suggested weight for a lathe that has a 30" diam capacity

the lathe itself weighs 200lb and the bench im building weighs about another 100lb. is that enough to make it not dance with me while turning big off center/not balanced pieces? or should i fill the two pockets i made with sand to add another 50lb total?

Reply to
bizHB
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How big is big? How off-balance is not balanced? How slowly can your lathe turn and still maintain usable torque? Details, details...

My lathe weighs 600 lbs, btw.

Bill

bizHB wrote:

Reply to
Bill Rubenstein

Judging by the advertised specs. of lathes on the market with 30" diam. capacity, it's hard to believe a 200 lb. general purpose lathe could be designed to swing 30". Is it an unmodified machine, professionally designed, engineered and manufactured? I realize that mass alone doesn't determine a machine's capabilities, but that seems too skimpy to start even 30" platter blanks, unless maybe the blank is round, homogenous, lightweight and balanced. I don't think an additional 150 lb. will allow a 200 lb. lathe to swing 30" of anything you are likely to turn.

Bracing to a wall or ceiling or fixing to the floor might end your waltz, but you two will sure shuffle in place or more likely the bearings and headstock castings will jitterbug or rock & roll. Probably better to be a 'wall flower' than dance to the total exhaustion of both of you. :) Just my own experience and opinion, which may not be typical.

Turn to Safety, Arch Fortiter

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Reply to
Arch

my lathes slowest speed is 425 rpm. the biggest piece ive turned so far was 20" but i got the lathe because i liked the idea of being able to do 30" i just havent been able to get my hands on any chunks that size. i think pieces over 20" will be at worst square and a bit off center. but most will be close. the pieces till 20" will most likely be logs cut the length of thier diam and them turned sidegrain. so i guess im asking how much weight is needed to hold down a 20" diam by 8" wide (most likely green) branch or trunk wood turning sidegrain? just as a comparison i looked at the oneway 1224 lathe and it weighs

300lb. do people who own that lathe feel that its sturdy and heavy enough or did they add more weight? thanks ~B
Reply to
bizHB

Build it, mount a 30 inch off-center/unbalanced blank, turn it on, stay out of the way, apply lessons learned to building mark II...nothing quite like experience if you've come to be asking this question at this point in the build, rather than before starting...

FWIW, my piddly little 20-inch swing lathe weighs in at over 800 lbs.

Weight-wise, you are in the same range as a ShopSmith (180-200 lbs or so) plus a 100-lb bag of chicken feed laid on the ways. That happens to be a combination I've actually turned on, and I would not care to try it with a 30 inch swing, never having approached the Shopsmith's 17 inch swing - however, that setup is also limited by small spindle size and a low speed that's too high. It would dance with a piece of firewood you'd have a hard time getting a 4 inch cylinder out of.

Given the limitations of the internet as a communications medium, I admit I could be judging you harshly - perhaps your setup is well designed, and has a nice slow speed drive system with a beefy spindle, yet does not weigh much, and will actually work fine. If so, consider going to the local reloading supply place and getting some shotgun reloading shot, which weighs a bit more than sand, and fill your boxes with that.

Good luck with whichever of Mark I or Mark II works out for you.

Reply to
Ecnerwal

Man, that's not enough to turn 5" weed pots. I have experimented extensively with the weight issue, having owned several lathes and having built several benches. Yeah, you can get by with 300 pounds, total, but it is very, very far from ideal. If you build a big, sturdy bench with a large (full length, full width) boxed-in container for sand, and then start pouring in sand and using the lathe after each sandbag is added, you will quickly realize that more weight is better, and better, and better.

A lathe really smoothes out and settles down for small pieces (5" - 6" tall, 9" bowls) at around 700 pounds. For medium size pieces (up to 10" hollow forms, 12" - 13" bowls) 1000 pounds seems adequate. Right now I wouldn't own a lathe/bench combo that doesn't weigh at least 1000 pounds, except for my mini-lathe, of course. It was a real eye-opener when I first began experimenting with this, you've got to experience the results to believe it, but it really makes a difference.

I remember when my Powermatic 3520 was delivered, I began using it as it was, weighing 700 pounds out of the box. But then I put in a 16" wide shelf, added another 350 pounds of sand, and the results were very much more to my liking.

And I'm not talking about roughing large, out-of-balance blanks. I don't do large work, and I do a pretty good job of rough truing before the blank is ever mounted on the lathe. Even for general turning after the piece is roughed and balanced, a heavy lathe is a joy to use. It really smoothes out and makes all the turning steps more pleasurable. Massive weight is the key to making your lathe perform the way it was meant to. Once you try it, you won't ever want to go back to a lighter lathe.

-mike paulson, fort collins, co

Reply to
Mike Paulson

In my opinion, 425 rpm is too fast to start just about ANY piece which is off balance. The heavier it gets, and the greater the diameter, the more dangerous it becomes.

The problem is mitigated a great deal if you are able to use tailstock support. Without tailstock support, I'd go for a coffee break if I were sharing a shop with you and you fired up a new project such as we are discussing.

Bill

bizHB wrote:

Reply to
Bill Rubenstein

A stationary mass is a great mitigator for rotating mass, but not the end all and be all. Stiffness of the lathe, headstock, and shaft are also important. A two ton lathe with a 1/2" shaft poking from a sheet metal headstock is not going to spin a 30" bowl for very long. Bolting a machine to the floor adds mass and stiffness, too.

Dan

Reply to
Dan Bollinger

Not sure of the mathematics. Bill, Ec, Mike or Dan can explain it better, but I think the difference in swinging a 24" blank and a 30" blank would be surprising. The increase in the stresses involved isn't linear.

Turn to Safety, Arch Fortiter

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Reply to
Arch

Mine has a metal frame. It is bolted to two two by fours which are glued to the concrete floor with silicone. It never dances but can still shimmy.

Reply to
Gerald Ross

Hello HB I've got a lathe that I turn up to 31" on, it has a 3 1/4" hollow shaft with double tapered roller bearings, the lathe itself weights in at approx. 1000 lb. and the stand is another 350 lb. and it is bolted to the concrete floor with 6 bolts.

Turning a 30" log you darn well keep it under 100 rpm if it is at all out of balance, and even when round I would not go faster than 200 rpm

It will actually flex the concrete floor if going faster than 100 rpm with a 30" rough cut reasonably balanced half log blank.

The speed of the 30"D blank going by your tool tip at 350 rpm would be similar to a 1" thick dowel spinning at 10.000 rpm, a little fast I would suggest.(if I'm wrong someone will let me know I'm sure) O yes if your blank has some humps and bumps , and you are turning at

60 rpm, you are taking 1 chip of wood per second, and if you really ramp up the speed, make it 3 chips per second, as wide and thick as you dare take them, (and that spinning 250 lb. blank does not stop if you just took a bit much) a presumed experienced turner of course does know what happens then .

My suggestion is buy a good lathe and start turning 12" to 16" bowls and if very good at that you will probably know how much lathe you really need, for turning large wood, I hope.

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Have fun and take care Leo Van Der Loo

bizHB wrote:

Reply to
l.vanderloo

Another way to look at it...

The perimeter of a 30" blank spinning at 350 rpm is traveling 31 mph (50 k). That's moving right along -- way too fast for comfort.

Bill

snipped-for-privacy@rogers.com wrote:

Reply to
Bill Rubenstein

That works out to about 45 FEET per second. If he gets a catch, that's how fast the tool will leave his hands ... and his control.

MAN, I love this craft! zoom, zoom

Reply to
W Canaday

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