I need to make a 5.625" #43 drill. My first question is where I can purchase some #43 drill rod?
My plan is to grind a small groove on the end of the drill, and a tounge shape on the drill rod. Then chuck the drill in the headstock and the drill rod in the tailstock of my lathe and silver solder them together. This will be my first attempt using silver solder. So if any of you guys have any hints or tips, it would be very much appreciated.
We've made a number of "longer" drills in the same method except that we used turned down drills in a drilled and reamed hole in the shaft.
The turned down section were about 1/2 the diameter of the drill but an even size to be able to fit a reamed hole and was about twice the drill diameter long. The "extension" is a rod of the correct size that is drilled and reamed with the same size of hole that the drill was turned to. The turned down drill section is then pressed into the drilled and reamed hole and soldered in place. The resultant drill will run much truer then just soldering it on the end of a rod.
That's fine if you can buy them but we were making drills in the 36-48 in lg bracket. We had to get down inside a hole that was 30 inches deep with a magnetic drill. That's when we started making our drills longer.
We found that drilling and reaming a hole in the shaft and turning the backend of the drill in a lathe made the whole assembly run truer. And when you're 30 inches or so from the chuck, any runout is bad.