Author Topic: amount of reflex/deflex AND bamboo node spacing  (Read 4017 times)

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Offline arachnid

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amount of reflex/deflex AND bamboo node spacing
« on: May 24, 2015, 04:54:35 pm »
I`ve been wondering..... How do you determine the "right" amount of a glued-in reflex/deflex design?
It seems to me that most people just do it randomly...

and while were talking about bamboo- what is the minimum "safe" spacing between nodes?
I have a large diameter pole but the space between nodes is only 6-7 inches. Safe of trash?

Dor
« Last Edit: May 26, 2015, 04:50:54 pm by arachnid »

Offline bushboy

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Re: amount of reflex/deflex
« Reply #1 on: May 24, 2015, 07:24:55 pm »
I go with a hint of deflex and loads of reflex to a point.as tillered reflex will be lost and deflex will increase due to set.
Some like motorboats,I like kayaks,some like guns,I like bows,but not the wheelie type.

Offline bubby

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Re: amount of reflex/deflex
« Reply #2 on: May 24, 2015, 09:54:54 pm »
Dor i think most guys do some experimenting to try and get whay they feel is that sweet spot, some may also pm an experianced hmm owyer that builds alot of d/r bows
failure is an option, everyone fails, it's how you handle it that matters.
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Offline Mark Smeltzer

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Re: amount of reflex/deflex
« Reply #3 on: May 25, 2015, 01:41:51 am »
I have tried many different combinations and some worked and some didnt.  Also depends on if you're talkin glass bows, selfbows or laminated wood.

Offline arachnid

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Re: amount of reflex/deflex
« Reply #4 on: May 25, 2015, 03:24:32 am »
laminated- bamboo/white oak backed ipe.

Offline Del the cat

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Re: amount of reflex/deflex
« Reply #5 on: May 25, 2015, 03:52:29 am »
I think it's down to feel.
If you assume your dead straight bow was stressed to 90% then you can't add much reflex without going over 100%, unless you add a bit of deflex to compensate or go longer or wider/thinner on the design.
Too much reflex is a pain on the tiller.. hard to get to brace and then you come in underweight (or so I've heard O:) )
Bottom line there is no "free lunch" with bows. Ok some designs are geometrically more efficient, but you are still limited by the materials.
It depends whether you want smooth and forgiving or pure speed... hunting or flight?
That's why we all keep messin' with the wood :laugh:
Del
Health warning, these posts may contain traces of nut.

Offline arachnid

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Re: amount of reflex/deflex
« Reply #6 on: May 25, 2015, 06:59:51 am »
And on the same topic (kind of....). I have this piece of bamboofor backing. it has this "knot" (???) sticking out
of one of the nodes (the one closest to the tip). Will it pose a problem?
I also have to narrow this part of the bamboo since it`s right in the middle of the width taper towards the tips, so
I`ll probably have to cut through this thing... SOOOOOO, what do you say?




Offline Dances with squirrels

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Re: amount of reflex/deflex (New question and picture added)
« Reply #7 on: May 25, 2015, 07:19:39 am »
That knot is a serious concern. Equally as concerning is the lateral gauge a few inches above it. I'd look for another piece.
Straight wood may make a better bow, but crooked wood makes a better bowyer

mikekeswick

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Re: amount of reflex/deflex (New question and picture added)
« Reply #8 on: May 25, 2015, 04:35:56 pm »
Chances are that's just in the rind. Until you scrape it off you won't know for sure. All nodes on bamboo have those 'knots'. It's just a leaf that hasn't had it's 'root' cut off flush with the surface.

Offline arachnid

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Re: amount of reflex/deflex (New question and picture added)
« Reply #9 on: May 26, 2015, 12:48:58 pm »
Chances are that's just in the rind. Until you scrape it off you won't know for sure. All nodes on bamboo have those 'knots'. It's just a leaf that hasn't had it's 'root' cut off flush with the surface.

How do I scrape it? from the sides or from the top?
and while were talking about bamboo- what is the minimum "safe" spacing between nodes?
I have a large diameter pole but the space between nodes is only 6-7 inches. Safe of trash?

Offline Badger

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Re: amount of reflex/deflex (New question and picture added)
« Reply #10 on: May 26, 2015, 01:05:16 pm »
  When I am doing a glue up I have pretty much settled on about 3/4" deflex mid limb and then reflexing about 3" past the back of the bow. That seems to be the sweet spot where I can maintain my profile pretty well through tillering. If I end up with 1 1/2" reflex when finished I am happy.

Offline KS51

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Re: amount of reflex/deflex AND bamboo node spacing
« Reply #11 on: May 26, 2015, 10:25:10 pm »
Node spacing is not really a concern.  Each node does affect how you tiller since the limb is thicker at a node and depending on how you finish the back, each node is a chance to accidently violate the back.  For that reason the fewer the number of nodes the easier it is.  Undercutting just after a node is the thing to watch out for.

One side note.  Based upon some research into bamboo properties, the base of a bamboo stalk is typically stronger than the top.  The node spacing is also smaller at the base than at the top.  However, plant age has a greater effect, with 5 years being about the peak time for bamboo strength.  Both of these effects are due to fiber bundle density at the outer surface.

Ken

Offline Dances with squirrels

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Re: amount of reflex/deflex AND bamboo node spacing
« Reply #12 on: May 27, 2015, 06:27:36 am »
Mike, zoom in on that gauge. It certainly appears deeper than the rind.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline PatM

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Re: amount of reflex/deflex AND bamboo node spacing
« Reply #13 on: May 27, 2015, 10:27:05 am »
 That is just a leaf scar but not all bamboo types have leaf scars on every node.