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
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.
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.
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
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.
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
Mike,
Thanks for the link! I will have to make one of those. I have enough materials for that already.
Keep checking the base board. After a few trips to the glue up oven it may warp.
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.
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.
What part of Tx are you in,? :coffee:
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.
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.
(http://184.72.239.143/mu/42c40adc-fca5-d803.jpg)
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.
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.
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.
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.
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.
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?
(http://i1231.photobucket.com/albums/ee503/Jamey_Burkhart/012.jpg)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.
That red oak may need a backing, particularly if you are adding reflex. I'm thinking linen. Maybe George will chime in.
QuoteOriginally posted by okie64:
(http://i1231.photobucket.com/albums/ee503/Jamey_Burkhart/012.jpg)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.
How thick were your laminations? I think I can draw something up like that, but the lam thicknesses and limb widths, I am not sure of yet.
I was hoping to come up with a design that would work with both wood and glass longbows, but from what I am learning, this may not be possible?
The backing is 1/8", core is 1/8", and the belly is 1/2". The belly lam doesnt have to be that thick. I'd rather have it a little too thick than too thin though. The powerlam is 1/4" thick in the middle and tapers to a feathered edge on both ends. You can probably come up with something that will work on wood and glass. I've only built wooden bows though.
The 1/8" backing and 1/8" core are Red Oak?
Sorry but I'm developing CRS. Can't Remember Stuff ;)
Mike,
Yes, the picture of the design showed 1/8" back, core and belly of all Red Oak for the practice run. I have changed the design a little, lengthening the riser block to 18" and reducing the severity of the curves at the fades. I also reduced the amount of deflex to 1" and changed the reflex to 3", so if it loses some to string follow, hopefully I'll still have a little left.
I am also playing with a design using two tapered lams for the core.
Think about backing the Red Oak lamination on the back. Maybe linen or silk. Something that will not apply more compression to the belly.
I'd be a little worried about the Red Oak on the back with nothing to hold down tension splinters.
Increasing the riser length will also cut down on the working length of the bow creating even more of a tension problem on the back. So does the additional reflex.
I know you are using three laminations but I'd start thinking of this as a unbacked Red Oak board, which is what it will be after glue up.
Mike,
Would bamboo T-molding, like they use for doorway thresholds between two rooms of hardwood flooring work as a backing?
That's a dang good question. Give me a day or two to go down to Lowes and take a look at it. I can't quite picture (in my mind)how it's glued up.
I'm thinking any wood will add compression to the Oak belly. Maybe a very thin piece of Hickory.
That's a dang good question. Give me a day or two to go down to Lowes and take a look at it. I can't quite picture (in my mind)how it's glued up.
I'm thinking any wood will add compression to the Oak belly. Maybe a very thin piece of Hickory.
I'd kinda like to know if that bamboo flooring will work on bows too. I kinda figured it would probably work good for belly wood but I'm not sure about backing?
Okie64 the Verticle cut flooring will work for a bow belly. It actually makes a pretty snappy bow that's easily rasped and tillered. It needs a backing & I like Hickory. You have to use the expensive flooring. The cheap stuff at Lowes is full of glue voids.
Would this be an example of the bamboo flooring you could use to make a bow with?
(http://images.lowes.com/product/converted/836216/836216094010lg.jpg)
Kris
Would a red oak core with hickory back and belly lams work?
Yeah that would work fine. Hickory is not the best belly wood but it will work. Ive used it as belly wood a few times. You just have to be careful tillering or it will take a lot of set.
Ok, thanks. I picked up a bunch of hickory today and a little bit of ash too. Would ash work better on the belly?
I dont think it would be any better than hickory but I'm not for sure. I've made selfbows from ash but never tried it as a belly wood in a laminate. I've heard of people using ash as a backing for lighter woods like cherry.
