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.
309484

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 ;)

309493

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.

309497 309496 309498

Some of the heavy stuff
309499 309500 309501

[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.

309496 309498


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!!:D

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.

[William C Rogers]

Well compared to Leo's and Olaf's lathes I have a 700 mini PM 90 (still setting up after move). To move I put it on a couple oh HF small moving dollys. It was top heavy doing that. I haven't noticed any stability problem, but also have not cannot turn the mass you guys can. Still learning.

Note: Olaf, thanks for reminding me to put a floor sweep near the lathe.

[Olaf Vogel]

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.


John

Sorry for the thread hijack - these are all very good points.
For a 22" swing, it does look a bit light, but offers a lot of features for the price.

With manufacturing mostly overseas and shipping weight being an economic issue, there is the temptation to make them lighter.
Something that didn't apply in 1880 when mine was poured.....
(and still running on the original babbitt bearings...)

[carl mesaros]

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.

Very good point John and the specs below prove that the higher end lathes use a wider footprint along with more mass.

Grizz 766 23""
Grizz 733 19"
Oneway 2036 32"
Robust 29-30"
Powermatic 3520B 24"
Laguna Revo 2036 26"
Jet 1642 20"

[Dennis Nagle]

Mine weighs 4008 lbs but once in a while an out of balance peice will make it shack and "almost" move. It is an Oliver 20D.

http://i9.photobucket.com/albums/a60/djnagle/010_zpse9058a7c.jpg (http://s9.photobucket.com/user/djnagle/media/010_zpse9058a7c.jpg.html)

[Thom Sturgill]

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.

Very good point John and the specs below prove that the higher end lathes use a wider footprint along with more mass.

Grizz 766 23""
Grizz 733 19"
Oneway 2036 32"
Robust 29-30"
Powermatic 3520B 24"
Laguna Revo 2036 26"
Jet 1642 20"

I would agree totally. Lyle Jameison has an interesting video on You tube about this -https://www.youtube.com/watch?v=AWYEPfqRet8 (https://www.youtube.com/watch?v=AWYEPfqRet8)

[Dale Miner]

Mine weighs 4008 lbs but once in a while an out of balance peice will make it shack and "almost" move. It is an Oliver 20D.



http://i9.photobucket.com/albums/a60/djnagle/010_zpse9058a7c.jpg (http://s9.photobucket.com/user/djnagle/media/010_zpse9058a7c.jpg.html)

Color me envious.

[Leo Van Der Loo]

Olaf, yes the gussets are required, as the single centre web isn’t able to stop the twisting, so at the lathe mounting areas I have welded the gussets in and there is no twisting as is.

I used the pieces of thick walled high pressure pipes to have nothing to stumble over, 6 bolts in the concrete hold it down, originally I had just four but found that the working of the lathe would loosen the bolts in the concrete, so added two at the heavy end, I never had to re-torque the bolts again.

I have moved and brought the lathe along, that was quite a chore, disassembled the lathe and though still heavy pieces I could handle them, the base was near impossible.
using steel pipes as roller I was able to get it closer to my trailer, them with a hydraulic jack I was able to lift one end high enough to back the trailer under that end, then with a come along pulled it into the trailer, sliding it out was much easier, (Back-up and a hard stop got it to move right out, didn’t hurt itself :rolleyes:)

I have a couple of pictures of people that used higher placed weights to reduce oscillation/vibration, I also talked to a turner years ago that used weight on a rod to help steady his home-build lathe, (John Williams I think was his name) I had pictures of his setup, but somewhere along the line with getting new computers I have lost them, but there was a writeup about it, and the anti-vibration setups in the pictures below sure look like a takeoff of his idea.

According to John he did have to fiddle with the height of the weights every time to get good results, anyway he bought a new big Oneway lathe and never looked back.

Here are the pictures I have, but I can’t guarantee that they do work as was claimed :)

309544 309546

This doesn’t look very safe, and I doubt that there is much need for it, if only turning relative small pieces like shown, but it was proffered :D
309545

[Leo Van Der Loo]

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!!:D

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.

Yes John it isn’t all straight forward, however weight at center height will do more than that same amount strapped low to the legs, as you will have something like a lever,.... where the power is applied to the top and it can move/lift a lot more weight at the bottom with relative little power/weight shifting, a lot more is required to move that same amount of weight at the spindle height, splay the legs and the low weight will have more affect, as the lever affect diminishes, but adding a tripping hazard, it isn’t always a win-win.

