Author Topic: Fibreglass laminated longbow - how to build  (Read 49052 times)

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Fibreglass laminated longbow - how to build
« on: February 15, 2011, 11:30:28 PM »
Some time ago I mentioned making archery bows.  There was some interest by forum members so here is some of the detail involved in building a glass laminated longbow.

I will be talking about “we”.  I have made quite a few dozen glass laminate bows over the last 15 or more years.  This has been a hobby although I have sold a few here and there.  A friend has become involved in the last couple of years and has done more of the final carving and finishing than I have.  Thus the two of us are involved in this project.

First a bit of terminology.  The “handle” area is called the riser of a bow.  The thin tips of the riser (top and bottom) are called the fadeouts.  The side nearest the archer is the belly of the bow and the other side the back.



A 66 in. bow made some time ago with the same mold we will be using.  It is resting on it's belly unstrung.



A closer look at the riser area.  The riser is Kingwood with some decorative veneer in the middle and the overlays are Kingwood Yew and Ebony.



Belly side of the riser.

I will be using inches because all of the components are available in that format. 

This type of bow is made up of fibreglass laminations on the outside with several layers of wood in the middle.  The bow we will make will have 4 thin wood laminations in the core.  One or two pairs of these laminations will be tapered (0.002 in. per foot), the remaining two are parallels.  The wood pieces usually range between 0.040 and 0.110 in thickness as they need to be bent over a form.  Most of the bows made on this form are composed of 4 wood laminations but I have used 5 in some bows.

The glue used to join the laminations and fibreglass together is epoxy, several types are suitable but I have used Smooth On for quite some time and like it's properties.

We will aim for a bow of about 60 lb. pull at a 28 in. draw.  All other things being equal the weight depends upon the shape of the bow, it's length and limb width, the thickness of the wood laminations and thickness of the fibreglass.  To some extent the thickness of the glue lines will effect the weight however we will be keeping them as consistent as possible – you will see this further on.

Our longbow has a complex shape – it isn't straight – in order to improve performance.  The shape will give it good arrow speed along with little hand shock.  I have used bows in the past that had so much hand shock that I had to check my teeth for missing fillings after a few arrows. :bugeye:  Such bows are unpleasant to shoot and can easily lead to wrist and forearm problems. 



The above photo shows the mold we will use along with two shaped risers.  The top surface of the mold in the foreground will become the back of the bow and the bow will end up with that shape when finished.  The top part of the mold along with heat strips is in the background.

In general we want a bow that has decent arrow speed and is consistent.  All things being equal a longer longbow is more consistent so we will be building a 66 in. bow.  If the finished bow weight is low we can cut it down to 64 in., increasing the weight.  Any shorter than 64 in. with this particular design and it doesn't work out well.

I will write this thread as a series of entries and may take a few weeks before being finished.

John.

Offline Jonny

  • Hero Member
  • *****
  • Posts: 781
Re: Fibreglass laminated longbow - how to build
« Reply #1 on: February 16, 2011, 04:15:49 AM »
Great stuff never delved in to bows but intrigued by the layered laminate glueing and setting and retaining the bend.
Been meaning for 16 years to make up a block form of laminated blank but never got round to it.


Have been shown a few times on stocks and how to set them over etc, quite frankly it scares me to death on several thousand £ of stock.

Tried Elm, quite springy and very strong.
So is the birch ply from Rutland Ply but also very stable.
http://pic20.picturetrail.com/VOL15/728921/1243583/228059233.jpg
http://pic20.picturetrail.com/VOL15/728921/1243583/311528971.jpg

Ever thought about pulling the bow up like how V springs should be made?

Offline Gerhard Olivier

  • Sr. Member
  • ****
  • Posts: 314
Re: Fibreglass laminated longbow - how to build
« Reply #2 on: February 16, 2011, 06:36:09 AM »
Archery and Bow hunting is one of my many hobbies

Will be following this with lots of interest.


