¿ªÔÆÌåÓý?Copper based alloys like brass and bronze require different tool bit geometry than tooling for other metals and plastics. In short, most materials - at least on these small lathes - will like some top/back rake so the sharp edge can slice into the material better, whereas tooling for bronze or brass should have zero back rake, as in flat topped. Brass doesn't slice or curly-Q away in a string like other metals or plastics, it kind of crumbles into a thick brass dust for lack of a better term. Once you see/hear/feel it machining right you will know what I am trying to describe.?I bet if you turn metal or plastic your chatter goes away. But you need a flat topped tool bit, i.e. zero back rake, special just for brass. Its just a whole different animal than steel, aluminum, plastic, etc. Those crappy lathe tools with the soldered on carbide tips generally suck on these little machines because they have no top rake and neither can they hold a sharp edge like HSS can. (Some of them even have a negative rake which only large machines with lots of power and rigidity can get away with using. They are useless on a mini-lathe though.) But with brass those cheap flat topped/zero back rake carbide tipped tools suddenly try to work pretty well. If you have some try one, it will at least work better than any tool designed for steel/aluminum/plastic. Brass/bronze is finicky, if there is any back rake the tool will repeatedly and rapidly dig in and break loose - chatter - and that sounds like what you are running into. Wrong tooling for the material at hand. ?I had a link to a web page that showed the basic turning tool geometries and also showed the flat topped tooling shapes ideal for brass, and so of course I cannot find it now. Hmmm. Hopefully somebody will recall what I am talking about and post a link. (?) ?Cheers, ?John Z., York, Pa. USA. On 2/11/2013 9:11 PM, William McBride wrote: ? |
