First Laminated Longbow. A Few Questions.

[b0whunter]

Hello,

I have built board bows and they turned out well, so I am wanting to graduate to building laminated R/D longbows.  The equipment I have is as follows:  band saw, belt/disc sander with lam grinding "jig", drum sander, various rasps, files, sureform, etc.  

For my first laminated bow, what types of wood, how many layers and what lam thicknesses should I use?   I don't have any tapered lams yet, so my first will probably be with straight lams of all wood.  I am wanting the length to be 66"-72" and a draw weight of around 50 lbs @ 28".  I would like to have a nice riser like the ones I've seen you guys make.  

I do not have a form yet, so I will need to make one, but I don't want to just pull one out of the air.  Does anyone have a plan for a mild R/D bow form that they would be willing to share?   That way I can just get stations and offsets to work from in building my first form.  I will probably have to use dowels and bands to apply the pressure, since I don't have an air compressor.  

I know this is a lot of questions, and some are subjective and can have many answers.  I just need some guidance for this build, as this is new territory for me.  

I appreciate the help.

Thanks,
Charles

[K30bowfisher]

I may have misunderstood your question. This would apply if you are looking for a glass laminated bow, if you are into all wood, I don't know anything about it.

Either get ahold of Kenny M here on the site, he has a couple of killer r/d form designs that he sells. Bingham's Projects also offers some good r/d designs and instructional materials. I believe that 3 rivers also has a r/d design for sale. Swissbow on the site here has one available for download on his website too.

Good Luck with your project.

[okie64]

You can make a r/d form out of a 6 foot 2x4 and some short scraps of lumber. Lay your 2x4 flat and screw a post in the center a couple of inches tall. Then put your deflex posts at midlimb just a little shorter than your center post. then just make your end posts a couple inches taller than your center post depending on how much reflex you want it to have. The thicknesses that always work best for me on a trilam are 1/8" backing, 1/8" core and 3/8 belly. For the backing I always use hickory. Cherry, maple or about any hardwood will work for the core, and for the belly osage is hard to beat. For the riser you can stack 3 or 4  1/4" pieces of wood and glue them on then just shape it how you want. There are  a lot of different ways build a trilam. Thats just my two cents. It probably would be a whole lot easier to just build a backed bow with straight limbs to get the feel of it first.

[Swissbow]

If you want to build an all wood d/r-bow the i would consider a form with more reflex, because your bow will not hold the reflex and loose most of it after been strung the first time. If you go for a glass bow, then your bow will hold the form and keep almost all of it's reflex. You can find lots of great examples of all wood or glass bows on this site.

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Andy

[b0whunter]

Thanks for all the responses.  I really appreciate the info.  

I'm certainly not opposed to a glass laminated bow, I just figured that it would be more advanced.  I intended to work up to doing them as I progressed.  If it isn't any more difficult than an all wood laminated bow, then I suppose I can start there.   I just have no idea on the thicknesses and number of laminations.  I like the looks of the wedge type risers that are laminated into the bow, with the belly lams on the top of them.

[7 Lakes]

I posted some pictures on another thread, of a simple form for all wood laminate longbows.  It beats the rubber band method hands down & you can add as much deflex or reflex or both as you like.
The yellow thingy on top is a ruler used as a pressure plate.  The  black, marker marks on the form are for something different, ignore them. Remember to build your heat box wide enough to put the spring clamps on either side.  They will be easier to put on and you can get more of them.
Any questions feel free to call.

 http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=125;t=004820

[b0whunter]

Mike,

Thanks for the link!  I will have to make one of those.  I have enough materials for that already.

[7 Lakes]

Keep checking the base board.  After a few trips to the glue up oven it may warp.

[eflanders]

If you use URAC 185 you will not need an oven and it has basically all of the other good features of Smooth-on except that it is for all-wood bows only.

[Loren Holland]

B0w,
Same harper has a great build along on BBI, using a 2x4 and blocks.  I have used TB3 on all wood bows successfully and its great for the price, but I agree with eflanders that there is no beating URAC on an all wood bow, plus you don't need a heat box.  I think Ipe is a little easier to get than osage, and cheaper. You can back it with hickory just as easily (maybe more) than bamboo. I agree that with all wood you are still going to have set, so glue in several inches of reflex and you'll keeep a couple of them. I wouldn't do a tri-lam at first. I would jsut back a good piece of ipe.
for a good looking riser, without having to make a bandsaw cutting sled, i would stack either a yellowheart or osage riser with a purpleheart accent stripe, or either bocote or zebra with 1/16 maple, 1/8 Paduak, 1/16 maple stacked accent stripe...looks good without fitting curves if you haven't done that yet.

