pierce and drift

[dickb]

I have made a few hot set tools and hammers and have had trouble getting the oval hole to line up with head of the work. What I have been doing is first punch a round hole about the size of the small dimension of the oval and then drifting with an oval shaped drift.

Even though I try to be careful, sometines the long axis of the drift isn't in line with the long axis of the work.

I've come up withthe following idea. Next time I'll use a punch a little bigger than the small dimension of the drift and get a nice round hole plus a bulge on either side of the punched hold. Then I'll lay the work on it's side and flatten the bulge a little. Hopefully this will help me line up the drift better.



On the other hand how about forgetting the oval drift and hust punch an oversize hole and lay the work on the side and flatten the buldg and (hopefully) squash the oversize round hole into an oval.

I'd like to hear any comment on this before I fire up and hammer a way.

Thanks :confused:

[D.Bernard]

Punch a slightly smaller oval hole first. Hit blank, rotate 180d hit again, rotate again etc., etc. Doing this will help set the hole straight on the blank. After you have punched through, drift with the size drift you want the finished hole to be - but don't drive completely through. stop a bit shy of the finished size, re-heat the blank, inser the drift, lay blank side on anvil and strike on both sides to flatten out the bulge from initial drifting, then completely drive the drift through and finish up. I learned this from Nathan Robertson at a workshop we had here last year. Walked away with a nifty 2 1/2 lb straight pein hamer.

[ironstein]

you could also try heating one side hotter than the other to help the drift center up where you want it.

[jimbob]

sounds like you just need to take a little more time lining up the hole when starting to punch the slot...making sure it is correct to start with, if its off you can correct it . also if you look at a hammer eye it has and hour glass profile so when you put the wedges in the wood will move to the swell to keep the head from flying off.
as for the oversize hole its easier to use a narrow slot punch than a large round punch . you could always drill a large hole . I've also heard of a couple of small holes drilled at each end of the slot to help keep the slot lined up

[Iron Falcon 72]

As I recall when one of the Gunter young'uns was showing us at the Saltfork conference this year how he made his repousse hammers he punched a couple of small dimples along the centerline even with each end of the desired location. He also did the "hammer, spin it, hammer" technique described above.

[Mark Aspery]

I would be inclined to move away from the punched round hole and go more towards a slot (or slit) punched hole and then open that out to a oval (or hammer eye) shape.
That way the long axis is taken care of.
The slot punch is easier to orient along the axis of your work.

[solvarr]

At the Brian Brazeal hammer making class last weekend we used a punch that had an oblique slitting chisel profile in the front.

One light tap and you can see if you are lined up by the imprint in the work.
I found this style of punch much easier to align and work with than flat bottomed punches.
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[Frank Turley]

I use an undersized, hafted "slot punch" which is pretty much the elongated shape of the finished eye. I don't continuously rotate to get rid of the burr. I attempt to have one forepunch side and one back punch side. I drift from both sides. While the drift is in, I turn the piece on it's side and use a flatter to get rid of the side swelling. In Spain and parts of France, the side swelling (bulge) is often left on the hammer and is considered part of its aesthetic.

Many hand forged hammer eyes and top tool eyes in the U.S. have straight sides and half round ends. I think the reason for this is that it is easier to forge the punch and drift cross-section in this way as opposed to forging and shaping an oval cross-section. There is nothing wrong with the oval; it is just more time consuming for a hand forger to get it right. Lots of manufactured hammers have oval eyes.

As a rule of thumb, the length of an eye can be twice its width.
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Edited November 19, 2009 by Frank Turley