Primitive Archer
Main Discussion Area => Bows => Topic started by: BryanR on May 23, 2015, 03:38:05 pm
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I know where the problem is, just not sure how to fix it. The left limb, which is the top limb, isn't bending evenly. I tried scraping the outer portion of the limb, and I took scrapes from the bottom limb. Maybe I'm too impatient, any suggestions on finishing the tiller? I stopped working this bow for today.
It's red oak board bow, 67" NTN, trapped like the original. Hopefully you can see the front and back in the photos. Right now, I have 2" of set on the top limb and 1" on the bottom. Should be on target to hit 50#.
Thanks, Bryan
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The left limb is bending too much close to the handle with the whole outer limb needing to bend more and the right limb is similar but not quite as bad. You need to be really careful now to avoid a hinge on the left limb.
My advice is to have a really close look at exactly where the set is located. Don't touch where the set is and remove wood where the set is lower.
Now would be a great time to make a tillering gizmo. They are priceless for bows like this one.
Have you trapped the belly? It looks like it in the photo but I can't be sure? If so that the reason for a lot of the set. Red oak is much stronger in tension than it is in compression. I have used it with a 40% trapped back and no problems.
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If you already have that much set and the bow is barely bending apart from the inner limbs you are fighting a losing battle.
DON'T pull a bow farther back in the hopes that non-bending parts will suddenly start bending if they don't show they are starting to bend at a shorter draw length.
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Basically what PatM says to much set already. Those mid limbs are stiff. You try bending it back a bit and glue a lam on the back or belly and re tiller. I have fixed (limb tip ends) like that and tiller turned out perfect.
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It doesn't need scrapes... it needs a rasp taking to it!
Measure the thickness taper on the limbs. You need to get it reasonably even with a decent taper befor you start bending it.
For an ELB I work on a taper of about 1.6-2mm every 6"
Yeah, I know the units are mixed but mm are V uhandy for thickness measurements.
You need to see that the tiller is off before it is so obvious... it's about getting your eye in and practice.
Del
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Bryan,
Since the Sudbury Bow is in pieces at the Peabody Museum no one has seen the tiller of the original. I tried viewing it but an appointment was required. Go figure. But they do have many bows to see. I had a good time. I even saw what looked like board bows which were probably made from wagon stock.
Anyway, I digress. The Sudbury design is such that the wood is narrow coming out of the fade and the amount of wood increases just before and just after mid limb and narrowing to the nocks.
An area where there is a large amount of wood should do its share of the bending while areas with little wood should bend very little. That seems to be the opposite of you have there. Too much of the bending in your stave is happening right off the fades. That always results in too much set for most designs. Not all. Most.
So, in my view, the Sudbury should have a good part of the bending in the wider area and not so much elsewhere making it a pretty darn good design.
I never made one. Just applying logic. But I'm sure I'll get disagreements. :) That's ok.
One more thing. When making a full primitive bow, that has its widest point just off the fades, that's where most of the bending should take place with not so much towards the nock end resulting in a more circular tiller. To have too much bending at the narrow nock ends will yield too much set.
Look at the English Longbow. The true ELB has the handle as its widest point. The well tillered ones come full round...circular. I'll get disagreements here too. :) That's ok.
Too salvage your Sudbury work on the widest area and leave the other areas alone.
Hope this helps.
Jawge
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The Sudbury is a petty advanced design. I've seen very few stiff handled Native bows either in photos or in museums.
The bow was taken from a Native American that a farmer shot in Sudbury, MA. Kind of sad really.
I grew up in Chelmsford, MA which is somewhat close to Sudbury.
I know....who cares. :)
Jawge
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I agree with Jawge on how to tiller this bow. I've made a few Sudbury style bows. Unfortunately, the only pics I have are of the first one. Tiller isn't perfect, but it shot really well. You can see that I really don't have much bend close to the handle, and a lot of bend where it flares out mid limb. If you deviate much from that, the hand shock is terrible and the set is excessive. Josh
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The Sudbury bow is not in pieces. The tiller is pretty easy to determine by the detailed measurements that have been available since at least Pope's time.
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I was using the measurements in the illustration from the Encyclopedia of NA Bows. The thickness measurement is shown as 9/16th mid limb. I went with a straight line from the end of the handle (1" thick), through the 9/16th thickness at the widest part, to the tips. I feel comfortable with the layout I have, just not the tillering.
I'm amazed that you guys can look at a photo and know where in the process I went crazy.
Mike - I used a tillering gizmo, but my limbs were so flat I wasn't seeing any value. Also, my trap angle was 45 degrees which seems to be similar to the illustration in the book.
Pat - Your comment is right on, because every trip to tillering tree made me want to pull it a little farther each time.
bow101 - Yea, you and Pat are right about the set. I measured this morning and it's still 2" being unbraced overnight.
Del - The first tool I picked up yesterday was a rasp, but put it down because it seemed too aggressive. Your point about seeing the tiller being off before it's obvious -- I probably did see it and chose not to....
George - The observation about wider areas bending more than the narrow areas will come in handy next time I attempt this one. I was originally thinking this was a bend through the handle design, but comments here seem to indicate the opposite.
Josh - Thanks for the pic. That's a good example of what mine isn't doing... :)
I learned just as much from this thread than I did building the bow so far. Be patient, bend the wider areas more than the narrow ones, be patient, be patient.... I'll finish the tiller. I love this bow design and would like to see it bend correctly even if it ends up being 10#.
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Here is a video showing the bow. You can see it looks a bit whippy at the tips but we don't know what type of string the bow had originally. The theory was that the bow was left strung for years before the string was lost.
