Ebay Spindle/VFD combo's

[Bob La Londe]

Tapping

VFDs (some types) ARE used for threading and reversing, but we are usually talking fan cooled low speed motors. My Hurco has a 5HP motor, but top speed is only 3600 RPM. It has a secondary motor inside the case for cooling at low speeds. and low frequencies.

The low speed listed for most of the Chinese 3 phase spindles is 8000 rpm. Not suitable for tapping I would think.

For most of my perpendicular tapping I spot the work piece on the mill with a ball mill. Then I drill on my big drill press, and tap with a tapping head on a smaller drill press I bought just to hold my tapping head.

Combo

I was just wondering about that myself. I think if you were running off 3 phase you would be "ok", but if using the VFD to convert from single phase to 3 phase you might want to buy separate so you could buy a larger VFD. I do not know if there is a specific factor for de-rating, but the VFD can not provide full rated power typically when being fed with single phase. From the few I have read specs on I think I would de-rate at about 30%.

NOTE - VFDs: Some manufacturers like KB Electronics do make VFDs that are ONLY single phase input. Those and those only I would use upto their rating.

NOTE - TAPPING: I am a little leary of rigid tapping anyway. If I do any tapping on my Hurco CNC mill I will use a floating tap head (probably not an auto reversing one like I have on the drill press) and a spiral flute or spiral point tap, and just plan to shoot the tap through in one shot at recommended RPM. I doubt I will ever do any tapping on my mini mills. I am currently running a 28000 RPM spindle on one, and a 20000-34000 rpm spindle on the other. I will probably replace those mills with ones that I will install Chinese variable speed spindles on, but I still doubt I would ever tap with them.

[Al_The_Man]

Of course all VFD's will include motor reversal, if you want precise low rpm performance you need to copy the commercial systems and put a P.G. or encoder on the motor spindle.
You will find that all these systems that perform spindle orientation for tool change etc have a encoder for this purpose.
Modbus is nice because it frees up P.P. I/O in Mach etc, and also the speed is set by frequency value, so there is no PWM to Analogue circuitry required and its associated calibration.
Most VFD models have a P.G. option available.
BTW, do most users here take advantage of the auto-tune function and the free downloadable PC monitoring and set up software through the USB port?
Al.

[stealthshooter]

Can anyone tell me how much the 1.5kw,2.2kw and 3kw spindles weigh?

Thanks much!