New Grizzly lathe

[jwavem]

Has anyone done a review on the new Grizzly lathe Model G0456? It sounds to good for the price of $1500, 2 HP, 20"swing and variable speed.

 

[n7bsn]

Considering that they are only starting to arrive in their stores, my guess would be no.
But, based on comments in other forums. The 1-1/2x8 head-stock is going to be a problem (fewer 3rd party sources for parts), as the the high low end speed (500 rpm) and the lack of a hand wheel.

 

[hcbph]

There's a good thread going over at woodnet.com. Might be worth your time to have a look at it.

Paul

 

[coachlou]

Griz

I was anxiously awaiting the arrival of the new
Griz, but from what I've been reading, I think they really missed the boat on this one. I have the Griz cabinet saw and I'm very happy with it.
The new lathe, however, leaves a good deal to be desired. The low end speed is 500rpm, the high end is only 2000rpm, the built in disc sander seems more of a hiderance than a help, there doesn't seem to be any means for outboard turning, and the spindle size would be a real problem for me. In short, I'm probably going to take my saved up pennies and look in some other direction (or wait until Ive saved a few more).

 

[hcbph]

I had bought a Jet 1642 last spring for a job then heard about the Grizzly coming out. This is one time I'm glad I bought what I did, when I did.

 

[bob elliott]

Among the other things already discussed, I went to the PDF owners manual section and learned of a few other negative points.
1) D/C motor
2) Morse taper items are not removed from the headstock with a knock out bar. Instead, a threaded nut has to be placed on the spindle first & the morse taper item can be inserted after that. Then the morse taper item can be removed by loosening the nut. If one forgets to mount the nut prior to inserting the morse taper item, doesn't that mean you are "screwed" in terms of ever removing that morse taper item?
3) #2 above could also indicate that the spindle is not hollow.

Bob Elliott
Central FL Woodturners

 

[dkulze]

For $1500 or so you could definitely chase a nicer lathe. The Nova DVR comes to mind.

Dietrich

 

[Bill Grumbine]

Among the other things already discussed, I went to the PDF owners manual section and learned of a few other negative points.
1) D/C motor
2) Morse taper items are not removed from the headstock with a knock out bar. Instead, a threaded nut has to be placed on the spindle first & the morse taper item can be inserted after that. Then the morse taper item can be removed by loosening the nut. If one forgets to mount the nut prior to inserting the morse taper item, doesn't that mean you are "screwed" in terms of ever removing that morse taper item?
3) #2 above could also indicate that the spindle is not hollow.

Bob Elliott
Central FL Woodturners

Hi Bob

My Poolewood is built this way, and I have on several occasions forgotten to install the thread protector before inserting a taper. After the initial panic was over the first time, I developed a method for removing the taper, involving vise grips and a hammer. It ain't pretty but it works.

I also worked with another turner and machinist to develop a vacuum chuck that will work for solid headstock lathes, as well as any other lathe on the market, so that is not an issue either. However, there are plenty of other reasons not to buy this Grizzly lathe.

Bill

 

[bob elliott]

Hey Bill,

Yes, I'm well aware of your vacuum chuck for solid spindle lathes.

The thing with this Grizzly though, is that I just can't get past the D/C motor. We had a club lathe with a D/C and it was completely gutless! We had continuous complaints from most demonstrators until we got our Powermatic 3520a.

 

[john lucas]

If you get the smaller steb centers or mini drive centers you won't be able to get them out even with the nut in place.
I too do not like the DC drives. At slow speeds they suck and that's where you really need the torque.

 

[jwavem]

Review not needed

Has anyone done a review on the new Grizzly lathe Model G0456? It sounds to good for the price of $1500, 2 HP, 20"swing and variable speed.

Thanks for the information. I think I'll cross this one off my wish list. It did sound to good to be true.
jwavem

 

[MichaelMouse]

As Sherlock says, speculation without data is dangerous. Wonder what he'd say about speculation with only copywriters' information? Especially a copywriter who doesn't seem to know much about lathes.

Does it strike anyone else that 500-2000 may not necessarily be the spindle speed, but the motor, instead?

The low-torque complaint also seems strange given that DC motors are used in locomotives, haul trucks, and scores of other torque-hungry applications. In the small stuff, complaints probably had do with the old SCR controllers, which certainly pale in comparison to new high-frequency MOSFET types.

