Rail Gun Vibrations

[Bob Kingsbury]

Harold Vaughn used counter weights to dampen out
moments in the barrel mounting and upper I -beam. Finding
that the I-beam on my rail rings like a gong, I'm looking for a way
to deaden this. I'd prefer not adding more weight. Any suggestions
on how that could be changed

 

[Boyd Allen]

Bob,
I believe that Harold used the weights to raise the center of mass of the top of his rail gun to where it was more in line with the center of thrust, and while this reduced the amplitude of barrel vibration it was not done to damp vibration so much as to reduce it at the source. As for damping, Gary Ocock uses a Delrin sleeve between his barrels shank and the block that clamps it. I have heard that putting a piece of target paper under the block can help. Also I believe that it is common knowledge that Eric Stanton wraps his rail barrels so that vibration is damped between shots when running a group. Although I don't have a rail, i can tell you that putting a Sims Deresonator (gummy rubber donut) on a bag gun barrel will turn the typical ringing sound that happens when it is tapped. to a "thunk". BTW if you want to see what a hot shooting rail looks like, go back through my posts and you will find a picture of Gary's.

 

[mks]

Harold Vaughn used counter weights to dampen out
moments in the barrel mounting and upper I -beam. Finding
that the I-beam on my rail rings like a gong, I'm looking for a way
to deaden this. I'd prefer not adding more weight. Any suggestions
on how that could be changed

I have never even seen a rail in person, but how about sticking Dynamat to the surfaces you want to stop ringing? Dynamat is a self-adhesive sheet used to dampen acoustic vibration for high end stereo systems in cars. Sorbothane is available in sheets with different formulations with a range of damping properties, also.

How is the action attached to the I-beam? If it is just bolted to the web, then reinforcing this joint so that the action is more solidly connected to the flanges should reduce the amount of vibration transmitted to the rest of the web. The web is the weakest part of the typical I-beam.

Cheers,
Keith