[TheForge] Drift?

[Albin Drzewianowski]

A drift is used to make a hole larger and/or to achieve the final shape of 
the hole.

For example when making bottle cap openers, I punch a small hole than use a 
tapered round drift to open the hole up to its final size, say about 1".  So 
the tip of the drift is small enough to fit through the punched hole and the 
thickest part of the drift is 1".

Another example is a square drift.  When I need a square hole to accommodate 
a carriage bolt, I drill a hole the size of the small square section just 
under the head of the carriage bolt. Than I use a drift that starts as round 
at the tip, that fits into the drilled hole and transitions to square at its 
thickest part.

For hammer heads, assuming you have first slit the head with a slitting 
chisel, they you would use a drift  that is chisel shaped at the tip and 
transitions to the oval shape you want for the hammer eye.  Making hammer 
head eyes, you might use a pair of drifts, one to open up the slit and then 
a second to achieve the final shape.

For a hammer head you would not drive the final oval shaped drift  all the 
way through. You would drive it in from both sides, so that you achieve the 
desired "hourglass" shape to the hammer eye.

Final comment on the shape of the drift.  A blacksmiths drift usually has 2 
tapers.  There is the long gradual taper  on the end which goes into the 
hole.  But there is also a short taper at the hammer end of the drift.  The 
length of that taper should be just a little bit longer than the thickness 
of the material being drifted.  This allows the drift to easily pass through 
the material once the desired diameter/shape has been achieved.

You can make drifts out of mild steel, but if it is going to be a drift that 
you use a lot, it is worth going to the extra effort of making the drift 
from a harder steel.  I usually use coil spring and then use as forged.  No 
real use in heat treating, as the drift is in contact with the hot steel so 
long it would loose any temper you had initially achieved.

Hope this answers your questions.

D-ski
Westminster, MD
"The lyf so short, the craft so long to lerne"

----- Original Message ----- 
From: "IowaHarry" <iowaharry at fastmail.net>
To: "The Forge" <theforge at mailman.qth.net>
Sent: Thursday, April 10, 2008 8:45 PM
Subject: [TheForge] Drift?


> Hi All,
>
> Being new to blacksmithing I am unfamiliar with the concept of drifting. 
> At work I am familiar with the iron workers drift pin. A fairly hefty lump 
> of steel tapering from approximately 1/4 to 3/8ths of an inch at the tip 
> to the fat end near 2 inches being 14 to 16 inches long. I have some 
> fairly large scrap stock I thought I might make into hammers and handled 
> punches. Is this the type of drift I need to do this or is a hammer drift 
> a special tool?
>
>
>
> thanks, Harry
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