For a quick DC primer http://www.electricmotors.machinedesign.com/guiEdits/Content/bdeee3/bdeee3_1.aspx

I'm willing to bet that we're dealing with step pulleys first, motor control second. Building anything less in today's market would seem foolish.

Other "features," like the disk sander do seem odd, with one detractor elsewhere mentioning the thrill of trying to slow the lathe using it as a handwheel. Shouldn't be much of a problem, of course, because DC motors with MOSFET circuitry can brake pretty damn fast. Sharpening can be done there, that's for sure, and segmented turners should love it, if it's as sturdy as it looks.

Another detractor mentions the gap bed, with more misunderstanding demonstrated, as they forget a gap bed allows repositioning of the toolrest behind or in front of the piece without having to dismount it, the chuck or faceplate and cope with the vagaries of misalignment.

In short, folks seem to be jumping in to fault it on both the innovative and traditional design characteristics.

Of course, I've got the same data, or lack of it, that others have, just trying to think a bit more positively. Want to bet the copy is going to change real soon?

 

[Joe Fisher]

Does it strike anyone else that 500-2000 may not necessarily be the spindle speed, but the motor, instead?

The product manual is available at Grizzly's website. The manual says:

Specifications:
Spindle Speeds..... 500-2000RPM

Main Motor:
RPM.....2000-9000RPM (Variable)

The exploded parts diagram shows a single pulley on the motor and spindle. One range fits all.

-Joe

 

[Steve Worcester]

I would not discount it for any of the other reasons. Spindle thread is OK, same as my 70yr old metal lathe, through headstock is not a huge issue same as the Poolewood, DC motor no biggy, especially at 2hp. Single pulley DC is the deal killer. My guess was inorder to provide sufficient torque at the low end, they had to program it to 500rpm minimum, which for larger swing, is a deal killer (for me).

And the disc sander? It would not be something that I would have asked for in a list of must have lathe features.

http://www.grizzly.com/products/G0456

 

[Andy Hoyt]

I can only imagine that the guys in the Grizzly Left Over Parts from Other Machines Department cobbled this thing together - and not one of them has ever spun wood.

 

[Bill Boehme]

Behind every silver lining, there is a dark cloud. Every type of drive system for a lathe will have both advantages and disadvantages. I will mention some of these for various types of drives.

I am a bit surprised to read several responses concerning low torque at low speed for DC motors because typically DC motors reach their peak usable torque at stall and zero usable torque at theoretical peak RPM. Between these two extremes, torque and RPM are essentially inversely proportional. Since horsepower is the product of torque and speed, it peaks near the mid-point of the speed range and that point is defined as the rated RPM of the motor. Frequently the wiring, bearings, commutator, and brushes are not designed to operate all the way up to peak RPM since it would serve no useful purpose. The maximum speed is limited by defining the rated maximum operating voltage.

The speed of DC motors is easy to control with simple electronic switching circuits that makes them attractive from a cost standpoint although good DC motors are more costly than AC induction motors. Speed controllers for DC motors often are such simple devices that they do not utilize any torque or speed feedback. A lack of speed feedback can be especially bad and may be the reason that many turners interpret it as lack of torque at low speed. Briefly, what happens when the torque load increases is that the motor current increases proportionally, but the applied voltage (which governs the speed) stays the same. Some of the voltage that was used to control speed is now being used to pump more current through the windings so the available voltage for speed control is now less. The bottom line is that you need not only torque, but also speed regulation and electronic variable speed DC motors and drives don't do the job of providing both simultaneously. Also, keep in mind that the closer you get to zero speed, the less power output will be available.

