Hi Fred
A few ideas:
**EDM Do a Google search on EDM
http://en.wikipedia.org/wiki/Electrical_discharge_machining
You would have to bring the piece to someone with a large enough machine to
accomodate
the part
**You can go after the part with a hole saw (center hollow) and take out a plug
of metal including the broken tap, but only if you promise not to ever break
another tap ;-) you could ream the hole, then put in a precise plug (with a
tapped
hole in it) and "get it stuck" with 638 Locktight, that is if it is in an
area you are OK with making a larger hole in. Warm the holy part (not more than
spit sizzle) and cool the plug till the fit is a few thousands between, apply
638 and you will have one stuck plug! When it gets stuck half way, you will
have to hole saw out the plug for the first hole saw hole!
**I am not sure where the hole is, but did you ever see Pauls Swiss cheese swing
arm? Perhaps you can make yours into a piece of Swiss cheese with a hole where
the broken tap is?
**I remember seeing tap removers for two and three flute taps, they have prongs
to fit down the flutes. Perhaps have a look in McMaster, MSC and do a Google
search for broken tap removers. Search Google for procedure for removing broken
taps in aluminium. Now you will probably be breaking your promise, but on
purpose
break off another tap like you already did in a sample piece and try removing
or plugging first. As far as removing stuck stuff, like Craig mentioned
you can "beat it" if that doesn't work, "beat" it and "heat" it and then "beat"
it. Watch out heating, i don't know what type of aluminium it is. I think if
you stay under 300F it's probably OK but first try ~ spit sizzle temp (~212F).
Of course you probably have a beautiful paint job on it! If thats the case,
go under paint get hurt temp.
**Bring the piece to a machine shop and I think a nice milling machine and a
nice
carbide cutter may get the job done?
**For the future, unless it is a fitting that needs max. strength, drill hole
over-sized
for a 60% fit instead of 75%, I like Tap Magic for aluminium and use
a very sharp tap, I like gun taps (no 1/2 turn in and 1/4 out needed), you can
still get bottoming taps.
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358433#358433
|