Re: [CAD_CAM_EDM_DRO] Low range gears on Bridgeport Series 1

I installed a VFD on my series 1 and used the original motor (1hp). The slow speed-hi range performance isn't very good as this is
were you need the torque. The VFD usually allows me to drill pilot holes in hi range and larger holes in low range by only changing
from hi to lo, not switching belts, which saves a lot of time when drilling, even one hole.
I would think that your motor could probably produce around 3 times the torque of a 1hp at any given speed but you will still have
torque problems if you scrap your back gear. The best way to check is to try drilling some large holes at all the belt positions in
hi and lo range, this will tell you if you can eliminate the back gear.
I would be very concerned about the quadrupled available hp, how are you going to prevent your self from using it? There seems like
there is great potential for machine damage here. I suggest that you limit the current in your VFD so as not to exceed the original
current to the motor. Let us know how the tests come out.
Bob KB1FRW

ptengin@... wrote:

> Group,
>
> I just completed installing a VFD on my Bridgeport series 1 J head. It
> runs like a charm. I only have single phase power here so the VFD is the
> converter, variable speed and dynamic brake all rolled into one. Well, now
> that the new motor runs so nice and quite, I notice a lot of bearing noise in
> the backgear assembly. I could go in there and refurbish affected parts but
> before I do that, I figured I would ask all how often they use low range now
> that the VFD can give superb low RPM performance.
>
> I used a 3 HP TEFC motor and a Yaskawa 3 HP VFD. Since the original motor
> on the machine was a 3/4hp, I opted for the 3 HP motor/vfd package to give
> good torque at low Rpm's. I don't think the machine itself could handle the
> full 3 HP endmilling etc. Removing the backgear parts and storing them in a
> box sounds like a reasonable thing to do if the motor can handle low RPM
> applications. What have you folks found?
>
> Thanks
>
> Peter
> THRD, Inc.
>
> [Non-text portions of this message have been removed]
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