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Tool room lathe to slant bed program conversions

Bill is more knowledgeable than I am.
I am only expressing my point of view.
I honestly appreciate when you guys get into it. The answers are above the pay grade of the original question but, still enjoy the debates. There's some Japanese guy just doing yard work, wondering what time dinner is and then out of nowhere, Godzilla and Ghidorah destroy the countryside again. 🤣
 
Mathematically, the Y axis always exist, and the three axes follow the right-hand rule.
The Y axis may or may not be controllable, but that does not change axis definitions.

Following the right-hand rule, the Y axis points upward on a rear-type lathe, whereas it points downward on a front-type lathe.
I understand that, but there is no physical Y axis on the machine for the OP to test that scenario on his machine. For the X+ direction to be towards the rear of the machine and Y+ pointing down, then the Z+ would have to point towards the Left (towards the Chuck in most two axes lathe configurations), therefore, it would be more helpful to the OP to determine if G02/Go3 need to be transposed from what he has with his front turret machine, to look at something tangible such as which direction Z+ is pointing,
 
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G02/G03 would need to be switched if the machining is being done on the positive X side in both cases.
Not so. Considering X+ direction being towards the rear of the machine as the base line, when a machine is made in the configuration of X+ at the front of the machine, its.tantamount to the X+ as well as the Tool Turret being rotated about the Centre Line of the Machine, accordingly, neither G02/G03 nor TNR Comp codes change; see the extracts from the Fanuc Manual in my earlier Post with regards to G41/G42
 
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IME, there is no difference in programming. Also, apart from only working with left hand tools, the layout of that Emco is completely normal so idk what everyone is talking about.

Flat bed lathe X+ is away from the spindle. Slant bed X+ is away from the spindle. The physical difference is that everything is rotated 135° about the spindle. The cartesian difference is nil, and the programming difference is nil.
 
IME, there is no difference in programming. Also, apart from only working with left hand tools, the layout of that Emco is completely normal so idk what everyone is talking about.

Flat bed lathe X+ is away from the spindle. Slant bed X+ is away from the spindle. The physical difference is that everything is rotated 135° about the spindle. The cartesian difference is nil, and the programming difference is nil.
Absolutely correct. No difference for either G02/G03 or TNR Comp G Codes.

Regards,

Bill
 
I understand that, but there is no physical Y axis on the machine for the OP to test that scenario on his machine. For the X+ direction to be towards the rear of the machine and Y+ pointing down, then the Z+ would have to point towards the Left (towards the Chuck in most two axes lathe configurations), therefore, it would be more helpful to the OP to determine if G02/Go3 need to be transposed from what he has with his front turret machine, to look at something tangible such as which direction Z+ is pointing,
It can always be tested, irrespective of whether Y axis control is available or not.
I had tested this about a decade back on a 2-axis front-type lathe which needed reversal of G02/G03. This was not unexpected, because CW/CCW directions are determined when we look at the plane of the arc from the positive side of the third axis. In the case of arc on XZ plane, we need to look from the positive side of the Y axis. Since the positive Y axis is downward on a front-type lathe, we need to look at the arc from below the XZ plane, i.e., upwards. But, we look at it in the downward direction. Therefore, CW appears CCW,, and vice versa, to us. For the purpose of control, G02 is always CW arc, and G03 CCW arc.

Z axis is towards the tailstock only. It is the Y axis which changes direction: upward on rear-type and downward on front type, as per right-hand rule (assuming X+ away from the spindle).
 
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Again, not so. See the extracts from the Fanuc Manual in my earlier Post with regards to G41/G42.
We use G42 on a front-type lathe, as shown in the manual:
1718619468839.png

And, we use G42 on a rear-type lathe also:
1718619572072.png

Therefore, G41/G42 are not switched, even though G02/G03 need switching.
 
The physical difference is that everything is rotated 135° about the spindle.
This makes all the difference. After 135 deg rotation, we start looking at the arc from the opposite direction. That is why CW appears CCW to us, and vice versa. Therefore, G02/G03 switching is needed.

If you stand in front of me, with you face towards me, then what is CW for me is CCW for you.
 
I can further explain why G41/G42 do not need switching, but most people do not seem to be interested.
 
This makes all the difference. After 135 deg rotation, we start looking at the arc from the opposite direction. That is why CW appears CCW to us, and vice versa. Therefore, G02/G03 switching is needed.

If you stand in front of me, with you face towards me, then what is CW for me is CCW for you.

You are mistaken. The operator perspective is entirely irrelevant.

The difference between a slant bed rear turret lathe and a flat bed front turret lathe is that the entire coordinate system is rotated around Z. X+ is always away from the spindle, Z+ is always away from the spindle. In physical space, Y is inverted.

From the perspective of the machine's coordinate system everything is entirely unchanged, therefore there is no switching of codes, and a program that runs on a rear turret slant bed will run unmodified on a front turret flat bed.
 
As I explained earlier, G02/G03 need switching, but G41/G42 do not.
You are wrong. When working in the X+ for both the Front and Rear Tool Machine, G02/G03 remain the same.

Gregor is saying exactly what I'm saying. I explained the concept of everything being rotated about the Centre Line of the machine back in my Post #24, the same as Gregor has. You agree with Gregor but not when I say basically the same thing. It seems to me you want to argue a point (wrongly) just for the sake of argument All Hat and No Cattle tis you.

Considering X+ direction being towards the rear of the machine as the base line, when a machine is made in the configuration of X+ at the front of the machine, its.tantamount to the X+ as well as the Tool Turret being rotated about the Centre Line of the Machine, accordingly, neither G02/G03 nor TNR Comp codes change; see the extracts from the Fanuc Manual in my earlier Post with regards to G41/G42
 
You are mistaken. The operator perspective is entirely irrelevant.

The difference between a slant bed rear turret lathe and a flat bed front turret lathe is that the entire coordinate system is rotated around Z. X+ is always away from the spindle, Z+ is always away from the spindle. In physical space, Y is inverted.

From the perspective of the machine's coordinate system everything is entirely unchanged, therefore there is no switching of codes, and a program that runs on a rear turret slant bed will run unmodified on a front turret flat bed.
AbsoBloodyLutely

Regards,

Bill
 
One can understand only if one tries to understand.
Yes, nothing changes for the machine, but our viewing direction reverses. That makes all the difference.
Instead of arguing, it is better to test it
 
You both are wrong. Test it.
Already did that test many years ago when I encountered my first Mazac M5 with Front X+ Turret and Rear X- Turret on the same slide. Front Turret programed exactly the same as a lathe with X+ at the rear of the machine. X- Turret G02/G03 and G41/G42 are transposed.
 

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.
 








 
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