Pwncnc spindle insight

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey Rick,

@SemperFi77USMC

Is there a significant difference in performance between the 1.5 and 2.2

if you want to run a 2.2 kW spindle on 120 V, the needed rated input current of the VFD will be higher than any domestic circuit in the U.S. is able to provide. That is the reason why Omron/Hitachi produce VFDs for 120 V only for spindles up to 0.75 kW, and why cheap chinese VFD “manufacturers” simply omit the rated input on their VFD nameplates and manuals (see here). That’s also why Daniel of PwnCNC says he does not offer a kit for 2.2 kW @ 120 V. They offer only 1.5 kW @ 120 V, or 2.2 kW @ 240 V.

@Aiph5u

@Aiph5u

I would always avoid considering 110 V VFDs/spindles except if you stay with 0.75 kW mechanical motor output at maximum, because with higher power, with 100 V class you need too big wires/fuses. In the U.S. you usually have split-phase electricity which means you can use a 240 V outlet (e.g. a NEMA 6 or NEMA 14) for higher power devices like VFDs/spindles.

Be aware that when you buy a spindle, …

@Aiph5u

on chinese spindles, the power rating is often wrong.

People who intend to buy a 110 V VFD for a 2.2 kW spindle motor should always be aware that

1. serious VFD manufacturers don’t produce VFDs for the 100 V class stronger than 0.75 kW and that
2. those manufacturers who do offer them, simply omit the rated input current and input power in kVA both in the manual and on the nameplate, in order to make people in 110 V countries believe they can get away with a 30 A circuit. If you simply calculate what the rated current at the expected input power would be on a 110 V 2.2 kW output VFD, if it wasn’t omitted and they would write it on the nameplate or into the manual, no U.S. citizen would buy it as there are no circuits in domestic environment that deliver 110 V with more than 30 A.

For higher power devices like VFDs/spindles, ovens, air conditioners, electric heaters, car chargers, etc., there is 240 V, because for the same power (kW) of your device, you need only half the current, which means half the wire strength and half the fuse strength, as explained here.

@Aiph5u

With air cooling, the fan rotates with the spindle rpm, which can be a problem on low speeds. Water-cooling makes cooling independent of spindle rotational speed, which means good cooling even at slow spindle speeds, which is good for milling metals and plastic. But if you want to mill only wood, you will use high speeds, so the fan will rotate fast enough, so the decision is mainly if you want to avoid the plumbing.

Air-cooled are often required to run at least at 8000 rpm, while water-cooled can run as low as 6000 rpm.

Water-cooling also means that the spindle can be cooled after it is stopped, until it is really cooled down.

Welcome to the forum!