Survey: Which Side of the Spindle Centerline do Most CNC Lathes Cut?

All of our slantbeds cut towards the operator (turret behind the spindle)

Regards Daveb

BottleBob wrote in news:4484E2FE.110667D3 @earthlink.net:

The majority I have worked with work back (top) side. (slant-bed) 4 axis will work top and bottom. We do have some OLD machines that have slides front and rear.

As a Tech..Id have to say the front side. The rational being tooling is used in a upright position and visible to the operator.

There are any number of adjunct tooling that is used to save space and travel time of the tools, that cut on both sides of the part and indeed are very handy for speeding up cycle time when properly thought out.

Gunner

"If thy pride is sorely vexed when others disparage your offering, be as lamb's wool is to cold rain and the Gore-tex of Odin's raiment is to gullshit in the gale, for thy angst shall vex them not at all. Yea, they shall scorn thee all the more. Rejoice in sharing what you have to share without expectation of adoration, knowing that sharing your treasure does not diminish your treasure but enriches it."

- Onni 1:33

Depends on the tool and the sweep of the part. When one side of the diamond tool gets worn or chipped we will cut on the other side. With $1200 tools you can't let yourself get to religiously attached to either the right or the left.

My Hardinge cuts on the front (CHCN I). My Yang 45 deg slant bed gang tool came new set to cut on the back side. But I changed the X prms so it would cut on the front. Why did Why do that? Cause it's damn hard to see if an insert is dull with a little mirror much less change it upside down. So now X+ is toward the operator just like my Hardinge.

Front. Inserts facing chip pan more often than up.

Wes S

Anthony:

Top and bottom, eh. That's very interesting, nothing like the additions of more variables. Are these slant-beds those proprietary machines you mentioned, but couldn't give any details about, some years ago?

I've been working on CNC Swiss types the past couple weeks. They cut on the back, the front, the top, the bottom, around the sides and right down the middle. And that's BEFORE anybody gets creative and starts sticking tools in places where there aren't supposed to be any places.

If you're asking about "normal" lathes, then that's simpler. For the past

30 years, since people (mostly Japanese people) started designing CNC machines from scratch, rather than just putting controls on traditional frames, the turrets have been on the back, away from the operator. The reason for this should be obvious: When lathes got turrets, instead of just small tool posts, the turrets, index mechanisms, coolant delivery systems, etc., became rather large. If a large cluster of tools, hydraulics, coolant tubes, and more, were mounted on the front of the machine, it would be between the operator and the spindle. So would the slide that the turret moves on, and at least some of the hardware at the end of the ballscrew. That's good for changing inserts, but bad for loading/unloading parts, which is what operators do most, and most often.

If the turret's on the back of the machine, however, then the operator can belly right up to the spindle, can see what's happening, and can even load heavy parts without needing to be the incredible hulk, or nine feet tall.

When CNC lathes got good enough at making chips that they started making a LOT of chips, then it became important to keep those chips off the slideways and dump them into a conveyor. That led to the development of slant-bed machines. If you try to slant a machine whose spindle is on the front, you only have two choices. You can slant the cross-slide up from the spindle so that its outboard end is right in the operator's face, and the operator needs a step-ladder to see the tool that's actually cutting at any given moment. Or you can slant it down from the spindle, and dump chips and coolant right on top of the operator's shoes.

But a slant-bed machine with it's cross-slide and turret on the back is easy to use, from the operator's standpoint - except for that part about tools being upside down, and an endless supply of inserts and small allen wrenches being constantly dropped into the chip conveyor. Some builders have simply reversed "normal" spindle rotation and used left-hand tools on back-mounted turrets, to keep the inserts on top; but that never quite caught on. Threading is one reason. Such machines just naturally make left-hand threads. If, for some strange reason, you really, really want to make a right hand thread, then you're going to need upside down tools and CCW spindle rotation anyway. So you may as well get used to the upside down stuff, buy some extra allen wrenches, and enjoy the other advantages.

Twin turret machines are a different set of rules, of course; and usually involve some unpleasant compromises. And, in today's world, there are a million different twists and variations on the most basic designs, to serve people who want to do milling, cross-drilling, polygon machining, broaching, heat-treating, knitting, and stamp collecting, all in a single, hands off, bar-fed, robot unloaded, operation. In fact, about the only people who work in just two axes anymore are hopeless luddites who won't just open their damned wallets and spend a lousy $500K for a good multiplex machine, or CAD jockies who THINK they're thinking and working in

4-space; but whose only actual production ends up on the flat side of a big slab of plotter paper.

Back side is where it's at, BB. The front of a machine is just something to hold the paint you're gonna scratch all to hell with yer belt buckle.

KG

Kirk Gordon wrote in news: snipped-for-privacy@gordon-eng2.com:

It's a lot more fun, isn't it?

BottleBob wrote in news: snipped-for-privacy@earthlink.net:

No, I can't give any information on the proprietary machines. But, maybe I misunderstood what you were asking. I understood you to be asking where the slides were located in relation to the spindle and operator. From other responses, some interpreted the question to be which way the tools were facing regarding the operator. Generically, I supposed the question is the direction the spindle is rotating, relative to the operator, to turn the OD? In our case, that is almost universally away (clockwise, looking at the face of the spindle, spindle on the left end of the machine, from the operator's standpoint.) To turn counter-clockwise, normally imparts a lifting force to the machining slide, and this is not a good situation when you are trying to hold microns.