Sorry to say it is usually headstock bearings. It might be a loose pulley
knocking on the key. But even if it is, by the time you get the thing apart
to fix a key properly you might as well replace bearings while you're at it.
Good luck,
--
********
Bill Pounds
http://www.bill.pounds.net/woodshop
"william kossack" <[email protected]> wrote in message
news:K2OTb.213579$xy6.1102525@attbi_s02...
> I have a grizzly g8691 lathe.
> It seems to work OK but at higher speeds it produces a knocking noise.
> I'm going to try and take the cover off this weekend if I get the time
> but I'm wondering what the noise could be?
>
"william kossack" <[email protected]> wrote in message
news:K2OTb.213579$xy6.1102525@attbi_s02...
> I have a grizzly g8691 lathe.
> It seems to work OK but at higher speeds it produces a knocking noise.
> I'm going to try and take the cover off this weekend if I get the time
> but I'm wondering what the noise could be?
>
Maybe you should switch to a higher octane fuel.