Drawings of Qin crossbow trigger
I like this little genius machine since the first discovery. Does anyone know how to manufacture (cast) it cheaply with permanent moulds？
Your casting inventory is the three components and the two bolts. You can cut that down by using commercially available bolts and scaling the holes to match.
I would suggest making a full scale model out of transparent acrylic or something like that. It is critical to get the notch in the trigger exactly right or you will have premature releases of the string.
The sear and the trigger are simple shapes and it is easy to make reusable moulds. The claw and sight module is more complex. An experienced foundry man would be the best person to ask if you intend to use sand casting. For lost wax, you could make the claw module wax master in two halves and join them together before investment, but that requires precision alignment.
You also need to consult information on the shrinkage rates of the alloy you want to use otherwise the holes will be too small and will need to be re-bored.
If you already know all of this, sorry for boring you.
I would suggest making a full scale model out of transparent acrylic or something like that. It is critical to get the notch in the trigger exactly right or you will have premature releases of the string.
The sear and the trigger are simple shapes and it is easy to make reusable moulds. The claw and sight module is more complex. An experienced foundry man would be the best person to ask if you intend to use sand casting. For lost wax, you could make the claw module wax master in two halves and join them together before investment, but that requires precision alignment.
You also need to consult information on the shrinkage rates of the alloy you want to use otherwise the holes will be too small and will need to be re-bored.
If you already know all of this, sorry for boring you.
The sting locked at the two notches introduces a downward component force which prevents undesired operation since the different heigh of the bow and the notch. But I recomment a inner oblique or arc notch to aviod upward jumping string.
In ancient china, the numble of triggers manufactured above was quite large, so it is unbeliveable through wax lost casting method or non-reusable casting mould. There must be a genius method beyond our thinking. Other ways like 3D printing, metal line cutting are good alternative choices.
I got a great ideal on how to casting it yesteday. 3 layer moulds are need to casting the notch and regulator as a whole. The top mould is for the notch "A" and regulator, the bottom mould is for the opposite notch "a". While the middle mould is for the curved band and the cylind link parts (two bolts you reffered ). The key solution lies on the mobile abilities of the middle mould. In other words, the middle mould is formed by two sub-moulds.When pouring melted metal, it is one as a whole tightly. When mould unloading, it can divide into two parts. Massive production is possible by this method. I will up load those figures late, hoping for your great comments and judgements!
In ancient china, the numble of triggers manufactured above was quite large, so it is unbeliveable through wax lost casting method or non-reusable casting mould. There must be a genius method beyond our thinking. Other ways like 3D printing, metal line cutting are good alternative choices.
I got a great ideal on how to casting it yesteday. 3 layer moulds are need to casting the notch and regulator as a whole. The top mould is for the notch "A" and regulator, the bottom mould is for the opposite notch "a". While the middle mould is for the curved band and the cylind link parts (two bolts you reffered ). The key solution lies on the mobile abilities of the middle mould. In other words, the middle mould is formed by two sub-moulds.When pouring melted metal, it is one as a whole tightly. When mould unloading, it can divide into two parts. Massive production is possible by this method. I will up load those figures late, hoping for your great comments and judgements!
In ancient times there was a trick to making large scale repetitive castings. A metal mould was made and used to cast hundreds of wax masters which were then sprued together in casting trees. Fifty or a hundred objects could be cast at one time. In China some of the final clay forms have been found where this was done for coins and arrowheads.