Ever tipped over a lathe?

[Brian Kent]

I was doing some base (from to back) vs height comparisons on a couple of lathes.

I know you can make most lathes flex or walk with too much speed on a big off-balance piece.
But has anyone every tipped over a lathe?

Something I do not want to do once, ever, in the life of the lathe (and in the life of me and of little shop assistants).

[daryl moses]

I suppose it's possible but I've owned two different lathes and never even come close to tipping one over.

[John K Jordan]

I was doing some base (from to back) vs height comparisons on a couple of lathes.
I know you can make most lathes flex or walk with too much speed on a big off-balance piece.
But has anyone every tipped over a lathe?
Something I do not want to do once, ever, in the life of the lathe (and in the life of me and of little shop assistants).

To get an idea of what angle a riding or zero turn mower can take jack up one side until it feels unstable. It's amazing how much tilt is possible, far more than feels safe.

I haven't tried this with a lathe but from the way the legs of most mine are spread and the way the weight is distributed directly over the center I suspect you would have to work very hard and probably destroy the lathe before it got to the tipping point.

BTW, concerning walking lathes - a friend of mine has turned large bowls from heavy blanks outboard on a fairly small fold Delta lathe. Instead of stabilizing with massive weights he simply fastened the lathe to the stud framing of his garage with pipe clamps. This used the mass of the building instead of the sandbags to dampen the vibrations.

JKJ

[Brian Kent]

Excellent idea, John. I currently have my Delta 46-460 anchored to a large table with 100 lbs. of pebbles in each support. I could get the table top shaking early on, but have gotten in the habit of starting slow enough to avoid that.

I am looking at the Grizzly G0766 and G0800 (for more than double the cost). The G0766 has feet 20" apart vs. 26" for the G0800. Add to that a little lower ways and 50% more mass, 2" lower spindle height, lower low end speed of 60 rpm on the G0800 vs 100 rpm on the G0766, and that "chuck guard" screen. Lots of geometrical reasons to go for the G0800, but I am not planning to set any size and weight records on what I turn.

Since I may never get a second chance to do this right, I am intentionally over-thinking.

[Reed Gray]

Hmm, never heard of that happening. I have looked at some of the new 16 and 18 inch lathes and have thought that the footprint was just too narrow for my taste. Can't remember which ones specifically, but there were a couple. Main difference would be a wider foot print will be better for balancing out uneven blanks.

robo hippy

[John Keeton]

Brian, the wide footprint was one of the features that drew my interest in the Laguna Revo 1836. With my ballast box on the lathe, it is rock solid.

[John K Jordan]

Since I may never get a second chance to do this right, I am intentionally over-thinking.

For a lathe (perhaps in the middle of the room) with a stand which seems too narrow for security it should not be rocket science to engineer a support to widen the footprint an inch or two, perhaps by adding 2x4 or steel bar against the floor. Until you do the math it's amazing how much difference even a small extension can make in stability.

JKJ

[John Keeton]

John, I guess what continues to puzzle me is that some of these lathes with large swings are being manufactured with what would seem to be less than desirable footprints. One would think that increasing the capacity of the lathe would necessarily indicate the need for an increased stance. But, I am not an engineer - only relying on what would seem to be common sense.

[Steve Arnold]

I live in earthquake country, but even here I don't think my lathe would tip over. It would probably just slide around on the vinyl flooring of my shop.

I hope though, that I never have to find out if I'm right.

[terry mccammon]

Well I am an engineer and I agree with John. I see equipment whose base seems narrow. I have never tipped a lathe over, but when I was teaching myself to turn I had a Nova 16-44. I also did not have a bandsaw. So I mounted an extremely heavy piece of soaking wet ash which was nearly square, plus there was a big lump sticking out the back side. At the lowest belt speed the near side legs were jumping about an inch off the floor.

It would be a fun exercise to calculate what sort of moment arm would be needed to tip a given lathe. My guess is that one could do the trick with a seriously out of balance lump.

[John K Jordan]

John, I guess what continues to puzzle me is that some of these lathes with large swings are being manufactured with what would seem to be less than desirable footprints. One would think that increasing the capacity of the lathe would necessarily indicate the need for an increased stance. But, I am not an engineer - only relying on what would seem to be common sense.

