Lathe mass?

[carl mesaros]

I have been reading with great interest the ongoing discussion about the new Grizzly GO766 lathe. I currently am turning on a Jet 1642 and have been considering moving up to a lathe with more swing and additional power and more mass.
So I started to compare specifications for several lathes, Powermatic 3520B, Oneway 2036, the new Grizzly 766 and 733, and the Laguna Revo 2036.
The net weight (not shipping weight) numbers were somewhat surprising. My current lathe weighs 410lbs and with large bowl blanks it shudders a lot.
So here are the specs.
3520B 630LBS.
Oneway 2036 800LBS.
Grizz 766 496LBS. Grizz 733 419LBS.
Laguna 2036 710LBS. Laguna 2436 770LBS.
I guess what I'm trying to say that weight has a bearing on lathe cost. And I think it is worth it to have the additional mass.
I recently saw the new Laguna lathes and was impressed. Don't know much about the motor but it has the Delta VFD. 6209 and 6208 bearings and very massive. I have put my lathe up for sale and plan on purchasing either the Laguna 2036 or the 2436.
Has anyone had a chance to check these out?
Just adding something to think about and discuss.

[John Keeton]

Weight distribution is important, as well. Additional mass high on the lathe can decrease stability. Stance of the base is important. If the legs are not splayed sufficiently, that can be a problem. I have about 350# of ballast on my 1642-2 and enjoy good stability. But, then, I don't try to turn 250# out of balance blanks.

[Olaf Vogel]

In general I'd agree that the more mass, the better.
Mine is about 1600 lbs and I've had that bouncing up and down - not comforting!

When I built my new shop, I agonized about how to add mass, or bolt it down to the concrete floor.
As the same time, the question was how to raise the lathe to my desired height (I'm 6'4").

It hit me one night that the solution is simple - if somewhat brut force.
Jack it up the desired height, put wood blocks under to keep it there.
Then pour concrete footings around, and over top (by about 3")

So its now secured to the floor (via rebar) and about 1000 lbs of concrete (which is real cheap).
I've had some huge blanks on there and it doesn't move - at all.
IMG_0576.jpg

sorry, no idea how to rotate these images - the orientation is somehow encoded.

Admittedly, if I ever want to move it, it will be a real pain the a**.
Olaf

[charlie knighton]

that is completing some serious planning, Olaf

[Reed Gray]

For shear mass, I don't think you can beat the Serious lathe, and it has a price to match. Adding ballast is another way to do it as is bolting it down to the floor, but some say that if it is too rigid, you wear out parts faster. I remember looking at the Grizzly and Jet lathes and thought their feet were rather close together. I have never been a fan of Grizzly tools. Cheap, but hit and miss unless you are buying their industrial grade lathes. Laguna does have fairly good quality, but their customer service is not the best.

robo hippy

[Thom Sturgill]

I find these discussions interesting. Like John I turn on a 1642 but mine is the 1 1/2HP version and no ballast, so 410#.

I mostly turn smaller items and am careful to get my piece is balance as quickly as possible so the extra mass has not been a big issue. On the other hand when I turn really *small* things - finials and doll house pieces - I need speed and the stability of a good spindle running on really good bearings. As a result I am looking to 'upgrade' to a smaller OneWay 1224 (300# - 4500RPM) while keeping and eventually replacing the 1642 with a Robust Liberty (also 410#).

BTW, the Robust American Beauty - short bed with Tilt away is 690#.

[Jeffrey J Smith]

Having turned on a Jet 1642 with 360 pounds of added ballast down low (I'm thinking that's 770 pounds total mass) and a Robust American Beauty at just shy of 700 pounds, it ain't the weight but the distribution. I was little surprised when I first took a trial spin on an American Beauty - with 25" of swing, the bed seemed very low compared to the Jet at the same spindle height. With the splayed legs and a little time spent levelling, the AB is literally as solid as a rock. I can routinely spin out of balance blanks that have twice the mass of anything the Jet could handle at easily twice the rpm's without moving a bit.
Take a good long look at the lathes that are most common out there - the Jet, Powermatic, Laguna, Grizzley, et al - and the clones that are just one tier down - they're all tall and leggy with what seems to be a narrow footprint. More weight up high where it's not helpful. Only the OneWay, the Robust and the Magma are any different. At the risk of igniting a flame war, after turning on something a little different and not based on 19th century machine design aesthetics or materials, the difference is astounding. For stability, you can pile on the cast iron like the serious does, or resort to bolting the thing down (without resolving the vibration issues), or you can design with modern materials and processes.
Okay, go ahead - I've already ducked down behind the pile of sandbags that used to hold the PowerMatic in place. Fire at will...

[George Troy Hurlburt]

Get a Robust and be done with it. A lathe with many features and factory backup. Made in USA.

[Thom Sturgill]

Good point - get a machine with a large swing (even if you don't do large diameter) to handle out of balance blanks. The larger the swing the lower to the ground the bed, and hence the center of mass, will be.

