New owner questions

[Bernoulli]

I just bought a Kingston-Conley mill/drill. I guess it weighs in at about 800 pounds. I'd like to put it on a mobile base. It has a 1/2HP 3-phase motor on it. I don't know whether it makes more sense to get a VFD for it or put on a reversible single phase motor (about 1HP) so I can run it off a single phase. Any advise on these two ideas is geatly appreciated. Thanks

[Paul T.]

If you plan to use the mill much at all, I would strongly recommend the VFD approach. Also, 1/2 HP VFD's are pretty affordable or can be found used.

Advantages-

Runs smoother than a single phase motor.

Gives you infinite speed control.

By adding the low cost breaking resistor you get automatic braking and controlled reversing, which is great for tapping.

I added a VFD to my Bridgeport clone about a year ago and its been great, I'll never have another mill without it.

Good luck-

Paul T.

[Bernoulli]

Thanks. I was a successfull bidder on Ebay yesterday for a VFD. I'm not conversant in electrical matters, but I imagine I'll be able to muddle through.

[sandman2234]

I was thinking that VFD only made sense when talking about running them on 3 phase. Something about not being feasible due to power balance or something with single phase power. But this is only a rumor, but might ought to be checked into. If that is true, then you would have to find a 3 phase motor also, so that approach isn't good.
David from jax

[len]

Many VFD's can be run from single or 3-phase power to generate 3-phase output. The drawback for using single-phase input is that you have to de-rate the VFD. The ones that you can do this with will have the ouput power rating specified somewhere for each input arrangement. What makes this possible is the fact that most modern inverters rectify the AC line voltage (whatever phase) to create a DC power bus, which is then switched to simulate 3-phase output. Since the power factor for 3-phase input will be higher than for single phase, there will be more power available for the DC bus, hence more 3-phase output power. Other than that, the inverter could care less how the DC bus was created.

Older inverters that use other means of generating 3-phase may not accept single-phase input. To avoid dissapointment, I would assume that it can't unless shown otherwise.

len

[Bernoulli]

Well my VFD arrived today. I've been reading all that I can find. My understanding is that I need to get a box to mount it in that will protect it yet allow it to cool. I'm not exactly sure how to accomplish these mutually contradictory requirements. I imagine I can remove the current electrical box and switch and mount it all there on the side of the tool.
Any advise as how to proceed is greatly appreciated.

[MikeH]

My suggestion is a metal box with lots of louvers to allow air flow for cooling. They would also keep chips out (especially if they have window screen behind them.