Primitive Archer
Main Discussion Area => Bows => Topic started by: Tommy D on April 14, 2020, 01:20:37 pm
-
Would appreciate any thoughts/ comments on this bamboo backed ipe that I have started tillering today. I made the Eric Krewson tillering gizmo - clever idea - can see how it helps a lot.... but not quite sure how it would work with a R/D bow?
Anyways here are some pictures - not sure if it’s too stiff out towards the tips. Bow is 67” NTN - symmetrical tiller at the moment - but I swing both ways/ am open to suggestions when it comes to shorter bottom limbs. I shoot split finger. This one has a “power lam” between the bamboo and the belly. It’s about 45 lbs at 24 inches - last pic. Not shooting for any particular weight really but would prefer it stay -50-55 range at my 28 inch draw. I guess I have some wriggle room to pike it. It’s taken about an inch of string follow so far
-
I would recommend more bend in the outer half of the limbs. Looks nice and even though. You may be close to your desired draw weight already.
-
I would recommend more bend in the outer half of the limbs. Looks nice and even though. You may be close to your desired draw weight already.
Totally agree with doc. If you had another 2-3" of reflex out at the tips your tiller would look like it does now. But, you don't. So make them move a touch more.
-
OK ... I have tried to take more off the outer half ... not sure if I should keep going ... and I am going to make them narrower tomorrow ... but this is how she looks at 28” ... 50lbs ... still on about 1” of set since I started...
What’s everyone think ... still more off the outer half?
The one limb came out glued up with more reflex ... it seems to work better with this as the lower limb? Would that make sense - stuffed limb at the bottom? Yes
There is a place where the reflex transitions to reflex that I can’t decide whether it’s a flat spot and needs some material removed or if that’s a function if the transition from Reflex to Deflex....
I’ve gone with a new handle type than the cut out window!!
A few more pics... unbraced, at 20, 24 and 28 inches.
Also at 67 inches ntn any thoughts one how short I could pike it to pick up a few lbs?
It seems to shoot nicely ... definitely feels like it prefers the weaker limb at the top.
Not against going asymmetrical tiller either...?
-
More off the outer 1/3 of both limbs.
-
Also at 67 inches ntn any thoughts one how short I could pike it to pick up a few lbs?
did the 1" of set you developed show up while tillering the last few inches or happen earlier on?
-
Early on... hasn’t changed since I’ve been reducing the outer parts...
-
I think it looks good enough now. Could it bend a tad more? Maybe. But the drawn profile pretty much matches the bow unbraced.
-
Is there a taper in the bamboo to the tips? On the photo it looks like the bamboo strap is on the same level over the total lenght.
If there is no taper in the bamboo than you have to make the outer limbs quite thin to get them bending - and that will cost drawweight.
Greetz
Cord
-
I cut the bamboo to the shape of the bow which is a pyramid and then thinned to a knife edge so assume by default it’s gotta taper in length I would have thought. Had another look at it on the tillering tree - finding it hard to make myself take more off the belly! It’s at full draw and not taking more set. And I’ve realised that I don’t draw the 28inches I thought I did when I shoot... so have definitely overdrawn the bow. I am just not sure I want to take off more. I will thin the tips and have another look. There is a bit of hand shock when I shoot it ... but tips still chunky. Maybe that’s the addiction of bow building ... it’s all so final when u over do it u can never wind the clock back! Sometimes the old pilot adage .... Any landing you walk away from is a good landing could hold true for bow building!
Next question though is that now I’ve realised that I really do draw closer to 27 than 28 ... do I take some off the tips and how much?!
-
I would say the bow is done - the more you tweak the more can fail and the bow looks fine.
As Pearly said before: Looks good enough.
Build another one to improve your skill and learn from this one...
Ymy2cents
Greetz
Cord
-
Put it this way, Tom. When I go to shoots I look at bow tillers the whole time. It answers a lot of questions. If you were ahead of me on a target your bow wouldn't catch my eye as a bad one! Enjoy the bow, it will serve you well for a long time.
-
Thanks everyone ... I will take Pearly’s comments as a great compliment! Have just re-read one of Dean Torges articles on tillering. Also read his bit on fixing chrysals/ frets with plugs ... and there is a great comment about how he could probably have built a whole new bow in the time it was taking to fix an old one!
I cut out another bamboo back and I have a belly lam ready to go. Might try and squeeze a bit more R/D out of it ... but the Ipe sure doesn’t like to bend. I’ve done a couple with lemon wood, one with Pacific yew “scraps” off the belly of a self bow and I tried a Eucalyptus (Sydney BlueGum) one once that fretted badly on the belly... but this Ipe sure feels like it wants to explode when I try and put a bit more bend in it.
Any thoughts on doing a triple lam with 2 thinner Ipe strips. I was going to try a maple core but the old timber yard is shut due the current state of affairs!!
-
People do multi lams but you're already likely close to the point of diminishing returns as far as how much reflex you are putting in.
-
Thanks Pat - interesting - any idea why one reaches a point of diminishing returns?
I was watching this you tube clip about “Opa Bows” ... https://m.youtube.com/watch?feature=emb_title&time_continue=134&v=m5ZUD8PyKAU
I know it’s developed into more of a horse bow/ static recurve ... but am intrigued whether I could do something similar with Ipe and bamboo...
-
Too much reflex and you will end with more set.
The more set the slower the 'rebound' speed of the wood.
The r/d design allows the use of well reflexed outer limbs. The deflexed section lowering overall strain and allowing a lower string angle at full draw. This lower string angle means you are bending a thicker piece of wood and thus storing more energy. The design when executed well speaks for itself. Very low handshock, stable and fast. :) What's not to like other than being a wee bit tricky to tiller haha
I think you have done a good job on this one. The trick when figuring out a 'new tiller' is to pay a lot of attention to exactly where the set shows up during tillering. You should always follow the bowyers bible 'mantra' of no set inner limb, a little mid limb and the rest out to the tips. The wood will always tell you how it should be tillered, it hard to hear sometimes though!
As for multiple lams - yes that is definitely the way to go to achieve 'accurate to your form' glue-ups. Bending too thick ipe belly lams leads to many problems. One is the different profile in your limbs. For a r/d bow I would always go with a tri lam.
-
Here is a pretty extreme version of a r/d. Just for fun :)
-
Thanks for all that info. That’s certainly some extreme R/D ... does it feel very different to shoot?
-
(https://i.imgur.com/e9EGQiT.jpg)
Ok - starting a new bamboo backed ipe. Might as well make the most of the sunshine and lock down!
I’ve decided to kerf some wedges and do some static recurve tips. But only for 5 inches. Bow is 72 overall and I have pre-tillered it to brace height at about 25 lbs and a bit whip tillered.
Gonna glue on the bamboo back today.
Thinking of shapes to go with.
Can’t decide between straight reflex or a mild deflex with quite a bit of reflex ... as in image. Aiming for 55 at 31” for a friend. Figure if this goes tits up I can shorten it and aim for 27 inches which is my draw.
(https://i.imgur.com/4CFlVZy.jpg)
-
(https://i.imgur.com/m8QmOwB.jpg)
(https://i.imgur.com/bZs0UHJ.jpg)
On the tillering tree now ...