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  #31  
Old 06-29-2020, 04:03 AM
mturnerb mturnerb is offline
 
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I set up DRDT-2 per instructions and cannot tell a difference between dimples done with it versus the C-frame. I tried every technique when I did the training class at Synergy back in 2016, and have used the C-frame with a hammer from time to time (I have both).

Physics alone would suggest that any perceived superiority of one device over another is erroneous. The die will do what it is designed to do if the proper force is applied to properly prepared material - velocity is the only difference in techniques and count me "dubious" as to whether that has anything to do with it.
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  #32  
Old 06-29-2020, 02:39 PM
PilotjohnS PilotjohnS is offline
 
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Quote:
Originally Posted by mturnerb View Post

Physics alone would suggest that any perceived superiority of one device over another is erroneous. The die will do what it is designed to do if the proper force is applied to properly prepared material - velocity is the only difference in techniques and count me "dubious" as to whether that has anything to do with it.
I agree. Also beatings things with a hammer seems an imprecise method; although many Ferrari's were built this way.
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  #33  
Old 06-30-2020, 07:42 AM
jacoby jacoby is offline
 
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Quote:
Originally Posted by mturnerb View Post
Physics alone would suggest that any perceived superiority of one device over another is erroneous. The die will do what it is designed to do if the proper force is applied to properly prepared material - velocity is the only difference in techniques and count me "dubious" as to whether that has anything to do with it.
I did a rough estimation of a #8 screw dimple with a 2lb hammer and a 5 lb hammer. I ignored the mass of the set holder since it's (sort of) 0 due to the spring. I also ignored the flat area of the die since it has almost no effect on the dimple. I used the area of the dimple itself (0.340" diam; 0.050" depth)

Swinging the hammer at 5 m/s (which is a pretty good whack but very doable), you get ~2400 psi out of the 2 lb and ~6000 psi out of the 5 lb. #40 and #30 will be even higher.

Your average pneumatic squeezer is rated for 3000 psi. I don't know what the drdt2 is rated at, maybe half that?


That said, I tested the c-frame vs my pneumatic with a 1-1/2" yoke when dimpling the tank and couldn't tell the difference. And i've used the c-frame, a 3000 psi pneumatic, a 6000 psi pneumatic (gator jaws) to dimple #30 and #40 and they all look exactly the same to me.
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  #34  
Old 06-30-2020, 10:10 AM
mturnerb mturnerb is offline
 
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Originally Posted by jacoby View Post
I did a rough estimation of a #8 screw dimple with a 2lb hammer and a 5 lb hammer. I ignored the mass of the set holder since it's (sort of) 0 due to the spring. I also ignored the flat area of the die since it has almost no effect on the dimple. I used the area of the dimple itself (0.340" diam; 0.050" depth)

Swinging the hammer at 5 m/s (which is a pretty good whack but very doable), you get ~2400 psi out of the 2 lb and ~6000 psi out of the 5 lb. #40 and #30 will be even higher.

Your average pneumatic squeezer is rated for 3000 psi. I don't know what the drdt2 is rated at, maybe half that?


That said, I tested the c-frame vs my pneumatic with a 1-1/2" yoke when dimpling the tank and couldn't tell the difference. And i've used the c-frame, a 3000 psi pneumatic, a 6000 psi pneumatic (gator jaws) to dimple #30 and #40 and they all look exactly the same to me.
I'm no engineer, but my point is this: It takes a certain amount of force to permanently deform the metal from it's pre-dimple shape to the post-dimple shape. Under-dimpling results from inadequate force - we all agree on that. BUT once adequate force has been applied to create a permanent properly formed dimple, in the proper shape the die is designed to create, more force will not improve the quality of the dimple. I would hazard a guess (admittedly a GUESS) that more force than required is more likely to deform the material beyond the "ideal dimple" shape, if the die allows enough compression travel between die halves. If the die limits the travel, then no amount of force (unless enough is applied to deform the die) will change the shape of the dimple.
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