Recurve Bow Build

K

Kamn

Guest
So I have had a few people ask to start a thread on the Bow Im building.
The goal is to have a 60" recurve bow with a draw weight of 30#'s @ 28"'s of draw.
Also, note that this is my first ever build, I have never done this before so Im learning as I go BUT I have spent the past 2 months reading every piece of info I could find on this subject trying to give myself a bit of a head start before I laminate anything.
I like traditional recurve bows and long bows that are made from multiple laminations of wood and fibreglass.....they are works of art in design and style and you can be unique with what you build from materials to shapes and lengths. Plus, they can be used for hunting and what better than hunting with a bow you made.

So lets get started,

Limb Materials for this bow are 2 layers of Black fibreglass(72") that are .030" thick each (.060 total), 1 parallel(72") Hard Maple lamination that is .080" thick, and 2 tapered(36") Hard Maple laminations that are .100" thick with a .002 taper. The riser (handle) is made from 2 pieces of Padauk with a piece of Curly Maple sandwiched in the centre.

Limb Materials (left side of table)
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Riser glued up
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What has to happen is, the limb materials need to be sandwiched around the riser with epoxy in a form and then baked for 4 to 6 hours. In the form it will be 1 layer of glass, 1 parallel lamination, the riser, the 2 tapered laminations (glued butt to butt and layed length wise with tapered portion going to the tip of the bow), and then the final layer of glass.

The form needs to be 1-3/4" thick since this is the thickness I like as well as the material width I ordered. Most guys will glue up sheets of plywood to that thickness but I just ordered an 8' length of 1-3/4" x 9-1/4" LVL......they come really straight and no glueing required. I made a template on a heavy sheet of card stock

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I used a Bear Grizzly 58" recurve for this template but changed the riser shape a lot and then stretched the limb area 1" to bring the bow to 60"s. The template is just half the actual bow, its easier to manage. Then squaring up some lines along the LVL for bottom and centre (this keeps the template even side to side), I copied that onto the LVL and cut out with a jigsaw an 1/8" away from the lines to leave space to do final shaping on a spindle/belt sander.

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also cut out the riser and shaped on the sander

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Then did some more shaping and fitting of the two

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The thing about the form is that the surface must be smooth and level throughout otherwise the bow can be formed with a twist or really badly aligned.

Then when I felt it was ready, I glued up melamine onto the form for a smooth flat surface and added pins throughout so I could strap the bow down with heavy rubber banding as well as I cutout for 3 c-clamps, one for the centre of the riser and 1 at each end of the riser where it fades into the limbs.

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The Oven
when its all ready to go and the bow has been layed in the form and pressured down, the epoxy that keeps it all together needs to be heated for proper curing, so you need to make a oven for the bow.
Its made from 1/2" plywood, some 1x2's, screws, a little glue, reflective insulation, and the heat comes from 4 - 200watt light bulbs.

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and I added a thermostat switch that cuts out at 150 degrees Fahrenheit.......dont need any more heat than that

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The oven cost a bit up front but its a one time cost that gets used over and over


I will post more as it comes, but thats what I have for now

If you are looking to do a project like this, materials and plans can be had from places like Binghams
 
Nice. I will make time to read through this eve. Gotcha bookmarked now.
 
Ahh yes, nice! Starting to get enough warm days to start flinging arrows down range here in Ohio.
I'm definitely following along
 
This is what is great about this forum.
Yes we all like motorcycles, but more importantly we all build shit!

Badass man I'm jealous I need to try my hand at one of these.
 
Soon it will get glued up, I just need a good half day to prep the tapered ends of the riser and then roughly 5 hours of bake time
 
So after it is glued and baked I assume you sand/trim to final shape in the handle/riser area etc?
 
when it gets pulled out of the form, the tips need to be cut back and shaped, and yes the riser gets shaped for a handle and a shelf for the arrow. Also need to tiller the bow, basically its stringing it and looking for any slight twisting in the limbs, if it exists you can sand the opposite side of the limb to get it straight AND the sides of the limbs can get sanded away a little to get the draw weight in to where you want it within certain limits
 
Are you using prepreg fiberglass? Just wondering what the bake box is for since most epoxy resin cures at room temp.
 
Subscribed! Can wait to see this come out!
Man, now I'm going to have to start posting bow builds! I'm about due for another selfbow anyway lol .
Looking forward to this, Kamn

advCo said:
Are you using prepreg fiberglass? Just wondering what the bake box is for since most epoxy resin cures at room temp.

Boyers glass comes as pre-cured strips. Curing in the oven is thought to offer better temperature resistance (or to speed up the Curing process).
 
Here is a link to the fibreglass Boyers use http://www.binghamprojects.com/proddetail.php?prod=UL
The epoxy is from a company called Smooth On and its there EA-40 line which says to cure it at 140 degrees for several hours
Here is some info on the Epoxy https://www.smooth-on.com/products/ea-40/
 
Well this past weekend I was able to get further ahead on the build..........

I saw another bow build where the guy covered the face of the form and the top pressure strip with EPDM rubber and I liked the idea because it gives the a little cushion and pressure back in any places the form may not be perfect, so I did the same

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I got my inner tube straps cut and ready

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Waxed the form face and pressure strip (1-3/4" strip of galvanized 16g sheet that goes on top of the bow before getting pressured down)

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Then I got the wood and fibreglass strips cut, cleaned, and high temp tape on the shiny side of the fibreglass, which means that I also need to wear rubber gloves from this point forward to keep everything clean

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while I was mixing and prepping the epoxy in equal parts, the wood strips went in the oven to worm up which helps open the grain to allow the epoxy to soak into the grain......you don't want any dry spots at all or its gonna blow apart on you when you string it up

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Prep the form with saran wrap to try and control the epoxy that will spill out during the cure

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Then it was time to lay the layers of fibreglass, tapered maple, riser, parallel maple, fibreglass, and the pressure strip. Then the bitch part of clamping and strapping it down to the form with slippery epoxied layers but I managed somehow

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Then into the oven for 5 hours


And later that day

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BUT, I had a problem......the damn layers shifted slightly on me while cooking!!! FFFUUU@@@KKK

WHich means I will need to work harder at correcting this by trimming the sides all along the bow on the sander, then I can go ahead and find centre and go from there

More to come
 
Some things I learned and figured out
1. the oven is too hot.......I need to bring the temps down with lower watt bulbs. I nearly burned the saran wrap
2. I need guides down the sides of the form to keep the layers from shifting
3. I will need heavier rubber bands....probably truck inner tubes or motorcycle because I had a few bands pop on me when strapping it down and 1 popped while cooking which meant me opening the oven and quickly securing another band
 
Very cool!

I say build the inverse of the form and then put a sealed firehose between the two, clamp them together and air it up.
 
Kamn said:
Some things I learned and figured out
1. the oven is too hot.......I need to bring the temps down with lower watt bulbs. I nearly burned the saran wrap
Unless you need humidity, you can also manage heat with muffin fans. In the dry boxes I build for ceramics, we want the humidity out, so muffin fans do the trick. You can also install a dimmer switch. I've also built them with baseboard heaters as the heat source. I want 180° to 200° in my dry boxes, and those methods have given me that control.
 
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