Sorry for the hi-jack, but well worth it I think :o

[Roger Chandler]

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!!:)

Just as a point about the bed thickness on the G0766 that JK mentioned ..... the spec sheet lists the bed at being 10 inches in width........my 18/47 G0698 is 7" in width on the top and 8.5" on the bottom.........not sure if their measurement is at the top of the bed or bottom of its casting, but if the spec sheet is correct, then they have added considerable mass to the bed, over the 18/47 units and the stance is wider as well.

[Dale Bonertz]

Carl,
The only experience I have had with the new Laguna is that our woodcraft store got one of the first units to test drive. It has been used at our club meetings and it seems to be quite and runs smoothly. The demonstrators were impressed by it. Now this doesn't speak of their ongoing customer service issues in which I hope they have cured. It also doe not speak of the lathes longevity since any new machine may run and operate smooth at first and after a bit of wear and tear things change. BTW it was the 2036.

[Olaf Vogel]

Yes John it isn’t all straight forward, however weight at center height will do more than that same amount strapped low to the legs, as you will have something like a lever,....

Heres a practical example, if somewhat rough in execution:
http://www3.sympatico.ca/3jdw8/antivibration.htm

A lot of old metal lathes employ the same idea. The motor is mounted above:
http://vintagemachinery.org/photoindex/detail.aspx?id=11728

If you are worried about a 500lb lathe with a 50lb top heavy mass tipping over, you can always attach it to the wall (loosely), but the point about vibration damping remains.

btw rigidly attaching the headstock to wall for the same purpose does not work.
Don't ask how I know....😳
olaf

[carl mesaros]

Carl,
The only experience I have had with the new Laguna is that our woodcraft store got one of the first units to test drive. It has been used at our club meetings and it seems to be quite and runs smoothly. The demonstrators were impressed by it. Now this doesn't speak of their ongoing customer service issues in which I hope they have cured. It also doe not speak of the lathes longevity since any new machine may run and operate smooth at first and after a bit of wear and tear things change. BTW it was the 2036.

Thanks for the information Dale. There just hasn't been much written or discussed on this lathe. The numbers sound good but as you mentioned hard to say on the longevity side. The electronics (Delta), and bearings (one step above Powermatic) seem fine. The only concern would be the motor, which I understand to be a DC brushless. Is that good or bad?
The lathe (2436) has the size and weight I've been looking for. I'd love a Oneway or Robust but hard to Justify almost double the price.
Thanks again for the information.

[Roger Chandler]

Thanks for the information Dale. There just hasn't been much written or discussed on this lathe. The numbers sound good but as you mentioned hard to say on the longevity side. The electronics (Delta), and bearings (one step above Powermatic) seem fine. The only concern would be the motor, which I understand to be a DC brushless. Is that good or bad?
The lathe (2436) has the size and weight I've been looking for. I'd love a Oneway or Robust but hard to Justify almost double the price.
Thanks again for the information.

Carl........the Laguna line used to be the same as the Grizzly.......at least in the 18/47 lathe. My [well it has been sold now, but] Grizzly G0698 has a D/C brushless motor [2 hp] and it has been going strong for over 5 years with pretty steady usage. I did some research on D/C brushless motors, and they are smaller than A/.C and are generally more efficient than a carbon brush motor on most A/C for the same hp rating. They can be used with a controller inside the motor to read torque requirements so they are suited to applications where low rpm and high torque are required, such as wood turning. They also run much cooler than a brushed motor.

I would think you would be in good shape with the Revo 2436. There is a NZ turner who has gotten one [basically same lathe with another label on it] and he speaks highly of it over on WOW........don't remember his name off the top of my head. The Revo 2436 has a place to connect an outboard attachment at 90 degrees to the ways, if I recall, so you might like that feature as well.

Do a google search for brushless D/C motors and read up on them........they are used in lots of industrial settings where reliability is required, so if you educate yourself, you might alleviate your concerns.

