first take down build taper rate questions

[S.newman]

hey guys
 I'm building a design very  similar to 58' Bingham's take down
 I made small adjustment to the riser shape and that's it
i plan to use 2 tapers in the limbs which are 1 3/4 wide

i plan to use 2 (.001) tapers @.06 and 2 veneers @.05 per limb which will bring my stack to .220 minus the wedge
shooting for 45 lb. bow

my biggest question being my first take down is taper rates? should i use more taper or stick with .001
what is the difference in tapers? what does it do?

what is the difference and reason to use different  taper rates?  general knowledge tells me it is used to help the bow bend and
preform a certain way through out the draw cycle.

any info is appreciated as i will be making a few different limbs to see if i can tell any differences anyway
but I'm sure someone on here has done some extensive research on this topic and can shed some light

thanks

[kennym]

I’m guessing this is a recurve since 1.75 wide , I think binghams used .002 total in those .  Maybe Stic or Kirk can help you a bit more, I’m a D/R guy …

[S.newman]

yes kenny it is a 1.75 width if .002 total is the number i should be ok
I'm going to make a set of each one (.001,.002,.003) and
see if i can tell a difference or even notice a difference in limbs

thanks for your input much appreciated

[Kirkll]

With the Binghams recurve design you can easily get away with an .002 forward taper rate because the hook isn't very aggressive...

Now you mentioned the you made some changes to the form... If that change included making a tighter radius hook end, you may want to rethink your forward taper rate and use just one .001 taper....

What happens is that as the limb starts getting thinner at the tips, you start loosing torsional stability. The  more radical you make the hook, and further you put your tip notches out on said hook, the more it wants to go sideways with less than a perfect alignment...

Building recurves, there is a learning curve.... THE most important part of building these things is starting out with the limbs mounted perfectly square to the riser block the full length of the limbs. You can adjust the straightness with the width profile, and adjust it with tip notch depth.  ALWAYS shape your limb profile a bit wide at the tips so you have room for adjustment.

Once you get to the point where you can keep a string on these things and have them draw straight without limb twist, THEN you start learning how taper rates, wedge location and length, working limb length, limb balancing, Tip wedges or no,  and preload comes into play for getting higher performance.....

Welcome to a HUGE rabbit hole.  It can be a lot of fun.     Kirk


Look at these photos getting my limbs perfectly square before mounting them on my riser block.
This is a HUGE thing..... 

https://photos.app.goo.gl/UzS2LqJwCvXYW5cn8

[S.newman]

that makes alot of sense to me kirk appreciate the info and pictures
ill be making a sled for my drum sander as well.
im looking forward to the process for sure
trial and error until i get what i like, then make it even better from there i guess
we will see how it all goes
again thanks for the input makes alot of sense and give me a grounding point to start from

[Kirkll]

Enjoy the ride, but be patient, and don’t be afraid to ask questions as you go along to make things go smoother.  There are a lot of little tricks you can learn along the way, and most the guys on this forum are happy to share their experiences with you.

Good luck, and post photos of your build if you can…..  Kirk

[Crooked Stic]

Everything Kirk said and the form build needs to be good also.

[S.newman]

here is couple pics of where I am now ...waiting on the glass to get here in order to glue up the limbs and
 make sure they are aligned proper before I shape the rest of the riser.
after looking at the riser design I'm not quite sure i like where the accent pieces exit into the limb pad areas
ill change the design for the next one but for this one 
I may end up putting caps on the pad them self to cover any of the glue lines that may be exposed if I don't cap it
will this be an issue down the road? should i use glass of will maple be fine most likely do this before I do the limb bolt hardware?
I'm already finding thing i can improve on but I'm enjoying the process for sure

[S.newman]

stic
i used a cnc to cut the form so it should be pretty dead nuts to what i programed it for
also used it for the riser which i know dead nuts square on my surface plate and indicators
all were programs with the same origin so everything is accurate to each other and all tempelets and jigs are dead nuts
I'm sure ill find something i messed up though and will have to fix it lol

[Kirkll]

Some guys use hardwood to cap their limb pads, some use glass or phenolic. Personally I like linen phenolic the best, but use hardwood now and then, but stay away from glass limb pad caps because I’ve seen them split after installing the threaded inserts and location pins…

I do not know what system you are using for drilling your riser and limbs for hardware, but I would highly recommend using 2 location pins for limb alignment, and an oversized bolt hole in the limbs. I like a 2.5” spread between mine having one above the insert 1/2” and another pin located 2” below the insert.

Another little trick that will save you grief is when drilling your limbs, make the outer limb pin holes a slot instead of just a hole. I use a mill with a machinist table and mill my slot .040 in length.   What this does is give you a first time every time fit, and eliminates noise coming from the tight holes binding up as the wedges flex.

Food for thought.   Kirk.       What kind of woods are you using in that riser?

[S.newman]

hey kirk
that's what I plan on doing is using 2 locater pins with one bolt
I will slot the one pin hole location like you suggested
I plan on machining a limb bolt jig out of aluminum to make sure it is repeatable with accuracy
the wood I used on this one is curry maple and African mahogany (these are woods I had laying around the shop) plan to buy some nicer exotic hardwoods this week also have been working on a vacuum chamber to stabilize all this maple burl I have. I ordered some g10 as well
you guys weren't kidding when you said welcome to the rabbit hole of building trad bows lol. I'm enjoying every bit of it
steve
 

[Kirkll]

 

Wait till you try getting a string on a new set of RC limbs a bit too far out on the hooks and have it flip on you…. I had to clean out my shorts a couple times having it do it on the tiller tree. 

All kinds of fun ahead…