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Drill bit and file assassin!


#1

Help:

It seems like I have no mercy on my my files and drill bits- but
i can not figure out what I am doing wrong. Even with lube I
burn out my drill bits especially pearl drill bits in minutes or
even seconds at a time. Am I pushing down to hard - or not
enough?. Also, my best files are not at their best. I have a
file brush but it does not seem to clean my files well (which
direction are you suppose to use the file brush anyway?) Also, I
always file properly (away from me instead of towards me-learned
proper filing techniques at Revere) but besides that what am i
doing wrong? Also, my best coolest file from Germany has a bit
of rust on it!! (must of spilt one two many lattes near my
bench). What is the best way to clean up the rust and bring my
file some what back to peak condition?

Signed the Tool Assassin
AKA DeDe


#2

DeDe, use a miniature steel brush on a mandrel for a rotary tool
and gently go over the file. Let the bristles do the work; it
doesn’t require a lot of pressure, only enough to keep it in
contact with the teeth. It knocks off rust and that stuff that
won’t come out no matter how diligent you are with the card file.
Wear goggles, of course, while using rotary tools.


#3

DeDe, clean metal from your files with a piece of copper tubing.
Use 1/4 or 3/8 copper tubing that you can buy at any hardware
store. Then hammer one end flat after cutting a piece to about
6" total length. You have in your hands one fine file cleaner,
just push the flattened end across the file width wise and it
magically removes silver or gold buildup!

Gary in Redding, Ca


#4

HI Dede,

I guy I once worked for would coat dull files with a little
nitric acid, scrape them with a wooden paint stir stick, to
remove some of the acid from the teeth points, let the steel
etch for a bit and then rinse them clean. Supposedly, the acid
cuts the metal in a way so as to sharpen the teeth.

At least it cleaned the hell out of them! They looked brand new
and seemed a bit sharper, but I’m not sure of the efficacy of
this method. Has anyone else heard of doing this?

As for drill bits, it seems that the dull bits are the ones to
break most often…too much force is applied on them. If you
look at the tip of a drill bit with magnification, you’ll notice
"faceted" cut angles on the spiral, creating the point. With a
little practice, you can learn to quickly sharpen them on a
whetstone, as you would a graver. That and lubricatrion can make
a drill last quite a while.

Jesse


#5

Hi Dede,

A couple of things come to mind about the drill bit problem. I
drill lots of holes from .010" to over 1" in all kinds of
materials (including precious metals), some hard & brittle to
some soft & gummy.

When drill bits seem to dull quicker than expected, the 1st
thing I check is speed. If the bit is turning to fast the result
is usually a lot of heat at the point of contact. This tends to
anneal the cutting edges & a dull bit results. There are charts
available showing the speeds for most metals used in industry,
but the precious metals aren’t listed. The speeds for all metals
increase as then size of the bit gets smaller. A range of speeds
I’ve found works for me on most precious metals is: #50 drill
bit, 3800 rpm to #54 drill bit, 4800 rpm. As the drill bits get
smaller the speed increases. These speeds are based on an
outside edge cutting speed of 70 feet per minute.

Another thing that can cause a bit to loose it’s edge quickly is
insufficient pressure while drilling. When not enough pressure is
applied to the bit, it just rubs the material being drilled and
doesn’t dig in, it just gets hot. This quickly anneals the
cutting edges & they roll over.

Another cause may be poor quality bits or a bad sharpening job.
When buying small drill bits, buy the best available, they’ll pay
for themselves in the long run.

 Also, my best files are not at their best.  I have a file
brush but it does not seem to clean my files well (which
direction are you suppose to use the file brush anyway?) Also,
I always file properly (away from me instead of towards
me-learned proper filing techniques at Revere) but besides that
what am i doing wrong? 

The file cleaning brush, called a file card, looks like
miniature bed of nails. Brush the card across the grooves in the
file parallel to the grooves. In a double cut file this requires
brushing from 2 angles. Individual pieces of material left in the
grooves after brushing with the file card can be picked out
using a sharp scribe or other pointed tool.

Also, my best coolest file from Germany has a bit of rust on
it!! (must of spilt one two many lattes near my bench). What is
the best way to clean up the rust and bring my file some what
back to peak condition?

You might try coating the rusted area with ‘Naval Jelly’, a
phosphoric acid based product that’s sold for rust removal.
Hardware stores usually sell it. The other option is a good stiff
brushing with a file card followed by an overall coating of some
rust removing product available at the hardware store. Be sure
to clean the rust removal stuff off with denatured alcohol (don’t
use rubbing alcohol, it’s about 30% water) or some other solvent
not containing water. The old timers used to give their old
’dull’ files a nitric acid bath. The acid would dissolve part of
the metal restoring a degree of sharpness to the teeth. The files
wouldn’t be as good as new, but they’d be sharper. Don’t think
I’d try it though.

