Posted by BillS on June 07, 2005 at 13:19:18:
In Reply to: Re: What could be causing our hob machine vibrations? posted by Ron on June 06, 2005 at 21:18:23:
I don't think the frequency of resonance is changed by number of hob gashes or speed of rotation, since the hob only acts to excite the natural resonance of the system. Like when you strike the blank and you hear it ring. That ringing is the resonance of the blank.
Using the paper isolation you are damping that vibration, meaning that it dies out much quicker, and it is harder for the hob impacts to sustain the oscillation. Slowing the hob down allows the induced vibration to die out between cutting impacts.
Are you cutting a ring gear? Bolting a web, or a crossbar, or an enclosing "lid" to the gear would most likely help. CI would be better than steel. This would enclose the space, so that it doesn't behave like a bell.