Gerhard
Guernsey
Channel Islands

Offline DavidA

  • Hero Member
  • *****
  • Posts: 1184
  • Country: gb
Re: Fibreglass laminated longbow - how to build
« Reply #3 on: February 16, 2011, 08:33:55 AM »
jcs001,

Hate to be picky,  but that isn't a longbow.  It's a recurve bow.

Dave.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #4 on: February 16, 2011, 08:34:29 AM »
The last photo is missing from my first post so here it is:



Bottom of bow mold in the foreground (along with two riser blanks).  The top of the bow mold is in the background along with the two heat strips.

The bow mold is 2 in. wide and made from high density particle board (rangerboard may be another name).

John.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #5 on: February 16, 2011, 09:41:30 AM »
Jonny - Not sure what you mean by making V springs.  The way I am describing for laminating a longbow is one of many different methods.

DavidA - you have touched on a controversial subject.  As I understand it, according the the rules of the North American Longbow Safari, a longbow is such as long as the riser shelf is not centre cut (needs to be at least 1/8 in. off centre) and as long as the string does not touch the belly side of the limbs (except at the tip).  I think this is the general application in other areas although I have no idea what the "rules" are in your area.

Having said that, longbows of this type perform very similarly to recurves.  Bigger archery meets in our area will sometimes differentiate between "primitive" bows and laminated bows - primitive bows usually are longbows without fibreglass laminations and tend to be fairly straight although I have seen wooden recurves occasionally. 

Certainly will not argue that this design is really pushing the envelope as far as longbows/recurves go.

John.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #6 on: February 16, 2011, 11:04:32 PM »
Continuing:

We have to get by the tedious but necessary parts before stringing the bow up.  I will start with forming the riser.  The riser can be made of wood and even plastic (micarta) - I prefer strong heavy woods as the weight will help in shooting and the strength may be necessary particularly in a heavy bow.  There are lots of forces involved.  In the case of this bow we are using actionwood - dyed fine maple laminated into blocks - fancy expensive plywood. ::)  However other options are available including purpleheart, bubinga, kingwood - your imagination and budget are the limit.  I believe that Jonny's post earlier shows something similar to actionwood.

You will see in the photo below a plexiglass template showing the shape of the riser.  In this case the riser will be about 18.5 in. long and will be 2 in. wide to match our mold and the fibreglass and wood layers.  Before marking out the riser block with the template, it is important to have the top and bottom surfaces (sides of the riser) parallel.  Planing them or using a thickness sander is a good idea.



Once the riser is marked out in pencil it is cut out using a bandsaw.  I take a lot of care to square the blade to the table and install a good blade as the better the cut the less work sanding it to shape after.  The bottom of the riser, will eventually be against the back of the bow and it is critical that it fits the mold.  The top is less critical as long as the curves are very even and clean.  It is also critical that the bottom and top of the riser be at a right angle to one of the sides.  If they slope in relation to each other the glue up will become almost impossible. :hammer:  Epoxy in it's unhardened form has a very close relationship to grease.



This is one type of sander that works well to shape the riser after it has been cut to shape.  I tend to use a horizontal belt sander (6 x 48 in) but it takes a bit more care as the table cannot easily be used.  Notice the two risers on the sander table - both have the bottoms to the left.

The fadeouts must be less than paper thin once finished.  Using a piece of wood to help hold the fadeout area against the sander helps to get them even. 

Getting the riser even and ready can take some time - it must not be rushed or the final bow will be a mess.

All sorts of decorative ideas can be pursued with the riser.  You will notice the riser of the bow in the first photo on this thread.  That riser was cut in a very even curve with the bandsaw and three contrasting veneer layers were glued between the two riser pieces.  It is best to do this before cutting the riser shape.

John.

Offline Powder Keg

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 933
  • Country: us
  • Machinist Extraordinaire
Re: Fibreglass laminated longbow - how to build
« Reply #7 on: February 19, 2011, 03:49:46 AM »
Looking great so far!!! Do you have to bake the glue to get it to set up? I need to finish putting my crossbow togather. If there were 50 hours in a day I might be able to get caught up? Maybe not :(
Wesley P
A Gismo ??? If it has a flywheel or spins and is made with small parts. I'll take one! If it makes noise, moves, or requires frequent oiling and dusting it's a better deal yet. It's especially right if its shiny and bright; but if it's dirty and dull it wont mater at all...

