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Tool room lathe to slant bed program conversions

No need to test anything, I am speaking from experience already. I program and run both daily, and have used a lot of different types of lathes in the past.

Since I know for absolute fact that Bill and I are correct, yet you are insistent that we are wrong, I wonder if you have used some inverted X lathe that has confused you? Those exist, but they're uncommon. I've never actually encountered one.
The bridgeport EZ path and SW industries conversational lathes I have run disagree with your experience. The Haas TL1 lathe is consistent with a slant turn lathe but if you look down at the top of the tool a G02 makes a CCW move and G03 makes a CW move. When hand coding I have to force myself to picture the part as if I was looking up at the bottom of the tool like you would on a slant turn.
 
The bridgeport EZ path and SW industries conversational lathes I have run disagree with your experience. The Haas TL1 lathe is consistent with a slant turn lathe but if you look down at the top of the tool a G02 makes a CCW move and G03 makes a CW move. When hand coding I have to force myself to picture the part as if I was looking up at the bottom of the tool like you would on a slant turn.
I have tried to explain the logic behind it, but my posts are not being read with an open mind.
I am basically a teacher, and I cannot afford to speak irrationally.

Anyway, if logic has no place, the vote is 2:2
Let somebody else break the tie.
 
X+ is always away from the spindle, Z+ is always away from the spindle.
If you mean x becomes numerically larger as you go away from center, yes. If you mean the x plus direction is always away from center then no. Lots of rear turret lathes have x as minus, with the numeral getting larger but the absolute value becoming more and more negative as you go away from center.

Did that make sense ? X = -10.5312 is a larger part than X = -3.215, even tho the x number is much smaller, is what I'm trying to express.

There is actually a standard but a lot of people don't follow it.
 
Hi All:
Here's how I think of it.
A "toolroom" lathe where the tool is right side up and runs on the side of the part nearest the operator will have X+ moving toward the operator, so as X dimensions get bigger, the tool moves toward the operator.
This is how conventional manual lathes are set up...cutting edges of tool up, and CCW rotation of the spindle when looking from the tailstock toward the headstock so the rotation of the workpiece forces the material against the top of the tool and shears a chip.

If you imagine yourself floating face down above the lathe with your feet pointing toward the operator side of the lathe you are looking from the conventional orientation for a manual lathe and aiming your eyes onto the top of the tool.
The spindle is on your left side.

X+ works conventionally.
G02 G03 works conventionally but SEEMS backward because you are looking at the top of the tool instead of the bottom of the tool.
G41 G42 works conventionally but SEEMS backward because you are looking at the top of the tool instead of the bottom of the tool.
Tool tip radius works conventionally but SEEMS backward because you are looking at the top of the tool instead of the bottom of the tool..

On a CNC slant bed lathe with a turret:
Imagine yourself laying face up below the workpiece with your feet sticking out the back of the machine.
The spindle is still on your left side.
You are still looking at the top face of the tool but you are looking up to do it.
Everything still works exactly the same, except that if you programmed the toolpath in something like Mastercam you have to look at the CAM view plane upside down as well so you don't get confused, because CAM programs default to the view orientation that is most common...that for slant bed lathes with rear turrets.

But as angelw and Donkey Hotey and others have pointed out, as long as you are rotating the workpiece in M03 and the tool is positioned so the tool will cut when the workpiece rotates in M03, it doesn't matter whether you are floating above the lathe looking down or laying in the chip pan looking up.
If the spindle nose is on your left and you are looking at the top face of the cutting tool, the toolpath you write will be identical...you just have to tell the CAM program which turret to use when it writes the code.
"Rear Turret" and "Front Turret" or "Upper Turret" and "Lower Turret" are not good terms when you are trying to wrap your head around this, but those are the terms they use.

What seems to often mess people up is that the CAM systems out there seem to all be laid out to default views where the tool is to the rear of the workpiece and the cutting edge of the tool is facing down, so that view orientation has become "conventional" and the view orientation of manual lathes and toolroom lathes now seems "backwards"
But it's only the view orientation that has changed...the programming remains identical.
The "rules" that CW tool tip interpolation is G02 and CCW is G03 depend on how you view the tool.

Donkey Hotey refers to my getting my shit in a knot about this in post #12.
In my case I was commissioning a Haas CL-1 for a customer and these are set up by Haas with the axis definitions and tool orientations like a conventional manual lathe and like their TL series, so it was confusing to program it in Mastercam until you flipped the view plane upside down.
Since the CL-1 is ideally suited to running gang style tools on both sides of the spindle I thought it was a particularly dumb way for Haas to set up the slide and tool orientations, and a lively discussion ensued, very similar to this one.

