On 2 May 2004 14:27:19 -0700, (FLowen) wrote:
Milling machinist wannabee is the proud new owner of a 25 year old
Bridgeport Series I vertical mill, being delivered this week. I will
be using the machine to fabricate firearm parts, mostly small parts.
10 pounds would be an unusually heavy piece. Being a newbie I need
some real basic advice.

1) My concrete floor is out-of-level by 1/4" side-side across the 2'
width of the machine base, and 3/8" front-back along the 3' length of
the base. Would leveling pads be advisable?...or would steel shims
under the base bolt holes be just as good? Or is anything at all even
necessary?

A mill doesn't *have* to be level, but it is nice if the coolant drains
off in the correct direction, and if parts don't roll off the table on their
own. Either leveling pads or shims would be fine to compensate for
the tilt of your floor. It doesn't have to be perfectly level, but getting
it closer sure won't hurt.

2) I have single phase power. The mill is a 3 phase 2HP. No CNC
equipment in the foreseeable future. I will add a DRO, and probably
traverse power feed (I have longitudinal). I believe the power feeds
are 110VAC plug ins and if so would be a separate circuit. I have
gotten the full range of recommendations. Some say a static electronic
converter at $150 is plenty sufficient; others say I should go with a
$500+ rotary converter with a 5HP capacity (I don't plan to add any
other 3 phase equipment); and one fellow suggested making a "pony
motor" from a used 2-5 HP 3 phase motor, wired with the 2 legs of
single phase input power to 2 of the 3 motor terminals, and then the 3
terminals to the machine, equipping the pony motor with a hand start
pull cord, ever hear of that? I'd like to hear the thoughts of you
experienced folks.

I'd use a VFD or a rotary converter. A rotary converter is dead cheap
to build, I wouldn't buy a commercial one. You can make it self-starting,
start it with a pony (small 1 ph motor), or even rope start it. For the size
converter you need, self-starting design is very practical.

My rotary is bigger (20 hp), so I start it with a 0.5 hp 1ph pony motor
to reduce the starting surge currents down to something my electrical
service can handle. I use it to run several machines, including a 7.5 hp
lathe. I'd guess I have $50 total in it.

The other alternative is a VFD. A 2 hp rated TECO VFD from Dealer's
Electric www.dealerselectric.com will handle your mill spindle. It also
gives you the ability to fine tune the spindle speed by varying the drive
frequency. I use one on my mill for that very reason. It cost right at
$200 for a brand new in the box unit.

3) Suggestions as to a good 2 axis (with the 3rd on the spindle if
affordable) DRO system a capable mechanic inexperienced with DROs
could retro-fit?

I like this one http://www.star-techno.com/index3.htm

Gary