[carl mesaros]

[QUOTE=Roger Chandler;2394015]Carl........the Laguna line used to be the same as the Grizzly.......at least in the 18/47 lathe. My [well it has been sold now, but] Grizzly G0698 has a D/C brushless motor [2 hp] and it has been going strong for over 5 years with pretty steady usage. I did some research on D/C brushless motors, and they are smaller than A/.C and are generally more efficient than a carbon brush motor on most A/C for the same hp rating. They can be used with a controller inside the motor to read torque requirements so they are suited to applications where low rpm and high torque are required, such as wood turning. They also run much cooler than a brushed motor.

Wow Roger thanks for all the information. One of the "selling points from Laguna" talks about increased torque at low rpm because of the DC brushless motor.
I have followed your comments about your Grizzly 698 for quite sometime but didn't realize it also ha a DC brushless motor.
I am really looking forward to your review of the new GO766. Hopefully it arrives soon.
Thanks again Roger for the info.

[Eric Coyle]

years ago buddy dave tuttle showed me his lathe stand built with baltic biirch hollow end legs which he filled with sand for wieght/mass. When he moved, and you pay by the pound, he just dumped out the sand, filled the hollow legs with his lathe tools (instant packing boxes!!) and moved on. Very clever I thought.

Eric in Calgary

[Scott Brandstetter]

Was poking around on the internet and looking at lathes and took a look at Nova 2024. All of a sudden this thread came to mind and I was surprised to see that the assembled weight of this large lathe is only 350#. I know this is a popular lathe but really got me thinking how a lathe of this size could be so light.

[daryl moses]

Was poking around on the internet and looking at lathes and took a look at Nova 2024. All of a sudden this thread came to mind and I was surprised to see that the assembled weight of this large lathe is only 350#. I know this is a popular lathe but really got me thinking how a lathe of this size could be so light.
For one reason it is only 24" between centers.

[David C. Roseman]

I guess I must be missing something in this thread when John and others speak of adding weight "high on the lathe." Sure, higher on the lathe raises the lathe's center of mass. But I'm not sure what that means in the context of several of the Asian-built models mentioned. :confused: The cast iron leg design on the Jet, Grizzly, Laguna, PM and others makes it easy to add lots of weight low on the lathe, actually lowering the center of mass considerably. Here's a pic of my Grizzly G0733, with a ballast box made from the lathe's packing crate. I was able to get 450 lbs of masonry sand in the box, no problem, in nine 50 lb plastic-sealed bags. Don't know what the net weight of the lathe alone is, but shipping weight is listed as 547 lbs, and I don't recall the pallet and shipping hardware being more than 100 lbs, if that. So I figure my lathe as ballasted is around 900 lbs. FWIW.

[Cary Falk]

Don't know what the net weight of the lathe alone is, but shipping weight is listed as 547 lbs, and I don't recall the pallet and shipping hardware being more than 100 lbs, if that.

I have issue with the stated weights of the Grizzly lathes. G0733 - net 419lbs, shipped 550lbs; G0766 - net496, 662lbs shipped; PM3520 net 630lbs, shipped 682 lbs. I have many Grizzly tools and none of them came in a 166lb box. 50lbs at best which is what PM is quoting. My ex Jet 1642 had maybe 50lbs of plywood and pallet. I think I will weight the parts of the G0766 when it arrives and report back for the record because I have nothing better to do.:D Where did you get the bed attachment on the right side of the lathe that the rool rest is sitting on? I didn't think Grizzly offered one.

[John Keeton]

I guess I must be missing something in this thread when John and others speak of adding weight "high on the lathe." Sure, higher on the lathe raises the lathe's center of mass. But I'm not sure what that means in the context of several of the Asian-built models mentioned. :confused: It means one has to add even more ballast to offset the added weight higher on the lathe. I also have considerable ballast on my Jet 1642-2, similar to what you have done.

[Roger Chandler]

Where did you get the bed attachment on the right side of the lathe that the rool rest is sitting on? I didn't think Grizzly offered one.

Cary, there were several vendors around the world that carried their own model of the same 18/47 lathe......David's bed extension likely came from Busy Bee (CT128 lathe) in Canada or perhaps it was Laguna.

[Thom Sturgill]

An adult on a bicycle has a center of mass somewhere near the level of the seat. An adult on a motorcycle has the center of mass somewhere near the level of the wheel hubs. Anyone who has ever ridden both will tell you that a motorcycle is more stable than a bicycle. I think the same logic and physics apply to the lathe, while this idea of putting weight above the lathe seems to be trying to create the effect used by wire walkers.

