I recently sold my small lathe (7"x12") and a mini-mill. I have a couple prototypes I need to whip out for a project I am working on. I will need to machine some parts as small as 1/2" and several pieces of
12" x 12' x15". Obviously it would be impossible to do a large job on a small mill. However is a large mill capable of doing small jobs with accuracy?DL
It can make parts of any size to whatever accuracy it's capable of in small regions, which is almost certainly better than the accuracy it's capable of over full travel range.
I routinely make parts considerably smaller than 1/2" on my Bridgeport, and on my 15" lathe.
I do not see why not?
If it doesn't have a DRO you may have trouble reaching the X handwheel or bumping the Y one while leaning close with a magnifier to pick up a scribed mark. The 24" table on my mill is a good size for following a line by eye. For me a 9" x 48" (?) Bridgeport is too big for this, not that I'd refuse one. That one is CNC anyway but I checked in case I found a manual mill the same size.
A properly adjusted Bridgeport (a 9x42 with DRO) can be set within
0.0002" fairly easily. To change the last digit I tapped the crank handle with the chip brush. I had to alternately tighten the slide lock a bit and tap the handle to lock it at 0.0000.Uneven wear on the dovetails makes this level of precision hard to hold. A smaller second-hand machine isn't as likely to have seen as much production use, but you have to check carefully.
jsw
Thanks for all the information guys. DL
A good one is. If it can machine big stuff to within a couple tens of thousands of an inch, it can do at least as well on small stuff.
the real problem with small stuff on a big mill is visibility - you just have to trust your gauges
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