Trying to break Hooke’s Law

 

1. I am not a mechanical engineer or a physics major, but it seems to me that the spacer will do 2 things: first, it will allow the hammer to transfer its energy to the “nail” sooner than without it; and second; it will allow the “nail” to be propelled further than without it, by the time the hammer hits the stop block. This assumes that the spacer itself doesn’t absorb any energy, and that there is no reduction in the total energy imparted to the “nail” because of the earlier contact and longer travel.

   Posted by Red Five       04/29/2009  at  07:40 PM  



2. Where I would go with Newtons Kinetics. The spacer will take a portion of energy to start moving, thereby reducing the direct impact of the hammer. Without the spacer, the hammer delivers the strike directly to the nail at an unimpeded velocity.

   Posted by cmblake6       04/29/2009  at  09:13 PM  



3. cm - my drawing isn’t perfect. Assume the spacer is sitting on the nailhead. So we don’t have a “cue ball hits the 9 ball which then hits the 8 ball” situation.

   The way I see it, using the spacer is that same as if the nail was taller.

   Posted by Drew458       04/29/2009  at  10:01 PM  



4. Drew, cmblake is on the right track. The hammer effectively hits the nail sooner, but must now accelerate both the nail and the spacer block - which I assume is not massless. If both the nail and spacer masses are negligible compared to the hammer head, then the nail may be imparted more energy.

   This problem could go either way, depending on exact numbers, dimensions, spring constants, and masses, etc.

   Posted by ooGcM taobmaetS       04/29/2009  at  10:42 PM  



5. OK, here’s my humble opinion.

   Technically, you’ll transfer more energy fro the spring to the hammer (same push + more distance = more energy).  Unless the additional distance traveled by the hammer/nail is really significant, your actual effect will be negligible.  Of course when the distance becomes significant, the push of the spring will begin to diminish and the problem starts getting really weird. 

   The velocity of the firing pin when it hits the primer is more important than the slight extra energy imparted by the extra distance.  Once the firing pin has the same velocity as the hammer, extra distance traveled by the hammer doesn’t have any practical effect, even if the hammer is technically transferring more energy.  Transferring more energy to the final stop won’t drive the firing pin any harder.

   If the hammer/transfer bar/firing pin assembly are all in contact when the primer is impacted, again, the velocity is the most important factor.  energy = velocity squared x mass divided by 2G If the push of the spring has started to decrease, even slightly, you won’t get more velocity in the assembly.

   The spacer, having mass, will absorb some energy in the process of transferring the energy to the nail, but that energy will in turn be transmitted to the nail when the hammer quits pushing and the spacer continues by inertia until the nail stops it.  The mass of the spacer will slow down the speed of the transfer very slightly, but that’s about it.  Total effect = zero.

   In practical terms, fugedaboudit.  Nice theoretical exercise, nil functional difference.  If you want to have a difference, find a titanium hammer, firing pin and transfer bar.  The energy imparted by the spring remains the same, but with roughly 40% less mass, the lock time will be significantly quicker.  A stiffer spring would help too, but your double action pull would go up.

   Posted by Dr. Jeff       04/30/2009  at  12:44 AM  



6. yeah but if the gahaitus isn’t connected to the shin bone what the heck have you got left?
   Unless the twizzle clamp isn’t working which means you have to restart your puter in safe mode.
   There ya go.

   Now I’m heading for the kitchen where fortunately we have bottled water, making stong damn strong tea and grab fudge cake and hope I don’t get sick.

   Its been a trying day.  Construction next door, cut our water supply. Better then yesterday when they ran over the gas main.  Talk about sick. Gak! They make sit-coms on this stuff.

   Posted by peiper       04/30/2009  at  09:17 AM  



7. You may want to take into consideration the thickness of the “board” also, just for safties sake. You don’t want to drive your nail through it.

   Posted by harleycowboy58       04/30/2009  at  02:02 PM  



8. Simply, yes. 

   As the spring is constantly loaded against the lever, it is a simple matter of more time for the hammer to accelerate before contacting the nail.

   As to the math, I’m no mathematician.  Just seems logical to me.

   BoynSea

   Posted by BoynSea       04/30/2009  at  03:46 PM  



9. Damn!  I meant yes, there is more force WITHOUT the little green spacer.

   I need another beer.

   Maybe not.

   BoynSea

   Posted by BoynSea       04/30/2009  at  04:05 PM  



10. I’m a mechanical engineering student, and this is a lot like some of the problems we’ve been working on recently.  Here’s my take on it.

    The hammer will hit the the nail with more force if the spacer is not there, since the spring will be impart a greater force into the hammer.  Spring constant are measured in lb/ft (force/distance), so the greater the number of feet (or whatever unit of distance we’re using) the spring can decompress, the more force transferred from the spring to the hammer.

    If you want an analogy, imagine dropping a rock from 10 ft, and a rock from 10 miles.  The rock from 10 feet is gonna bean you in the head.  The rock from 10 miles is going to turn you into a crater.  Since gravity has a greater distance over which to accelerate the rock, it moves faster and hits harder.  Same concept with the spring and the hammer… greater distance = more force.

    What the spacer will probably do (could vary depending on the thickness of the spacer and such) is increase the work done on the nail, work being force imparted over a certain distance.  Since the nail with the spacer will move farther, the force from the hammer will be exerted on it for a longer distance, hence more work despite the force being slightly less.  An increase in work wouldn’t really help out a firing pin at all, though.

    In a nutshell, spacer = less force, delivered sooner (although the difference in time would probably be very very small).  If you want more force, go for a stiffer spring.

    Posted by IAmSpartacus       04/30/2009  at  04:31 PM  



11. Looks like a firing pin arrangement for a Colt Trooper/Python. The only purpose that the green spacer (transfer bar) has is to prevent to pin from being struck if the trigger is not pulled back sufficiently. Of course it also serves to render the weapon useless if the transfer mechanism malfunctions. And it always happens at the worst possible time.

    I agree with cwblake and boynsea - the spacer will slightly reduce the velocity of the hammer by reducing the amount of time that the hammer is accelerating from the impetus imparted by the spring. Of course that assumes that the hammer is accelerating through the entire course of the spring’s decompression. I would expect that the rate of acceleration would be decreasing constantly as the spring approaches rest.

    Posted by sig94       04/30/2009  at  06:12 PM  

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