[Mike Most]

What part of Tx are you in,?  

[7 Lakes]

Elflanders is right about the URAC-185 if allowed to dry around room temperature.  

If you are forced into the garage for your glue ups with sub freezing temps use a heat box or at least clamp on shop lamps.  

URAC is a great glue when used for wood to wood.  Do not use it on glass applications.

[b0whunter]

Mike Most,

I'm in the Temple area.

I have a little bit of black walnut, mahogany, aromatic cedar and some poplar that I can use to laminate a riser block from.  I have a friend that is getting me some hickory, but i don't know how long it will take him to get it in.  I would hate to waste good wood on a practice run.  The only wood that I have on hand to make limb lams from right now is red oak.  I know this isn't the best wood to use, but would it be serviceable for a practice run to test out the method and glue up process?  I would like the bow to be shootable for at least a few times, then I can hang it on the wall as a decoration.  If we pretend this is better wood, such as hickory, are lam thicknesses of 1/8" OK?  I drew up a quick plan (see picture below) showing the general idea I am trying to produce.

 

The plan shows three 1/8" lams for the back, core and belly.  The riser block fits between the core and belly lams.  It also shows three 1/16" lams on the back as an accent.  Am I anywhere in the ballpark on this design?

Thanks for all of your help!  I don't mean to be a pain and ask a jillion questions, I'm just trying to figure all of this out.

[eflanders]

As a test I would think you are fine using the oak laminations.  I am guessing that with the thickness and quantity of the laminations, this will be a very strong pulling bow but that will depend on the width and taper of the limbs.  One area that I think will give you the most headaches are at the fades.  Getting the oak belly lam to bend to fit your fades without cracking may be quite challenging (and a good learning experience).  I would heat treat the belly lam to help get it to shape and to add to it's compression strength.  Use a heat gun and (cook the lam to a nice milk chocolate color)clamp it slowly to the shape of the fades.  Once formed, leave it clamped for a couple of days to rehydrate the wood and to keep the shape.  Once this is done, you can glue up the bow.

I would also "trap" or round the edges as oak tends to pull a sliver really easily.  Also be sure to tiller the bow slowly and properly (don't pull it beyond your draw length). to prevent too much string follow.  Most of all, have fun and learn from your mistakes.  That is what a test bow is all about.

[eflanders]

I forgot to add that the riser woods you are listing may be a bit too soft and too flexible depending on how they are all laminated together.  I would use the harder denser woods (mahogany & walnut)for the bulk of the riser and use the soft woods (cedar & poplar) for the thin accents.

[7 Lakes]

Build it relatively long, you'll be able to cut it down within reason to gain weight if you need to.  

Are you going to back it?  If so, I wouldn't use anything that would induce compression on the belly.

[okie64]

I agree with eflanders that getting your wood to bend that sharp around your riser is goin to be a real chore. The design youve got drawn out with your belly lam goin up the backside of the riser is more like a glass bow design. I'm not sayin it wont work with wood but I had a friend who tried to use this design on all wood bows and they kept breaking right where the belly lam went around the riser. I've never tried that design myself. You could probably make the riser longer with a longer curve to it and make it work.

[b0whunter]

I hadn't planned on backing the test bow. I'll probably use all red oak throughout.  The plans are just some quick stuff I drew up in a CAD program. I lengthened the riser block from 16" to 18" to help lessen the tight curves at the faded and now I am having trouble getting a constant radius curve through the back my riser block to make it easier to mark and cut.  I have compound curves at about the last 1-1/4" of each end of the riser block, where it is getting thin and tapering into the limbs.   For the all wood lam, I changed it to 1" of deflex and 3" of reflex, since you said that I will most likely lose some to string follow.

How does this sound?

[okie64]

Heres a pic of a riser design typically used on wood bows. Top to bottom its hickory backing,purpleheart powerlam, cherry core, and hickory belly and  handle. Be careful adding a lot of reflex. It can make tillering a little tricky.

[7 Lakes]

That red oak may need a backing, particularly if you are adding reflex.  I'm thinking linen.  Maybe George will chime in.