Re: [CAD_CAM_EDM_DRO] Re: mill servo conversion ?'s

carlos_is_dead wrote:

>I'm not sure that the model number is E660. These look to be the
>motors offered in this auction:
>
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3830503711&indexURL=0#ebayphotohosting
>
>There the moddel number is 0660.
>

No, I think the seller there misread the label. The numbers he quotes
match perfectly with
the ElectroCraft data I have on the E660. Reliance bought out whoever
bought out ElectroCraft
some years ago.

> Not sure who the error belongs too. I
>would also be interested to hear more about these motors if anybody
>has any experience with them or other knowledge about them. Namely,
>how do these compare to the 600 in oz Ameteks offered at camtronics,
>

I thought the Ametek motors at Camtronics were a bad deal due to the 4-5 Ohm
resistance. They are still more powerful motors than the EC/Reliance E660,
which has an 11 Ohm resistance. This SEVERELY limits the power, and
especially
the peak ratings of the motor. (For comparison, my 75 V, 1/8 Hp cont.
rated motors
have 1.5 Ohm resistance. But, they are much bigger and heavier than
either of the
motors being discussed.)

>what sort of power supply would they require, and where would one
>acquire such a power supply.
>
>

All these motors are different. You'd want a 120 - 160 V supply for the
E660
with the -05 winding as those have, and probably 80-120 V for the Ametek.
The E660 would need a large belt reduction, while the Ametek could be
used direct drive or with a smaller reduction ratio. A power supply
with 15 A
average current rating should be sufficient for a milling machine.

>I suppose I'm not really interested in the latter questions if the
>motors don't compare favorably with the servos from camtronics.
>

Well, I would recommend a larger motor than EITHER of those for a Bridgeport
Series I -sized machine. Note that Bridgeport uses a motor from SEM, with
a peak current rating of 24 A at 120 V (Or is it 42 A?). That is 2880 W or
3.8 HP!

Jon