The object of most every turner's desire these days seems to be three-phase AC induction motors with variable frequency drives (VFD) and they do indeed have a lot of advantages with simplified mechanical drive systems, but they also share some of the shortcomings of DC motors with electronic drives, not to mention that the drives are very expensive. The AC motors needed for inverter duty (i.e., variable frequency drives) are also expensive because they must withstand the harsh electrical environment of very high voltage spikes that would punch through the insulation of normal motors and must also withstand the harsh temperature environment when the motor is running slowly and not getting enough cooling air from the fan. The one thing that is different is that line frequency and not the applied voltage govern AC motor speed so speed regulation is normally much better than with DC motors, especially if the VFD uses either sensorless vector or encoder vector feedback (the latter is too expensive to even think about). These motors have a "base" speed, usually 1750 RPM, which is the speed when operated at 60 Hz. Below this speed, the drive is programmed to provide full torque output and above this speed, it is programmed to provide full horsepower output -- another way to say it is that above base speed, torque decreases inversely with increasing RPM. Just as in the DC motor case, the slower the motor turns, the less horsepower output is available. So either type of drive, AC or DC, will tend to seem wimpy at low RPM compared to a pulley drive lathe with the same sized motor. There are two ways around this problem: The first is to have a pulley drive system with at least two speed ranges (the cheap way). The other way is to use a much bigger motor to make up for the lack of oomph at low speed (the un-cheap way).

The humble, cheap, and technically boring mechanical variable speed drive offers a great advantage that the two previous systems do not. It is capable of outputting full horsepower at all speeds. This means that at the low end of the speed range, it will have a huge torque advantage over the electronic systems and it will be equal to them at the upper end of the speed range. The motor only runs at one speed so it is always happy. So, what is not to like about it, other than the fact that it is not high-tech? For one, mechanical parts wear and these mechanical systems have a tendency to set up mechanical resonances under various load and speed conditions. They also tend to be noisy and need much more TLC maintenance to keep them going. The belts also are doing well if they go for a year under regular use. It is hard to find a mechanical variable speed lathe that goes below 450 RPM, although they usually go to at least 3000 RPM at the top end. If you looked a trace of their speed on a chart recorder, you would also see that the speed is not a smooth value, but rather a very rough line that hovers around a central value -- sort of like looking at a seismograph. I suspect that this could affect the smoothness of the surface a turning made on this type of lathe (or maybe not -- it might be like a ROS finish).

Finally, the most humble step-sheave drive system. It has all of the good features of the above types plus lower cost. The downside is a limited number of spindle speeds and the extra effort (?) to change the belt from one sheave to another.

I haven't given my opinion about the Grizzly lathe, but you would not want to hear it anyway.

Bill

 

[john lucas]

Very interesting Bill as always, I enjoy your posts. I base my comments on practical experience. I've owned 2 DC powered lathes with 1 1/2 horse motors. I could stall both at low speeds with ease taking very light cuts. I then had a VFD installed on one of the lathes with a 1 1/2" horse 3 phase motor. Even as low as 60 rpm I had a great deal of trouble stalling the lathe even with big cuts. Now I have a 3 horse VFD and cannot stall it without taking huge cuts at very low rpms.

 

[Bill Grumbine]

Another detractor mentions the gap bed, with more misunderstanding demonstrated, as they forget a gap bed allows repositioning of the toolrest behind or in front of the piece without having to dismount it, the chuck or faceplate and cope with the vagaries of misalignment.

Well George, uhh, I mean Michael, I am a detractor of the gap bed, probably the one you mention in your post. Past experience with you is a good indication that this is one of your typical swipes. I based my comments on my own EXPERIENCE turning on gap bed lathes, specifically the Powermatic 90 and the General 260. I also have experience with a Blount lathe as well. There is no misunderstanding involved.

Do you really want to start on me here too?

Tell us about your experiences turning on one of these lathes, or any gap bed lathe. Do you have any? Let's parse your comments here:

...a gap bed allows repositioning of the toolrest behind or in front of the piece...

Really. I would like to hear how a gap bed allows a tool rest to be positioned behind the piece, i.e. between the piece and the headstock, since there is no bed there on which to rest it.

The fact of the matter is that there is no place to put the tool rest, and the "vagaries of misalignment", whatever that is supposed to mean, are very easily dealt with by simply unscrewing the chuck or faceplate with the piece still in it and moving the tool rest behind it, i.e. between the piece and the headstock. Of course, you cannot do that with a gap bed lathe, unless your banjo is equipped with anti gravity devices, not to mention stabilizers to keep it from wobbling while it is hovering there in midair.

To sum it all up Mouse, feel free to post your opinion, but if you are going to contradict and insult me (again), expect me to call you on your statements, and ask for proof. You didn't have any in the other place, and I suspect you won't have any here either.

