Attempting my first laminate longbow. I have forms, air hose, hotbox, and a good attitude. I’m sure I’ll have a bunch of questions and I’ll use the search function and won’t ask the same questions you guys have answered over and over. I’m gonna start with one though. Specs desired..... 66” r/d longbow. 50# at 28” Clear glass Nice veneers Laminations?? I don’t know. How would I make weight? I know there must be some kind of equation but given woods inconsistency, I’m sure nothing is set in stone. Any help will be much appreciated.

By the way, I’m a decent selfbowyer so I am pretty crafty, but feeling a bit over my head on this before I begin.

I went with Binghams to begin with, don't try to reinvent the wheel first time around. After building a few recurves I am now designing a R/D based on the Bingham design. I have studied and shot some R/D bows and have tweaked the blue print and redesigning on ACAD. Also I am currently reading Traditional bowyer, more unnecessary fun. It is a lot of info to take in. I am getting ahead of myself now, because I am trying to understand tension and compression of wood. I would like to build a bow without FRP (fiberglass-reinforced plastics). Just my two cents. John

No equation that I've ever seen. Mostly trial and error.

Bingham Projects has a draw weight chart that I've used to get close on a few bows.

We could get you in the ballpark with stack height, but your design, shape, taper rate, riser length, and such can cause your draw weight to be different than ours.

Whatever you do, keep very detailed notes on each build, and you'll soon be able to get closer to your target weight on your own than you will with outside help.

I don't have my build info here, but I'll look when I get home.

Every thing Jeff has said and I would agree to using Bingham Projects weight charts but I would also suggest staying on the lite side because a lighter bow can always be used but a bow that is too heavy ends up on the wall. Also if it ends up lighter than you want you always have the option to shorten the bow and gain weight. Like Jeff said keep good notes than if the bow ends up too light you will have a very good idea of what bundle thickness you need to make weight on your next bow. And believe me there will be a next bow....Marc

Yup, I have a 90# + bow that is probably going to be a wall hanger. Look at the Bingham models and find one similar to your design and then go to the weight chart and shoot for lower. Once you have taken the first bow off and weighed it, there is a formula for calculating future bows. Just remember that as a general rule double the width, double the weight. Double the thickness, octuple the weight. So, as you can see draw weight is very sensitive to thickness.

Yep Jeff is spot on. Did you design the form yourself, or is it a copy of a current bow?

Are you going to bring your own laminations? If not call Bingham's and they'll get you close.Personally for first try I use colored glass and maple limbs instead of more expensive clear glass and veneers.

The forms were given to me. I shot a bow built from it and it is really a good shooter. I have some different ideas about limb tips. They need to be narrower and the profile could b changed a little. This I know from selfbows. Nothing wrong with it just a little sluggish and shocky.

The first one will kind of be a swag as far as weight goes. The next one you can adjust and be very close on draw weight. Records the more detailed the better.

Ok well starting out. I will nix the veneers and go with black or maybe green glass since my riser block is greenish. Can someone give me an idea of what size and how many core lams I need to order? I understand I won’t make weight so let’s say 40# and 68”. Gives me room to cut it down if too light. I will eventually grind my own lams. I have everything I need but I’ll do the store boughts first. So how many lams at say .02”? Thanks!

All you have to di is get on the phone with the folks at Bingham, give them an idea of what you are building and they can fix you up.

Call Binghams, very informative and will answer your questions on lamination thickness per weight. When you receive them measure with micrometers and make notes. John

It will also help with tapered lam's.

Sorry not "bring" lams but "grind" lams dang autocorrect.

Ken, my personal opinion is, if you want a 66" bow 50# @ 28", then that's exactly what you should go for from the get-go and see how close you are.

My first bow, through Binghams, was right on the money.

You don't want to figure it like that, .020" lams. I'll get some info tonight. Sorry I didn't get it yesterday. I was grafting apple trees all afternoon and forgot all about it when I came in.

My regular d/r longbow in the weights we're talking about has a 16" riser, and four wooden lams total. Three tapered lams on the back side of the riser, and one parallel on the belly side. The parallel lam might be around .040", and I'm guessing the three tapers would be around .090" at the butt end. Don't quote me on that though. It's been a while since I made a glass bow. I'll have to look.

Taper rate is a whole other discussion yet.

Thanks Jeff. Still researching the whole taper thing. I don’t know, those forms may have been built per the Binghams plan the more I look at them.

Good luck! I'm going to go the Bingham way for my first build as well.

Ok Ken, here we go. This would make a bow from my latest d/r longbow press that would be 50# @ 28". This would work with most limb woods. There are only a couple that are weak enough to require us to add a few thousandths in thickness.

66" d/r longbow 50# @ 28" 16" riser

Total stack .420" Total taper .0045/1"

3 pair of tapered lams .090 @ .0015/1" 1 pair parallel lams .050 2 pc Bo-Tuff .050

A few quantifiers... My bows are 1 3/8" wide at the flares. When finished, the reflex is such that the tips are 1 1/2" in front of the handle. I trap my limbs, narrower at the back, wider at the belly.

Possible concerns... Not all suppliers will grind lam tapers at .0015/1". They mostly like to do them at either .001/1", .002/1", or .003/1". But I grind my own lams so...

You could go with all .002/1" tapers, but I think .006/1" total taper is a bit much. It makes the limbs whip ended.

I prefer less than .005/1" and think .004/1" is better, but when I do all three tapers the same thickness and all at .0015/1", I have less time invested, it's easier, I get .0045/1" and the limb action seems fine.

They don't care if you mix and match the tapers to add up to the total taper amount you need. In other words, you could get two tapers at .001/1" and one taper at .002/1" for a total of .004/1" and they wouldn't care. I've done that many times when I used to have them do it.

The most appropriate taper for any given bow depends on how much deflex and reflex is in it, how it's oriented in the limbs, and how you'd like the limbs to act.

All these numbers are beginning to remind me why I've been making nothing but selfbows the last few years :^)

Wow, that didn't come out the way I typed it. Try this.

- 3 pair of tapered lams .090 @ .0015/1".

- 1 pair parallel lams .050.

- 2 pc Bo-Tuff .050

Great info Jeff! I am going to grind my own lams, or attempt to. I’m building a jig to mount my smaller bench beltsander to. Probably gonna be a learning experience on the tapers but I think I can figure it out. You’ve been a great help. I greatly appreciate your input. I’m just not a buy a kit kind of guy. Now that I see what lams cost, I don’t think I’ll be a buy lams kind of guy. Though, here pretty soon, you’ll probably see me post that I wish I would’ve bought the kit. Haha! I’m hard headed enough to fail and come back swinging! I always told people “ if you whip me, your gonna have to do it every day till I whip you”. The same goes for projects!

The easiest way to grind your own laminations in the beginning is with a sanding block.

All you do is cut the lamination to the thickness that you want the butt, or thick end, Then get some 80 grit sandpaper and a sanding block,

Divide the lamination into 1/4's and draw a line across it at each mark.

Start at the mark closest to what is going to be the thin end and sand away the first mark sanding all the way to the end. Redraw that line. Go to the second mark, and sand from there all the way to the end removing both marks etc..

it takes about 10 minutes per lamination. Mesure the thin end with a micrometer to check your taper.

The amount of material that you remove in a .001 per inch taper over the length 36" of is only about 1/32" at the thin end.

I disagree, Frank. That's not the easiest way. It may be the cheapest way, but the easiest and best way to do it is with the proper tools.

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