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Drilling holes through sterling silver rod


#1

hello,

I’m trying to drill a 1.2mm hole into sterling silver rod, 3.5mm
diam. I ordered the wire in rod form and is SS hard.

I have two (or is it three) problems: one is that the drill bits keep
breaking (and I am using a lubricator), and the other is that when I
do achieve a hole all the way through, its not centre front to centre
back but off line. and quite often the opening on the side I’m drill
through is messy and misshapen. I have managed to make this work but
right now I’m failing miserably :-(. I’m using a bench drill.

Any advice would be brilliant.

Judy
France


#2

As far as centering the hole, side-to-side, and keeping it clean and
not ragged, have a carpenter/wood worker friend cut a “V” block,
preferably from a hard maple. The “V” keeps you work aligned. Loosely
clamp a straight edge to the drill press table, so that the tube to
be drilled is “centered.” Tighten the clamps on the straight edge to
hold its position. With the “V” block you would be setting up a jig
to allow repeatable performance, and, it’ll be easier and safer to
hold. You’ll smile. (IMHO)… don’t wear gloves.


#3

Hi Judy,

I am thinking that you want to drill the 1.2mm hole straight through
the 3.5mm sterling wire to make a tube. This will give you a tube
with a wall thickness of a little over 1mm. If this is correct then
the way to go about it would be by using a lathe. This way you can
more accurately hold the drill and 3.5mm wire for drilling. The
other option is to have someone make you tube that has a 1mm + wall
thickness tube to start with. I would not try drilling the wire
without the accuracy of a lathe. My eye, and bench drill aren’t that
accurate.

Blessings,
David B. Anderson


#4

Bonjour, Judy!

I recommend you use a carbide drill or endmill those will not
break… you should still use a lubricant to prevent breakage, but
usually drill bits are made out of high speed steel and you will need
something stronger.

Your other problem is alignment… I recommend you use a drill press
and mount a machinists’ vise on the drill press table. You can get a
Ryobi 10 inch drill press for under $100 USD, but the machinists’
vise could be somewhat more expensive depending on where you look.

Good luck
Andrew Jonathan Fine


#5

Cross drilling round bar-stock accurately is always difficult. You
need a drill press, a drill vice, a small centre drill (smaller than
the required hole), and a strip of metal about 8-10" long - a steel
rule will do fine.

Put the centre drill in the chuck, the rod in the vice, and place
the metal strip on the rod so that it, more or less, balances.
Carefully lower the chuck so as to lightly pinch the strip between
the centre drill and the rod. Unless the tip of the drill is exactly
over the centre of the rod the metal strip will tilt. Carefully move
the vice until the strip is horizontal, and when it is, secure the
vice so it cannot move. If the strip is less than one degree off from
being horizontal (this is quite easy to see by reference to something
truly horizontal), the drill will be off centre by less than 1/1000th
of the diameter of the rod.

At this point, remove the strip and start the hole with the centre
drill, then replace the centre drill with the required drill and
drill the hole.

Regards, Gary Wooding


#6

Judy,

  1. First you need to “square” the top of the tubing to make sure
    it’s level, including finishing/polishing, etc.

  2. Measure, measure and measure again to mark the top rim of the
    tubing, dividing the circumference where you want to drill,
    indicating the correct placement of the holes, ie. at 3 o’clock & 9
    o’clock.

  3. Use a small steel square to extend a line down the tubing from
    each mark on the rim. Measure your required distance down each line,
    ie. 4mm; place a very small, accurate mark where you want to drill.

  4. Using a small ball bur, make a very small divet on each mark (be
    sure to brace the tubing so it doesn’t move, and the flexshaft
    holding the bur to keep stray movement at absolute minimum) to be
    drilled.

  5. Begin drilling in each divet using a very small lubricated drill
    bit (much smaller than you need), one hole at a time.

  6. Graduate to the finished hole size.

Practice on copper tubing first.

You can use a fine permanent marker to mark your measurements or
score the marks/lines w/ a metal scribe, used lightly to not mar the
metal too much.

Tubing is trickier to drill because of the curved surface of the
metal. When drilling sheet, use a metal punch on a steel bench block
and lightly hammer the divet into the surface to mark where you want
to drill. If you punch on wood, the sheet will warp.

There ya go…

Kay Taylor


#7

Judy,

You are attempting a most difficult drilling task! The bench drill
will not make it easier. If you don’t have a flex shaft or a micro
motor I would recommend a small hand drill. Hold the rod in a pin
vice or hand clamp. If using a hand drill then hold the rod in a
bench vice with wood jaws or clamp the pin vice in the bench vice.

The first step is to get the hole centered on the end of the rod. I
would use a small ball burr to get a depression because a centre
punch is tricky on such a small piece.

Start drilling and carefully observe the hole grow to the full
diameter of the drill bit. Tilt the drill slightly to correct any
wandering…if the hole appears to too close to the left edge then
tilt the drill to the left and the hole will creep to the right.
There is no ‘hole’ yet, just the drill bit getting to the full
diameter. You will see if it is centered easily as the hole grows
bigger, continually adjust the tilt as needed.

When the hole is centered start drilling down. Keep the drill bit
lined up with the silver rod as best you can, drill down 0.5mm, turn
the rod 90 degrees and repeat, always drilling all the way down from
the top each time. If using a hand drill with the rod in a vice then
you need to walk around the vice.

