ORIGINAL: fredsedno
Try using the same size drill inthe original hole, but run it in reverse[backwards] turn drill very slow with moderate infeed.This will sometimes back the broken piece out[sometimes not]. Kerosene has been the reccommended cutting fluid for aluminum.Sharp drills perform with fewer problems.
fredsedno
If your motor mount is aluminum, or composit. you can soak it n a pan of alum mixed with water. Use a strong mix. THe alum will desolve the steel bit. Needles to say, this wont work getting a broken drill or tap out of steel. It has to be a non ferious mount as the alum will attack any ferious metal.
Another tip. If you are using the aluminum mounts. and you kind of miss getting the alignment correct on a hole. there is an easy fix. Tap the hole out to one size larger than the screw size you are using, but don't tap it all the way through, just enough for the tip of the tap to come through about 1 turn. We are going to put the taper to work. Get a short piece of aluminum round the size of the hole you just tapped. Thread it for a long enough length to go through the mount lug. Now, this is extreamly important, use soap, water, and the acohol and clean every last bit of oil from both the hole and the treaded aluminum rod. Now put the threaded rod in your drill press and the mount in a vise that is locked down well make sure the thread are started clean by screwing the rod in about 1 turn maximum. Holding a bit of down pressure on the drill press, turn it on. It will screw in the aluminum and snap of the end of the rod at the top of the mount lug. File it smooth, top and bottom and it's like the off center hole was never started.
Aluminum has a nasty habbit of self welding to another piece of aluminum if there is not lubercation. This habbit though is put to use here because what you have just done is to pressuer weld the threaded rod into the motor mount. This won't work with anything other than aluminun. It turns out that this is how they weld together those flat aluminum plates in the freezer of your refrigerator. They form two plates with the 1/2 the tubing and place the plates face to face and use a pressure roller to tracet the edge of the tubing. Just the pressure is all that is needed to weld them together. Works on motor mounts very well also.
I have one that I missed the hole by 1/2 diameter. I did this fix and was very leary that the 1/2 thread would hold up to tapping and then multiple screws run and out of it. Worked like a charm.
Don