Author Topic: Bamboo back/Belly/ sepele center. Help?  (Read 1009 times)

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Offline DC

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #30 on: November 07, 2017, 03:19:36 pm »

Here is one view of these nocks. I used osage for the static limb tip and then carved out the nock. Hope you like it.
So, a pin nock with broad shoulders. Cool. Thanks
Vancouver Island

Offline Msturm

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #31 on: November 07, 2017, 09:58:44 pm »
If the total bow is 64 in. will a 15 in riser be too much? I mocked everything up and it seems like it will leave me with very little working limb. Should I make this riser significantly shorter?  (keep in mind the profile is going to come down quite a lot.



Thanks!

Offline Del the cat

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #32 on: November 08, 2017, 12:06:41 am »
Blimey, I'd think the riser wants to be much more subtle than that.
Dunno how you'd bet boo to follow that, and I'm assuming you won't have a cut away, so you won't need that great depth.
Maybe I've no kept up with the thread, so sorry if I've lost the plot....
I can't see why a riser needs to be more than 8-10" long and 1/2" thick. (Call me old fashioned  ;D )
Del
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Offline Msturm

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #33 on: November 08, 2017, 07:45:33 am »
Thanks Del!  I went by the riser on another glass longbow of the same length. Once I had it all put together for the dry run it looked pretty funny. I will be trimming it down quite a bit. Just needed some reassurance.

Msturm.


mikekeswick

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #34 on: November 08, 2017, 09:15:52 am »
No you want it longer! Sorry to disagree Del!
Keep it at 15 inches long and about 1 thick (personal preference here) but with differently shaped fades outs. You want it no more than a 1/16th thick 1 1/2 inches from the ends and an 1/8th thick 3 inches in. From there you can steepen the taper upto the full thickness of the handle.  If you take the more orl ess standard handle/fades length of 4 inch and 2 inch with normal fades then imagine sticking a 1/8th thick powerlam onto the bottom of it you are more in the ballpark. You need the longer thin section to go past the 'normal' fades to avoid any hinges off the handle but at the same time it needs to be thin enough not to make the transistion too stiff and abrupt. When working very ends make sure the last 1/2 inch is transparent and a true 'featheredge' or less you will get poor gluelines. Once the riser is shaped you can heat the ends of your boo lams and bend them to fit the fades. It is well worth doing this again to avoid poor gluelines and having to use excessive clamping force.

Offline Msturm

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #35 on: November 08, 2017, 10:45:55 am »
Thanks for the heads up. I will draw out some new lines on it and post a pic to see what you think thanks for the measurements.  Mike, so I think I am understanding this correctly; making the transitions real long and very thin actually lends itself to a working fade transition extending the working limb.

Offline joachimM

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #36 on: November 08, 2017, 11:51:34 am »
I have no idea how well that sapele works in compression

Since the sapele is at the center of the limb, it will hardly contribute to the compression properties of the bow. The tempered boo will take care of that.
Remember, 10% of the thickness provides 50% of the compression (or on the back, tension) strength.
Sapele isn't particularly dense, which is a good thing if you ask me. No need for heavy dense wood at the center of a limb if it ain't doing anything else but providing thickness and an glueing surface...

By the way, Steve T: great bows. Why not make a build-along? We don't see this style of bow often on PA.

« Last Edit: November 08, 2017, 11:57:56 am by joachimM »
Tillering is easy. Problems arise when a bowyer thinks he's right and the wood is wrong.

Offline SteveT.

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #37 on: November 08, 2017, 03:27:21 pm »
With regard to the riser length, I make mine 10 inches.3.5 for each fade and 3 inches for the grip. Seems to work fine, even for 70 inch bows.And I make them1 to 1.25 inches thick, and 1 inch wide. I shoot off my hand so no need for a shelf. Thanks for your compliments on my bows.As for a build along, Ive done that years ago here and there. It's great for you guys to learn from, but kind of defeats my efforts to put on classes 1 on 1 for a weekend. I'll think about it. I've shown a lot of what I do in a build along, but not near everything. Lots of us know it's the little things that add up to make a great bow.

Offline PatM

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #38 on: November 08, 2017, 03:49:08 pm »
I have no idea how well that sapele works in compression

Since the sapele is at the center of the limb, it will hardly contribute to the compression properties of the bow. The tempered boo will take care of that.


 He only mentioned that because he was suggesting that the Sapele temporarily be the belly for tillering purposes.

Offline SteveT.

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #39 on: November 09, 2017, 04:54:22 am »
OK JoachimM. If you search on Paleoplanet ,"rope and wedge build-along", you'll find my tutorial. It's still on there, and shows how to build a core and all the way through the glue-up of the bow. Photos and explanation of how I do things. Hope that helps you.Oh yes, it's in the composite bows section.But a google search brings you to it.
Steve Thomson

Offline Del the cat

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Re: Bamboo back/Belly/ sepele center. Help?
« Reply #40 on: November 09, 2017, 10:25:38 am »
No you want it longer! Sorry to disagree Del!
You're not dissagreeing on the main point which is the shallow angle of the fade. The thicker the riser the longer it needs to be for the gentle fade.
I see it as "alt agreement"  ;)
Del
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