On Sun, 03 Dec 2017 16:36:52 -0800, wrote:

I have a small lathe that I am slowly making into a much more
rigid and accurate machine. Part of the process has been to add more
bracing to the bed. The bed is cast iron and the added bracing pieces
are also cast iron. Dura Bar. The bracing had to be bolted in place. I
couldn't think of any better way to do it.
I started on this project years ago but I posted something in
another newsgroup that made me think of this. I was worried that the
bolted in bracing might be a problem because of vibration, being
bolted in and all.
But as it turns out the bolted in parts should actually dampen
vibrations. Even though the bolted in pieces fit as perfectly as I can
make them (they are lapped to fit) I thought the interface might lead
to problems. Turns out this interface should dampen vibrations, even
though everything fits well and the bolts are quite tight.
I guess my seat-of-the-pants engineering worked better this time
than actually thinking about it.

Eric

Interesting. In industry, there is an old method of vibration damping
that involves letting parts slip against each other. I don't know if
that's going on in your case, but it's something to consider.

Something else to keep in mind is a long story, but the short version
is that Reed-Prentice once had a young engineer who decided that he
could reduce headstock vibration by doubling the thickess of the head
casting(s). It turned out that it made vibration worse.

--
Ed Huntress