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #8 on: February 22, 2011, 05:03:18 PM »
Wes:

Yes, any bow building epoxies that I am familiar with need heat.  The "smooth-on" epoxy I use will harden at room temperature but it can take quite a few hours.  The heat strips shown in an entry above (the photo of the mold lying on my table saw) are hooked up to an electric controller plugged into the mains.  I regulate the heat to between 130 to 140 F for about 3.5 hours - this isn't very critical. 

Each heat strip is surrounded by a strip of galvanised sheet metal (2 in. wide) - one on each side and then a piece of wide teflon tape.  The tape prevents the epoxy from sticking to everything and the fibreglass from being scratched up.  The heat strips lie directly against the bottom and top fibreglass laminations and I use an oven thermometer to monitor the temperature.

In the past I've used a large heat box made with plywood enclosing 4 - 100 watt electric bulbs.  A salvaged stove oven thermometer can be hooked up to this to keep the temperature fairly even.  The box is fairly big as it has to fit the mold with a decent amount of space around it.  In use one would leave the mold in the box under heat for up to 6 hours as it takes a while for the mold and laminations/glue to get warmed up sufficiently.

It is my understanding that heating the epoxy also cures it so that it won't release until the outside temperature exceeds the curing temperature.  Bows sometimes end up in hot places - the inside of a car in the sun for example.  Being that epoxy can soften with heat, one does not want to have a bow de laminate in hot weather.

John.

Offline J. Tranter

  • Jr. Member
  • **
  • Posts: 49
Re: Fibreglass laminated longbow - how to build
« Reply #9 on: February 22, 2011, 09:08:00 PM »
Is the riser template and the bow mold your own design or is there some place you can get them?

John

Offline Ray

  • Jr. Member
  • **
  • Posts: 95
Re: Fibreglass laminated longbow - how to build
« Reply #10 on: February 22, 2011, 09:42:42 PM »
As stated before, that is a recurve...not a longbow.   Do you make longbows also?     Ray
Waco, Texas

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #11 on: February 23, 2011, 11:39:58 AM »
This particular mold is one that I bought from a fellow who decided to sell off ones he had made.  I have made my own molds also including longbows and molds for take down recurve limbs.  I don't know of any one selling molds although there may be some around.

A bow mold isn't that hard to make - one way is to use a thin template (eg. 1/4 in. particle board) cut to the design you want and then use it as a router template to do the final shaping on the mold itself.  The riser template is made from the bow mold (the bottom must match the mold exactly and the top (belly side) is designed for the final riser shape. 

I started with fairly straight longbows and then began to build them with more curves in the risers and limbs.  If you are designing your own a review of what's available and different designs on the net will give you ideas for a design.

Recurve / longbow - see previous explanation - feel free to call it what you want.  Note that the limbs on a recurve are thin and wide - the limbs on this bow are thick and narrow.

John.

MrFluffy

  • Guest
Re: Fibreglass laminated longbow - how to build
« Reply #12 on: February 23, 2011, 02:11:57 PM »
Watching with interest, I have a recursive wooden bow with detachable wooden limbs and I did think this was a recursive bow on first glance but looking and checking the local regs I can see where the distinction appears. On my bow the string actually lies touching the limbs of the bow when strung but not under drawn position as the final end of the tips curve away from the archer, whereas this has some pre loading nearer the riser end of the limbs. Exactly as you state.

I doubt I'm going to go out and start laminating my own bows, but I'm still interested to watch it come together, whatever it ends up being classified as.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #13 on: February 23, 2011, 09:36:23 PM »
MrFluffy - it doesn't really matter what the classification is as the process of making the bow is pretty much the same - in the end it is just laminating wood and fibreglass on a mold.  Glad to see your interest.


