[TheForge] Wanted suggestions on hammer tooling.

[Andy Vida]

Loktr@aol.com wrote:
> 
> Ive been
> thinking of making a bottom die with about a 1.50 hole in the center.  Drilling
> from the side of the die and putting in a 1/2" acme lock set up to hold whatever
> tooling.  Turning a relief on the 1.5 die "post" and drilling a dimple to
> locate it.  I am curious as to what others think.  The shoulders of the die above
> the post would normally be supported by the flat part of the bottom die.  I am
> worried about whether a 1/2" acme screw hole will get flattened to the point
> of the screw not working.  I would drill and tap on the bottom side of the die
> block.

	Depends on how thick the block is and how it is heat treated.
	You will not be using that die without tooling in it, yes?  
	The hole should see significant support from the screw itself.
	As long as you are not exceeding the elastic limit of the steel
	you should not have a problem with crushing the hole.  I would
	perhaps suggest, though, that the die be heat treated to
	something better than the annealed state.  The force of the blow 
	will be concentrated on a relatively small, ring-shaped area 
	defined	by the hole and the shoulder of the tool you have 
	inserted.  A 4140 die at, say, RC-35 to RC-40 will be very tough 
	and have high elasticity.  At that hardness you can do the HT on 
	the solid die, then bore the hole.  I would keep the fit as tight 
	as is practical.  I don't imagine the tool should ever get hot 
	enough to eat up a 0.005" clearance, but I've not done the 
	calculation.  The hammer should sink away the heat.  A tighter 
	clearance should provide for safer operation.  Also, make sure 
	the post is deep enough.  I would recommend at least as deep as 
	it is wide, or a little more to stabilize it against unanticipated 
	lateral loads.  I know you intend on using a set screw, but screws 
	have a bad habit of working loose under violent	vibration and 
	sometimes smiths get really focused on what it is they are doing.  
	If things get loose and the post is shallow and something gets 
	misaligned under the top die...
> 
> I have read that LG suggests running these hammers at 275 rpm,  Clifton Ralph
> suggests going slower.  After watching him work I know I dont need to go
> faster but am wondering how slow is too slow, pros and cons?

	I would say go slow and work your way up.  I don't like fast
	hammering.  I never feel I have the control.  It may be that
	my reflexes aren't so fast, I don't know.  It's the same with
	grinding blades.  I like to go REAL slow on a belt grinder.
	I had my belt grinders geared WAY down.  Took a little longer
	but I got the results I wanted and managed not to relieve myself
	of body parts in the process.  I admire the guys that can rip
	away a 6000 sfm.  I'm not one of them.

	Also, I think that for certain sorts of bottom tooling I
	would not want to be working anywhere near 300 BPM.  If you
	are, for example (and I cannot imagine that you would do
	this, but I can't think of another example at the moment)
	you were running a thin fuller up the center of a bar from
	the bottom ( I told you it wasn't a very good example) you
	would want to be using precise single blows and not a
	machine gun procession.

	Now that I think of it, I am beginning to like the idea of
	an automobile transmission twixt the motor and the clutch.
	Even an old wide ratio three speed would provide for a
	broad variance in hammer speed.  A ten thousand speed
	truck tranny might be a bit over the top.  Then again...
> 
> I am planning on running and endless flat belt and will machine the pulley to
> give the speed i want.

	Or use a transmission to drive the pulley.  A bit more work,
	I grant you, but it would provide for an awful lot of flexibility.