Evidence of horse bits go back as far as 3500 BCE. There seems to be a lot of controversy regarding there use. Were they first used in driving bits or riding horses? It would seem logical that horses were driven first or lead while pulling sled like contraptions. At any rate, evidence of 3mm groves in horses teeth proves that early horses were trained using bits made of rawhide, bone or some type of rope. These artifacts have not survived so conclusive evidence just does not exist today. Not being an archaeologist but being a horsemen I am going to assume that the first device used in controlling horses was what we know as a hackamore. From the hackamore it would naturally follow that crude bits were placed in the horses mouth. These bits were carved or pounded out and shaped by hand but casting metal bits most certainly followed quickly. The first use of metal castings technology traces to India and China around 500 BC. The above information only serves to provide information as to when man started the process of casting bits, which is the way we manufacture horse bits today. It is noteworthy that the earliest bits found were snaffle bits, which are still the most used bit in training horses today.
Horse Bits made using Sand Casting.
While the first bits were made of copper then later bronze and later compounds of iron, nickle and tine were made. These bits were easy to form and also had some benefits such as not rusting and producing more salivation, but had there problems. As late as the 1980's nickel was being used when making bits but a number of horses had allergic reactions and these bits were soft which made some bits like overcheck bits unsafe . Iron bits originally were formed using a method called sand casting. Actually it is quite simple. After creating a finished bit by hand forging or creating a wooden facsimile of the bit you intend to produce, parts of the bit is disassembled. A metal frame that is split in the center and bolted together is placed on a flat surface and a layer of finely sifted damp sand is placed inside the frame. Then the part you wish to produce is placed on top of the sand. Then another layer of finely sifted sand is placed over the bit part. Once sufficiently covered the remainder of the frame is filled and packed down until it is very firm. At this point the mold is unbolted and the top half is removed exposing the part to be casted. This part is now carefully removed. The top half is bolted back onto the bottom half and the mold is ready. Using a tube, an inlet hole is punched into the sand until it reaches the bit part then outlet hole is punched. The frame is now ready to be filled. Metal is melted and poured into the inlet hole until it can be seen coming out of the outlet hole. Once the metal is hard it is removed from the sand. At this point any joint marks found are removed by a grinding process. Once this is completed the parts are placed into a tumbling machine which will begin the polishing process. This can take up to 48 hours. Once the tumbling process is completed the bits parts are now assembled. As an example the ring will be placed through the hole in the mouth piece closed and then welded. These joints must be ground smooth and prepared for hand polishing. Most of these bits made of iron had to be chrome plated to keep them from rusting and give a shiny appearance. The bit is now complete and ready for use. Some of these bits are still being sold today. However, the chrome will eventually chip or peel and then rust . This caused them to be replaced after a short period of use. You will also hear of sweet iron bits. Some think this was a relatively new invention, when in fact it is a quite old natural process that allows iron to rust and create a patina. When the patina (a fine coating of iron oxide on the surface of a metal object) develops the rusting process will cease. Currently this process is not caused by aging the metal. It is now a process that manufactures have perfected and it should be noted that these bits will rust and should be coated with a natural substance like Vaseline to keep them looking new.
Horse Bits made using the Lost Wax method.
The lost wax or investment casting method of producing bits is what is used today by any "quality" horse bit manufacturer. Both English Bits and Western Bits are produced using this method along with spurs and stirrups. The process is essentially the same except that a wax replica is produced of the bit parts to be produced. These parts are attached to a tree like form so multiple parts can be formed at one time. The wax parts are sprayed with a gravy looking substance which creates the mold. Metal is heated and poured into the inlet hole. The wax comes out of the outlet hole ahead of the metal. Thus the name "lost wax". The metal is allowed to harden then the mold is broken exposing the bit parts. There are no edges on these part as there were on the sand casted parts. These part will go straight to the tumbling machines for about 24 hours. Once the tumbling process has been completed the parts are ready for assembly. Assembly completed, bits will be hand polished and packaged for shipment. Today most all bits are made of stainless steel also known as inox steel. It has a minimum of 11% chromium by mass. The Chromium creates a film over the bit which reduces rusting. The name "stainless steel" used in the late 1800's, was miss named from the beginning. A more correct name would have been non corrosive steel. Most bits are made with a grade referred to as 18/8. This grade is well suited for bits, spurs and stirrups. It is strong and stays shiny. Stainless steel is not the hardest of metals but unlike the old malleable iron bits will flex before breaking making the most suitable metal for modern horse bits, spurs and stirrup irons today .