Grinding laminations

Laminations for bow limbs can be made from a variety of woods including yew, rock maple, ash, elm, zebrano, black walnut and exotics.  My preference is for light in weight strong woods with good flex.  If clear fibreglass is used usually the wood underneath will be chosen for pattern and beauty.  A plain piece of maple may give good results as far as speed and durability but does not look that good under clear glass - of course stains and the like can be used if needed.

As mentioned previously we will use a layer of 50 thou glass on each side of the bow and 4 pairs of wood laminations between the glass.  In this case we are aiming for a bow of about 60 to 65 lb. - this is determined by glass thickness and wood thickness (all other things being equal).  With this bow we want a wood lamination thickness of about .336 in. measured at the thick end of the tapers.  Being that we will use 4 pairs of laminations we are aiming for two tapered pairs (one will also work well with this design) of about 0.100 at the thick end and two  (.336-.100-.100)/2 = 0.068 in. thick parallels.  This total thickness can be a bit less or more (say 5 thou or a bit more either way and be compensated for when finishing the bow - more on that later).

Note that the total wood thickness is the key - the figures above are just estimates as I don't like to go less than 0.100 on tapers - less and the thin end is extremely thin.  We could use 3 pairs of laminations or 5 however thicker laminations become difficult to bend and 5 pairs become somewhat difficult to get into the mold before the epoxy starts to thicken.

I rip laminations from 2 in. thick x 36 in. long stock with a well tuned bandsaw aiming for a finished thickness of about 0.135 in. or so.  Once cut they are run through a thickness sander to get the final thickness.



Running a pair of laminations through the thickness sander.



A poor pair of book matched osage orange laminations shown as they would be placed in the bow limb (overlapped just for the photo).

Adjoining laminations will be book matched in the bow limbs so that they are in the same position in the limb but a mirror image of each other - for example the first lamination cut from a given block will be on the lower limb against the fibreglass at the back of the bow and the adjoining piece will end up against the fibreglass on the back of the bow but on the upper limb.

72 in. laminations can be cut and used however they will not be book matched and they are difficult to handle so I seldom use them.  36 in. laminations will be scarf joined before glue up if necessary.

I use a drum style thickness sander get good accuracy on the laminations as long as I run them through the sander several times once they reach a point near the final thickness.  It is best to use fairly aggressive sandpaper (60 grit) as that roughs the wood up for the epoxy.  It is a bit of a slow process to grind a few pairs of laminations.



All laminations are run through the sander using a board underneath - the board has sandpaper glued on it so that the laminations stay onboard - otherwise they may shoot out of the sander like a small projectile.  The photo shows two laminations beside the sandpaper covered boards.

Tapers are created by running laminations through the sander with a tapered board underneath.  I commonly use tapers that are tapered 0.002 in per 1 in of length - others may use 0.001 per inch.  My bows have the tapers arranged to be thick end in the centre of the bow and thin end at the tips.  One company I know of tapers laminations from thick at both ends (middle of bow to each tip) to thin in the middle.  That particular model shoots very well.

Bow Glass:

Fibreglass is available in different widths, thicknesses and colours.  I normally use clear and black and have 0.040 and 0.050 thick for bows.  Since my molds are 2 in. wide that is the width I use.  For longbows (thick limbs) I use 0.040 or 0.050 depending upon the desired bow weight, for flatbows and recurves (bows with thin wide limbs) I use 0.040 glass.

John.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #14 on: May 16, 2011, 10:59:47 AM »
Continuing on:

I had a few things come up that prevented continuing on this thread.  Will continue now with the hope that I can finish it soon.

Referring back to the photo of the bow mold:

The back of the bow will be at the bottom of the pile of laminations while the top of the pile will be the belly.  When we put the laminations together in the mold the stack will be as follows (top to bottom):
- one layer fibreglass (in this case clear glass).
- two layers of wood laminations (usually includes the tapered pair)
- riser
- two pairs of wood laminations (parallels)
- final layer of fibreglass (since we will be putting snakeskin on the back of the bow we will use black glass here).

