Possibly a dumb question, but I come from the wood bow side of the tracks...

When tillering a wood bow one always has to exercise the limbs, working from a long string to brace and then out to full draw in stages. Is this done with FG bows as well or is there a different procedure to working out to full draw on the tree?


Thanks,
Mark

From what I have heard and in my personal practices, glass D/R longbows can go straight to brace and full draw after shaping the limbs.  Just make sure those edges are smooth and radiused.  I am not sure about other types (Hill, recurve, etc.).

My glass hills get strung up on a standard length string right off.  I'll even take it to  full draw before tillering.   No harm done.   Once you add glass,  it's not coming undone unless there is a problem with layup. ..... so far! 

I smooth the corners before shooting but no exercise needed

Quote from: kennym on January 16, 2021, 01:51:45 PM
I smooth the corners before shooting but no exercise needed

x2

I don't exercise them per se. But they do get worked on the tillering tree. I do something with glass bows I haven't heard of others doing. I dynamically balance them on the tree relative to my holds like I do with wooden bows. I don't assume that any predetermined measurement will balance ANY bow just right, wood, glass, or whatever. Only takes a few minutes.

Dynamic meaning getting the limbs pulling straight?
I dont get full unless the limbs are fairly straight.

Early in the tiller, bow is pivoting on that scrap piece of lam, heavy on the right limb and needs more scraping to move the riser to the left.
I need to get more setup like roy's tree

That's why I don't make them gwass bows, too darn easy to tiller.

Plus gwass dust makes me itchy...

   

Mike, Dynamic balancing is how the bow balances while being drawn on the tree or being drawn when shooting it.

Dynamic tillering is our main goal while tillering for equal limb timing.

Static balance is how the bow balances just sitting in the tree cradle.

I like to exercise my bows. But its mostly because I start to get impatient at the tillering stage. So I figure if I come at it like you would a self bow, you lessen the chances of screwing up.

Dynamic tillering is a good trick to use. I also like to try and mimmic a three finger draw with vinyl tubing over carabiners.
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Now I thinking maybe I should rig up a prosthetic arm to hold the bow and a hand to pull the string?

Limb timing Okay.
Dynamic to me is when you put tillering blocks on the bow and mat have to move one way or the other to get them without twist. Can also be done by deepening the grooves and side dressing. So start with wider width on the tips
.

The only time I have excersized my hill bows is when I have built them in stages. If I build a stave and only glass the back then I draw it repeatedly while I tiller and align  the string. When done I glass the belly.

Stag,

is there a particular design you find works better if you build in stages?

Willi I just build hill bows so I cant really comment on other designs.

Quote from: Stagmitis on January 21, 2021, 06:17:26 PM
The only time I have excersized my hill bows is when I have built them in stages. If I build a stave and only glass the back then I draw it repeatedly while I tiller and align  the string. When done I glass the belly.

What do you feel the benefits are of building in stages as you describe?


Mark

Mark a couple reasons..

Sometimes with a single glue up (Not always) a bow will give me fits with limb twist, string alignment and tiller right out of the gate even though I know my lams,nocks,dimensions were all as perfect as they could be. Occasionally I end up with a flat spot in the limb(not sure why) This really bugs me and even though I can correct it I feel like the bow just wont be right.

Because Hills have a deep core they are more subject to internal wood stresses especially with natural material such as Yew.

With a double glue up I can first excerise the limbs removing all stress, easily achieve string alignment and tiller and fine tune limb bend then add glass when everything is perfect. Few times Ive done this the bow seems to have a nice smooth draw and performs better.

Occasionally I end up with a flat spot in the limb(not sure why)

What are you using for a form?

The fire hose method?

I use to use a firehose but have switched to clamps. Cant remember if it happened with the clamps. Any ideas Roy?

Oh, my form is 1.5" cabinet grade plywood. I used to use the LVL stuff but dont trust it since I have had them warp before.

If the mid limb posts you clamp the bow down on are too wide, it will give you a flat spot at mid limb.

My mid limb posts are maybe 1/2" wide where the bow rests on.

I just had a brain storm here, I might grind a very slight concave surface across my mid limb posts.

Couldn't hurt and may help..

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