About 10 years ago I did my first hornbows with usual bow- woods as a core: ash, elm, black locust, wild cherry………The glueing turned out to be a kind of not to much reliable The glueing procedure itself was becoming more and more a thing of chaos and even some horror: glue drying to fast, fingers full of glue, glue everywhere, all things glued up but not the horn to the core- wood…………….these flops made me to think the whole thing over, to reset and to update my mind about traditional glueing of laminated bow- construction. Remember 10 years ago the infos dealing with hornbows and other laminated bows were not as wide- spreaded as today. It took me another 4 years to become able to manage the procedure in a more secure way. When glueing bow- lams with natural glues it is a must to organize the whole procedure very carefully. Clean and degrease the parts to be glued with curd soap, coat them several times with a thin solution of glue: water- glue= 5 : 1. Take care that the workshop is well- tempered- 77F, as well as the glue- 150F, preheat the wood and the horn to about 75F. Place your clamps or rope ready for to go. When the glueing is done fix the lam to a straight and stable wooden lath for to make sure that the bow will stay aligned. Maybe you want a reflexed or recurved bow, so fix the bow to an according wooden form. This procedure is called glue- shaping. The Japanese makers of the traditional Yumi- bows are using a rope and wedges made of bamboo for to glue- shape the multicurved yumis.
After having done my experiences in glueing bow- lams I ended up in using selfmade clamps for to match as exactly as possible the needs of a well working glueing.
The clamps are made of mountain- maple slats cut to 3″ in length, about 1/2″ in thickness for the bottom piece and 1/3″ for the upper piece, width is about 1″. For to screw them down I use thread rods and fitting nuts, countersinked into the bottom piece of the clamp. It´s also a good idea to use winged screws, but for to develop heavier pressure I prefer to screw the clamps down with a ratchet wrench.
It´s also possible to do these clamps by glueing small pieces of wood at their internal sides for to guide the lams not to slip out of place. But don´t do them to thick, otherwise you can´t produce the necessary pressure: I leave an open space of about 1″ – 11/2″ in width and about 1/3″ in thickness, you can make clamps with more or less open space matching the different cross- sections of the lam.
Before using the selfmade clamps open them up, organize the glueing well, prepare all tools you need, take care for the right temperature of the workshop and the glue. The advantage of these clamps is that you can develop pressure where it is needed, more or less. Don´t screw them down to heavy. Just as far as the glue is flowing out of the glueline.
These clamps are highly effective, done by yourself you´ve to buy screws, nuts and thread rod. Choose them made of iron not made of aluminium, as I did it for the first time. Iron is much more stable.