Before laminating the bow the two pair of matched laminations that go on the back of the bow (under the riser on our form) must be joined.  If they are not then usually they will float apart when placed in the form under pressure, leaving a gap in the bow.  I do a scarf joint on them and use some quick set epoxy to join that, making sure that they are book matched before gluing them together.  Once the glue has set it is easy to use a sanding block to smooth both sides of the joint.

The scarf joint can be done on a belt sander or by hand with a sanding block.  The photo below shows a scarf joint between two yew laminations on a built bow.  Look just to the right of centre of the photo, near the back (bottom) of the bow 3rd lamination up.



Glue up:

Once all the lamination pairs are ready they are laid out on a table and the epoxy, application sticks etc. are prepared.  It is important to have everything ready to go because there is a limited amount of time to mix and apply the glue.  With epoxy the warmer the room is the less time there will be available.  However if the room/epoxy is too cool it will not mix or spread well.  I like to have the room at about 70 F or so - it is a good compromise.

Latex/plastic gloves are used to minimize skin contact with the epoxy and the table is covered with plastic or newspaper to reduce cleanup.

Before applying glue the mold is set up with bolts and air hose ready to go.  Since I leave my compressor attached to the air hose while the glue is hardening, all of this hardware must be ready to go.  This includes turning the regulator on the compressor down to 0 (zero) and bleeding the air hose.  It is helpful to have two people to do the glue up and put the laminations in the mold however I have done this alone in the past.

Glue is applied to all bare surfaces (excluding the outside of the fibreglass laminations).  Thus each joint will have two applications of glue.  This insures that there is sufficient glue in the joint and also that no areas are missed.  A good light is a help both to assist in seeing that glue is applied evenly and to see any dirt, hair or other objects that may have been introduced into the joint.  (One bow I saw a few years ago had a piece of grass embedded between the clear glass and the adjoining lamination).

Extra amounts of epoxy are put in some areas - the fadeout areas and on the bottom and top of the riser.

Once the laminations have sufficient glue applied, they are stacked together with the riser in the middle and fibreglass tape is used to hold things together as the bundle is placed in the mold.  It is also possible to use a couple of elastic bands near the tips of the bow the help hold things together.

To be continued.....

John.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #15 on: May 18, 2011, 11:32:58 AM »
Here are a few photos to go with the discussion about scarf joints and preparation of the mold. 



Shows the two laminations being placed together - use a straight edge along side to ensure they are glued straight.  In this case the 72 in. piece of clear fibreglass next to them was used as a straight edge.  This is being done in a heated room as my shop is too cold in the winter.



Using a couple of small weights to hold down the joint while it cures.  Plastic around the joint keeps the epoxy from curing to the hold down.



The mold ready to go.  Note the white fire hose in the background, heat strips laid out.  The bolts are also ready to go along with their spacer blocks.  It is worth doing a dry run before applying epoxy to the laminations.



The laminations and riser are now in the mold and it is bolted together.  Note the two clamped "fingers" used to help hold the riser in place.  There are matching fingers on the other side.  The thermometer can be seen between the two fingers.

Fibreglass tape can be used to hold the riser and laminations down to the bow mold as the top is being put in place.  It won't however hold things in place once pressure is applied with the air hose.

This is a critical time in the layup as once the fire hose starts to inflate the laminations and riser will try to move around.  Wet epoxy has very good lubricating properties.  At this stage the air hose is connected to the firehose and the pressure is very slowly increased from 0 to about 60 psi.  I do this in stages, checking carefully to ensure that the laminations have not moved in relation to each other.  It is always nerve racking as it is difficult to remedy any problems at this stage.

Note - use floor wax on any parts of the mold or fingers that may come in contact with epoxy.  It will prevent it sticking.

Once the pressure reaches about 60 to 65 psi and everything is being pressed down nicely (may take 5 min. or so), the controller for the heat strips is turned on.  I use an instant read thermometer between the air hose and the top heat strip to monitor the temperature.  Over about 1/2 hour I will let the temperature rise to about 135 F or so.  This isn't critical but don't be too far out on either side of that figure.

