Hey guys.
This winter I'll be making a bow.
Most likely a hickory backed osage.
Want to make it 65-66" or so.
Tossing around the thought of trying to make one with LOTS of r/d.
Something like a Kanati...
(http://i748.photobucket.com/albums/xx121/Zradix/kanati.jpg)
My thought was starting by laying out and tapering the osage as normal.
Then thinning it out on the belly with a nice radius..maybe to about 1/2 thickness in the center of the riser so it can handle the bend.
Then..and I'm not sure if I should do this before or after gluing the backing...I'm thinking of adding a stack of thin wedges to the belly to strengthen, fill up the space and use as a power wedge.
After that either glue on a one piece handle or possibly just continue stacking thin pieces for the riser/grip area.
Ideally I suppose it would be nice to do this in a tri lam, but at this point I have no idea how much I'll have to scrape away during tillering.
What are your thoughts?
Ever seen anything along those lines?
One of my worries is by not having the wedges sandwiched between the belly and back I'm worried they might just pull away when flexed...
Thanks! :thumbsup:
Wow, lots of questions in there. Let me see if I can answer some of them ....
The thinner the lams, the easier they are to bend. With that said, I think you should do a tri-lam.
I think this type of build is a good candidate for using supertiller and trying to calculate a proper stack thickness.
Also I would put a power-lam, or even a fulle riser (or something in between) in between the backing and the core/belly lam. That way it cannot pop off.
What draw weight are you looking for?
I think for 50# @28" for a 66" bow, you probably need a stack thickness of about .600, assuming a 12" riser or powerlam. and taper of about .006"-.0075"
I'd plan to shoot a little high on the stack, and a little wider than you think you need so you have some room to maneuver.
I'd go with 3/16" hickory backing (~.190)
3/16" core, and a 1/4" osage belly lam. each lam .002" taper.
total stack of .630 ... that shoudl egt you there.
I'd glue it up 1.75" wide, and be prepared to narrow to 1.5" if needed.
WOW!
Thanks Ben.
:notworthy:
Just so happens I was thinking about 50#..not much over.
Have to admit...sorta sounds like this thought may very well be above my pay grade...
...just as a thought....
Is it "ok" to heat bend an osage belly through the riser section?
Sounds like a tri lam to me:) And Bens specs are right on. Wonder who told him all that stuff:)
Thanks for the back up Roy.
:thumbsup:
I made a couple similar to that this year... reflexed as much, deflexed as much, but a little more gentle right in the handle there on the front where that one looks 'kinked'... got another one going right now... bamboo backed osage tri-lams they are. They're shorter length and heavier weight than what you're shooting for... with no power lams, and my handle pieces are glued on the belly side... no issues. My advice? Don't make it more complicated than it has to be.
Mine are 1 1/8 - 1 1/4" wide at the flares and within a few pounds either way of 60# @ 28".
sounds promising..
Thanks
Unless I want to hand taper the lams..I'll need better tools for a tri lam.
Ok, gotcha. That would make it tough. I'll cut and grind them for ya if ya send em.
I might suggest having someone tape the lams for you. Talk to KennyM, when I was angry at my thickness sander a while back I asked if he would taper lams for me if I sent him material and he quoted me a price.
You could send him your stuff and get it back prefectly tapered and thicknessed.
http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=010185
this is a bow I made, basically how I'm describing to you. Onl;y difference is you'd make it an R/D profile .... You can see that the riser is basically a thick powerlam, and then theres a glued on chunk on the belly side to thicken it up a bit.
Honestly, it wasn't very hard (and I'm not much of a woodworker). These bows come off the form basically tillered ... all you do is cut the front profile, check the tiller on the floor to confirm, and I usually go straight to a low brace.
Only the backing strip goes on the backing side of the riser, so your core and belly lams don't have to make that extreme bend.
I'm working on one now I will post in the next few days and it literally took me like 15minutes to tiller. When you have the right taper in teh stack, the tiller is much better than anyone can possibly get going just by eye ... it's almost ridiculous.
Jeff and I are apparently mentally linked here ....
One last thing ... It's easier if the backing strip is in one piece and not spliced, so you can always use a parallel backing strip and only taper the core and the belly ... just give them a little more taper ... like .003" each for the same .006 total.
For these tri-lams I usually figure between .001"-.0015" of total taper per .100" of stack thickness. That usually gets me really close .... probably closer to .0015"/.100" than the lower end actually.
Tri Lam, Johnny Boy. And I could induce a lot more d/r if I wanted too.
