Thread: Minimum Hp

Hi
Just bought a #4 without a motor.
What is the minimum hp motor (220v s.ph. that can run the lathe (not for production run)

Originally Posted by patro00

Hi
Just bought a #4 without a motor.
What is the minimum hp motor (220v s.ph. that can run the lathe (not for production run)

You'll be dealing with only 1/3 the power 'pulses' per rev of a 3-phase, and need to also consider the 'slip'characteristics of the motor and wot happens when the several power-traverse mechanisms want their rations.

Might be better served as to avoiding RPM drop and sympathetic vibration in certain ranges if you go for, say a salvaged 7.5 to 10 HP 3-phase motor run off a 10 HP+ rated VFD for much the same outlay as a new(ish) 7.5 or 10 HP sgl phase motor. That presumes the 3-phase starter/contactor/overloads/controls are still in place and usable or restorable/adaptable. But you haven't said that.

Bill

I'm also kind of interested in the answer. Is there any point to putting a 7.5HP or 10HP motor on a #4?

Edit: I guess my question overlapped with thermite's answer. Sounds like it's not completely unreasonable to step down to a 7.5 or 10HP motor (three-phase) if it comes with a larger one.

Originally Posted by sfriedberg

I'm also kind of interested in the answer. Is there any point to putting a 7.5HP or 10HP motor on a #4?

Phase quite aside, NFW you are likely to be able to find wall-power for a 40 or 50 HP ... or even a 20 HP single-phase if you could find one.

Anyway - even production work at a 'combat speed' didn't usually NEED even half that. Stock size and limits to just how much DOC is actually needed for a given shape matter, too. Look at how much a fairly stout 'engine' lathe can deliver on 10 HP or less, and how seldom such are maxed-out, power vs tool life limits.

Biggest dif is the turret lathe was intended to be worked literally to death, and as rapidly as possible, then, having earned its keep several times over, been replaced with a more productive one yet. Economics and time-value exercise, not just engineering.

Stout construction and gobs of power were just to make that sacrifice count for as much as could be and insure the same firm got the replacement orders, not a competitor with marginally higher thoughput, ROI, or reliability stats.

Neat to learn from, challenging to the mind, but otherwise not the best of choices for general-purpose or occasional use.
Tooling .. power .. floor space... set up skill...and general awkwardness for other than slam-bang-thank-you-ma'm mindless repetition.

Bill

Originally Posted by thermite

Phase quite aside, NFW you are likely to be able to find wall-power for a 40 or 50 HP

Which was rather the point of my question, Bill. I agree that a 20HP 230V single-phase motor is sort of stupid with 100A FLA. 10HP three-phase is on hand. 20HP three-phase would be an expensive upgrade, but easily doable with PhasePerfect without taxing a 200A service. Also, neither patr00 nor I were asking about the #[1-4]A series machines with their 20-50HP (and up) motors. Wasn't the largest standard motor for a #4 closer to 15HP?

Originally Posted by thermite

not the best of choices for general-purpose or occasional use.

Good point. Not my question. I've got both a 16x40 engine lathe and a Hardinge DSM-59. I could make enough use of a larger turret lathe that I've acquired an old Royal ram turret to see about fitting it on the engine lathe. If a good W&S#4 came alone at the right price (in the tooling-poor Pacific NorthWest it may be a while), that would be a far superior option. But that's pointless if a #4 needs 15HP to get out of bed in the morning, thus my interest in the original question.

Sounds like swapping to a less powerful motor is not a problem, so let me ask a related question of my own. The original W&S motors on a lot (all?) of models were two-speed. Easy replacement motors will be one-speed. Is there any fundamental reason the motor speed shift couldn't be disabled/ignored, or hooked to a VFD-based speed selection? Any mechanical interlocks or clutches related to the motor speed shift that might not be obvious from looking at old catalog entries?

Originally Posted by sfriedberg

10HP three-phase is on hand.

That, and a suitable VFD, is probably your best bet.

Wasn't the largest standard motor for a #4 closer to 15HP?

Largest COMMON motor might be a better query, and I don't actually know, but suspect 15 and 20 HP WERE more common than 40 and 50 HP (which can be found on google as of a search earlier today).

Even the largest of factories have power budgets.

Sounds like swapping to a less powerful motor is not a problem, so let me ask a related question of my own. The original W&S motors on a lot (all?) of models were two-speed. Easy replacement motors will be one-speed. Is there any fundamental reason the motor speed shift couldn't be disabled/ignored, or hooked to a VFD-based speed selection? Any mechanical interlocks or clutches related to the motor speed shift that might not be obvious from looking at old catalog entries?

Any alternative motor that has a different NEMA 'frame' is going to require at least SOME rework. That opens the door to mechanical speed change mechanism as well as VFD, and could insure the VFD is not taxed, nor torque or power sacrificed at the extremes of its range.

Worthwhile if, as you noted, you DO have appropriate workload to make use of the better features of a turret lathe. Given the drop in relative cost and improvement in quality and variety of affordable carbide tooling since the heyday of these machines, it might be preservation of the higher-end RPM you'd want to focus on.

Bill