building a loooooong recurve

[JamesV]

This bow will be 70" NTN with 1 3/4 glass limbs, 21" riser, .040 glass both sides, mild recurve. Target weight 55-60. Any suggestions for stack thickness at the fades and taper rate. Tricky I know but someone out there has the correct specs, if not, after the build I will have the specs to share.

Thanks,

James

[Pat B]

James, the purpose of recurves is to get more out of a bow. At 70" you will hardly put the recurves to use.

[MoeM]

Or you`ll need a much longer riser...

[dfrois]

FWIW, the 70" target bows usually have 25" risers, and accomodate draws of more than 31". So, unless your draw is 32" or more, you may not be getting the most efficient design for your recurve. Unless your goal is smoothness, more than speed and cast...
As for the stack, have you checked the Bingham's weight chart? It may be a good starting point. Or measure a sorter bow, and decrease 2 to 2.5# for each 2" more in the riser, and adjust thickness by the usual rules: twice the width equals twice the weigth, twice the thickness equals 8 times more weigth. For all else equal, of course...

Just my two cents. Then again, what do I know????

Good luck with your project.
DF

[dfrois]

Sorry, I meant "measure a SHORTER bow..."

DF

[Mike Mecredy]

I'd have to see the shape of the back of the riser, and the amount of recurve in the tips to advice on a stack thickness. But a guess off the top of my head I'd start with .300.  I do know you'll need a longer riser though, at least 24", that is, if you want to optimize performance.  I re-limbed an old de-lamed bear recurve, that was 64" and the riser was around 24".

Plus at 70" long your brace ht. will probably be around 12".

[John Scifres]

Hi James.  Can you tell us why such a long recurve?  I'm just curious as I haven't a clue about stack thickness etc  

[JamesV]

John.............

This long recurve is a brain child of another Gang member (name withheld), why I really don't know, I am just going to be the builder. My thinking is that hopfully the finish product will be more like 64-66", maybe with a Super Kodiak or Super Diablo limb profile, something that would have a good chance to be a good shooter with some performance.

Mike..................

Thanks for the suggestions, I also have reservations about performance from a 70" recurve but I am not designing this bow. From what I understand the profile will be more like a wide limb R/D longbow with mild recurve tips. Either way it should be interesting and I will keep everyone posted.

James

[Mike Mecredy]

Here's the spec. on a Kodiak special I re-limbed, and brought back to life, 3 years ago.
(here's a link)  http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=14;t=003694;p=1

Was a total of 66" long, (64" NTN) and it had a 29 1/2" riser, 1 3/4" wide, the stack thickness was .260 at the fades, it came out 48# @ 28".

[JamesV]

Thanks Mike.....

Good information and very nice work on the re-limb job.

Thanks again

James

[Mike Mecredy]

Okay, it's been a few weeks, how'd it turn out?

[JamesV]

Mike.............

All the material is here and I am ready to go but I am only the builder not the designer. This project is the brainchild of another gang member (name witheld). This member is one of the "worker bees" for the CATCH A DREAM SHOOT held this weekend and has been very busy the past few weeks. I will certainly keep you and everyone else in the loop when it does come together.

Thanks Mike,

James

[JamesV]

OK guys, here is the final dimensions for the recurve. 68" NTN mild recurve profile, 24" riser,
I 3/4 .040 glass, target weight 50-55 @ 28". All I need is the stack thickness at the fades and taper rate, to do the build. I will post pictures along if anyone is interested.

Thanks guys,

James

[JamesV]

This is the form that will be used

 http://i1217.photobucket.com/albums/dd390/Hy42dra/New%20Bows/bigformresized.jpg?t=1373994609

[LittleBen]

Should be a nice target bow. Looks like lots of deflex, and obviously plenty of length. Should be extremely smooth, and extremely stable.

Probably alot of fun to shoot, doubt it will be the fastest thing around, but thats certainly not shy we all shoot trad bows.

Look forward to seeing some pics.

[dfrois]

Looks good, James. I, for one, would surely like to see how your build goes. I'm sure others would too. I have been reading some on target bows, and it seems that a long recurve is, for geometric reasons, inherently more precise than a smaller recurve. Of course, that shows more on long distances, 50, 70, 90 or 100 yards...not much difference at short hunting range. So the long recurve idea, with a long riser and shortish limbs, is probably quite good as far as accuracy goes...

Best of luck. DF