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|04-10-2019, 10:16 PM||#1 (permalink)|
Bridgeport Textron motor options 3 phase to 1 phase VFD rewind or replace
Curious what the best options are. Starting the long expensive process of a CNC retrofit, at least starting on something that was CNC to start with, albeit an ancient Bridgeport knee mill. All electronics have been removed and are getting replaced.
Basically the guts of a series 1 with varispeed and a backgear. Only quirk is the motor shaft faces up so it does limit motor length.
Do I just get a new 220v motor, have my 3 phase rewound, get a DC motor? Any point to having a variable speed motor with a varispeed drive? Any advantages to keeping the 3 phase motor with the VFD vs a 220v motor? I've heard the VFD's don't last.
Current motor is in good running condition.
|04-23-2019, 02:16 PM||#5 (permalink)|
Mad Science of Paintball
Join Date: Jul 2011
I've been running VFDs for over a decade now, and to be honest, at this point they're preferable over single phase.
I have something like nine or ten in total, although not all of them are hooked up at the moment. The Logan lathe and Exacto mill both have 2HP WEG VFDs, the horizontal bandsaw and the belt grinder have KB Electronics ones (the enclosed, dust-proof ones popular with the knife grinders) the horizontal mill, gearhead drill press, Sheldon lathe and the vertical bandsaw all have Automation Direct VFDs (plus I think I have another for the Rockwell grinder) plus a giant 10HP Polyspede that will go on the big lathe once that's back up and running.
The only failures I've ever had, were last year, the AC Tech unit that came with my Sheldon when I bought it in 2008, finally croaked. According to the receipts I got with the lathe, the previous owner had probably bought it in 2003 or so, meaning it lasted some 15 years- and as you can imagine, I used it pretty hard for the last decade.
I'd have simply replaced it with another AC Tech, but at the time, all the dealers I could find were out of stock on the 3HP model, so I bought a 3HP Automation Direct.
The only other failure I had was with the Logan CNC conversion- apparently my controller didn't like the signal connections to the VFD and something popped internally. The VFD still functions just fine, it just will no longer accept remote-input signals. You have to use the onboard controls.
That was an Automation Direct unit, and I swapped it with a WEG I had laying around.
There is absolutely nothing wrong with those original Bridgeport motors (barring, of course, problems with that particular motor, like bad bearings or having been overheated, etc.) I'd have no qualms with slapping a 2HP AD VFD on that machine, wiring the factory start/stop switch to it, and goin' to town.
If you're doing a CNC conversion, you can easily connect it to most typical controllers and let it start and stop the spindle, and vary the speed within a limited range. Most controllers will give you an option of "ranges" too, so if you tell it "high range", you'll manually move the Vari-Drive to top speed, if you tell it "mid range" you'll have to manually dial it down, etc.
But apart from that, you can let the VFD and whatever CNC controller you're using, set the actual RPM.
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