If you end up with a three phase Bridgeport (or any other equipment for that matter) one method of operating it on common household "single phase" is with the use of a VFD,or Variable Frequency Drive. Not to be confused with a Volunteer Fire Department - two different things. Don't get confused - the results could be bad. :tired:
Low speed torque is a problem with VFDs. In this case it is a step pulley machine so the speed can be approximated with the belt first, then fine tuned if necessary with the VFD. It comes in handy.
Depending on the HP rating of the motor and it's intended use, a VFD can be had for relatively cheap - the one in this thread was about $160 and can be remotely controlled, which will come in handy in the near future for this machine.
This is one way to mount a VFD on a Bridgeport. It may be a temporary home for it as this machine is slated to be converted to CNC within the next few months, but here's some pics anyway - might give some of you ideas.
I do not have any dimensions or even a sketch of this thing. I put it together using scrap and simply cut to fit as I went. I kinda had a plan, but I more or less designed this on the fly.
It was made from a piece of 4" aluminum angle, a piece of 1/4" AL plate and a piece of 1/8" AL sheet - all scrap sized pieces. All of the material was cut on a 14" miter saw with an 80 tooth carbide tipped blade. It was all rather sloppily TIG'd together - some of the material was in rough shape and should have been acid etched prior to welding.
If this was a final installation, the wiring would have to be covered and secured and so forth - but for now it is good to go until the retro-fit. Only the safety grounds are hanging out but you will notice there is no strain relief on the cables. It was mounted direcly to the belt housing with 4 #10 tapped holes in the housing. The shield on the right of the VFD is to keep belt dust out of the VFD. The belt and pulleys create a nice, gentle breeze which will help keep heat build down.
This is a single phase installation as you might be able to see by the 3 prong plug mounted to the pole behind the mill. I ran wires for the third phase but I will likely leave this the way it is. Undecided.
There is another thread about the mill here:
http://www.cnczone.com/forums/showthread.php?t=10535
And another thread about the shop in general:
http://www.cnczone.com/forums/showthread.php?t=14398
Enjoy the pics, guys.
Scott