When you are 1mm deep you can see if the hole is following the
centre of the rod. It may help to remove the bit from the drill,
place it in the hole, and rotate rod and drill bit together so you
can see that they are lined up from all angles, but with practise
this can be done on the fly by feel and observation.

If the hole is leaning to one side, then re-drill from the top at
the correct angle, that is you must get the bottom of the hole back
to the centre of the rod before drilling any deeper.

Keep going like this 0.5mm at a time until you are half way through
the rod.

Repeat all of the above from the other end.

When the two holes meet you will be able to see through the hole.
Small corrections can be made by gently drilling from the top at
each end to bring the two holes into line.

I could have said get a tube in the first place, but then you would
not have asked the question! With practise freehand drilling can be
extremely accurate.

Regards, Alastair.


#8

Bag the “tubing” remarks; but the directions hold true for rod, but
you can shorcut by drilling through the rod if the rod is diveted on
one side and secure in a vise on the drill press.

Sorry about that,
Kay Taylor


#9

Judy,

In addition to the other responses you’ve received, consider using a
bushing with your drill press. Make a holding fixture to hold the
bushing on top of the material that you are drilling through. The ID
of the bushing should be just slightly larger than the drill bit, and
this ensures that the bit stays in position as it bites into the
material. This will significantly help the “walking” that you’re
experiencing.

Also, with the material thickness you’re working with compared to the
hole size, be careful about building up heat on your drill bit tip.
With a bushing you’re able to “peck” at the hole, thus avoiding heat
buildup.

Even with a bushing, you may not get the accuracy that you want with
a drill bit. Consider using a smaller bit and finish the hole with a
reamer, with a bushing guiding each one. Reaming the hole instead of
drilling it will give you more accuracy. You could even consider an
end mill, but I doubt that you can get one as small as you are
looking for. Good luck… this task isn’t for the faint of heart.

Jamie


#10
I recommend you use a carbide drill or endmill those will not
break... 

Carbide is many times more brittle than steel. If the work is not
held totally immobile it is way too easy to break a carbide drill
bit.


#11

Andrew,

I recommend you use a carbide drill or endmill those will not
break... 

Just where do you find these unbreakable carbide drills and mills ???

I use mainly really small mills (15 tapered with.15mm tip) and the
carbide ones break if I breath wrong. HSS is tougher but too
flexible, high cobalt HSS a nice middle ground.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#12
Unless the tip of the drill is exactly over the centre of the rod
the metal strip will tilt. 

Gary lays out the old-school, tried and true way of drilling a rod
on-center. Drilling like that in an offhand way (without machine
tools - ie milling machine) is one of your more difficult things to
do. A couple of strategies: buy a center finder for all sorts of
reasons. Then you can mark the center of the rod and at least
transfer your marks for bench drilling - don’t guess. And step
drilling is key, too.

If you have a machine tool - miller or drill press, then you can use
this:

http://littlemachineshop.com/products/product_view.php?ProductID=2747

or any versions of these:

http://littlemachineshop.com/products/product_view.php?ProductID=1240

or maybe these:

http://littlemachineshop.com/products/product_view.php?ProductID 60

To get you there… And, as Gary says, use a center drill first -
they are stout and rigid and will punch a center spot on-center
first, and then you can change to your drill and have it on the same
center…


#13
I'm trying to drill a 1.2mm hole into sterling silver rod, 3.5mm
diam. I ordered the wire in rod form and is SS hard. 

A trick that I picked up from a machine shop is to make a block jig.

Get a small block of wood. Drill a hole through that your piece of
stock just fits. Mark your center line over to one of the sides of
the block parallel to the stock hole. Drill a hole through at 90
degrees to the stock hold the size of your bit. This gives you a
guide and keeps the stock from rolling on you.

When they have to do such a trick repeatedly, they make the block
out of aluminum and add a set screw to lock the stock in place.

A drill press still helps, even with the jig, especially if you are
doing repeats.

Ron Charlotte – Gainesville, FL


#14

Alastair

This is an excellent and precise description for a truly difficult
task. The only addition I would add is that of a tiny bubble level. I
mount one on my flex shaft handle when I need a steady hand to hold
my flex shaft and make sure that gravity is doing its job and I as
the taskmaster, am guiding the drill straight. This allows me to keep
my eye on the level, knowing that the drill bit understands its job.
A drill press would be helpful but some jobs I can’t get the piece
under the drill press because of the size constraint.

Karen Christians
Cleverwerx


#15

jeffD,

Just where do you find these unbreakable carbide drills and mills

Kodiak Cutting Tools

I use mainly really small mills (15 tapered with.15mm tip) and the
carbide ones break if I breath wrong. HSS is tougher but too
flexible, high cobalt HSS a nice middle ground. 

Okay, that’s a lot smaller than I am using. I am using.05 inch
carbide on 0.15 inch thick tool steel at a feed rate of.015 inches
per minute. Not only doesn’t the bit break, it doesn’t even get warm.
Of course, I use olive oil for cutting lubricant.

Best,
Andrew Jonathan Fine


#16

thank you so much for all of your replies. All this is
extremely valuable and I am already improving my drilling into the
rod. I have tried using a carbide drill - one successfully and two
which broke :-(. But I have filed the surface, worked a dovet and
managed to drill a hole which is much ‘cleaner’ and I was using a
small vice to hold the work in place. So, a big step forward and I
am so pleased.

I apologise for not making it clearer that I am endeavouring to
cross drill and not produce a tube, though that is also
very useful.

many thanks again.

Judy
France