Bingham 62" Hybrid Longbow?

[Archer Dave]

Hey everyone,

I have made several self bows and would like to try our a glass bow.

I was thinking about purchasing the Bingham 62" Hybrid Longbow plans and trying one of those for the first laminate bow.

What do you guys think about this bow? Is it a pretty good performer? Is it a decent first laminate bow to build?

I would love to see pictures of ones you guys have made.

Thanks
Dave

[Archer Dave]

Are there other form patterns out there like this? Any free one on the net?

[kennym]

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=011684

[Trux Turning]

Go with the one Kenny posted- it's a good one

[fujimo]

x2 what trux says
its a really great bow- and all the help is right here.
i have built two now, and on the third in the next short while- just getting the lams all ground up!
check out kenny's new forward riser longbow!- its very cool too!!!!  

[Archer Dave]

Excellent. Thanks Kenny. For the link and for your design.

Can I ask a few questions since I am not still super clear and the laminate bow builds.

If I wanted to build the 60" 45#@28" the chart on the plan calls for .320" stack of lam and glass. How would you go about sizing the various pieces in the limb? Is there a ratio for the thickness of the stack to each component in the limb?

I guess what I am trying to ask is how do you know what glass thickness and laminates thickness to get to get to the .320"? Or can you use any combo as long as it adds up to the .320"?

Also I guess this bow only uses glass on the back and not the belly?  Looks like from the back of the bow it is 1 glass, 1 parallel wood laminate, and 1 .002" wood taper laminate? Is the .320" stack measured with the butt thickness of the taper?

Is there a reason not to use glass on the back and belly like a lot of commercial bows?

Sorry for all the newbie questions, I am just not very clear on that and have not been able to really find much info on the net about it. I think once I have the concept and understanding about this aspect I will be on my way. I am a wood worker and machinist so the skill is there, just not the understanding about the relationship of the components to get the bow to the right draw weight.

Thanks
Dave

[Trux Turning]

Glass is on the belly and back- I'd use .040 glass for the bow you describe (45@28). You do measure the taper thickness at the end- I use 1-.001 taper, 1-.002 taper and 1- parallel (.040) the tapers need to add up to 200. I put both tapers on the face side of the riser and the parallel on the belly.

[kennym]

Like David, I use 2 - .040 glass on that bow, both faces of limbs.

My layup is different but makes no diff as long as you dry run and make sure the riser fits on top of lams you want under it.

My layup from back of bow is

glass
a parallel(veneer)
a .002 taper
riser
.001 taper
parallel(or veneer)
glass

I make the .001 tapers thin enough that they will bend up the belly ramps on riser, say .060,
.002 taper at .120 2 parallels at .030 each, and 2 glass at .040 each.

Once glued it is composite, so in my opinion doesn't make a bunch of difference.

Dave's way is every bit as good as this way, just a different route  to .320"

do a dry run!!

[Archer Dave]

Kenny, Trux, - Thanks for the replies.

OK that makes a little more sense. However does the number of laminations on the inside not have any bearing on poundage as long as the stack adds up to .320"?

You guys both talk about using .040 glass is this the deciding factor on reaching a set poundage? Or could .030" or .050" be used if the stack remains .320" to reach 45#?

That is where I am unclear, because I have read some places that say the thickness of the glass is what determines draw weight.

If this is so, is there a general range that should be used with your chart to know when to use the different sizes of glass?

Thanks,
Dave

[Archer Dave]

One more quick question.

Can these bows be built more simply like the Bear Archery bows that only use one parallel between to layers of glass?

The reason I ask is because this would considerably lower the price and allow me to get building sooner.

Thanks a lot,
Dave

[fujimo]

in theory, as long as it makes the stack height, BUT the desired ratio between glass and lams is 20 to 80- so about 20 to 25% of the stack should be glass,
the more lams, the thinner they are, and so they conform to the tight radii around the riser section- thicker lams wont bend as easily leading possibly to gaps in the glue line- there are 2 schools of thought on this- more lams will be better performers than less lams- for a bunch of different reasons i have read.
more lams can be a little trickier to get all lined up, when they are all slimey- but i like it for ease of bending- just make sure you use the thinner lams on the belly where the tighter radius is!

good luck mate.
a lot of better bowyers out there than me- i am sure they will chime in with their thoughts and practical experience.

[kennym]

Several things change draw weight, most bowyers say most important part is distance between glass. Which is core/veneer thickness.

Different thickness glass will change also as glass is stiffer per thousandth than wood/bamboo.

Dave's layup would save you one set of lams and work just fine, my reason for 2 parallels is simple, I love clear glass so I use 2 tapers and 2 veneers....

More core layers is like plywood, stronger because if there are faults, it won't be clear thru the one lam..

[Archer Dave]

Hey guys I appreciate the info. I think I might start work on the form and then start getting the supplies for the bow.

Are there any good books about making laminate bows that I should look into? Or any good sites that cover all the details of lay up and construction practices?

Thanks,
Dave

[Archer Dave]

Thanks again for the help. I had one more question.

Both the Kenny R/D Longbow plans only go from 40-55#. The 58/60 is in 5# increments with a stack increase of .005", while the 62/64 has a increment of .010" per 5#. Would this be consistent up or down beyond the chart's range?

In other words if I wanted to build the 60" for my wife at 30# would I use a stack of .305"? Also what thickness glass would I use at that weight? .030"?

Thanks a lot for helping me learn this stuff.

Dave

[fujimo]

i would search for "stack calculator" on here- punch in your numbers and see what she say!

[Archer Dave]

Thanks, I tried the one found on here but the numbers it outputs are drastically different they what is on the patterns for Kenny's bows.

[fujimo]

yea i dunno- might need to see what kenny says