Goldfish Development. Baby goldfish are born much darker than they will be as adults. This may be because dark colors helps these small, vulnerable fish escape the attention of predators. With proper husbandry, the fish gradually change color and develop orange or gold scales. Fancy goldfish may develop color patterns including white patches.
Posts: 1,396. Re: Bits for hand drilling hardened steel. If you want to experiment with carbide drilling on the cheap, buy a carbide tipped masonry drill bit set. They are about $20 a set new, but I find them at garage sales for about $1 for the set all the time and that's why I use them.
Most drill bits for consumer use have straight shanks. For heavy duty drilling in industry, bits with tapered shanks are sometimes used. Other types shanks used include hex-shaped, and various proprietary quick release systems. The diameter-to-length ratio of the drill bit is usually between 1:1 and 1:10. Much higher ratios are possible (e.g., aircraft-length twist bits, pressured-oil gun drill bits, etc.), but the higher the ratio, the greater the technical challenge of producing good work.