I've been trying to make a winding key for a clock I have--the winding
shaft is about .140 inch square, so I need a hole about that size. The way
I have tried to do it is: in a 5/16 steel round rod, I predrilled one end
in the lathe, using a drill about .140 diameter. I prepared a square key
with a bit of taper. Then heated about 1 inch of the predrilled shaft to
red, maybe orange (it cools quick) and hammered the key into the hole. It
took a couple of heats. Result was a square hole, but the shaft bent a
bit, so when I tried to turn the shaft afterward to clean it up (I want a
smaller diameter), the hole was off center, and I could not clean it up
Tried again, this time holding the key in a vise, and hammering the shaft.
How is this done? Commercial keys are nice and slender, and the hole is
nice and neat.
I am a locksmith, and I recommend just buying the right key rather than
making yourself crazy. These keys are commonly available at either lock
shops or clock shops and they should cost you less than a couple of cups of
Think how bad you will feel if you bugger the clock's winding stem.
To answer your question the commercially available keys are either cast or
To use your method of forging a key, use a short length of rod, drill and
pound, then insert a square key stock you have center drilled on both ends
and turn the assembly between centers. This way your OD will parallel your
Better yet, get one of those nifty clocks that set themselves to the signal
from the atomic clock and always have the correct time.
I made a key about that size by going to a hobby shop (Home Depot might have
them) and buying a square brass tube which was the right size then soldering
that tube into a larger key I had laying around... works great!
I made one, by drilling to the size of the flats and then using a square
broach i made from drill rod. I just hand ground to size and put a decent
relief angle on it, and tapped it into the hole. Worked in one go.
If you want to do a hot broach, you want to hold the whole shaft as you
thrust the square shaft into the key.
Cold broaching works better as you don't have the shaft of the key in the
low strength condition.
In addition, using a series of broaches will make things easier. Start with
th round hole and gradually broach the hole square. This will reduce the
stress of the work on the shaft area.
Lastly, you can do a hot forge of the whole thing, pressing the metal around
the shaft in a mold.
Losing weight is easy! If you ever want to lose weight, eat and drink less.
Works evevery time it is tried!
Here is a lathe operation method to create a square hole in a shaft. The
shaft could then be fitted in a piece of tubing for a better appearance.
Brazing should be sufficient to secure the floating piece for your
A bar holder was used to hold the stock for milling on the lathe.
I used to make custom clock keys. You need to make or buy a square broach of
the correct size. Drill a hole in some brass stock that is smaller than the
distance over the corners of the square, but bigger than the flats. Now
broach the hole, but not all at once. Withdraw the broach frequently to
clear the swarf. Note that the winding squares on a clock are usually
tapered, but the hole in the key is usually not. I used to make my own
broaches from square files.