Having worked many years in power plant construction, I know that there any stationary machine had its legs bolted down on grouted pads after levelling.

[David Delo]

Having worked many years in power plant construction, I know that there any stationary machine had its legs bolted down on grouted pads after levelling.

Had a customer once in MI whose shop burned down destroying his CNC machine. Insurance company gave him a large lump sum of money to replace it only because it was bolted to the floor. If it hadn't been bolted to the floor, he would not have been covered insurance wise because that piece of equipment wouldn't have been considered "a part" of his shop. The insurance company sent their claims guy in there specifically to see if the machine had been bolted down. Not sure if insurance reasons might be why you see equipment bolted down in commercial & industrial setting or not.

[David C. Roseman]

Had a customer once in MI whose shop burned down destroying his CNC machine. Insurance company gave him a large lump sum of money to replace it only because it was bolted to the floor. If it hadn't been bolted to the floor, he would not have been covered insurance wise because that piece of equipment wouldn't have been considered "a part" of his shop. The insurance company sent their claims guy in there specifically to see if the machine had been bolted down. Not sure if insurance reasons might be why you see equipment bolted down in commercial & industrial setting or not.

Thom and David, interesting point. I suspect that is indeed the case in many commercial settings. The way a policy is written may require equipment to be "permanently installed" in order to be covered as part of the premises, as distinguished from being scheduled separately. Bolting a machine to the floor may be enough to make it a fixture in many jurisdictions, hence permanently installed. An identical machine sitting next to it that is not bolted down may be a dead loss. Good reason to read the policy carefully before the fire, hurricane or roof collapse from snow load. :eek:

[David C. Roseman]

[snip] Where did you get the bed attachment on the right side of the lathe that the rool rest is sitting on? I didn't think Grizzly offered one.

Cary, Roger is correct. Mine came from Busy Bee, and is for the Craftex CX802 18 x 47 lathe. Bolts right up to the G0733. Here's the link: http://www.busybeetools.com/products/outboard-extension-for-cx802.html Price is stated in Can$, BTW. I think I paid around US$100 two years ago, including shipping, so either it's on sale now or the price difference is due to the tool rest not being included. Can't recall if mine came with a tool rest. The banjo height extender is bored to 25 mm, so the OEM Grizzly tool rest fits, in any event. My extension came painted green, but Grizzly had sent me a small bottle of touch-up paint for the G0733, so I just painted it to match.

OP, apologies for the thread hijack!

[Thom Sturgill]

I had not thought about the insurance angle, you may well be correct. I know the only reason we had a safety engineer was because we got enough reduction in insurance to pay his wages plus some. I've often thought that if I sold insurance to woodworkers, I would probably want to raise insurance rates for customers with non-flesh sensing table saws by enough that they would upgrade for the savings, and things like lathe safety cages would have to be installed if I visited. A lot of safety 'regulations' are really insurance related not government and not based on real engineering either.

But this is drifting way off topic.

[Olaf Vogel]

We are talking about stability and IMO there are two separate issues:

1 - Stability - the lathe falling over is clearly not desirable. Design considerations like: a wide stance for the legs, lower centre of gravity, more weight, are all good measures. After purchase customization or install things like: mechanically fastening it down, adding more weight will all help.

There’s many good, easy solutions for this as mentioned above

2 - Resistance to vibration, caused by unbalanced blanks is much more complex.

The motorcycles vs bicycles is not a fair comparison (this is a bit off topic, but give me a chance)

The "stability" of a two wheeled vehicle (bike) is generated by the gyroscopic effect (rational inertia) of he spinning wheels. The wheels on a motorcycle are much heavier and spin much faster than those of a bicycle. Hence a motorcycle could have more "stability".

In fact it could have so much that you would not be able to wrench the bars off a straight line. Both are designed with a angle on the headstock, known as rake, and an offset on that angle, known as trail. Manufacturers spend huge efforts tweeting both to get a blend of straight line stability vs agility, the ability to turn the thing. http://www.motorcyclejazz.com/motorcycle_physics.htm#wheel_stability

A Harley will go straight down a road because it has tons of rake and trail, less because of the high weight, but won't turn that well.
A Ducatti, will have much less rake and trail, hence will turn better,but have less straight line stability. The physics of steering can get really complicated.