The mold and bow are then left at temperature for about 3 hours (again not critical) and then the controller is turned off, the pressure left on and it is left to cool.  After an hour or more (depends upon how impatient you are), the pressure is relieved and the top of the mold can be removed.  This is the result:



The belly of the bow is facing up - this turned out flawless with no air bubbles under the clear glass and all laminations stacked nicely.


John.


Offline spuddevans

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1590
  • Country: 00
  • Portadown, Northern Ireland
    • My Photo website
Re: Fibreglass laminated longbow - how to build
« Reply #16 on: May 18, 2011, 12:47:36 PM »
Note - use floor wax on any parts of the mold or fingers that may come in contact with epoxy.  It will prevent it sticking.

You can also use plain old brown parcel tape, there is virtually no glue that can stick to the shiny side of parcel tape.


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Brass_Machine

  • Administrator
  • Hero Member
  • *****
  • Posts: 5258
  • Country: us
Re: Fibreglass laminated longbow - how to build
« Reply #17 on: May 18, 2011, 03:04:13 PM »
This is very cool to see!
Science is fun.

We're all mad here. I'm mad. You're mad.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #18 on: May 19, 2011, 12:25:23 PM »
Gentlemen:

Thanks for the tip on the parcel tape.

Yes the white "bulging" part is the firehose.   Just conventional fire hose with a fitted aluminium plug at the far end and another fitted plug with a 1/4 in. tapered pipe thread in the other to accept an air hose fitting (or a schreader valve if using a foot pump to inflate it).  It pays to be cautious with these plugs as they can become a real projectile if they "release".  Quite a while ago I tested an airhose on the back deck, pumped it up to 60 psi and left it while I was doing other things.  The sun got at it (it was dark blue) and when I came back one plug was gone and I never did find it.  None of the neighbours was missing or injured so I guess it "missed".

Continuing on:

Most of the photos from here on in were taken by my friend as he did the finishing on the bow.

Once the bow is lifted off the form, it is very rough - lots of very sharp epoxy on the edges and the ends aren't even.  At this point the edges are cleaned up on a belt sander and each limb cut to about 1.5 in. over the final length.  The length of this bow will be 66 in. (nock to nock) so it is initially cut to about 69in.  I put masking tape in the back of the bow to allow for layout lines.

It is helpful to have a long piece of plate glass to use to lay out the centre line but I have used a chalk line also.

A centre line is drawn the length of the bow and measurements are taken to each side to lay out the limbs.  The limbs can be cut with a wood bandsaw blade or ground down with a disk grinder.  If a bandsaw blade is used the teeth will be ruined in about the first inch leaving it to cut/burn it's way through the remainder.  I have a couple of old blades I use but because they are so dull they do wander some.

I cut well off the lines and then sand down close to them.  The final shaping will be done by eye using the centre line as a guide.  Initially one does not wish to take too much off the limbs or round them excessively as this can be done later to bring the bow down to the desired weight.

The riser can be cut to rough shape with the bandsaw or with a hand hacksaw or it can be sanded to shape with various machines or a sanding drum in a drill press (I don't like to do this without a bearing support under the drum as it's hard on the drill press).

For some reason photobucket won't work right now so I will leave for now and include photos relating to this part of the narrative in the next day or two. 

John.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #19 on: May 21, 2011, 08:46:02 AM »
A few photos to go with the last part of the narrative:



The bow in rough form, before cleaning up the edges.  The glass table is my friend's layout table.  (Not sure if SWMBO is aware of this.)



Bow with centre line marked out.  This is fairly advanced as the limbs are close to being finished and it is now strung.  I get the limbs close to their final shape before laying out and shaping the riser since the unfinished riser makes it easier to "eyeball" the finished limbs.

Once the shape of the limbs and riser are roughed out overlays are glued on.  These may be one or more layers and are usually applied to the tips (for reinforcement) and to the back and belly of the riser.  Epoxy is used and once the pieces are clamped in place, heat is used to cure it.  Short heat strips or a light bulb can be used to provide heat.

In this case my friend had a sheep horn (garage sale find) so used strips for overlays on the back of the riser.



The horn with one piece cut out.



