- Joined
- Nov 16, 2012
- Messages
- 5,596
If you can get it to a thou, I'd consider it good enough. After that, you're just chasing zeros on a machine that won't be able to hold that adjustment/accuracy anyway. Not saying you can't hold good tolerances on parts, because you can. And that's speaking from experience. But on these little mills things start flexing and moving quite a bit when under load.
Example: when you are tramming in Z, just reach up and push or pull gently on the head/column. Your indicator will move a few thou. The columns on these things (I have a LMS fixed column mill) are just not that robust. If you do like some people and you use a 1/2" or larger endmill, things will definitely flex more than a thou.
Just my $0.02,
Bill
I'm with Bill on this one. Thou, half-thou... -call it a day. I've only trammed my mills twice (after moving them) and I sweep-out a 4-5" circle and tweak things till it's as close to half-thou as possible. Then I'm good for another couple years. Assuming things are linear (which they probably aren't) this means you only have 0.00025 error/inch of inherent inaccuracy. -Not something you need to worry about in any kind of normal situation.
Without too much struggle, you can keep all your dimensions on smaller parts within a thou and if you pay more attention, even a half-thou. In all my general shop work, most parts much bigger than say 5-6 inches do not have tight tolerance requirements. Anything that has truly tight tolerance requirements should be milled slightly oversize and finished with some kind of appropriate grinding process.
On the rare situations that you need sub-half-thou accuracy in your machining processes, if you need it on a regular and predictable basis, you're playing in the wrong ballpark and should be looking at equipment with base prices close to the value of your home.
Ray