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Freeing broken drill bit


#1

This may not be new to some, but I discovered it today on my own and
it may help you in a pinch.

I had to get three pieces out that were not finished. Needed to
drill a bale hole in the pendant which was 3/8" thick or better.
First two went fine. Started small and progressively got larger bits
until I had enough for a 12 gauge wire. Large heavy shark tooth. The
third one I broke the bit. And it was way in there. I spent an hour
burning up bits trying to go around it and through it. I tried poking
it, banging it on the bench block, super magnet. Even cussing did not
help. I drilled the opposite side where I thought it would come
through. Used a ball bur to open it a little. Then took a Starret
drill punch and punched the opposite side. (For those that do not
know, these are spring loaded and exert a good amount of energy
force to give you a divot where to begin drilling.) Nothing. Out of
frustration as I knew I was going to scrap it, I punched it two or
three times and then another as I was so po’d. I turned it over and
there was the end of the drill bit poking out from whence it came. I
tried grabbing it with tiny needle nose to no avail. Two more punches
and the energy forced it out into the scrap drawer.

It may or may not work for you. I hope to never try it again!

Charlie


#2

try strong solution of alum next time.


#3

Hello Charlie,

a much better way is to lay your piece in old pickle and let the
acid do the job for you. The broken drill will be removed by the acid
without hard labor or stress. Clean work and no big deal.

Next time ask Ganoksin first before you get yourself in trouble.

Have fun and enjoy
Pedro


#4

Hi Charlie,

You’re going to hate this one: pickle. Works great for dissolving
drills & taps.

Mix up some fresh pickle, a bit on the strong side, get it hot, then
dunk the piece in it. Go get a long lunch, and you’ll come back to
black sludge instead of a solid drill bit. It may or may not be
totally gone yet, but it should be gone enough to rinse out of the
hole.

The reason for mixing up fresh pickle is that way it doesn’t have
any dissolved copper to plate out all over your piece.

Regards,
Brian.


#5

You can always try acid to dissolve the drill bit… You don’t need
to dissolve it completely, just enough for it to come out of the
hole. I work exclusively with titanium, so I’m not sure what you can
use on gold and silver that will dissolve a drill bit, but I get
good results with nitric acid. I’m not sure how that acid would
effect different metals, but it leave titanium alone.

-Chris


#6

Hi Charlie,

An old watchmakers trick is to boil the piece in alum to remove the
drill bit. I’ve actually changed and now boil stubborn drill bits in
some freshly prepared Sparex. It’s most efficient if the hole where
the drill bit is located is open on both ends. You did that as you
tried to pry the drill out. Even with the boiling technique, I always
attempt to punch a broken bit out from the reverse unless the piece
is too delicate.

Of course this technique doesn’t work if you have already set heat
or acid sensitive stones already set in the piece. Just to be on the
safe side I always make sure I’ve drilled out any holes before
setting sensitive stones. Glad you were able to get that drill out.
It’s one of the more frustrating things that can happen at the bench.

Larry


#7

Here’s another option if you have a pulse arc welder: Weld a piece
of steel to the end of the broken bit and “unscrew” it.

Jeff Herman


#8

I too use nitric acid to dissolve the occasional broken drill bit
from gold. I have never tried using a strong pickle as suggested
yesterday, but next time I may just give it a whirl to see how it
works for me. Hopefully it will be a long time though, before I get
a chance to make such a test.


#9

Sorry this is not posted as a reply, but am doing this from the shop
where I’m not really set up.

Take your item with the broken bit and cast it in the 'ol pickle
pot, (sparex type). You’ll be amazed at how quickly the bit
dissolves, 20 mins to 1 hour ish. Don’t pickle anything else during
this operation as it will copper plate while there is steel in the
bath.

Hope this helps.
Bob
R. Wise Studio


#10

if you stick the piece of metal with a broken drill bit in a
solution of alum mixed with water (you can get alum from your drug
store) it will eat away the drill bit leaving the gold or silver
alone. it works every time. it takes a few hours to eat it away but
you can use that time to work on something else rather than ruin
your previous work.


#11

The simple answer is always to mix alum in warm water, dump in the
piece with the drill and go do something else. Next morning, the
drill will be gone.

Judy Hoch


#12

Pickle has been mentioned here a few times - I’m presuming that is
an acid solution of some kind - can someone direct me to a (chemical)
definition please?


#13

yup

called sparex by the jewellery supply shops but you can get it
cheeper at pool and spa places its called sodiumbisulphate (not sure
about the spelling)

you can also use an ultra sound to shake them loose

les


#14

Hi Paul,

In the US, it’s sodium bisulphate. Don’t know about strength.
“Enough” is generally as much as anybody bothers with. You can get
it at pool supply places as “Ph Down”.

Regards,
Brian


#15

Has anyone tried the pickle trick with citric acid? Maybe I’ll test
with a broken bit “in advance of need” as they say in the funeral
biz. I don’t do this often, but it sure is a PITA when it happens.

Now, anybody have a trick for getting a broken drill out of a pearl?

Noel


#16

Hello,

Now, anybody have a trick for getting a broken drill out of a
pearl? 

Cover the pearl with fimo clay except the whole with the broken
drill. Place the covered pearl gently in a warm pickle and let the
solution do the job. Check on regular bases how the process is
developing. You don’t want to expose the pearl longer as needed to
the pickle. When the broke drill is solved, clean the free hole with
clear water and a small syringe. Remove the clay after a good rinse
with clear water.

I use sparex as a pickle solution, I have no idea if other pickle
solutions work the same way.

Have fun and enjoy
Pedro