Pieces cut and ready to apply.  The tape will be removed and the fibreglass will be sanded to get a good surface for the epoxy.  Note small "form" behind the bow.  This will be used to apply consistent pressure to the overlay as it is being glued.



Sheep horn now applied and the riser mainly shaped. 

John.




Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #20 on: May 25, 2011, 10:33:02 PM »
Now a bit on finishing/cutting the bow tips and nocks and bow finishing:

It is somewhat traditional (not everyone does this but I like to) to leave the tip at the top of the bow longer than the one on the bottom.  The reason is that the string is left on the bottom nock and when the bow is strung the string is slid up to and into place at the top nock.  If the tip is left long it makes it easier to slide the string up without pushing it past the end.

I always found that forming the nocks was difficult till I came up with a little simple jig.  I use a chainsaw round file to form the string nocks.



Shows the small angled block of wood with a chainsaw file in place.  A small spring clamp is sufficient to hold the block.  Always take your time with these and cut them gradually - a mistake at this point is difficult to fix.  Once they are cut sand them out to 400 or higher grit sandpaper - any sharp edges at all will eventually cut the string.



This is a bow I did a long time ago showing tip overlays.  The belly side has a clear glass overlay so it isn't very obvious.  The overlays on the back of the bow are white fibreglass and Kingwood.

Finishing the bow:

Once everything is done all parts are sanded off to at least 220 grit - more is better.  Gunstock oil finish (Birchwood Casey True oil is a good one) can be rubbed in several coats over the wood and fibreglass.  Don't use any kind of thick finish as it will tend to peel when the limbs bend.  Thin coats of lacquer spray finish are also good but I have never used it as I am not set up for spray painting.  I imagine similar spray bombs could also be used however.

John.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #21 on: May 25, 2011, 10:47:49 PM »
A bit more about finishing:





Notice how the addition of some moisture brings out the wood grain and the wood grain under the clear glass.  Also notice the curve of the shelf.  This helps to reduce contact with the arrow and help to give better flight.  The shelf will eventually be covered with leather or something similar and may be built up a bit at the high point.



My friend had some snakeskins and decided to apply them to the back of this bow.  That is the main reason the bow has black glass on the back.  I've never done this but it does involve stretching the damp skin on the back of the bow and glueing with white carpenter's glue or something similar.

I will have to find some photos of the finished bow - it turned out very very well and my friend is very happy with it - with both it's appearance and it's performance.

There are lots of aspects I have covered quickly in this narrative and other than photos of the finished bow I won't go into it further.  If anyone has questions I will try to answer them and elaborate a bit if need be.

Thanks for looking,

John.


Offline Bernd

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 3683
  • Country: us
  • 1915 C Cab
    • Kingstone Model Works
Re: Fibreglass laminated longbow - how to build
« Reply #22 on: May 26, 2011, 08:03:24 AM »
This was a very interesting thread. Learned a bit about making a bow.

Lot's of craftsmanship in something like that.  :thumbup:

Thanks posting it.

Bernd
You can't fix "STUPID".

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #23 on: May 27, 2011, 01:12:20 PM »
Thanks Bernd.

I've looked around and it appears I didn't take photos of the finished bow.  My friend is working out of town so next time I see him (may be weeks away), I'll get some and post them.  Hate to hold you in suspense. :palm:

John.

Offline steamboatmodel

  • Jr. Member
  • **
  • Posts: 11
Re: Fibreglass laminated longbow - how to build
« Reply #24 on: May 29, 2011, 12:16:00 PM »
Hi John,
Is the Fibreglass that you use the same as what is used for boat building?
Regards,
Gerald.
Be wary of strong drink. It can make you shoot at tax collectors--and miss. Lazarus Long

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #25 on: May 29, 2011, 02:33:50 PM »
Gerald:

No it's uni directional glass and not very flexible sideways.  I assume the boat building glass you are talking about is the woven cloth or something similar.

There may be other brands out there but most of what is available here is Gordon bow tuff which is strictly meant for bows (as far as I know it doesn't have any other purpose but you never know).

John.

