G0766 opinions, considering a new lathe.

[Dale Miner]

The full load amperage draw on 220 volt for a 3hp 3 phase motor is about 9.5 amps per leg (3 legs). If the 3 phase motor is being supplied with power from an inverter that has single phase input (2 legs) the supplied 220 volt single phase amperage needs to be at least 1.5 times the 9.5 amp output.

Something doesn't seem to jive if there is a listing for a 3 hp motor at 220 volt that draws 4 amps.

I have not seen a 0766 to examine the nameplates, but doubt seriously if the motor only draws 4 amps. A 4 amp full load draw would be just a tad over 1 hp output, and would be woefully underpowered for a 22" swing machine.

[Joe Kaufman]

Since you mentioned that you like to make big bowls, consider the spindle bearings. According to the G0766 parts list the spindle bearings are 6206 series one front and one rear. The PM 3520b has a pair of 6207 series on the front and one 6206 on the rear. The 6207 series are larger than the 6206 and higher in load rating. The spindle supported distance between the front and rear bearings is about 50% greater on the PM also a plus factor.

Recently, I replace the spindle bearings on my PM 3520b after about 15 months of use, due to a bearing noise. PM sent 3 bearings for warranty replacement. I took one look at the bearings (China) and purchased and installed higher quality bearings. The original bearings were made in Taiwan and had no exterior quality issues. I would not hesitate to install the original Taiwan manufactured bearings if they were furnished.

This is not intended to try to list the merits of one manufacturer or the other, just something to consider.

[Roger Chandler]

The full load amperage draw on 220 volt for a 3hp 3 phase motor is about 9.5 amps per leg (3 legs). If the 3 phase motor is being supplied with power from an inverter that has single phase input (2 legs) the supplied 220 volt single phase amperage needs to be at least 1.5 times the 9.5 amp output.

Something doesn't seem to jive if there is a listing for a 3 hp motor at 220 volt that draws 4 amps.

I have not seen a 0766 to examine the nameplates, but doubt seriously if the motor only draws 4 amps. A 4 amp full load draw would be just a tad over 1 hp output, and would be woefully underpowered for a 22" swing machine.

The motor is 2200 watts which equates to 3 hp, input, but loses some with the cycling of the inverter on output, which is the same with other makes as well. Not sure how they come up with the amp draw stats, unless the motor efficiency accounts for the lesser amp draw, or the "M" series inverter requires less amp draw? The motor plate does state 3 hp, and 4 amps draw, and the motor is continuous duty rated.

I can say from personal experience, that this lathe does not lack in power......I have turned some big wood on it, and it will sure throw the big shavings all over the shop. Mike's pic of his in the earlier part of this thread sort of shows the same thing.

[carl mesaros]

John I have been turning on the Laguna 2436 for about 4 months now and have been more than satisfied. It does seem they designed it with input from turners.

Mike, you need to make sure your family knows when you are at the lathe. Otherwise, you could become MIA in shavings!

i have not seen the 0766 in person, but I did take a good look today at the new Laguna 1836 while at Woodcraft. Laguna has somewhat of a checkered past on lathes, but from looks alone (I did not turn on it), it sure seems like they listened to folks. It was clean and with only a couple of minor things, very impressive. Nice, wide stance in the legs and some excellent design features and options. It would be helpful, of course, to hear testimonies from experienced turners before considering that option.

[John Keeton]

Carl, that is a big chunk of lathe!

[Roger Chandler]

John I have been turning on the Laguna 2436 for about 4 months now and have been more than satisfied. It does seem they designed it with input from turners.

I was impressed with the Revo 2436 when I first saw it online.........I can certainly understand your enthusiasm!

[Dale Miner]

The motor is 2200 watts which equates to 3 hp, input, but loses some with the cycling of the inverter on output, which is the same with other makes as well. Not sure how they come up with the amp draw stats, unless the motor efficiency accounts for the lesser amp draw, or the "M" series inverter requires less amp draw? The motor plate does state 3 hp, and 4 amps draw, and the motor is continuous duty rated.

I can say from personal experience, that this lathe does not lack in power......I have turned some big wood on it, and it will sure throw the big shavings all over the shop. Mike's pic of his in the earlier part of this thread sort of shows the same thing.

Roger,

I have not turned on this model lathe, and take your word on the power available to the turner.

You can't get something for nothing in the power world. 2200 watts is about 2.9+ horsepower with a 100% efficiency.

