Aircraft Drill Bits? I Need Long Bits For The Lathe

aircraft drill are long for the reach in sheet metal work..not for drilling deep holes
 
It's easy to add a drill to the end of a piece of round stock. If you take a 1/2 drill and turn a 3/8 dia x 1 inch turn at the end then drill and ream a piece of 1/2 inch stock and heat bar then press drill into stock. Make sure the stock dia is not bigger then drill dia. You can silver solder or heat shrink to lock together.
jimsehr
 
I have several extra long length twist drill bits that were bought for various jobs over the years. One job in particular was drilling a 7/16" hole 13-1/8" deep in a 4" bar of 4140HT steel. It was a blind hole application. For every 1/4" to 1/2" of drilling depth, you had to retract the drill from the hole to clear the chips to keep the drill from binding and breaking off. Took about 20-25 minutes to drill and another hour to let the part cool down for the next operation. The new supplier now sends them out to be gun drilled before any of the machine work is done. Just remember, regardless of the length of the drill, it has to be retracted many times to remove the chips and a good cutting oil added to the drill and hole while drilling.
 
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