So it does;t have much to do with the center of gravity….nor relate to lathes. So what does?
Neither motorcycles or bicycles go in a perfectly straight line. They oscillate left and right around the center line.

Similar to lathes,with an unbalanced blank loaded. They oscillate, left/right/up/down around the spindle.

Assume, that only the front legs are bolted down, so you know have a pivot point: the legs.
(Silly and we’ll never do it, but it simplifies the motion and explanation.)

Now spin up an unbalanced blank; lathe will rock back and forth, pivoting on the front legs, at a certain frequency, with a certain amplitude. The beat up General at the local high school did that beautifully. Narrow stance, lousy bolting made it worse.

So how to minimize that vibration?

Here’s an example:
Take a soup can, hold it close to your chest and shake it up and down by 3 inches, 3 times a second. Easy
Hold it at arms length and try to shake it at the same frequency and amplitude. Very Hard.

So to dampen vibration we want the mass as far away from the pivot point as possible.
In lathe, you want it as high as possible (spindle height or higher)

So what about adding more mass? That always helps right.

Replace that soup can with a 20 lbs weight, shake to close to you body. Much harder than before to hit the same frequency.
Hold it at arms length and repeat. Likely impossible to shake at the same frequency and amplitude.

So more mass, farther from the pivot point (the floor) is even better.
Assume you could rigidly bolt the mass to the top of the headstock, this will provide even better vibrational resistance.
In my case the headstock assembly is about 1000#, all rigidly bolted together.

That's serious vibration damping.

__________________________________________________ ___________________
OK but we’d never set up a lathe with only the front legs bolted down. Normally we would:

Not bolt it down at all. The weight of the lathe will resist vertical vibration.
But if there’s little mass at the top, there not much resistance to vibration front to back. This would severely limit the size/weight of working with raw blanks.

Or: securely bolt all four feet down. Now you are trusting the lathe to provide mechanical stiffness and strength. The headstock bolts to the bed, likely very strong. The bed bolted to the legs, likely very strong. Triangulated legs, likely very good. So all that vibration is being rigidly transmitted to the feet, not always that strong and could break.

The bolts and anchors holding everything to the floor - not that good. That vibration over a long time can works a lot of things loose, included lag shields in concrete. In my case, I don’t trust them, and just poured more concrete to ensure nothing moves.

Overall, it depends on the problem you are solving.
(can you tell I was a physics geek?)

Olaf

[carl mesaros]

Carl........the Laguna line used to be the same as the Grizzly.......at least in the 18/47 lathe. My [well it has been sold now, but] Grizzly G0698 has a D/C brushless motor [2 hp] and it has been going strong for over 5 years with pretty steady usage. I did some research on D/C brushless motors, and they are smaller than A/.C and are generally more efficient than a carbon brush motor on most A/C for the same hp rating. They can be used with a controller inside the motor to read torque requirements so they are suited to applications where low rpm and high torque are required, such as wood turning. They also run much cooler than a brushed motor.

I would think you would be in good shape with the Revo 2436. There is a NZ turner who has gotten one [basically same lathe with another label on it] and he speaks highly of it over on WOW........don't remember his name off the top of my head. The Revo 2436 has a place to connect an outboard attachment at 90 degrees to the ways, if I recall, so you might like that feature as well.

Do a google search for brushless D/C motors and read up on them........they are used in lots of industrial settings where reliability is required, so if you educate yourself, you might alleviate your concerns.

Well I did it. Last Friday I drove to Columbus and picked up a new Laguna 2436 lathe. I took advantage of Woodwerks Laguna 10% off sale and by purchasing the 20" bed extension they gave me the 12" swing-away.
I will submit a full review once I have it set up and the shop re-organized.
I will say it was packaged very well. Thanks to my neighbor and his tractor, end loader,and Gator we got it unloaded and the legs mounted. What a job!

[Roger Chandler]

Well I did it. Last Friday I drove to Columbus and picked up a new Laguna 2436 lathe. I took advantage of Woodwerks Laguna 10% off sale and by purchasing the 20" bed extension they gave me the 12" swing-away.
I will submit a full review once I have it set up and the shop re-organized.
I will say it was packaged very well. Thanks to my neighbor and his tractor, end loader,and Gator we got it unloaded and the legs mounted. What a job!

Congrats Carl on the Revo 2436..........looking forward to hearing about your impressions and experiences on the first couple of projects!