 

[Bill Boehme]

Mr Lucas,

After thinking about it some more, I can see your position and I agree with what you say. My dealings with DC motor servo systems always involve a velocity feedback loop which means that the applied voltage is not some fixed value determined by a potientiometer knob, but by the sensed conditions of an electronic feedback control system. Under those conditions, the motor does indeed have full torque at stall because the control system will be applying full rated voltage to the motor. However, the big failure of speed controls on lathes are that they are just that -- nothing more than speed controls -- and they assume that the usable load torque (i.e., the torque other than what is needed to turn the motor at the desired speed) is zero. So, when the speed is low, so is the voltage applied to the motor. That limits the torque to whatever current can flow at that voltage while the motor is stalled. Not a good situation.

Thanks for pointing this out. I had an idea fixed in my mind that was based on what I am used to dealing with and just overlooked the obvious. I guess that I can't handle things that are simple. I need to revise my comments above.

And as you noted, most AC VFD's have plenty of torque at very low speed. That is because the drives are able to pseudo measure motor speed by sensing sync slip angle and then adjusting the drive frequency to make up for the sync slip.

By the way, I am converting my mechanical variable speed lathe to an AC VFD drive system. I was able to get a Baldor Vector Drive and a 1.5 HP Baldor TEBC motor with encoder feedback on eBay for just a couple hundred dollars. If new, they would have cost over $4K. Not that I need it, but the motor can develop full torque even without turning and go as fast as 6,000 RPM continuous duty. My lathe will also be a lot heavier when I am finished because the modification also includes two 60 pound transformers to convert my 240 volt power to 480 VAC power. I am still searching for some line reactors.

Bill

 

[Anthony Yakonick]

The gap on my 260 is filled, just couldn't take it any more.

 

[Bill Boehme]

The low-torque complaint also seems strange given that DC motors are used in locomotives, haul trucks, and scores of other torque-hungry applications. In the small stuff, complaints probably had do with the old SCR controllers, which certainly pale in comparison to new high-frequency MOSFET types.

Michael,

My last response to Mr. Lucas concerning DC motors would also be applicable here as these vehicles would be using an automatic control system with a velocity feedback loop which would always allow the maximum torque that is achievable for any given speed.

SCR's, Triacs, Diacs, MOSFETS, or Insulated Gate Bipolar transistors are all just the output power switching devices and have very little importance in this particular situation on what the low speed torque is. Without a means of sensing velocity, the controller is essentially running open-loop and what is really happening in the lathe DC controllers is that you are just setting an upper velocity limit when adjusting the potentiometer. Any subsequent change in load torque just causes the speed to drop off. Some smarter controllers try to "guess" the speed by comparing the pot setting to the current, but that can be fraught with stability problems, sometimes seen as speed "hunting". And, besides it is not very accurate anyway because of the variation between individual motors.

Bill

 

[MichaelMouse]

Well George, uhh, I mean Michael, I am a detractor of the gap bed, probably the one you mention in your post. Past experience with you is a good indication that this is one of your typical swipes. I based my comments on my own EXPERIENCE turning on gap bed lathes, specifically the Powermatic 90 and the General 260. I also have experience with a Blount lathe as well. There is no misunderstanding involved.
.

After about 20 years on Delta gap-beds, I'm pretty well experienced in how to exploit the strengths and work around the weaknesses. There are some who evaluate and analyze when encountering simple reality, where others bluster and complain. I believe the first group has a much better hope of understanding.

I find myself remembering the gap-bed almost fondly every time I go to fit my bowl steady to the new lathe. Fortunately the Teknatool folks left a convenient ledge for me to rest the bed clamp on below the ways as I fidget to align the stand and tighten the bolt, but it's no substitute for sliding the thing in right at the gap in the bed, that's for sure. Not to mention how easy it is with spindles to take the banjo off and fit a steady on the other side of it without removing the tailstock. Then there's the extra space if you faceplate a rough chunk, because you have a couple inches before you have to be precise enough to clear the bed.

But, I'm sure I bore you with all this, since you know it all anyway. For others, what is, in spite of our last President, is, and can represent either a challenge for you to understand, and possibly exploit, or be a cause of consternation forever.

