Built my BBI form..didn't work

[Echatham]

and dont forget to scrape the rind off of the boo becore tillering

[J.F. Miller]

you don't have to scrape the rind off of the bamboo before tillering, or ever for that matter. removing rind is one of the last things I do. usually after I decide a bow is ready for sanding and finish, after it has been shot a couple hundred times. you won't affect tiller or draw weight by removing the rind.

[Roy from Pa]

It looks like a bow:)

[Echatham]

Miller, ok thanks.... I was under the impression it was at risk of lifting a splinter or something with the rind on, that not the case?

[J.F. Miller]

yes, that is not the case. you don't have to remove the rind at all. or you can remove part of it or all of it. it's just a skin, so to speak.

clumsy removal of the rind can cause any piece of bamboo a problem. best done with sharp cabinet scraper and sanding with finer grits and with heightened caution around nodes. I don't put anything more coarse than 150 grit on bamboo back. it's important to only remove the rind itself. if you get into the power fibers, it is trouble.

[Bowjunkie]

I agree with Jamie 100%. I think that many of the folks who think they had a bad piece of bamboo, actually got a little too agressive with removing all the rind, too much sanding, and/or concerned themselves too much with rounding off the nodes.

I like to leave some 'lip' on the nodes, and a wisp of rind in the subtle valleys of the bamboo's back. It ensures I didn't get into the power fibers, and it looks really nice after dying and spraying.

Any time I see someone's bamboo back pristinely clean and sanded so that absolutely no hint of rind remains, and the nodes are knocked off and sanded a lot, I worry for the bow's durability and longevity.

[Zradix]

Originally posted by talkingcabbage:
Zradix, did you pretaper the ipe before glue up, or did you leave it the full 3/8" thickness?

I pretapered width wise.
But the ipe, belly to back was straight.

Thanks for the help gents!

[Roy from Pa]

Jeff, Jamie I have a question. If we trap the back of a BBO bow, aren't we cutting into the power fibers? How do we get away with this? I've done it many times.

[LittleBen]

Trapping shouldn't cut into power fibers anymore than a normal width taper. It would be very gradual.

I would guess that the problem comes because people are sanding alot midway between nodes and are cutting a large number of fibers in one area across the limb. Or nicking the back with the scraper ... who knows.

[J.F. Miller]

Originally posted by Roy from Pa:
Jeff, Jamie I have a question. If we trap the back of a BBO bow, aren't we cutting into the power fibers? How do we get away with this? I've done it many times.

I don't think having the back of your bow narrower than the belly has anything to do with getting into the power fibers.

I'm not sure what "trap" means to you, but if your bows aren't raising horrible bamboo splinters on the corners of the backing then you aren't getting into the power fibers. whether a bow has a rectangular or trapezoidal cross section is not relevant so long as you are only moderately chamfering the corners of the bamboo backing. if you get too happy rounding off those corners, you are inviting disaster in much the same way that you are inviting disaster by flattening the nodes too much.

[Roy from Pa]

By trapping I mean I angle my back side facets in maybe 3/16th towards the center of the boo from the edge of the limbs. Trapezoidal cross section would be the proper term.

[J.F. Miller]

got a picture that shows what your your cross section winds up looking like at mid-limb?

[Roy from Pa]

Not really, but lets say at mid limb, the back of the bow/boo is 3/4" wide and the belly of the bow/Osage is 1" wide. The edges are round.

[Bowjunkie]

I know what Roy's getting at, and I've actually had a couple splinters raise right there where the back and side of the trapezoid make that 'angle'... it usually happens at a node too... kinda where I filed into the side of the node as I created the trapezoid facet.

[Zradix]

I'm appreciating this exchange.

But you gents are talking over my head a little as I am a very inexperienced and simple man.

Should I round over the back on a BBI just like I would a board bow?
Doing so would keep the boo from going right to the edge..because it's just a top layer.

Thank you very much.  

[Roy from Pa]

When any boo backed bow is trapped/faceted, you have to be cutting into those power fibers. Heck they run the entire circumference of the boo.

Jeff that's a good point on the nodes. I might try on the next one to stay at little wide right at the nodes. Almost like a reversed scallop bow:) LOL Bamboo backed bows are a love hate relationship:)

[Zradix]

Originally posted by Roy from Pa:
.... LOL Bamboo backed bows are a love hate relationship:)

Doesn't take long to figure that out ...lol

Just learned a lesson about an hour ago...
If your boo looks like it has a light scrape when you get it that doesn't even go through the "skin"...it can still be cracked underneath...

I was taking a bit of the skin off and realized it has some lengthwise only cracks..so that sucks.

I'm gonna fill with thin super glue and hope for the best.

This thing is whipping my butt..lol

[J.F. Miller]

Roy, et al, this stuff is pretty hard to articulate with words alone, pretty easy in person with bows in our hands, or at least a pencil and paper.

certainly, the edges of the nodes that can get scalped when we round off those corners are the most dangerous. only time I've had a problem is when I got into the edge of the node too much. I only did that one time. took my lump and learned my lesson.     actually, that was also some inexpensive experimental Moso bamboo, too. the fella I got it from lost a bow or two to the same problem. that's why I don't fall for $5 slats of bamboo for backing.

obviously, we are cutting through some power fibers when we cut our backing to its width profile. if this were a problem at all, bamboo would be useless as tension safe backing material, but I guess it isn't since we've all made successful bamboo backed bows.

it does seem like I'm doing it a little different than you's guys. at mid-limb, I don't really employ a facet where the side and back meet. I only slightly round off the corner of the bamboo. the side of the bow is the facet. the corner where the side meets the belly gets rounded considerably more, and I do facet that area for tillering purposes and aesthetics. I keep the belly on BBO's pretty dang flat.

Z, what your asking/suggesting sort of sounds like it might be going overboard a little. go easy on rounding off the edges of the bamboo.

[J.F. Miller]

checks in bamboo going north and south can be remedied with c/a glue. I've done it a bunch of times without issue, even years and thousands of shots later.

[Zradix]

Originally posted by J.F. Miller:
checks in bamboo going north and south can be remedied with c/a glue. I've done it a bunch of times without issue, even years and thousands of shots later.

That makes me feel better.
Thank you