66" @ 29" draw Spotted gum decking flatbow / pyramid? y/n?

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Ben Cooper
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66" @ 29" draw Spotted gum decking flatbow / pyramid? y/n?

#1 Post by Ben Cooper » Sun Jul 03, 2016 8:43 pm

Hi all, this will be my 1st time building a bow (and my 1st post on oz bow) and I stupidly bought a 1675mm (just shy of 66") spotted gum board (from masters)... My intention was to build the bow at 68" since my draw weight is 29".
Will a 66" flatbow / pyramid bow be suitable for a 29" draw? Hoping to get around 50lbs draw weight.

Also, would you guys / girls recommend backing the bow? If so, any suggestions? The board is 19mm thick.


Thanks all!


Regards
Ben

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greybeard
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Re: 66" @ 29" draw Spotted gum decking flatbow / pyramid? y/

#2 Post by greybeard » Tue Jul 05, 2016 10:54 am

Ben Cooper wrote:........bought a 1675mm (just shy of 66") spotted gum board.......
Ben, once you allow for string nocks your n to n length will be about 64”. Hoping for a 29” draw length is a big ask in a flat bow. Somewhere in the 68" to 70" n to n range would probably be more suitable for your 29" draw length.

At this point in time you probably have not given any thought to the bow 'stacking'.

As a first time bowyer it may be prudent to tiller the bow to a maximum draw length of 25” to 26”. This will allow you to practice your tillering skills and hopefully have a working bow.

Designing the bow to work through the handle should help to reduce some limb stress. As you are using a hardwood wider and thinner limbs is probably a better option.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

Ben Cooper
Posts: 3
Joined: Fri Jul 01, 2016 12:40 pm

Re: 66" @ 29" draw Spotted gum decking flatbow / pyramid? y/

#3 Post by Ben Cooper » Tue Jul 05, 2016 12:05 pm

Ben, once you allow for string nocks your n to n length will be about 64”. Hoping for a 29” draw length is a big ask in a flat bow. Somewhere in the 68" to 70" n to n range would probably be more suitable for your 29" draw length.

Hi Daryl, a reply from another forum mentioned to glue longer tips on... would you recommend this? i would effectively glue an extra inch on both ends making it 68" with a ntn of 66"? or would this weaken the tips? the nocks would pretty much start where the original board ends.

Designing the bow to work through the handle should help to reduce some limb stress. As you are using a hardwood wider and thinner limbs is probably a better option.
So to have the handle working, would you recommend not adding a riser? i was going to laminated a riser on to create a thicker handle, but that may restrict the handle section from working? the thickness of the handle without adding a riser would be 19mm (3/4").

Thanks for the reply Daryl much appreciated.


Regards
Ben

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Re: 66" @ 29" draw Spotted gum decking flatbow / pyramid? y/

#4 Post by greybeard » Tue Jul 05, 2016 3:21 pm

Ben, when I add tips I prefer to have the string groove over the actual limb of the bow.
Tip Comp.jpg
Tip Comp.jpg (98.72 KiB) Viewed 2392 times
If your board is wide enough can you cut it down the middle, cut some ’Z’ splices in the matching ends and glue the two pieces together.
1 Z Splice.jpg
1 Z Splice.jpg (19.41 KiB) Viewed 2392 times
For added strength you can laminate a thin strip of timber over the back of the splice and a thicker sectioned piece on the belly to build up the handle.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

Ben Cooper
Posts: 3
Joined: Fri Jul 01, 2016 12:40 pm

Re: 66" @ 29" draw Spotted gum decking flatbow / pyramid? y/

#5 Post by Ben Cooper » Tue Jul 05, 2016 3:32 pm

Thanks Daryl, i will have a play and see... being my 1st bow and build it will be a learning curve.


Regards
Ben

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