But the bottom line is that you can view the tool from any orientation you want...a correctly programmed part will run uneventfully no matter where you choose to look from.
"Correctly" means the spindle is running in M03 and the tools are set up so they will cut and not rub.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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What about G02 to Go3? Do I need to switch those?
The answer has a tie at 2:2, and nobody has the veto power!
Test it yourself, and report the result.

I am assuming that both the rear-type and the front-type lathes have X+ away from the spindle axis.
 
The answer has a tie at 2:2, and nobody has the veto power!
Bullshit. When they first invented nc back in 1950, they standardized a way of describing how axis movements function. So there's a correct way and a bullshit way. It's not a matter for voting. It's either correct or crap.

Some mtb's chose 'crap' because it 'seemed more logical' to them, but it's still crap.
 
The bridgeport EZ path and SW industries conversational lathes I have run disagree with your experience. The Haas TL1 lathe is consistent with a slant turn lathe but if you look down at the top of the tool a G02 makes a CCW move and G03 makes a CW move. When hand coding I have to force myself to picture the part as if I was looking up at the bottom of the tool like you would on a slant turn.

Wait, so Haas did something right for once? :D
Per the others, yes I'm sure there are exceptions, but they are exactly that. There are lots of ways to cheat a coordinate system on a machine, and sometimes MTBs choose to do so for reasons.
I expect they chose go with Y UP so that CW/CCW look right to the operator and just inverted the sign on X so that it works like a manual lathe. Violates the standard cartesian system but it's a 2ax lathe, so what. Oddball controls too, so nobody cares about program sharing either.

Haas did it properly (@Donkey Hotey take note, I doubt you will ever see me say that again ;)) so that programs that run on their slant bed machines also run unmodified on the TL machines.

If you mean x becomes numerically larger as you go away from center, yes. If you mean the x plus direction is always away from center then no. Lots of rear turret lathes have x as minus, with the numeral getting larger but the absolute value becoming more and more negative as you go away from center.

Did that make sense ? X = -10.5312 is a larger part than X = -3.215, even tho the x number is much smaller, is what I'm trying to express.

There is actually a standard but a lot of people don't follow it.

Yes, they exist, but you'll go a long way to find one. It's a very legacy thing, and I really doubt if anyone is making a lathe like that anymore.
 
Yes, they exist, but you'll go a long way to find one. It's a very legacy thing, and I really doubt if anyone is making a lathe like that anymore.
Maybe, cuz they don't actually make lathes anymore. They make these wimpy-ass things that'd have a hard time cutting their way out of a wet paper bag, so it doesn't much matter what they say or do, it's all pretty much a joke.
 
Bullshit. When they first invented nc back in 1950, they standardized a way of describing how axis movements function. So there's a correct way and a bullshit way. It's not a matter for voting. It's either correct or crap.

Some mtb's chose 'crap' because it 'seemed more logical' to them, but it's still crap.
True. Not a matter of voting. I said that to ease up the atmosphere.
 
Maybe, cuz they don't actually make lathes anymore. They make these wimpy-ass things that'd have a hard time cutting their way out of a wet paper bag, so it doesn't much matter what they say or do, it's all pretty much a joke.
We've already had this fight bud. Need to find something else to argue about this time :D
 
Getting back to the OP's missive, my first CNC lathe was a Monarch Metalist. Bed perpendicular to the floor(90 degree slant??), behind spindle. CW normal spindle rotation, tool top facing operator. Just like the EMCO in the video.

To cut right hand threads, I just fed out from the spindle. ID threading was a bit scary watching the bar rapid into the hole.

Reversed spindle for drilling so I wouldn't have have a bunch of lefthand drills.
 
True. Not a matter of voting. I said that to ease up the atmosphere.
On a serious note, if OP believes me, he may read my post # 15, and program accordingly.
If not, he may follow a contrary advice, and he will start believing me.
 
If only the designers of the lathe in question had put this much energy into making these choices.

The backward rotating spindle has me questioning everything else. I think I'd program some goofy, huge tool nose radius inserts and try the cutter comp in free air to solve the comp question. Lots of good arguments both ways here but, I don't think they gave that much care to it in the first place.

Keeping track of spindle direction for things like threading and drilling would get annoying as hell. Thanks to everyone for forever scratching Emco off my list of possible machines to buy.
 
Wait, so Haas did something right for once? :D
Yes, they did, but my guess is that they did it for the wrong reason.
IOW they didn't do it to make it easier on the formerly manual lathe operator, rather to not have to do a damned thing to the control, only to reverse the rotation of the X-servo.

With that said, that Emco machine Donkey linked to is one f@cking demented design!!!
 
