Re: [CAD_CAM_EDM_DRO] Bridgeport Series I CNC - anyone?

OK, if it is a stepper model call Mariss at Gecko and order a set of G210
drives and specify that you need them for NEMA 42 motors. He will do a
modification to them that makes the adjusts the midband stabilization to be
appropriate for a large motor. He does not charge extra for this, but you
have to request it. The downside is the drive will not work properly on a
NEMA 23 or smaller motor now. No big deal as you are permanently connecting
them to big motors. Next find yourself a power supply as close to 80 VDC and
20 amps as you can. I used a 60 VDC supply and it was OK, but your rapids
would get a little better if you can get closer to 80 VDC. Download the
circuit Mariss put in the group files that dumps the excess energy you can
get from decellerating so that you don't smoke a drive from over voltage.
Wire it all up using half coil and you will have that part running. If you
have an axis that will not go above 5 - 10 ipm or so and all the others are
fine then that motor is partialy demagnitized and needs to be replaced.

For the VFD start scouring EBay or go to http://www.dealerselectric.com/ and
look at inverter drives. Both the units I have came from Dealers Electric.
They frequently list on E-Bay and have a minimum that is about %15 - %20
less than they list the same unit on their site. On one of mine it did not
sell on E-bay so I contacted them and they let me have it at the E-bay
minimum. On the other they sold it on E-bay and I missed the auction close
to someone else got it. They had a second unit listed on their site. I asked
if they would sell it to me at the price the one on E-bay just sold for and
they agreed. Point is, they seem to be willing to wheel and deal a little
and their service is great. You will need a unit rated at 230 V (assuming
that is what the mill motor is and it should be a 230/460) and you derate
the unit by 50% to feed it single phase in. So, if your mill is a 2 hp
spindle you need to get a 5 hp VFD and if it is 3 hp you need a 7.5 hp VFD.
You may be able to derate a little less, but 50% is the recommended.

You could do a static or a rotary phase converter instead, but from having
tried both my suggestion is save your time and money and just get a VFD. It
is a far better solution.

Tim
[Denver, CO]

-----Original Message-----

>Tim,
> It has steppers; I believe it's a '6' - and yes, it's a good ol'
>3 phase... now what? :)
>-Chris
>
>Addresses:
>FAQ: http://www.ktmarketing.com/faq.html
>FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/