If the string was a stretchable material it would have changed the dynamics of the string follow depending on what brace height it remained at for the longest period.
https://www.youtube.com/watch?v=WCm6VNbITwU
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PatM, thanks. You are correct. There is a drawing of it on P 34 of Native American Bows and Arrows Vol 1.
Jawge
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Wait. I just noticed I have mine trapped backwards. The last few seconds of the video show the back trapped (narrow back, wider belly). I missed that detail in the book.
Would that help with set?
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Read the first answer to this thread :D :D
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I agree with jawge, josh & pat.....IMHO..the Sudbury I believe had long tapering fades with the limbs the widest at mid limb. The tiller should look a little whipped tillered with most of the bending where it is the widest. I have attached a picture of one that the fades are bending just a bit at full draw. I got a little better performance out of it, but the funny part was, I wasn't trying. It's a trapped back hickory and spits and arrow pretty quickly. The main thing though is getting the most bending out of the widest part of the limb.
DBar
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Thanks DC. :)
Great pics DBar. Thanks for posting.
Looks like I'm starting over.
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Also remember that the Sudbury bow is hickory which can be a more "forgiving" wood than oak.
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Bryan,
I know your original question was specifically aimed at tiller. There are some things for you to consider if you are going start over. I believe that you made reff. to the "encyclopedia and page 34.
If you wish to assume that these drawings are accurate please take note of the following:
1: measuring from the center of the grip, the limb with the pin knock is nearly 20% longer than the other with the carved fineal.
2. The longer limb is wider than the shorter one.
3. The tips are of different thicknesses.....meaning the taper angle is different from limb to limb.
4. If the drawing of the permanent set is accurate then the bow had a circular tiller like Gun Docs' bow. How do I know that? even though the limbs have different amounts of set both ( in my opinion) show even bends throughout @ one.
5. You already noted the BACK is trapped and not the belly.
So the "old-guy" is voting for a circular tiller....at 67+" length the tiller will look like an English Longbow, unless the draw length is over 30" and I sort of doubt that based on my Eastern Woodland research.
Hope you find that useful, sir.
rich
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I guess making a replica is one thing, I just hope that Indian they got the bow off of in 1660 was a master bow maker and not a rookie like me. :) ;)
I'm not into making exact one of a kind replica's. I try to take into consideration the intent of the replica design and make a good shooter out of it. But that's just my way of doing things, different strokes for different folks.
Respectfully,
DBar
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Danzen,
Absolutely correct sir !!! I dont make exact replicas either, and I'm pretty sure the native bow makers did not use rules, straight edges etc. I make mine with finger width, palm, and "span" measurements.
What I was trying to say is that with the differences in the original, the permanent set was different BUT the tiller was aiming at being circular.
I meant no disrespect to your bow, sir. It is indeed "in the spirit of" as are my bows so I apologize if my post even suggested that, it was not my intent.
rich
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NO..No Rich.. no need to apologize to me! I was just warning Bryan to take the dimensions of replicas with a grain of salt. I have lots of respect for you and your bows Rich and I welcome criticism if I'm wrong......
Thanks
Bill
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Does the Encyclopedia show all the dimensions? I have seen the detailed measurements and was pretty sure the upper limb is just slightly longer and the lower limb a touch wider as you might expect a tree stave to verge towards.
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PatM,
It gives the total length as 67 1/8". the width of the top limb as 1 7/8", and the width of the bottom limb as 1 3/4". The belly is flat and trapped. The limb structure turns to oval towards the nocks. The handle is 1 3/ 3/16" thick and 15/16" wide. Bottom nock is 15/16" thick and 3/4" wide while the top is 3/4' thick and 3/4" wide. The design of each of the nocks is different probably to account for stringing.
This is a pretty advanced design. I think the bowyer would known the proper way to tiller it.
Looks like the wider part got more of the bend. Drawings show the unstrung profile.
I remember reading that the bow may have been left strung.
Jawge
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The Sudbury was on display at the Peabody about 5 years ago when I visited.
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PatM,
It gives the total length as 67 1/8". the width of the top limb as 1 7/8", and the width of the bottom limb as 1 3/4". The belly is flat and trapped. The limb structure turns to oval towards the nocks. The handle is 1 3/ 3/16" thick and 15/16" wide. Bottom nock is 15/16" thick and 3/4" wide while the top is 3/4' thick and 3/4" wide. The design of each of the nocks is different probably to account for stringing.
This is a pretty advanced design. I think the bowyer would known the proper way to tiller it.
Looks like the wider part got more of the bend. Drawings show the unstrung profile.
I remember reading that the bow may have been left strung.
Jawge
Seems likely that the bow was made as near identical from limb to limb as a person could make it without actually using calipers.
The nocks are 5/16 and 3/8 in thickness and the back is trapped, not the belly as has been mentioned.
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At the beginning of this thread, my tiller... Well, there was none. After several replies, I realized I trapped the belly instead of the back. Since I needed the practice, I cut the ends and made new nocks in order to flip the stave back to belly.
Three weeks later, the tiller is looking pretty good. The bow ended up being 69" ttt, 28#, 27" draw. It's holding a respectable 3.5" set. :-). The up side, there's not a tool mark on her.
I was surprised how much material came off during tillering. Learned a lot. Wood does bend. I can tiller. Slow down. Even had a twist that got worked out. Didn't expect it to shoot well, but I can group from 20 yards. The arrows are so slow, you can see the arc as they reach the target.
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Looks a lot better now man! The left outter is doing something funny
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Left outter, its a hinging! Not too badly though. Now, get a bamboo strip an glue it on the trapped back. I got a strip I will send you if you cant find any. How long is the bow?