If only the designers of the lathe in question had put this much energy into making these choices.

The backward rotating spindle has me questioning everything else. I think I'd program some goofy, huge tool nose radius inserts and try the cutter comp in free air to solve the comp question. Lots of good arguments both ways here but, I don't think they gave that much care to it in the first place.

Keeping track of spindle direction for things like threading and drilling would get annoying as hell. Thanks to everyone for forever scratching Emco off my list of possible machines to buy.

You're joking about the "backward rotating spindle", right?

If you do a lot of heavy turning in slant bed lathes you get used to M4...

Yes, they did, but my guess is that they did it for the wrong reason.
IOW they didn't do it to make it easier on the formerly manual lathe operator, rather to not have to do a damned thing to the control, only to reverse the rotation of the X-servo.

With that said, that Emco machine Donkey linked to is one f@cking demented design!!!

Haas did it because it's the correct and normal way to do it.

This little EMCO is an educational lathe. They're common over here in schools, colleges etc. But ignoring that it's a totally conventional slant bed design so idk what you two are talking about. The only odd thing about it is that the turret can only use left hand tooling, which is presumably for simplicity and cost reasons.

EMCO are a real MTB, made in Austria and Germany, so don't be too quick to assume they don't know what they're doing.

If you don't like the little one, try this one instead:
 
But ignoring that it's a totally conventional slant bed design so idk what you two are talking about. The only odd thing about it is that the turret can only use left hand tooling, which is presumably for simplicity and cost reasons.

That^^^ in bold.
Even if it is only for educational purposes.
I don't have a problem with the M04, makes sense even for rigidity, but my answer would have been to put the slide under the spindle not above it.
My real beef tho is with the turret's inability to take on "other hand" tools and requiring a monstrous contraption as shown in the OP's picture to do so.
 
You're joking about the "backward rotating spindle", right?

If you do a lot of heavy turning in slant bed lathes you get used to M4...
Nope, not joking at all. I just looked up some oil field machines and mill turns completely out of my realm and they all turn M3 with the inserts facing down for chip evacuation. The only exceptions I've seen were weird, non-standard machines like the Emco in this thread, or gang tool setups where you're using one tool to do ID work, then get to the back side of the part with the same cutter.
 
The drophead left hand upside-down threading tools worked better. Then you didn't have to try to accelerate in the width of a relief groove .... and you could do 45* pullouts if they were required.

I thought they made that lathe in a dual turret model as well ?
Metalist?? I don't know. There was a hollow spindle that had two turrets.
 
On a serious note, if OP believes me, he may read my post # 15, and program accordingly.
If not, he may follow a contrary advice, and he will start believing me.
Your Post #15
The usual convention has positive direction of the X axis towards the tool. So, it is towards the operator on a front-type lathe, and away from him on a rear-type lathe. This has the effect of the positive direction of the Y axis pointing upwards on a rear-type lathe, whereas it is downward on a front-type lathe. Therefore, everything which depends on the direction of Y axis, reverses, such as CW/CCW and left/right directions, as perceived by the operator.

Thus, with this type of axis convention, G02/G03 would need to be interchanged.

Clearly, you will argue Black is White just for the sake of it.


Sure the Y axis exists in the Right Hand Rule convention, even if the machine doesn't have a physical Y axis. But, as I've stated before, for the Y axis to be pointing Down with a machine that has X+ towards the rear of the machine, the Z axis of a lathe would have to have the Z+ pointing towards the spindle on the Left.

How does the OP determine which way the Y axis is pointing on a machine that has no Y axis? He could try test programs that include G02/G03 commands and see if the movement is CCW/CW for G03/G02 respectively for the X+ at the rear of Centre Line machine (as is convention), but then he would have to deal with Z being reversed from what is convention. To come to a conclusion as to which direction the Y axis points, he would be working from the Result of the program backwards. It would be far more logical and intuitive for the direction of Z+ to be examined and in chorus with the direction of X+, create the program containing G02/G03 moves accordingly. So why muddy the water for the OP by introducing the Y axis into the discussion?

Unless convention has been totally thrown out by the MTB, then a machine with X+ at the rear of Centre Line and Z+ towards the Right, G02/G03 will be programmed exactly the same as a machine with X+ at the front of Centre Line and Z+ towards the Right,

Most seasoned CNC Lathe programmers I've met, associate cutting an OD convex radius with G03 for a machine where the X+ is towards the cutting tool and vice versa with X- towards the cutting tool. A gang tooling machine is a good example of this where there are cutting tools arranged on either side of Centre Line. The Mazak M5 I've referred to is on the same page as a Gang Tooling machine
 








 
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