Most all woods will yield to bending with applied heat. The trick is knowing how, when, where and what type of heat is needed to achieve the desired results. In bow making heat can be utilized in many facets. It can be used to add reflex to a roughed out bow (most common use), it can be used to temper the belly of a bow to impart stiffness, it can be used to bring the string centers hot by manipulating the limb alignment or just to add recurves to the tips, both working and static. Using heat on any wood should be used judiciously as it said to weaken the woods cell structure on a molecular level. I’m not a scientist so I cannot expand on that any further other than to say don’t go overboard trying to manipulate wood using heat or the risk of a sudden violent explosion at full draw becomes suddenly very real. I’ll go over a few basic processes I use for wood manipulation in the crafting of bows.
Adding a couple of inches of reflex to a bow gives the bowyer/archer a couple of advantages. It will USUALLY leave the completed bow with either a straight profile or very minimal string follow after being “shot in” depending on the amount added. The added reflex will impart early draw weight to the bow increasing efficiency and overall speed.
To add it is best to have a caul or form. This allows the reflex to be more readily controlled and evenly applied to both limbs. Place the bow back side down on the caul and clamp it snugly at the center. Apply one each additional clamps on either side of center out about 6”-8” or so and apply just enough pressure to make it snug. Note: Take some heavy duty aluminum foil and make a sort of cradle to capture and hold the heat more efficiently.
Take your heat gun turn it on high and begin to warm an area approx 6”-8” long on the bows limb on both sides of the clamp and up to the fade on the bow. Keep the heat gun moving at all times to keep from scorching the wood. After a few minutes give the clamp a few turns and continue. Once the area is bent down enough keep adding clamps and heating sections of the bows limbs until you have worked all the way to the tips. Move over to the other limb and do the same thing.
Let the bow cool completely before removing from the caul. It may take more than one application to achieve the desired results. Important note: Do not try to force thick wood to conform to any caul. The wood should be no more than ¾” thick on the limbs for the best results. The thinner it is the better the set will take.
The recurving of a bows limb tip can be done with either dry heat or by steaming or boiling. I have had far greater success using moist heat or literally boiling the tips in water. First let’s talk about our form that we’ll use to bend the tip on. Extend the forms curve further than the desired curve on the bows limb because the wood will loose a bit of the curve after it is removed from the form. The belly of the bow must be supported with a steel strap or similar device or it will likely split during the bend.
Get a suitable pot and fill it full of water to as far up as you are going with the bend. Normally 6”-8” will do for most recurves. DO NOT plunge a room temp limb tip into boiling water. Heat the water and the tip up together for at least 45min. Limb tips should be no thicker than 7/16” thick and preferably thinner. While that is boiling get you form ready with the clamps and all other accessories needed for the job. Have the clamps pre-adjusted to where it only takes a turn or so to apply pressure. The whole process of clamping the band and making the bend need to be done within 30 seconds or so before the wood looses the required heat for bending.
It is a good idea to take your heat gun and apply some dry heat to the bend the next day and let it cool before unclamping. This will help “set” the bend to a greater extent.
Take care.. Sparky
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