Seems to me the math would include finding the location of the CG at the headstock end, the weight, the footprint, and the worst-case amount of force from the biggest out-of-balance blank at the most critical speed. The critical speed might be related to the cyclic period of the inverted pendulum from the foot to the spindle, such that each force in one direction would provide a reinforcing push at the exact time. All else equal, as the mass of the lathe increases, the force would also need to increase. In addition, to tip the lathe something would have to constrain the feet to keep the lathe from simply scooting back and the forth on the floor, perhaps floor friction or a solid obstruction. But it's been so long since I've done math remotely like this I wouldn't remember where to start.

I'm imagining the higher mass of the bigger machines might actually take more out-of-balance force to tip over than the spindle, bearings, or chuck/faceplate could handle and something would break or the work would come off the lathe. I once envisioned an emergency shutdown circuit based on an accelerometer could be built to power down the lathe in the event of a continued severe imbalance.

Since a tip-over would probably cause someone to get hurt I can imagine that a high end lathe designer might test or at least model this to avoid liability issues. I've never heard of a lathe tipping over. I did find one report of an accident from a tipping metal lathe when the guy tried to jack it up from below. If I get time (maybe in November!) I might try measuring the static force needed to reach the tipping point on my 3520b. With the bed extension it probably weighs over 700 lbs.

Four concrete anchors would let the thing be bolted to the floor. I have these for my big air compressor.

JKJ

[John Keeton]

I should have clarified, I guess. I doubt any of these machines would tip over under any foreseeable use. I would think the concerns would be more the vibration and its effect on the turning process and the lathe walking and perhaps getting out of level by slight twisting, etc. it doesn't take a lot to mess with the center alignment.

[Roger Chandler]

[QUOTE=Brian Kent;2609488
I am looking at the Grizzly G0766 and G0800 (for more than double the cost). The G0766 has feet 20" apart vs. 26" for the G0800. Add to that a little lower ways and 50% more mass, 2" lower spindle height, lower low end speed of 60 rpm on the G0800 vs 100 rpm on the G0766, .[/QUOTE]

Brian........be aware that a lot of the manuals and spec sheets are copied and pasted from model to model on the Grizzly lineup, changing only parts of the manual. My 0766 has a low speed of 60 rpm, even though the manual says 100 rpm. It was the same way with my earlier 0698, only it "hunted" at that low end speed, and one had to get to about 100 rpm for it to smooth out, and that was due to the encoder in the D/C motor. That is why they changed the manual and spec sheet for the 0698 to adapt as several purchasers questioned it online here and other places.......instead of adjusting the machine at the factory to the stated specs, they just found it easier to change the specs listed on the website and subsequent manuals.

I regularly sand at 60 rpm on my G0766. Also, be aware that some of that extra weight in the G0800 is because of the cage, comparator arms, extra tailstock swingaway, and such. Basic lathe, In my opinion will not be all that much heavier, but will be some for sure.

It is also advisable, and good practice to balance a blank before mounting to any lathe..........that being said, I did want to test the stability of mine, and have turned blanks that were unbalanced and nearly 100 lbs. to start. My 0766 handled it well, but finding that harmonic sweet spot on the rpms is necessary, and in doing so, sometimes you have to go beyond the minimum you start out with. I did one large unbalanced piece of ash that would make the lathe rock-n-roll at 200 rpm, but at 260 rpms, it settled into a sweet zone, and only had a little vibration, which got better as I went through roughing cuts...........just FYI, so you do not overthink things by a country mile!

[Brian Kent]

I'll buy one or the other, and if it is the one with a 20" stance, I'll add the low sand box and make something to widen the stance.

In a way I think I am deciding between tires rated at 112 mph, 130 mph, and 148 mph, when I set my cruise control at 70.

[brian zawatsky]

I'll buy one or the other, and if it is the one with a 20" stance, I'll add the low sand box and make something to widen the stance. In a way I think I am deciding between tires rated at 112 mph, 130 mph, and 148 mph, when I set my cruise control at 70.

Great analogy. I do the same thing all the time lol

I'm very happy with my 0766 as well. Being a hobbyist turner (and wishing to remain happily married) I couldn't justify spending any more than that on a lathe. I did however want the ability (in swing and hp) to turn a large bowl, and the bed length to turn balusters if I desired to do so in the future. Put 100lbs of sand at either leg and she is steady and solid as can be.