[Olaf Vogel]

Additional mass high on the lathe can decrease stability.

I'm tempted to agree, but also have reservations.
If you push against the lathe, or are trailering it and go around a corner, then absolutely this is true.

however, our typical turning scenarios are unbalanced blanks which cause vibration (back and forth, hopefully not up and down).
In such cases, loading the weight at the top, near the (or inline) with the spindle, might actually be optimal.
Note that most metal lathes (which bear huge weight) are built like that.

Assume the vibrations start to rock a lathe back and forth, then you want the weight as high as possible (rocking with the lowest frequency), to add stability (assuming it doesn't fall over - which is hard)
There was an article about a CDN turner who moved his lathe out in the summer and mounted a vertical extension on the headstock, with a concrete bucket about 4' above. He claimed it really helped stabilize things. To me it makes sense - assuming all other things are equal.

Optimally, you want the legs, at the headstock, very far apart, to counteract such stress.
On mine a 5' long steel 4x4 is bolted on, that's bolted onto a concrete footing. It won't move.

I have tried 250# unbalanced blanks and it works just fine. The headstock is rock solid.
However, I have seen the bed flex at that point...a bit disconcerting. Thats when I turn down the rpm's.

[Leo Van Der Loo]

I pulled your lathe off of the ceiling Olaf, much safer now

lathe.jpg

Mij lathe is over 2000 pound and bolted to the concrete floor, it acts as ballast that doesn’t move around, though I have felt the concrete flex a time or two with the heavy chunks of wood that I have spun on there.

heavy lathe.jpg lathe base.jpg Outboard turning setup.jpg

Some of the heavy stuff
large wood.jpg Maple bowl.jpg Maple crotch bowl.jpg

[daryl moses]

Holy crap, that's some serious wood. I would love to follow you around the shop for a few days Mr. Van Der Loo.

[charlie knighton]

oh.....start with tearing down building to get an I beam to set lathe on......omg

[Olaf Vogel]

I pulled your lathe off of the ceiling Olaf, much safer now

Awesome - thanks. I can stop wearing my hardhat around the shop now.

My lathe is over 2000 pound and bolted to the concrete floor, it acts as ballast that doesn’t move around, though I have felt the concrete flex a time or two with the heavy chunks of wood that I have spun on there.

lathe base.jpg Outboard turning setup.jpg

Interesting pics. You've done a few things I was speculating about. Successfully!

1 - the stance of your lathe (and riser) is quite narrow, OK its set into the floor and thats a pretty large diameter pipe (presumably full of concrete as well). But it shows that a wide stance is not required.
2 - most of your mass is up high: metal lathe, heavy bed, heavy headstock. To reiterate my argument above, its like a metronome. The higher the weight, the slower the oscillations. Lots of weight, like this and its harmonic would be very low, may a few hertz. However, we'll spin blanks at more 200 rpms, so those induced oscillations will be much higher. And their secondary harmonics will be higher by multiples. So the rotating blank will want to vibrate at say 60 hz. But the lathe will only vibrate at 3 hz.
Hence the top heavy design acts as damper.

Ex. the Citibank building in NY has a massive weight near the top floors to prevent it from swaying in high winds.
"tuned mass dampers - a 400-ton concrete ball at the top of the building - that would compensate like a stabilizing force for the movement in wind, was added"


Leo, you've shown that works. Despite it sitting on an i-beam - which does not have great torsional stability.
I know because my bed is made from two i-beams and I've seen these twist at high loads - similar to yours.

3 - from the first pic there you've added vertical gussets to the i-beam, presumably to counter that twisting. Did that help? I was considering having those welded onto my bed for the same reason.

Thanks for sharing the pics.
Olaf

[John Keeton]

Olaf, you and Leo are operating on lathes that are in an entirely different category than the typical Jet, Grizzly, etc., and handsomely so, I might add!!

But, in the lighter weight category, I will stick with my theory that simply adding more weight high on the lathe "can" decrease stability. Obviously, there are other factors, including the splay of the legs, which I believe is very important.

At the risk of stirring up the hornets, there are two things that concern me with the Grizzly 0766, based solely on the only pic available. The leg stance appears to be narrow, and the height of the bed (thickness from top/bottom) doesn't seem to be increased for the extra weight of the headstock and extended length of the bed. Add to that, the increased weight above the typical center of gravity, and I think the stability could be compromised. In addition, I think there may be some weakness in the bed that could cause sway affecting the alignment of centers.

For those that are purchasing, I hope I am wrong, as the lathe does seem to otherwise offer value. Again, none of us really knows at this point, if those conditions are true. When we get some hands on reviews, then more will be known. In the meantime, I am happy with my Jet!!

And, again, congrats to both you and Leo for some REALLY OUTSTANDING equipment and some extraordinary engineering and design work.