Making the hammer cup deeper

[Whaleman]

On my Hawken build my hammer cup is not deep enough. I have spent a lot of time bending and polishing this hammer and do not want to mess up. Is the correct procedure to use a regular drill to drill down until the point is where you want. Then to grind the bit flat and drill until flat. Having never done this the flat bit would seem to want to chatter around with nothing to center it. Thanks Dan

[chubby]

You do not say how deep the cup is already, that could make a difference on how you may want to proceed with making the cup deeper. i have already used a 4 flute center cutting end mill in the drill press to make it deeper, or you can sometimes use a carbide ball to work the hole! a lot will ride on the hardness of your hammer also! hope this helps  Chubby!

[Keithbatt]

Use an endmill in a mill of you have one or in a drill press otherwise. I've had good luck with small endmill a in a clausing drill press.

[David Rase]

I have taken a twist drill and sharpened it flat vs. the 118 or 135 degree included angle to square up the bottom of a hole.  In order for this to work you must drill the hole with a standard drill to the approximate depth so the flat sharpened drill bit won't wonder.  Find the id o your hammer cup, grab the appropriate sized drill bit, flatten it and deepen your cup.
David
I have also ground ball ends on drill bits and used them when making a patent or nock style of breech.

[Whaleman]

Two pictures showing how I don't think it is deep enough. Dan

[crankshaft]

   Looks deep enuf to me, but I am a novice.  I am wondering just how deep it needs to be?
 Heck, a flat hammer will bust a cap?

[D. Taylor Sapergia]

I think the cup is deep enough too.  If you go deeper,, two things can go sideways for you:  your hammer will reach further forward so that the nipple will come into contact at the back of the cup rather than the centre, and secondly, your tumbler may come to rest on the bridle before the hammer finishes its throw.

But on the RE Davis hammer, copying Ron Long's lock, the cup DOES need deepening.  And sometimes, the angle of the cup needs to be altered so that the hammer strikes the nipple squarely.  The photo above is an example of that.

I made my cutter from a 5/16" drill bit.  Like David, I ground it off flat.  But since the business end of the hammer is tapered, if a parallel sided bit is used, the cup may become very fragile at the bottom of the cup...walls too thin.  So I tapered the end of the drill bit over about 3/16" so the end of the bit is .270".  Then I ground some draft/rake on the edges so that they would still cut, and gave the same treatment to the flat tip, so that the bit would cut on the plunge.  Here's some images of the bit I made.  It has been used to alter at least two hundred hammers without having to sharpen it.












The altered bit is pictured along with an unaltered bit.  The last pic is the job it does.  The last thing to do to the hammer nose is to split it so caps dislodge themselves.  To do this I use a hack saw, a skinny flat file and a triangular file with a safe ground edge.  This hammer cup is .160" deep.

[Whaleman]

Thank you all for the advice. I will leave it alone. Dan

[Bob Roller]

I owned an N.G.Whitmore target rifle in the late 1950's that had a hammer that covered the nipple with a slot to vent the rubbish from the cap. The Grant Rifle in the Smithsonian has the same feature and was another Whitmore.

Taylor's pictures of the modified drill bit are,in the absence of a tapered end mill the ideal tool for altering a shallow hammer cup.I make them a lot shorter for rigidity in a milling machine.

Bob Roller

[SR James]

My Whitmore is exactly the same. The hammer cup completely encloses he nipple cone and has a slot in the front.

[Bob Roller]

My Whitmore is exactly the same. The hammer cup completely encloses he nipple cone and has a slot in the front.

Does your Whitmore rifle have a 12 groove barrel?
Can you post a picture of it?The one I had was a
match rifle with false muzzle and full length scope
and the stock was fine walnut,silver buttplate and guard
double set triggers,back action lock and no forearm.
It was a heavy barrel,40 caliber and about 1-1/8 across
the flats.

Bob Roller

[D. Taylor Sapergia]

Remember when cutting the cup deeper that the deeper you go, the further the hammer rotates.  This rotation will be limited by the contact of the tumbler and the bridle on the inside of the lock..  Also remember that as the hammer rotates further forward, so the mainspring drops further and may come down blow the bottom of the lock plate.  ... things to take into account!