I have been online Googling pahse converters. Will a static phase converter be adequate for a 1 HP Bridgeport mill or should I go with a rotary phase converter? Currently, all my tools including my SB Heavy 10 are single phase.
The static phase converter will work, but you'll be a little light on power, particularly since you already only have 1 HP. With static converters the motors run at 2/3's of the full rating. If you only doing work that doesn't need heavy cuts, you'll be ok, but if you need to make some serious cuts you could have problems.
I ran a 2HP Bridgeport with a static converter for many years and it never felt low on power even though we often took some pretty big cuts in steel, but with only half that power I think it would have been an issue.
However, if you can squeeze up the extra dough I would strongly consider buying a VFD for the mill instead of a static converter or rotary converter. VFD's rated for 1HP are pretty affordable. See
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for some pricing.
In addition to giving you true 3 phase from single phase input you'll also get speed control and controlled braking and reversing if you buy the optional braking resistor. If you have a step pulley mill this is a great enhancement. I have a VFD on my 2HP Bridgeport step pulley clone and I hardly every change the pulley setting and I never have to use the manual brake anymore. The controlled reversing is great for power tapping.
Thanks for the input. Marty and seberal others recommended the same dealer. I went to the web site and I am a little confused as to which model I should buy. Do i need to but an electrical box to install the unit in? Does it get mounted on the mill?
JB..Id go with a rotary...simply for the fact you may well wind up with other 3 ph machine tools in the future. And the Statics do NOT deliver full power to the machine.
On the other hand....rather than going with either, unless you want to build a cheap RPC, Id hunt around for a 3hp VFD, and utilize the far nicer ability to have virtually infinite speed ranges, instant reverse for tapping, and so forth. And with the 3hp VFD...it can be run at full power on single phase..it will make up the third leg just like the converters.
Just my .02USD
Gunner
Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken
My pleasure. My big old Gorton MasterMill, with the pulley head, became a marvelous machine to use, once I added a VFD and made up a "pendant" (remote control) and attached it to the head. The Gorton looks like a Bridgeport on steroids .
Ive also done the same with quite a number of Hardinge lathes for customers, as well as a 1501 Clausing here at my home.
Its good tech, and works damned well.
Btw...check Ebay also for good deals on VFDs. Some commerical sellers sell via Ebay and you can get some decent deals, with warranty, and of course lots of used ones. As in any used item involving electronics...I would strongly suggest reading the sellers feedback..but Ive helped a number of folks who have bought used ones off Ebay, all with great sucess.
The "braking resistor" can usually be picked up at a surplus electronics place for a couple bucks at most..so shrug...
Gunner
Gunner
Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken
Take a look at the GS1 and GS2 series of "microdrives". I have been using a GS1 on my old SB vertical mill for a couple of years. Works perfectly! I have 220V 1 phase in, 230, 3 ph out on a 1 HP motor.
I have used these drives (up to 5HP on a GS2) at the place I work and find them to be very reliable and easy to configure. They are a lot of bang for the buck. The 1HP GS1 is around $170.00, if I remember correctly. I could have built a rotary for less money, but lots more time.
Hi Joe, This is still AL, just posting from a different computer. I mounted mine in a standard "screw cover" electrical enclosure that I got from a local electrical supply place. I think it is refered to as a NEMA 1 enclosure. There are available in all sorts of sizes. I opened up a few of the knockouts on the sides for ventalation. I did mount it right on my machine just because I had a convinent place for it, down on a post on the rear corner of the base that used to be for a power table feed that I never got with my machine. I mounted the controls (start/stop, speed control pot) in a small plastic box up on the head of the machine.
I am likely going to do a similar thing on my lathe, but will likely just mount the VFD on the wall, as the lathe has less space on the base for the drive. hope that helps. AL
Again, my sincerest thanks. I'm a bit confused (which is easy to do) what is mounted in the nema box attached to the machine? I thought the speed control would be part of the VFD. Don't you use the normal on off controls aatched to the mill?
I dont like to mount them inside of anything, as they need some cooling air. the only thing you need to do, is put them somewhere where they arent covered with chips or spooge.
If you feel the need to enclose them..make sure its a box with at least 2x the size of the inverter, just so you can get some air flow inside the can.
Gunner
Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken
The VFD itself has outputs/inputs for remote controls. You can indeed use the controls on the front of the VFD (if equipped) but its far easier to simply mout a toggle switch and a potentiometer in a small box with a 4-6 conductor cable running to the VFD itself
Typically you have a toggle switch, to the left, run forward. Center, Stop, to the right, run reverse, and the potentiometer is the speed control
There are some variations..but typially its just a two postion low voltage toggle switch and the pot. Very simple.
Gunner
Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken
Well ... you can wire the original switch contacts to command the VFD, which is my preference, as it keeps the behavior constant. Putting the original motor switch *between* the VFD and the motor can lead to a zapped VFD -- unless the VFD is *way* overpowered for the motor (such as my 7-1/2 HP VFD running a mill with a 1 HP motor. :-)
Yep!
SPDTCO (Single Pole, Double Throw, Center Off) is the designation for the switch.
Though most VFDs can also be wired to accept three pushbuttons, a NC (Normally Closed) one for the stop function, and a pair of NO (Normally Open) ones for the forward and reverse commands.
And shielded wire is a good bet for the connections between your remote controls and the VFD, so electrical noise does not trigger it into various modes when you don't want it to. The longer the wires, and the closer they run to existing power wires, the more important this becomes.
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