Dave


#6
    It seems like I have no mercy on my my files and drill
bits- but i can not figure out what I am doing wrong. 

G’day DD: this begs a few questions; what sized drills are we
talking about? What machine do you use? Are the drills old or
new? You should be able to feel the sharp edge on a drill.
Compare it with a brand new one. Like everything else, when
someone has shown you how, drill sharpening is not difficult. But
you have to be SHOWN - you can’t learn the technique from a
description - at least I couldn’t. Just holding the conical edge
against a spinning stone and rotating the drill on it’s axis
won’t work. You can buy drill sharpening jigs in tool and
hardware shops, though I’ve never used one so don’t know how
good they are. Preferably get a workshop technician to
demonstrate drill sharpening. Wish I wasn’t so far away!

Next, the drill must rotate clockwise. No, don’t laugh - I
witnessed just that a week ago - I didn’t even see what was wrong
at first! and the person ruined the drill edges in a moment or
two. It must spin clockwise into the work piece.

Thirdly, the rules are; the softer the work the faster the drill
speed. But not too fast. For wood; very fast. For steel, slow.
Then the smaller the drill, the faster the speed. But again not
too fast - or you’ll overheat and soften the cutting edges.
Drilling gold and silver I never spin the drill faster than about
3000rpm, not even with drills smaller than one millimetre.
Whereas even the cheap handpieces can spin at 15 - 20 000 rpm at
full speed. I find drills don’t cut at that speed on metals. Use
a little saliva as lubricant for gold and silver - it works well,
believe me. WD40 or CRC556 for aluminium, soft brass and mild
steel. I find Oil is useless.

Am I pushing down to hard - or not enough?. 

It depends on what you’re drilling. Try and let the drill bit do
the work, but that said, use enough pressure to engage the work
properly. Lift the drill frequently to clear the swarf from the
hole.

Also, my best files are not at their best.  I have a file
brush but it does not seem to clean my files well (which
direction are you suppose to use the file brush anyway?)  

Files do wear out after a bit, and they also clog easily on soft
materials. If you use a wire brush or file card, brush in the
direction of the grooves in the file. To avoid that clogging -
especially on aluminium and fine silver to a lesser extent - give
the file a quick squirt of WD40 or CRC556 before starting; I’ve
not found anything to beat this yet. The older engineers used to
chalk their files, but these modern lubricants are far better;
they stop the swarf jamming into the grooves.

Also, I always file properly (away from me instead of towards
me-learned proper filing techniques at Revere) 

Never file back and forth; lift the file at the end of each
forward stroke for the return.

Also, my best coolest file from Germany has a bit of rust
on it!! 

Again, use the trusty WD40 or CRC556 after use to stop them going
rusty.

What is the best way to clean up the rust and bring my >
file some what back to peak condition?

Soak for a short while in commercial rust remover from the
hardware or paint store; it contains phosphoric acid. Can be
re-used. Or Coca Cola which also contains phosphoric acid (!!!)
Wash and dry well, then the WD40- etc treatment.

I’ll bet there’ll be a dozen more pieces of advice! But cheers
now, –

        /\      John Burgess
       / /
      / /      Johnb@ts.co.nz    
     / /__|\
    (_______) Mapua NZ is a pleasant spot even in midwinter 

(-4C last night! 12C yesterday, cloudless sunshine)


#7

On old worn files… When you go to change out you old pickle,
put it in a old plastic long tub, put the files in it over night
and in the morning you should have files that cut like new.

Steve


#8

Dear John Burgess:

Thanks so much for your input. I just wanted to anwser some of
your questions - I seem to go through my 1mm drill bits and pearl
drill bits like popcorn. Also, I have two flex shafts- one for my
stone settting ( a L series foredom) and my trusty, “I can’t
believe it is still running after all these years” , S series
Foredom.

I use bur life in liquid and solid form and that does not seem
to do the trick on my files. I am going to try the WD like you
suggested.

Have a great weekend

DeDe


#9

Hello Jesse!

Yes, I have heard of this file trick. I learned it from some
Russians twenty some years ago. Never tried it. My worn metal
file becomes my brand new wax file and so on.

They told me they would wet several worn files and stack them in
the sink. After a few days they would have a light rust. They
said the rust in essence renewed the teeth. The nitric dip just
removed this light rust. Always new it would work! I don’t
recall the ratio, but would be conservative. Try 10 to one for
30 secs. to one minute. No need for speed, we’re not etching,
just cleaning.

			Tim