4 amps x 220 volts = 880 watts = 1.18 hp @ 100% efficiency.

2200 watts ÷ 220 volts = 10 amps

Something doesn't equate.

The inverter can't increase the efficiency from input to output by a factor of 2.5. In fact, inverters decreases the thru put efficiency by some small amount.

I am curious as to what the rest of the motor nameplate info is. Things like volts, full load amps, rpm, service factor, temperature rise, etc.

There is an apparent discrepancy in some of the electrical info for the machine, but the motor nameplate should give the straight and skinny.

I have a shop vac that runs on 110 volts and claims to have 5hp. 5 hp on 110 would need about 35 amps, and that can't happen from a standard wall outlet thru a #16 cord. Obviously the shop vac manufacturer used a different formula for their advertising info.

[David C. Roseman]

I agree with Dale about a discrepancy somewhere. We really ought to drill down on this, as this power issue has come up a number of times. I have the Grizzly G0733 18" x 47" lathe, the "little" brother to the G0766. Its motor is rated by Grizzly as 2 hp, vs. the 3 hp of the G0766, yet the sticker on the motor housing says 5.2 amps. I've never stalled it, even roughing heavy 18" bowl blanks, so it has plenty of torque. The G0733 uses the same highly-rated VFD as the G0766 (Delta VFD-M series).

Dale, how would you go about measuring actual amperage draw on one of these machines with a clamp-on ammeter? Seems like that would be worth doing. Presumably we'd have to pull the NEMA 6-20 receptacle part way out of its electrical box in order to clamp on each conductor, as there is no ready way to access the conductors at the drive or motor and still have the lathe running. I haven't looked into it, so I don't know how the presence of the VFD circuitry affects amp measurement with a basic clamp-on meter.

Another question would be how to bring the motor to full amperage draw for an accurate test? Would we have to have someone turning a big blank, trying to actually stall the motor? Also, at what spindle rpms, since presumably the torque curve varies depending on pulley and speed selection.

[Roger Chandler]

I agree with Dale about a discrepancy somewhere. We really ought to drill down on this, as this power issue has come up a number of times. I have the Grizzly G0733 18" x 47" lathe, the "little" brother to the G0766. Its motor is rated by Grizzly as 2 hp, vs. the 3 hp of the G0766, yet the sticker on the motor housing says 5.2 amps. I've never stalled it, even roughing heavy 18" bowl blanks, so it has plenty of torque. The G0733 uses the same highly-rated VFD as the G0766 (Delta VFD-M series).

Dale, how would you go about measuring actual amperage draw on one of these machines with a clamp-on ammeter? Seems like that would be worth doing. Presumably we'd have to pull the NEMA 6-20 receptacle part way out of its electrical box in order to clamp on each conductor, as there is no ready way to access the conductors at the drive or motor and still have the lathe running. I haven't looked into it, so I don't know how the presence of the VFD circuitry affects amp measurement with a basic clamp-on meter.

Another question would be how to bring the motor to full amperage draw for an accurate test? Would we have to have someone turning a big blank, trying to actually stall the motor? Also, at what spindle rpms, since presumably the torque curve varies depending on pulley and speed selection.

I think there must be some formula that is being used by Grizzly that is not standard........not sure why, and it would be interesting to have some measurement like you mentioned David. Noting the oddity on the amp draw/hp rating here, I am wondering if perhaps something about the way the inverter is programmed makes this possible.....although that is over my head as far as my current level of understanding of things in the electrical/electronics world.

I appreciate Dale, and others like Ralph Lindberg and Bill Boehme who know so much more than I do related to these things........and of course, I sense that you also have greater knowledge as well David!

I do know that this lathe has lots of torque and power......I have not stalled it yet, but have no doubt I could if I tried to. I have stalled more than one PM3520b and also a Robust
American Beauty -3 hp version, so stalling the G0766 is certainly possible with heavy cuts!

[John Keeton]

For whatever difference it may make, the Grizzly uses the M series VFD and the Laguna uses the S series. I know nothing about this subject - just throwing it out there to see if that tells anyone anything.

As an aside, I must be doing something wrong or else a whimp turner. I have never stalled my Jet 1642-2. Nor have I attempted to.

[Dale Miner]

For whatever difference it may make, the Grizzly uses the M series VFD and the Laguna uses the S series. I know nothing about this subject - just throwing it out there to see if that tells anyone anything.

As an aside, I must be doing something wrong or else a whimp turner. I have never stalled my Jet 1642-2. Nor have I attempted to.

John,

Don't feel too bad.

The world needs whimp turners too.

Actually, when I had a PM3520, in low gear it was pretty tough to slow it down with anything smaller than about 16". In high gear at rough out speeds it was easier of course.

The 2hp 2436 I have now has less oomph in the mid range belt setting than the PM in low, but in granny gear belt setting is more than I can stall when running above 100 rpm's or so. Of course I'm older now and maybe getting a bit whimpy in my golden years.

The real test of power; "Is it enough to make the owner satisfied."

If a prospective buyer has a doubt, a test drive with a larger blank would be prudent.

I'm still curious as to what the rpm, service factor, etc, info on the motor nameplate is.

[Dale Miner]

I agree with Dale about a discrepancy somewhere. We really ought to drill down on this, as this power issue has come up a number of times. I have the Grizzly G0733 18" x 47" lathe, the "little" brother to the G0766. Its motor is rated by Grizzly as 2 hp, vs. the 3 hp of the G0766, yet the sticker on the motor housing says 5.2 amps. I've never stalled it, even roughing heavy 18" bowl blanks, so it has plenty of torque. The G0733 uses the same highly-rated VFD as the G0766 (Delta VFD-M series).

Dale, how would you go about measuring actual amperage draw on one of these machines with a clamp-on ammeter? Seems like that would be worth doing. Presumably we'd have to pull the NEMA 6-20 receptacle part way out of its electrical box in order to clamp on each conductor, as there is no ready way to access the conductors at the drive or motor and still have the lathe running. I haven't looked into it, so I don't know how the presence of the VFD circuitry affects amp measurement with a basic clamp-on meter.

Another question would be how to bring the motor to full amperage draw for an accurate test? Would we have to have someone turning a big blank, trying to actually stall the motor? Also, at what spindle rpms, since presumably the torque curve varies depending on pulley and speed selection.

David,


If the motor namplate gives the info, I would guess that is sufficient. If not, then measuring would be a involved process. To get full load amperage draw the rated full load rpm of the motor would need to be known. Typically a motor will run very near synchronous at no load, and wil slow to nameplate rpm's at full load.


Absent nameplate info, right or wrong, my method would be to measure the amperage on the single phase input because it is easier to access, and calculate the wattage input. To get full load, the frequency from the inverter would need to be adjusted to 60 cycles, no load speed measured, and then an adjustable brake method of some sort fashioned to load the motor until the full load 60 cycle rpm was reached. The amperage draw at that point x the input voltage would yield a value about 15% higher than the actual motor output.


I assume the motor is a nominal 1750 rpm full load 60 cycle motor. If so the synchronous speed would be 1800 for the motor, and the no load speed very near to 1800 rpm.


Horsepower is a factor of speed times torque. The torque a motor can deliver is for the most part a function of the rotor diameter and length. The slower the speed of the motor, the larger the rotor (and stator) need to be for the same horsepower output. With most current inverter powered wood lathes, the motors are oversped above nameplate rpm's and the advertised hp is with motor at the full load 60 cy rating. When the motors are running below 60 cycle rpm's, the horsepower is less, and when above 60 cycle rpm's the horsepower can be above namplate. Some inverters are capable of boosting motor torque at slower speeds to help compensate for a loss of hp at lower rpm's, but there is a limit to the boost.

I used to occasionally do some vibration analysis on rebuilt motors when still in the motor shop. To test a rebuilt motor, they (shop personnel) would couple the motor to a dynomometer and measure the amperage and torque curve as full load was reached. Methinks that is way to much trouble for what the answer is worth.

[Roger Chandler]

John,

Don't feel too bad.

The world needs whimp turners too.

Actually, when I had a PM3520, in low gear it was pretty tough to slow it down with anything smaller than about 16". In high gear at rough out speeds it was easier of course.

The 2hp 2436 I have now has less oomph in the mid range belt setting than the PM in low, but in granny gear belt setting is more than I can stall when running above 100 rpm's or so. Of course I'm older now and maybe getting a bit whimpy in my golden years.

The real test of power; "Is it enough to make the owner satisfied."

If a prospective buyer has a doubt, a test drive with a larger blank would be prudent.

I'm still curious as to what the rpm, service factor, etc, info on the motor nameplate is.

Dale..........this is the motor label. Not sure it gives you all the info you want, but this is what they put on the motor.

G0766 lathe pics 066.jpg

[David C. Roseman]

For whatever difference it may make, the Grizzly uses the M series VFD and the Laguna uses the S series. I know nothing about this subject - just throwing it out there to see if that tells anyone anything.

As an aside, I must be doing something wrong or else a whimp turner. I have never stalled my Jet 1642-2. Nor have I attempted to.

John, I've seen your work, and if you're a wimp, we're all in trouble!

On the issue of the Delta Electronics variable frequency drives, for Creekers who are interested, I looked into this a bit when I bought my G0733 three years ago, and also discussed it briefly a couple of years ago with a Delta Electronics tech at their Raleigh office when I was adding a braking resistor. Delta's product line for AC motor drives can be found here: http://www.deltaww.com/Products/Cate...D=ALL&hl=en-US

Both the VFD-S series and VFD-M series are highly regarded workhorse drives. The M series is newer and a bit pricier than the S, and can be configured for use with higher hp motors. As best I can determine from checking online today, the S series tops out at 2 hp for 220/230v motors. See links below.

Wolf Automation's website prices the M series at $336 configured for 2 hp 220/230v motors, and at $486 configured for 3 hp motors. The S series is configurable for up to 2 hp motors (I can't find an option for a 3 hp application), and Wolf prices it at $290 for 2 hp 220/230v. The drive pricing and options calculator can be found here on Wolf's site for the M series: http://www.wolfautomation.com/Configure3.aspx?ProductID=23057&x=107&y=15

and here for the S series: http://www.wolfautomation.com/Config...3778&x=68&y=18

The S series has been used for years on the Jet 1642EVS and the PM3520B, both of which max at 2 hp. John's post notes that the Laguna Revo 2436 also uses it. That may be the case with the standard 2 hp motor. But the Revo 2436 has a 3 hp option, so I'm thinking they may use either the M series for that, or the alternative E series. The VFD-S drive is also used on the Grizzly G0632, which is similar to the Jet 1642EVS. (some folks refer to it as a "clone" but I think there are differences).

The M series is used on the G0766, the G0733, and some of the other Asian-made 18 x 47 lathes that are similar to the Grizzly G0733. I think (but have not confirmed) that this includes the Busy Bee Craftex CX 802, the Hare & Forbes Hafco WL‐46A, and the Baileigh WL‐1847VS.

BTW, just want to point out to readers who may not be familiar with Delta Electronics, Inc. it is not to be confused with the Delta brand of power tools and machinery. Completely unrelated.

[David C. Roseman]

David,


If the motor namplate gives the info, I would guess that is sufficient. If not, then measuring would be a involved process. To get full load amperage draw the rated full load rpm of the motor would need to be known. Typically a motor will run very near synchronous at no load, and wil slow to nameplate rpm's at full load.


Absent nameplate info, right or wrong, my method would be to measure the amperage on the single phase input because it is easier to access, and calculate the wattage input. To get full load, the frequency from the inverter would need to be adjusted to 60 cycles, no load speed measured, and then an adjustable brake method of some sort fashioned to load the motor until the full load 60 cycle rpm was reached. The amperage draw at that point x the input voltage would yield a value about 15% higher than the actual motor output.


I assume the motor is a nominal 1750 rpm full load 60 cycle motor. If so the synchronous speed would be 1800 for the motor, and the no load speed very near to 1800 rpm.


Horsepower is a factor of speed times torque. The torque a motor can deliver is for the most part a function of the rotor diameter and length. The slower the speed of the motor, the larger the rotor (and stator) need to be for the same horsepower output. With most current inverter powered wood lathes, the motors are oversped above nameplate rpm's and the advertised hp is with motor at the full load 60 cy rating. When the motors are running below 60 cycle rpm's, the horsepower is less, and when above 60 cycle rpm's the horsepower can be above namplate. Some inverters are capable of boosting motor torque at slower speeds to help compensate for a loss of hp at lower rpm's, but there is a limit to the boost.

I used to occasionally do some vibration analysis on rebuilt motors when still in the motor shop. To test a rebuilt motor, they (shop personnel) would couple the motor to a dynomometer and measure the amperage and torque curve as full load was reached. Methinks that is way to much trouble for what the answer is worth.

Thanks, Dale! Whew, measuring draw on these lathes is, in any event, clearly way beyond what I'm able to do. The things I learn on SMC!