horsebow tillering question...

[makenzie71]

Well I gave up trying to find an easy way to make this from glass...turns out the easy glass way is a lot harder to pull off getting supplies.  Anyway...

What I got is a 48 X 1.75 X .75" red oak board...picked the best I could find for this...has one run out on the belly.  I've got it setup with the tips left full thickness the last 4.5", and the limbs taper from a 6" handle (will be narrowed and stacked a bit higher later).  I'm trying to get a base tiller to start from but my goal is to put bamboo on the front and back.  The back is straight forward...I've planed the surface the board to be as true as possible.

The belly, though, will probably have a contoured surface...do I need to get this a flat surface or do I do something different with the bamboo here?  Then there's the issue of tillering...after the belly is laminated, how do I tiller?  Cut off from the sides?

Also, at the ends of the limbs I'll be attaching 8" siyahs...glued and sinew wrapped.  When I put the backing on, do I continue all the way to the end of the stave and then plane the ends down for a mating surfave for the siyahs, or do I only back up to the siyahs?

I've got more questions, but I'll start there...

[Barrage]

I would continue the backing over the siyahs for at least a portion of it.  And if you're pretillering, you'll have to be careful not to get the ends bending too much.  If you do, when you glue on the siyahs, the increased leverage will mess up your tiller, causing your limbs to hinge just after the siyah transition. 

[makenzie71]

The ends are full thickness at where the siyahs attach...taper doesn't start until the end of the siyah so they shouldn't allow any bending.  That was one of my issues playing with glass; the tips bent which made the joints just pop off.  I've got enough bamboo to go up the sayahs at least a few inches, but then I'll be short on the belly and I think it'll be needed on both the front and back...I'll use something else on the belly then, probably...rawhide or maybe hemp since I've been wanting to use that for something lately.  Suggestions appreciated.

thanks barrage

[makenzie71]

I started doing the prep for my bamboo and getting ready for the siyahs and the siyahs start just after a node on both ends...should I cut out the middle of the bamboo and shorten the piece from there to pull the node away from the siyah?  I would think this would put less strain on the node.

[shikari]

Makenzie please put up some picks to give us a better idea.

[makenzie71]

I'm going to try and get them up this afternoon.  I've decided the node on the backing won't be much of an issue...the angle of incline is so slight that just a little heat will take all the stress off the inside of the node.

I just hope the thing turns out "bendy" enough and has the resilience to not set much.

[makenzie71]

Played around on ym break and think, even with such a light transition in angle, the bamboo will fail before I can get it to make the bend.  I'll try a little more steam but I'd hate to saturate my bamboo.

What's the best way to get a bend in bamboo?

[makenzie71]

Did a little reading and found a few people say bamboo bends like hot plastic when heated up...so I heated it.  IT made the curves okay.  Yay.  Put the my bamboo to my core and wrapped the thing in twine, then clamped all the high spots down.



Glue didn't set for some reason on one sayah, though...probably has nothing to do with my forgetting to put glue on it. Have to go in and adjust that.  But wow do I have a LOT of material to take off...for kicks I put the sayahs in the floor and put some weight on the handle.  No bend.  Little more weight...no bend.  Finally, I stood on the handle with the sayahs in the floor...160~165lbs put the handle 3" closer to the floor.  Wow.





Lots and lots of material needs to come off...

[El Destructo]

Mak...are you going to Sinew Wrap the Syahs down?? Or just going to use String or Twine??

[makenzie71]

Also, at the ends of the limbs I'll be attaching 8" siyahs...glued and sinew wrapped.

String and twine??

[makenzie71]

Haha I now went from limbs that were 3/4" thick, including the backing, to 1/2" and pretty consistant between the handle and sayahs...I can now draw the bow 4" from it's static position with a mere 128.8lbs.  I'm aiming for 45~50lbs...I think I'm going to have more bamboo than oak by the time I get there.  I really underestimated the strength of th elumber, here.  I'm going to be doing an all bamboo one soon and I think I'll be doing front and back laminations with a single layer of 1/8" strips for the core.

I did finish up the sayahs a bit.  I'll get some more pictures up tonight.

I would like it noted that this bow has been made entirely with my draw knife.  I bad mouth the draw knife frequently due to my experiences with it...but it'd been a while.  I'm having a lot of luck this time...it is taking off more than I desire at times, but not so much as to destroy my project as I had happen before.  I don't know if I'll ever like it as much as my hand plane but time and use may change that.  Fun stuff...

[makenzie71]

Yay another one bites the dust...

I got one of the limbs way too thin...took 8 passes at and the very last dug in and lifted way too much.  Ended up having core material half as thick as my bamboo.  On the tree it hinged really, really bad and when I took the string off it didn't really go back to proper static shape.  On top of that the bamboo crushed the lumber in the thinnest part and caused it to tear apart when unstrung.  It was coming along so well...so disapointed.  I may continue shaving it down, then put bamboo on the back as well...or something else...I don't know yet.  It's probably just trashed.  I'll post pictures of it later tonight.  Another one down due to my poor hand with a draw knife.

I'm going to have to go back to longbows and regular recurves...so many failures trying to pull off a horsebow has gotten me depressed.  I'm about ready to just buy one...

[Barrage]

Take all the belly wood off, thin the boo back down and try it again!  From the pic it looked pretty thick.

[makenzie71]

Yeah I started it at a full 3/4" of belly and then shaved down to 1/2 and then to 1/4 trying to keep in the 50lb draw area.  Ended up having to way under that.

I'm thinking of carrying a long, thin fade off the siyahs and handle and putting either 1/4" strips of bamboo or oak on the belly of the limbs...it'd be a long splice and I will have to nearly fully wrap the limbs now but I'm really hoping all my work doesn't turn into a completely loss with this bow.

[makenzie71]

Okay, I'm going to shave off basically all the red oak and splice back bamboo.  The pieces I put in the core I know need to be squared up...but do I need to be careful to keep the nodes intact on the belly lam?