(http://i47.photobucket.com/albums/f165/ROY-CHRIS/abc1.png) (http://s47.photobucket.com/user/ROY-CHRIS/media/abc1.png.html)
(http://i47.photobucket.com/albums/f165/ROY-CHRIS/kanati.jpg) (http://s47.photobucket.com/user/ROY-CHRIS/media/kanati.jpg.html)
Yeah, Roy is right on ... You can add all the reflex or deflex you want. Actually with a trilam you can even make recurves ... the only reason I bothered doing it as I did in that post was asthetic. I wanted it to be styled just like a glass bow (don't hate me for that Roy)
Yeah, I keep trying to get Roy to induce more reflex and deflex but it's like asking him to pull his own teeth... he's askeered :)
Damnit boys..this is starting to sound like a dare.. :saywhat: lol
Your bow is pretty cool there Ben..
Forward handle with an almost straight core and belly...cool way to skin that cat.
ok..ok...
Talking tapered lams ... I'm pretty sure I understand what a .002" taper means..it gets thinner by .002"/linear inch.
...but..and please excuse my ignorance here..do you start that taper in the middle? or do you leave the middle riser section full thickness?
OK JEFFRO, next tri lam is gonna look like a high tech, cough choke, recurve!
Benny, I'll let it go, this time.. :laughing: :deadhorse:
Zradix, when I grind tapered cores for regular backed bows or tapered lams for tri-lams, I grind them parallel from just outside one dip to just outside the other, and taper from there to the ends of the pieces. This leaves more wood in the dip and handle which helps keep It from bending as much and can help keep the handle from popping off.
One other note... on trilams, I put all of the taper into the core lam, and make the belly lam parallel so I have adequate room to remove material during tillering and weight reduction without worrying about going through the belly lam into the glue joint.
Just something to think about.
Good point Bowjunkie.
That's one of the main reasons I've been hesitant.
Any problems with doing a hickory, osage, osage tri lam?
Or should the core be something else?
An Osage belly lam, with an Osage core lam, will yield you one of the best tri lam designs you could possibly make. Bow wood doesn't come any better than Osage:) Like Jeff said, he leaves a little more material from dip to dip by doing a parallel taper on the core lam there. Another thing I incorporate in the riser area to add strength there is, I make my flares 1 1/4 wide, and I maintain that same 1 1/4 limb width out another 6 inches on both limbs, then I do a straight taper from that 6 inch line to the tips. I believe Jeff sort of does the same thing by cutting the limb profile 1/8th wider there when he cuts the bow out. Like Dean Torges advocates in his DVD.
I have seen so many new guys lose a bow because they get the area right out of the dips too thin, thus a hinge develops there! I tiller out the mid limb area first and leave the area outside of the dips till last, well I keep an eye on them and may remove a little wood, but I don't get too aggressive in that area until I'm almost at my final draw length on the tree. There is a lot of pressure placed on the area right outside of the dips.
No, nothing special to concern yourself with there. That could make a really good bow.
Roy, I usually taper in a convex arc from flares to tips. That's how Dean does it too... usually.
Ya convex arc, 1/8 wider cut out, same thing Bowdunkie:)
Uh... the same, only different.
My advice is to take their advice lol.
Regarding the core wood ... I think it's all about keeping limb mass down. So a lighter wood like walnut would probably be faster ...
So would shooting a compound ... or just tillering to 1# more draw weight.
I usually just pick a core wood that will look nice. With that said, nothing at all wrong with an osage core and an osage belly. Maybe you're losing 2fps over a walnut core assuming everything else the same ... maybe even less ...
I do think it looks cool when the core is the same as the belly, because it looks just like a backed osage bow, but you get that sweet R/D profile too.
QuoteOriginally posted by LittleBen:
...
I think this type of build is a good candidate for using supertiller and trying to calculate a proper stack thickness.
...
what is supertiller btw?
oh ...wait I went through this before..
It's some kind of program right?
Where might someone find this.
Googled it and couldn't find a download...
Just make the bow and tiller it super sweet:)
heck yeah!
I dunno..some of that stuff is a little too techie in a way..
But it sure beats making a bunch of bows the wrong stack I suppose.
When making a tri lam is there a general stack thickness, taper rate, bow length formula?
I'm thinking that much r/d is kinda unneeded and possibly a detriment on a longer bow.
thinking maybe 64" or even 62" would be a smarter use of the r/d.
What say you oh sages?
It would depend on your draw length. With that much reflex, it will maintain a string angle less than 90 degrees, and be more efficient, at shorter lengths. 58" would be easily done for a 28" draw, even shorter if you kept the length of the non-bending handle section to a minimum... and hence maximizing working limb length.
No formula that I've ever seen. How it all shakes down depends on enough other design specs that a formula wouldn't be much more than a ballpark anyway. The best thing to do is make your best guess, then keep records of each succeeding bow for future reference.
Thanks Jeff.
I guess it's cyphering time.
Jeff, how about an explanation of how you do the core lam tapers on a one long piece of core lam. Do you run the tip in first and take off more on the tip end, then as you move towards the flare your sled is tapering less? Then you pull it back out and do the other limb?
I would be interested to know also. What I have done in the past is taper two 36" lams, then splice them, then flatten the center section.