3" boring head in mini mills?

[Road_Clam]

Need some input from the mini mill pros. I have a mint , almost brand new Flynn model 63B 3" boring head. Currently it has a 1.25" shank. Thinking about buying an R8 shank and using it in my LMS 4190 mini mill? If i stick to 1/2 " tooling will i be able to use this head and not get a lot of vibration. (My gut feeling is a 3" head will be too heavy) . Thanks in advance !

 

[mikey]

A 3" head on a 190# mill is a really big boring head! You might be better off with a 2" head, or even a 1-1/2" head. You can use that 3" head if you keep the bores small and can run it slow enough but it makes more sense to put that Flynn in a drawer until you get a larger mill or sell/trade it.

 

[ferlum]

I use a 3" boring head in my mini mill. My column has been stiffened. For small holes it works fine. The farther you open it up, and the faster you go, the worse it wobbles. And it can get pretty bad. Counter-balancing with a 1/2" dowel pin or similar in the unused holes would probably help a lot. It's pretty easy to tell when you're pushing it too far. Start slow and increase speed slowly and you'll be fine. Don't expect to make holes over 1.5" or so.