OK, thanks for the help. I finished my form this evening. I built one like 7 Lakes showed in his link earlier. I was going to start on my bow, but things went to crud. I was trying to make my own tapered lam, using 4 small shims that I planed down with my lam grinder (.072" down to .018" , spaced 9" apart). It probably would've worked, but the piece of wood that I was using to make the tapered lam was to thin and would just bend in between the shims. I guess I'll have to buy one to use to make them. In the mean time, I guess I'll just use parallel lams.
Ash makes a nice belly wood but leave it wide. You can thin down the Hickory a bit. Are you still looking at making a three lam bow? If so The Ash needs to be relatively thick compared to the backing and core.
Mike,
Yea, I'm planning a 3-lam bow, kinda like the one in the picture that okie64 posted.
The place I got the wood from also had a bunch of maple. Is maple good for bows?
Thanks,
b0whunter
Maple will make a fine bow if left wide enough. But perhaps you are asking the wrong question.
You are looking for 3 bow woods with different properties. Just because one is a good backing doesn't make it good on the belly. I would think in this application Maple would make a good, thin core lamination. Your real problem here is to find a belly wood that can be cut thin enough to go up the belly side of the riser that's also strong enough in compression to stand the pressure from the core and backing. For that I would look at Osage or Ipe.
In a three lamination, all wood bow you need a combination of wood. A backing that's strong in tension. It's thickness is determined by the strength of the Belly Wood. The belly needs to be strong in compression or it will be crushed by the backing. Some of that strength may be substitued by building the bow wider with longer working limbs so the compression can be spread out. Thickness does matter on the belly. The core cannot be very thick or it takes away from the compression strength of the belly wood.
Mike,
I am going to wait until I get some tapered lams and some fiberglass to build the bow with the belly lams that run up the fades.
I decided to do one similar to the picture that okie posted. It is a more conventional all wood tri-lam longbow.
Well, I went ahead and glued up my bow tonight. What a MESSY job! I hope I'll get better at it. I went through about a half a roll of paper towels.
(http://184.72.239.143/mu/42c40adc-9971-d494.jpg)
I did a dry run and everything looked ok, but after glue-up, it doesn't look like I have enough of, or the right kind of clamps. I can see some air gaps along the edges of the lams. I don't know how deep they go or if they will be cut away when I shape the bow, but it doesn't look good now. It will probably be junk. What kinds of clamps do you folks use? I've seen some build alongs that use these spring clamps, but mine don't appear to apply enough pressure.
I use pretty much the same setup you got there with the same clamps. I use a flat steel bar pressure plate on top of the back to make sure it gets the pressure distributed evenly. I use one under the belly too if its a thin belly lam. What kind of glue did you use?
Ahh, ok. Maybe that's what I'm missing. I will gave to get a piece of aluminum or something, and some more clamps.
I used Tite Bond III for this one. Once I get better at building them, I'll get some URAC.
You can use another wood lam about 1/4" thick and it'll do the same thing or you can get the steel bars at home depot. Ive never used anything but TBIII and never had a problem with it. If you got all your clamps right down the middle of the bow then the edges are probably curling up a little. Maybe the gaps wont run too deep into it and it will still work. If you use some kind of pressure plate on the belly side be sure to put masking tape on it so it doesnt get glued to your bow.
Okie,
I'm hoping the gap doesn't run too deep. I'll buy some metal pieces this weekend. What thickness should I get? I also need to get some more clamps. I bought 4 of the trigger style clamps and 2 of them broke, so I'm going to spend the money to get some better ones. I have a friend that is a cabinet maker and he warned me that I should buy good quality clamps and that they cost more. I should have listened to him! He "told me so today, lol."
I think I used too much glue, also. What do you use to apply the glue?
My metal pieces are 1/8" thick by 2" wide. I use big screwtype C-clamps for the center and deflex posts. I use a popsicle stick to spread the glue around and I'm not sure you can use too much. I always glue both sides of all the lams to make sure I dont leave any gaps.
