Mock Orange Bow got ??'s

[crgibson]

I feel as I have a fair start with this 1 1/4" x 60" Mock Orange (syringa)stick. Flipped the tips approx. 1 3/4" with dry heat worked good no lifted grain,  4 1/2" brace, Tillered at present 30# at 24" w/ 1/4" positive lower limb or I think so. I would like a 26" draw to 27" Keep tillering or will it take 26" draw now? If I keep tillering to 26" will I gain weight or drop? and I would like to add tip over and under lays for fun but will this make tips to heavy? Any need to back it(rawhide) if I go to a 27" draw?   Thanks,Crg
 

[PEARL DRUMS]

This is my opinion, only an opinion. I would brace the the bow closer to 6.5", then check my tiller again. If the tiller is still good then by all means pull the bow until you hit your desired weight or length, hopefully its before 27", that way you can sand and shoot the bow in and not go too low.

[Art B]

At this point IMO, you should be tillering by feeling for limb strain alone. If, both limbs feel like they're receiving equal strain at what you have drawn now then bets are you can pull 'er right on back to 26-27" without tiller changing. I would figure 2# per inch increase in draw weight if you don't have to remove any more wood. No drawbacks for backings, only a plus in my book. That's a nice one to maybe sinew......Art

[J.F. Miller]

for a 60" bow, I would not brace it over 6" unless you need to in order to achieve proper arrow flight. during construction, there is no good reason to brace it any higher. if you are satisfied that the tiller is correct at 24", then pull it to 25" several times and check it again. if all is still well, pull it to 26", and so on. if tiller goes astray, make corrections and proceed.

as a rule, once I have a bow braced for the first time I never pull it beyond 5lbs over the target finished draw weight. (i.e. if I'm making a bow that I want 60lbs at 28", then I don't pull it beyond 65lbs, whether that is at 10" or 27")
drawing a bow under construction too far too soon is only inviting string follow or ourtright failure unecessarily. you lose weight both by removing stock and from compression.

once the limbs are bending gracefully and synchronously, "tillering" is as simple as removing wood evenly, and coaxing it incrementally to full draw, being ever mindful of draw weight and maintaining correct tiller.

in the last pic, it appears that you have positive tiller in the limb on the right, whichever limb that is. what matters most is that tiller is correct at full draw. it matters not what tiller looks like a brace height, although, if tiller is correct at full draw, it is almost always correct at brace height by default.

unless you are making tip overlays out of solid steel or granite, you'll not likely notice any affect on performance.

unless you fear for the integrity of the back of your bow, adding a backing like rawhide(which is quite heavy) is only adding mass to the limbs and robbing the bow, especially a light weight bow, of cast. if you have violated the growth ring that is the bows back or you have doubts about it being tension-safe, then back the bow. a good option in such a case is to lay on a backing of raw silk and cyanoacrolate(super glue). this is a very strong and lightweight backing. two courses of silk and c/a glue will do a tremendous amount of tension work.

[crgibson]

Top limb right side brace pic.

PD Thanks for your opinion I did twist the string up a bit to 6" brace checked tiller quick two times with the gizmo some light marks on outer reach of both limbs and a bit more mid limb on lower. I did not make weight because I was hoping for 40ish don't think shes going to make it but no doubt ill make 27" with no problem
 
Thanks Art B After PD post I did make a very slight tiller adjustment might have lost a few lbs. But before this change I did feel that I could ask the bow for 25-26" with no problem so now i am at 33# at 27". I'm really excited about the thought of sinew backing, will this up the pounds any or just add reinforcement? Art where you at in W Va I have been out that way a few times to the Appalachian String Band Festival at Camp Washington Carver Clifftop, W Va Good times only bows there are fiddle bows

Gosh JF thanks for answering all my questions and excellent advice. Top limb right side in brace pic. Do I have this all backwards? I thought in my brace pic that my left lower limb looks stronger. I never intended to brace any higher then 5 5 1/2 max 4 4 1/2"  i'm getting some wrist slip OUCH! I feel I was real close with my tiller at 24" so started easing it in at 25 26" and bumped 27" to get a weight 33# at 27" hope this wasn't to premature. The back of the bow looks very good and I new rawhide would probably be to heavy at low weight and would only back it now if you think I could up the weight some with the silk or sinew. So this bow is what it is, I should not get to greedy and be happy im not blown them up as often as I use to.

Thanks guys for the good help and advice. Take care, Chuck

[J.F. Miller]

silk backing won't increase draw weight. only sinew will do that. with enough sinew, you might raise the draw weight ten lbs.

pic of braced bow does show stiffer limb on left(lower limb), which means you have positive tiller on the right limb (upper limb), i.e. the upper limb is bending MORE than the lower limb, which is ok.

some folks make their lower limbs stiffer to accomodate their shooting style or because they design bows with shorter lower limbs (for balance in the hand). personally, I do prefer shorter lower limb, but in a finished bow 60-64" in length, I like only a very tiny amount of positive tiller(about 1/16") in the longer upper limb.  

it's quite sensible to brace a selfbow as low as you can while keeping bowstring off your wrist and getting good arrow flight.

[Art B]

If you're not satisfied with the bow's weight, then you would heat up and set back those limbs for a sinew job Chuck. I agree with J.F., you could gain 10# or so on a cool/cold day.

I live about 12-15 miles from Camp Washington  Carver. That area may have experienced a twister last nite according to my NOAA weather radio.......Art

[crgibson]

Thanks for the input JF and Art,

 Art,JF I would like to up the pounds on this bow if you guys think it will hold up. Love to give it a go for the experience if no nothing else. 2 or 3 sinew layers? Bow has fairly high crown would I come all the way down the sides then trim or more like 2/3 the way down? and how far towards the tips do I go? Would like to put my over tip overlays on now or should I wait till sinew job is done?

Should I put this bow on the back burner? is it a better winter time project when weather is cooler gets dang hot here in the summer. Plus it will take some time for me to find and process sinew myself or to order some. How much will a pound of sinew from 3 rivers do one bow, two bows?

Thanks you two, Crg

[Art B]

A high crown is great for sinewing IMO Chuck. Same effect as trapping the limb's sides. Helps concretrate the greater bulk of the sinew more to the crown which saves a lot of sinew/glue, thus a lot of physical weight.

It's not so much about adding a bunch of sinew to get the job done, but more about getting the most out of the sinew you use. And being smart about how you use it. Big difference with gaining/losing poundage due to changing weather conditions.

Just my recommendations here, but I'd stop the sinew short of the tips by about 8-10" and only sinew the 2/3 width like you mentioned. You can stairstep in from the side also with the layering. Concretrate most of the sinew down the crown of the limb.

Stairstepping the sinew layers in from the tips could save on materials also. Since the inner limb receives the greater strain (like the crown), only makes sence to add more sinew here, mid-limb even less and near tips very little.

Depending on shank size, 6-8 pieces will probably get the job done with some left over. I think I use something like 2 ounces of shredded sinew on average for a design like yours.

You could go ahead and sinew your bow now, but check weight and tiller during cooler conditions. Good luck.......Art