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anvil rebound test
Posted: Thu Aug 21, 2014 6:41 pm
I've seen lots of references to testing "percent rebound" on anvils using a 1" steel ball but naturally didn't have one. (The steel ball; I've got the anvil). I found VXB Bearings; they have "loose bearing balls", lots of sizes, a ten-pack of the 1" were $34 to my door. Nine friends will be getting X-mas presents! The test is described at anvilfire but am finding actually measuring the height of rebound hilarious. Would make good candid camera footage. Anyone know of a non-silly way to get the measurement?
Re: anvil rebound test
Posted: Fri Aug 22, 2014 8:41 am
If I have a ball bearing convenient I use that but I don't actually try to measure it (e.g. "dropped from 10 inches it returned to 7.25"). I just guestimate. The difference between "good" and "bad" is pretty obvious, especially if you get to try good and bad next to each other.
When I lack a ball bearing I use a light hammer. Use as light of grip on the handle as you can and let the hammer head fall with its own weight, pivoting on an imaginary axis through the end of the handle. Your hand is just going along for the ride and keeping things relatively straight. You'll feel the rebound in the hammer. The more rebound the more lively anvil is. Again, good and bad should be obvious.
If I felt the need to quantify levels of good and bad I would probably get a length of clear, hard plastic tube, maybe 20" long and slightly bigger ID that the ball bearing. Take a length of an old tape measure and attach it to the tube with numbers facing in. This should keep the ball from escaping and let you see how much return you get. You'll loose some energy to friction between ball and tube but it should be minimal if the tube it perpendicular to the face. Due enough runs of course to give you an good "N" and a fairly reliable answer.
On a related note, when testing anvil rebounds make sure you test many different spots on the face. I have seen a few anvils where the weld between the face plate and anvil body have started to fail in one section. One part tests well, 2" over not good. You can also hear the difference when you find one of these. Caveat Emptor