 

[john lucas]

Bill I have to agree with you on the DC motors being used to drive large items like train. When I was in the Air force and working in Radar Repair we had large DC motors to drive the Antenna's. These were slow moving very heavy items. I wonder why lathe manufacturers can't do that. Is it just too expensive to build in motors and controllers with this capability? Or it could be a size problem. I remember the motors on industrial machines being quite large.
I've only played with one so take this statement with that in mind. I have been playing with a 1/2 horse DC treadmill motor. It seems to be much stronger pulling than the 1/2 horse VS motor on the Jet mini. Of course I know horsepower is often overated. I was wondering if there is something in the motor that makes is stronger or is it the specific controller they use. I haven't had time to try and wire one controller to the each motor to see if there's a differnce. It would be too much hassle to mount each motor but I would love to try it.

 

[MichaelMouse]

The product manual is available at Grizzly's website.

The exploded parts diagram shows a single pulley on the motor and spindle. One range fits all.

-Joe

Found it. Curious, this dial-up guy even downloaded the 7.7mb, all the time thinking there was no way a savvy company like Grizzly could bring out such a foolish product in the current market.

They did! Brushed DC motor, cheap controller, single-speed selection on the shaft, the whole thing. Fortunately, it looks like they have enough room on the shafts to at least put two pulleys, because this is not going to be a big seller even in a price-point only market. Could be tough to get access to a potential belt change without a major redesign.

Look for this one to go out or be revised very quickly.

 

[Bill Grumbine]

But, I'm sure I bore you with all this, since you know it all anyway.

No Mouse, I don't know it all and do not pretend to. I asked you to explain how you can put the tool rest behind the piece being turned. Now you are talking about how much you like your steady rest and how it fits in, but no answer about the tool rest. Can you please stay on topic? Now that is a question to which I already know the answer, but I'll ask it anyway.

I don't have a gap bed lathe, and it makes no matter to me who does or doesn't. It is an inferior design for the type of turning being done today. If it had all the advantages you say, current lathe design would still incorporate it (Grizzly excepted), but even your new lathe doesn't have one. If you like it so much, why did you change?

 

[MichaelMouse]

Michael,


SCR's, Triacs, Diacs, MOSFETS, or Insulated Gate Bipolar transistors are all just the output power switching devices and have very little importance in this particular situation on what the low speed torque is. Without a means of sensing velocity, the controller is essentially running open-loop and what is really happening in the lathe DC controllers is that you are just setting an upper velocity limit when adjusting the potentiometer.

Well, not necessarily. MOSFET circuits at least are programmable to provide the proper combination of voltage and frequency to provide maximum torque through the range of the motor. Exclusive of feedback. Brushless motors use this.

All moot, because this turkey is really just a universal motor.

 

[MichaelMouse]

No Mouse, I don't know it all and do not pretend to. I asked you to explain how you can put the tool rest behind the piece being turned. Now you are talking about how much you like your steady rest and how it fits in, but no answer about the tool rest. Can you please stay on topic?

Ah Bill, another conceptual challenge for you, I see. As I said in the first, I can take the banjo off the tail end (or use a second banjo) and slip it in behind the (still) chucked piece. This does, of course assume that sufficient space is available to accomodate it. When there is insufficient space, I don't do it. Easy, isn't it?

 

[Bill Grumbine]

Ah Bill, another conceptual challenge for you, I see.

You just can't make a point without a personal attack, can you Mouse? I'm offering opinions based on experience on many different lathes and in many different turning situations. I will let my reputation and the quality of my work as a teacher and a turner speak for itself. So you think I am challenged, a poor turner, and a lousy communicator, huh? Many hundreds of others don't seem to think so. Want to go toe to toe in the turning arena? Let's see some of your recent work. You have so much more experience than I do on the lathe, you should be able to put me to shame quite easily. Put up or shut up.

 

[Jeff Jilg]

Bill (Boehme) - what are you building? It sounds darned big! Is this going to be for production work or do you just want to build a real big lathe? Got any fun pictures to share?

Did you see James Johnson's trailer mounted bowl coring rig at the TTT (I mean Texas SWAT) symposium?

 

[Jeff Jilg]

Alright, there are too many arguments floating around which are not resolving anything. I'm locking this thread.