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Can a big mill do small parts?

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TwoGuns

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Jan 9, 2010, 11:46:41 PM1/9/10
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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

Don Foreman

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Jan 10, 2010, 12:10:58 AM1/10/10
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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.

Bob La Londe

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Jan 10, 2010, 1:01:20 AM1/10/10
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"TwoGuns" <R-D-L...@neb.rr.com> wrote in message
news:e37cfe9f-0aba-48a5...@k17g2000yqh.googlegroups.com...

I do not see why not?

Jim Wilkins

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Jan 10, 2010, 9:54:48 AM1/10/10
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On Jan 10, 1:01 am, "Bob La Londe" <nos...@nospam.no> wrote:
> "TwoGuns" <R-D-Lora...@neb.rr.com> wrote in message
> .... However is a large mill capable of doing small jobs with

> > accuracy?
>
> 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

TwoGuns

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Jan 10, 2010, 10:27:27 AM1/10/10
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Thanks for all the information guys.
DL

cl...@snyder.on.ca

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Jan 10, 2010, 11:50:56 PM1/10/10
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On Sat, 9 Jan 2010 20:46:41 -0800 (PST), TwoGuns
<R-D-L...@neb.rr.com> wrote:

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.

Bill Noble

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Jan 10, 2010, 11:56:25 PM1/10/10
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the real problem with small stuff on a big mill is visibility - you just
have to trust your gauges

<cl...@snyder.on.ca> wrote in message
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