Thanks. I used my finger to spread the glue. I had a lot squeeze out. When I clamped it up, I couldn't see any gaps at all, but once it started to dry, the small gaps appeared. It looks almost like the wood curled a bit. It's been 24 hours, but I will wait until tomorrow to take it off of the form and check how deep the problem is.
bowhunter,
as far as the mess, get a roll of stretch wrap and some painters tape, tape up outside, wrap it to keep glue from getting everywhere. use this method and it will stay clean enough to do in the kitchen, and your old lady won't kill you.
you shouldn't have any trouble just using TB3, unless you are backing with boo, while i have used TB3 before with boo, it was about 80%. I would go ahead and use the Urac.
remember to alternate the side of the bow that you clamp...if you put them all in the middle then you can get the edges to curl up some
how long is the bow you are making? how high is the riser? if it is not so high then, the angle of the bend for the belly lam won't be so great.
another technique is to steam or heat bend that porion of the lam. I have shaped a belly lam to fit, by bending it that way, clamping it take that shape, letting it sit against the other two lams till it dries (let it sit a couple days to adjust moisture content before you glue) then pull off the clamps, tape, glue, wrap, and clamp again...the beauty of Urac is since its not going in a heat box, you don't have to do all the layers at once
oh i forgot...the boo flooring sections that were mentioned earlier...i tried it unsuccessfully last year
while vertically glued flooring is practically action boo, and will make a lam or go under glass well, its not a good backing...i became a lot less frustrated trying to build a boo backed ipe when i broke down and just ordered the right boo
QuoteOriginally posted by Loren Holland:
bowhunter,
as far as the mess, get a roll of stretch wrap and some painters tape, tape up outside, wrap it to keep glue from getting everywhere. use this method and it will stay clean enough to do in the kitchen, and your old lady won't kill you.
you shouldn't have any trouble just using TB3, unless you are backing with boo, while i have used TB3 before with boo, it was about 80%. I would go ahead and use the Urac.
remember to alternate the side of the bow that you clamp...if you put them all in the middle then you can get the edges to curl up some
how long is the bow you are making? how high is the riser? if it is not so high then, the angle of the bend for the belly lam won't be so great.
another technique is to steam or heat bend that porion of the lam. I have shaped a belly lam to fit, by bending it that way, clamping it take that shape, letting it sit against the other two lams till it dries (let it sit a couple days to adjust moisture content before you glue) then pull off the clamps, tape, glue, wrap, and clamp again...the beauty of Urac is since its not going in a heat box, you don't have to do all the layers at once
The bow is 70" knock to knock right now and the handle is about 1-1/2" to the belly.
I cut the bow to shape and did some preliminary sanding on it today. Good news! Most of the air gaps were gone after cutting and sanding. There is still a couple, but they are very small. I think they will only be a cosmetic issue. I started tillering the bow and have it pulling about 55# @ 16". It is still way too heavy, so I have some more work to do. The lower limb is about 2" stronger than the upper, so I need to do some more work on it. My target weight is 55# @ 28". It still has a bit too much reflex in the limbs. I added about 2" extra, hoping that it would lose close to that in string follow. If all goes well, I hope to take it hunting next weekend.
I glued up another yesterday, using better clamps and 1/8" aluminum strips to spread out the clamping pressure and it looks like it is going to work pretty well. Hopefully I'll have two new bows to take to the lease for hunting.
Now, bad news. While tillering, I noticed this on the belly of the upper limb:
(http://184.72.239.143/mu/42c40adc-452a-4617.jpg)
Tillering had been going well up to this point. I was trying to get the upper limb bending a little more toward the tip, but I guess I took off too much wood in the area through the reflex. I strung it up at a low brace height and exercised the limbs and thought it looked ok, but I noticed a the little "X" pattern on the limb after I unstrung it. At first I thought I scratched the wood with something, but on closer inspection, they were hairline cracks. I tried removing a little more wood on each side of this area, but when I restrung the bow and flexed the limbs a few times, I could see a slight hinge forming, along with more of these hairline cracks. Are these crysals?
I will get started on my next bow hopefully tomorrow evening. I hope the next one goes better.