains the steps in tillering, i built my first bow following it.  http://poorfolkbows.com/oak7.htm  youll want to pull it an inch or two at a time, checking to make sure its bending evenly, which in your pic the right limb looks stiffer. go slowly and dont remove too much at first, as youll end up with a very light bow. get the limbs to pull about 5 lbs under your draw weight while pulling about ten inches, then youre ready to move to short brace if its bending evenly.

[walkabout]

using a 4 inch block slid down the inside of the limb helps to show stiff spots and hinges by watching the gap between the block and limb. you can also search this site for"tillering gizmo" and it has a how to build a little tool which is invaluable in bow building. it leaves marks where the stiff spots are when used correctly.you could add your nocks now, it will help in keeping the string in the same place all the time, just dont cut them into the back of the bow deeply.you only need enough to keep the string in the grooves. good luck and keep posting your questions, were glad to help.

[TheBronzeAge]

Alright, that's helping a lot.  I had to fix the tillering tree so I could lock the bow in bent while I ran the block along, but it immediately showed me so stiff spots.

I've made the shallowest nocks I've ever seen.  Which should I worry about more: snapping the tip of the bow off, or having the string slip off shallow nocks?

[walkabout]

generally you should worry more about the string slipping while pulling it, as long as your nocks are within reason it shouldnt hurt i think most of mine are 1/8" deep or so, but only that deep on the sides.

[Eric Krewson]

Make a gizmo, remove wood slowly and your first bow will be a success.

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=001047

[bigcountry]

I think more bending is needed outer third on both sides.  And I would move to short string pretty soon.   I have learned that staying on long string too long makes the end outcome light.  If your getting 10" of travel, cut in the nocks and move to long string.  It will also put more pressure on those outer third to give you a more accurate picture.

 

Originally posted by TheBronzeAge:
Alright, I thinned out the tips some and pulled it again.  I swear it looked like it was bending more before I had to let go with one hand to pick up the camera, but given what I got do I need to thin the tips more?
   

Other questions:
1) I've been pulling the bow to the tillered point about 30 times every time to work out any kinks.  Good, bad, not enough?
2) When to add the notches for the string?
3) When to switch from the long tillering string to the actual bowstring?

Thanks everyone, it's very helpful to be able to ask experts.

[TheBronzeAge]

I've made some nocks, and I'll be switching strings next time I tiller (which won't be tonight).  I think I'm a few parts short for the gizmo, but I'll beg/borrow/steal what I need.

I'm also seeing a lot of stiffness in the outer ends of the limbs - currently one limb is marked for thinning across the last third and the other for the last half.  Hopefully that means I'm getting the hang of seeing the stiff spots.

[walkabout]

you can also just drill a hole in the block and wedge the pencil in there thats what i have till i round up the nut for the improved gizmo. another thing is that once you go to short string the areas toward the tips will bend more so you have to go slowly with those areas till youre just about at brace height(6" or so)i excercise my bows about 30 times or so after removing wood too to get the wood used to bending so youre good there. id scrape the outer thirds of the limbs  until they bend a bit better then brace it at 3 inches to see where it stands, then move inch by inch till you get it perfect. dont remove too much wood at once or youll create a hinge or end up light.

[TheBronzeAge]

I've added the nocks and got the ends bending a bit more.  Does this look OK to switch to a short string here, or should I get the tips bending more?

     
(The blue line is a true horizontal, since nearly nothing else in that picture is)

[George Tsoukalas]

More bending mid limb on to the nocks. There are buildalongs on my site. Jawge
 http://georgeandjoni.home.comcast.net/~georgeandjoni/

[walkabout]

i agree from midlimb out needs some work. are you checking the draw weight as you go along?its a pretty important thing in the tillering process in itself. never want to go over your target weight or youll get alot of set or string ollow.

[TheBronzeAge]

I haven't been checking the draw weight, mostly because I don't have any good way to.  It's much stronger than it wants to be, though.

I may get a chance to work on it this afternoon, and I'll thin the limbs out overall and especially mid to end.

Jawge - any particular location on your fairly large site that I should be looking for a bow like this?

[walkabout]

i use a cheap fishing scale i bought at walmart to weigh in mine, works for up to 50#. used to use a bathroom scale i set my tillering tree on but when i was tillering it gave me inaccurate readings.

[bigcountry]

Well, you won't be checking draw wieght until you get to short string and then only when its bending even with no stiff spots at brace.  And then only checking wieght until you see any sort of hinge or stiff spot you want to back off immediately.  

It would be the last thing I would worry about at this point.

 

Originally posted by TheBronzeAge:
I haven't been checking the draw weight, mostly because I don't have any good way to.  It's much stronger than it wants to be, though.

I may get a chance to work on it this afternoon, and I'll thin the limbs out overall and especially mid to end.

Jawge - any particular location on your fairly large site that I should be looking for a bow like this?