Offline steamboatmodel

  • Jr. Member
  • **
  • Posts: 11
Re: Fibreglass laminated longbow - how to build
« Reply #26 on: May 30, 2011, 08:23:21 PM »
Thanks John,
I looked at http://www.gordoncomposites.com/index.htm
Doing the limbs is a lot more complicated then I thought.
Regards,
Gerald.
Be wary of strong drink. It can make you shoot at tax collectors--and miss. Lazarus Long

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #27 on: June 03, 2011, 12:42:57 PM »
Gerald:

The way I have described is equipment intensive however works well and is efficient.  The first few bows I made were made with a bottom mold only and used rubber bands to hold the laminations down to the mold.  We used some pieces of inner tube to make the bands and used a plywood heat box with about 4 - 100 watt bulbs to heat it for a few hours.  There are a lot of simple ways as this is just laminating wood - some use a 2x4 to make a form etc.

If you want to start out small it isn't too complex.

John.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #28 on: October 09, 2011, 02:32:35 PM »
Gentlemen:

Just an update as I realize I have not provided photos of the finished product.  My friend (who has the bow) has been working out of town for some months and I haven't had a chance to get photos.  It will likely be worn out by the time he gets back as he does a lot of shooting. ::)

John.

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #29 on: January 08, 2012, 09:46:48 PM »
I finally got together with my friend and got a few photos.  He had been working away from the area for quite a while and when he came home had about a 2 month "honey do" list.

We actually built two longbows about the same time so I will show a couple of photos of each.  Note that one has snakeskin on the back.











The first bow (1st two photos) was sold this summer by my friend but he has kept the 2nd one (snakeskin backed) and has had several successful hunts with it.

We are in the planning stages for another two or three - I will build a takedown recurve for myself and my friend wants at least one longbow.  Just like tools there are never enough.

John.

Offline johnbaz

  • Jr. Member
  • **
  • Posts: 99
    • My Flickr
Re: Fibreglass laminated longbow - how to build
« Reply #30 on: January 10, 2012, 11:38:06 AM »
Hi John


Firstly- What a beautiful Bow  :jaw: :jaw: :jaw:

Second, I think the reason that folk are saying it's a recurve rather than a longbow is the fact the they are on different Continents, the people that are saying it's a recurve are saying so because here in the UK, a longbow is dead straight  with no 'recurve' and were used a few hundred years ago to defend the Realm..

Each male over the age of 14 years was required by the law of the land to practice for (I think) two hours per day in case they were called upon to defend king and country..


I'd love to see more pics of your bows, I only have an ugly Barnett Excocett but will make an effort to acquire something nicer  :ddb:



Cheers john :beer:

Offline jcs0001

  • Sr. Member
  • ****
  • Posts: 288
  • Country: ca
Re: Fibreglass laminated longbow - how to build
« Reply #31 on: January 11, 2012, 01:49:31 PM »
John:

Thanks for the comments.  To be truthful it seems that "longbows" in North America had gone a long long way from anything very traditional.  Faster, shorter and more recurved seem to be the way they are being taken.  I have an actual wooden English Longbow and there is certainly a huge difference in shooting between that and any of these.  I expect that 2 hours practice per day would certainly give me a terminal case of tennis elbow!

We are planning to build a couple more bows this winter and I may put up a few photos when done.

John.

Offline johnbaz

  • Jr. Member
  • **
  • Posts: 99
    • My Flickr
Re: Fibreglass laminated longbow - how to build
« Reply #32 on: January 13, 2012, 02:22:38 PM »
John:

Thanks for the comments.  To be truthful it seems that "longbows" in North America had gone a long long way from anything very traditional.  Faster, shorter and more recurved seem to be the way they are being taken.  I have an actual wooden English Longbow and there is certainly a huge difference in shooting between that and any of these.  I expect that 2 hours practice per day would certainly give me a terminal case of tennis elbow!

We are planning to build a couple more bows this winter and I may put up a few photos when done.

John.

Hi John

Can't wait to see pics of the new bows, I find bowmaking fascinating :thumbup:


Regards, John  :beer: