G0766 opinions, considering a new lathe.

[hu lowery]

My 766 is getting a few hours on it and seems to perform just fine. I'm not having any issues with the spindle centerline height, I think they cleverly recognized that we would rapidly be standing on a thick mat of shavings and raised the spindle height to accommodate that!

I knew that Grizzly had stated that the four amps wasn't maximum draw but I am very glad to finally get some real numbers! My twenty amp dedicated circuit should be fine. Thank you Sparky, much appreciated! Pretty sure those numbers are pretty closely in line with the draw an electrical engineer has been saying would be needed for a three horse motor.

Hu

[david privett]

kinda going back to the power issue discussion , I am thinking about replacing my 1 hp 650 cfm vacuum with a larger one, so my motor nameplate states that it is 16 amp 1 hp motor 125 volt. So not wanting to overload things I thought to use a inductive amp gauge and see what that thing was really pulling. Well to my surprise it is using only 4 amps with the vacuum running with designed load of the vacuum's suction fan , all I can think of is that depending on the company some rate their products at full load amps (FLA I see this on most usa made motors labels) and some at start up amperage as stuff that is made in asia . That might explain some of the variance of consumed power requirements of the g0766 and others, not even going down the variable speed change road.

[David Walser]

... That might explain some of the variance of consumed power requirements of the g0766 and others, not even going down the variable speed change road.

It might explain some of the variance, but it doesn't explain the discrepancy. 4 amps simply cannot produce 3hp. You cannot get more energy out of a motor than what's put into it. No amount of efficiency improvements allows a motor to create energy. As a practical matter, because of friction losses, you cannot get out of a motor 100% of the power that's put into it. This is true of electric motors, gas engines, and steam engines. So, if the lathe has 3hp of power, the motor nameplate cannot be correct. Grizzly's known for using parts from older designs for new applications. Perhaps they recycled the nameplate from another motor?

This reminds me of how Sears used to rate their Craftsman tools by "peak horsepower". The number may have been accurate, but it was highly misleading. In this case, I assume Grizzly made an honest mistake with the nameplate. I cannot see what they'd gain by intentionally mislabeling the max draw and there are lots of potential downsides (in terms of product liability). While I'm curious what the real numbers are, for me it's a non-issue when it comes to making a purchase decision.

[Roger Chandler]

I spoke with one of the tech guys about this........first off, this stuff regarding inverters, and such is beyond my pay grade! Anyway, he says the single phase 220 power comes to the inverter which converts it to 3 phase power, which then goes to the 3 phase motor. He says it breaks it down, and that motor is indeed 3 hp, and draws 4 amps? [he said a lot of other things I cannot quote verbatim, cause I cannot remember them like he said them! ]

He sounded very much like he knows what he is talking about........I think someone who knows this stuff much better than I should be the one to communicate, because they understand the nomenclature and have the technical understanding that I do not possess. He was wondering how Sparky took his measurements of amp draw, when I said one of the turners measured it.

People he said, can write anything on a forum........which is true, but I think there are knowledgable folks here that have no agenda, but are trying to understand, and I think there are people who are considering this lathe that are becoming either confused or gun shy about it because of these posts. I sure would like to see the two things reconciled!

I have no interest other than factual information being available to all interested parties........owners need to be able to have confidence in their lathe, and prospective customers looking for reliable information should be able to have that as well. I just don't know how to get that information reconciled and here for all to see, and of course that is not my responsibility anyway, but I care that people have honest and factual information. I do not want to bring anything to this discussion that muddies the waters for anyone. Perhaps someone who has knowledge and integrity, with no agenda could inquire and maybe get reliable information..........maybe that information in the owners manual is reliable, but some are missing something????

All I really know from personal experience at this point is that my G0766 runs great, seems to have plenty of power and has already proven itself to me with some big heavy wood turned on it. Other than that, a lot of the questions in this thread I cannot reconcile.

I know the math does not seem to correlate to what is stated on the motor label......I guess I need to stop trying to be helpful on this.......cause it seems I have reached the limit of my current level of understanding.

Additional: I wonder if perhaps the 4 amp figure was put there by someone who thought the amp draw on each phase was 4 amps? Would that total 12 amps on 3 phases? I guess I am muddying the water, a bit with that question but, I am trying to figure out the disconnect on the label and the math...........I should probably just stop trying to do that!

[Dale Miner]

4 amps @220 volts 3 phase is about 1.3 to 1.4 hp.

http://www.engineeringtoolbox.com/el...nt-d_1499.html

[Geoff Whaling]

I've created a new thread on power & VFD's.

[Sparky Paessler]

Roger

I measured the current draw with a meter that clamps around one of the supply wires (there are 3). It measured the magnetic field that builds up around the wire as current flows thru it and calculates the current from that. Very common way to measure current without having to break the wire and put the meter in series. Also after having read the user manual of the inverter unless they have completely locked out the keypad on the inverter you should be able to press the mode button until the display changes from F and the frequency to the A and the current is displayed. I will try that tonight. That doesn't affect any settings just changes what is displayed on the readout. From the readings I saw and 31 years of working with inverters and motors I feel that this is a 3hp inverter/motor setup. Cant explain the 4 amp rating on the label as the motor does draw more than that under full load. (looks like full load would be around 9 amps (which at 240VAC 3 phase would be 3hp).

Just a note on startup current. It is true that on Single Phase Motors the starting current is very high. They have a second winding (start winding) that is engaged on startup that draws a lot of current. The Start Cap shifts the phase of the input power so that the motor actually has two phases going to it which allows it to start spinning. When it comes up to speed there is usually a centrifugal switch that opens and the start winding is disconnected and the current drops down.
On a Three Phase motor there is not a start cap or a centrifugal switch. With three phases already the motor will start spinning without the cap or switch. Thus no extra windings are needed and the startup current is much closer to the regular running current. This is also one reason 3 phase motors are less expensive than same size single phase.

[Roger Chandler]

Roger

I measured the current draw with a meter that clamps around one of the supply wires (there are 3). It measured the magnetic field that builds up around the wire as current flows thru it and calculates the current from that. Very common way to measure current without having to break the wire and put the meter in series. Also after having read the user manual of the inverter unless they have completely locked out the keypad on the inverter you should be able to press the mode button until the display changes from F and the frequency to the A and the current is displayed. I will try that tonight. That doesn't affect any settings just changes what is displayed on the readout. From the readings I saw and 31 years of working with inverters and motors I feel that this is a 3hp inverter/motor setup. Cant explain the 4 amp rating on the label as the motor does draw more than that under full load. (looks like full load would be around 9 amps (which at 240VAC 3 phase would be 3hp).

Just a note on startup current. It is true that on Single Phase Motors the starting current is very high. They have a second winding (start winding) that is engaged on startup that draws a lot of current. The Start Cap shifts the phase of the input power so that the motor actually has two phases going to it which allows it to start spinning. When it comes up to speed there is usually a centrifugal switch that opens and the start winding is disconnected and the current drops down.
On a Three Phase motor there is not a start cap or a centrifugal switch. With three phases already the motor will start spinning without the cap or switch. Thus no extra windings are needed and the startup current is much closer to the regular running current. This is also one reason 3 phase motors are less expensive than same size single phase.

Hey Sparky.....thank you much for the explanation! I really do believe that your findings are accurate. I am not sure that the information given out by tech support is always in sync with the questions we are asking. They of course have a motivation to support whatever they put out, but independent analysts like yourself may ask questions that they are not necessarily comfortable with answering........just my thinking here!

I have no doubt this is a 3 hp motor at all.......with as much turning as I have done on as many lathes as I have turned on, I can tell that the power and torque is there. I actually have a meter similar to the one in your picture [also made by Fluke] and it had not occurred to me to even test the power with it.

Could you tell me where in the line did you actually place your meter? Was it on the wiring at the receptacle, or did you take the cover off the inverter and hook your meter on the leads going into it?

Just so you know........I trust your background and your information!

[Sparky Paessler]

Roger

I took the inverter cover off and measured both 240v single phase hot wires going into the inverter. That is where I saw a max of 10amps. I also checked the wires going to the motor on the three phases side where I saw the reading of 6.6 amps with the loading I was using. That was the more important reading as it is the current going right into the motor. Thanks.

Hey Sparky.....thank you much for the explanation! I really do believe that your findings are accurate. I am not sure that the information given out by tech support is always in sync with the questions we are asking. They of course have a motivation to support whatever they put out, but independent analysts like yourself may ask questions that they are not necessarily comfortable with answering........just my thinking here!

I have no doubt this is a 3 hp motor at all.......with as much turning as I have done on as many lathes as I have turned on, I can tell that the power and torque is there. I actually have a meter similar to the one in your picture [also made by Fluke] and it had not occurred to me to even test the power with it.

Could you tell me where in the line did you actually place your meter? Was it on the wiring at the receptacle, or did you take the cover off the inverter and hook your meter on the leads going into it?

Just so you know........I trust your background and your information!

[Sparky Paessler]

I did also just verify that with the inverter cover off you can press the mode button (I think it was 3 times to get to the "A") to display the amperage the motor is drawing.

[Jim Sevey]

Well- I'm confused. All I know is that I had a 1 1/2 HP lathe before I bought the 766. The 766 is dramatically more powerful and capable than my old 1 1/2 HP lathe. I'm happy with it. I'm glad there are knowledgable and curious people out there to keep the tool companies on their toes. You guys are way smarter than I am. Thanks for all the good information. That's what the Creek is for.

[Brice Rogers]

I am a new member and while I've read some posts here, this is my first time posting. I have been turning wood on a 9" craftsman lathe for about 3 years and finally bit the bullet and bought a Grizzly G0766.

I received my G0766 about 2 weeks ago. The crate was undamaged but the fasteners for the legs were laying in the bottom of the crate and the legs slide around during transit on the bed and removed some paint from one leg and scratched the bed. It is not terribly bad - - but disappointing. Two of the four bevel head screws holding the motor had fallen out and the other two were half unscrewed. The motor plate was only held by one of the two bolts, so the motor was "listing" and was close to falling off. Pardon the pun but the motor was hanging on "by a thread". The tail stock hand wheel wobbled because it was loose. That was all pretty easy to fix but disappointing for my major lathe purchase.

But then I took a look at the spindle. I discovered these things:
1. The threads were very rough looking and the leading and trailing edges had wire edges and were "torn" in a ragged fashion.
2. The spindle major thread diameter was out of spec for a class 2A - - With the wire edges, it measured 1.230". I think that it I would have touched up the threads to remove the burrs, etc. that the true measurement would have been closer to 1.225".
3. The unthreaded area at the base of the spindle was 1.260, which means that with some chucks, they won't seat all the way (there is a video of the G0733 by Harrison tools that mentioned the same thing.
4. The finish of the Morse taper looked rough, like the machine or machinist just took roughing cuts. In comparison the spur center and live center finish were much better.

I photographed the spindle and requested tech support send me a new and better one. They indicated that they were surprised with the lack of quality of the one I had. But tech support did not want to send me a spindle but instead wanted to ship me a 200 pound headstock assembly. I suspect that either they do not yet have spare parts or they doubted my ability to swap out the spindle. When I got it home, the roughness of the replacement spindle was a little worse and the diameter was even a tad smaller than the original one. Items 3 and 4 (above) were improved. In retrospect, rather than mess with freight shipping and pickup, I would have preferred to just dress the original spindle with a file, and sand paper. But it was undersize and I was reluctant to remove any more material.

So, here is my question for those people who have this new lathe. (1) What is the major diameter of your spindle threads and what is the surface finish like on the threads and morse taper ??? Am I just being too fussy? Is the quality of the spindle that I got representative of what Grizzly is shipping? I thought that the precision machined spindle threads should look at least as good as the finish on a $2.00 1" x 8 TPI bolt that I bought yesterday (BTW, the major OD of the 1" bolt was 0.996 which I thought was impressive and well within specs). If you have a better finish and size spindle, perhaps I should just wait until they get the bare spindle in stock as a spare part. I'm worn out from driving my pickup down to the freight yard (50 miles round trip). Looking for your thoughts.

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[Roger Chandler]

The spindle threads on my 0766 were in great shape, and when asked by another owner to measure it, I used a caliper and it measured precisely 1.25 inches in the threads.

[david privett]

yea the spindle threads are ruff , I would get on a list for a new one. maybe they can put it in the same package with the new banjo you will get.

[Dale Miner]

This is the first lathe I've seen that had chased spindle threads. All the others (and there have been many) have had ground threads.

It looks like the thread and relief areas were turned using very dull tools.

While the O.D. of the thread is under nominal, the pitch diameter is the more important dimension. That would require a set of thread wires to measure. When a chuck is screwed up to but not touching the unthreaded portion, does it seem like there is excessive loosenes in the fit between the spindle and the chuck (insert) threads?