cuttergrinder
Hot Rolled
- Joined
- Mar 16, 2007
- Location
- Salem,Ohio
This is probably a dumb question to most but here goes. Does having a lathe tool upside down or right side up effect whether you use g41 or g42
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No. Best rule of thumb with lathes is there is no rule of thumb. If you are cutting towards the headstock on the OD it should be G42. If you are boring towards the headstock it would be G41. There are way too many variables running a lathe to haphazardly generalize it like that.
Ok thanks guys. So if i am cutting towards the chuck, its G41 and G42 if cutting towards tailstock
You guys .... back to basics. There's the right-hand rule for axis designations and cutter left, cutter right offset for radius comp.
And then there's the better way, which is to write the damned program from the center of the tool nose radius and skip this radius comp entirely. It's a pain in the butt and doesn't do as good a job.
Well... no, that isn't correct...
Typically on a turret type CNC lathe when the turret is beyond the X-center..
1:OD turning - Cutting towards the chuck with TNR = G42
2:OD turning - Cutting away from the chuck with TNR = G41
3:ID turning - Cutting towards the chuck with TNR = G41
4:ID turning - Cutting away from the chuck with TNR = G42
Well, if he knew the rules then he wouldn't have to ask these stupid questions. We're talking basics here !Please, just behave like a fossil to be found in a Millennia or Two, and let us old(er) guys help them youngn's of today!
With z+ extending from the chuck towards the tailstock then x+ is always towards the operator. Unless the operator is standing on the back side, which I guess is possible but rare.if X+ is towards the operator.
With z+ extending from the chuck towards the tailstock then x+ is always towards the operator.
Clearly I have owned four ... no, make that five lathes with this exact configuration except x plus is not supposed to be away from the operator. X plus is towards the operator, x minus is away from center, towards the rear, with the turret moving farther in x minus the farther it gets from center.Well, no.
Clearly you haven't encountered the most common of CNC lathe configuration where the Turret is at the back of the machine and where X+ is away from the operator and Z+ is towards Tail Stock to the right.
This is not correct, period. Those builders should be shot.Further, there are the odd machines that have an increasing X- traveling away from the machine centre line; whether its towards, or away from the operator.
Holy shit, put a mark on the calendar, we agree on somethingI don't advocate the use of TNRC on a lathe and I calculate the true location of the tool. Tool Radius Comp on a machining centre is almost mandatory, as its the convenient method of obtaining size of a feature when using the periphery of a cutter such as an End Mill. With a lathe, diameter size is generally achieved using an X Offset, not a TNR Offset.
You can achieve the same thing writing centerline ... used to be a bit more work but with cad nowadays it's pretty simple. You're dependent on the insert being correct tho ... which they seem to be.However, it has its place in producing accurate profiles, for example roll forms if high accuracy of the profile is required.
I used to be concerned about this. But since I may have changed nose radius twice in twenty years, I quit thinking this was an advantage.And it also allows for Tool Insert with a different TNR to be swapped in with very little inconvenience.
Well, it is correct if it the tools are cutting upside-down. In that case it is a rolled-over configuration, where the operator really should be standing on his head on the other side. Or you could consider it a front-turret machine that fell over backwards.The qualification in my comment is "the most common of CNC lathe configuration where the Turret is at the back of the machine and where X+ is away from the operator and Z+ is towards Tail Stock to the right." And that is the most common configuration. I understand the Right Hand rule, but you saying that X+ away from centre line, with the one and only turret at the back is not the norm, is just making yourself out to be..., let see, ah yes, Johnny Larue.
Poll the whole damned world for all I care, look at the international standard and see what is correct.Poll this very Forum on the subject and see what result you get.
Otherwise, common or not, it is wrong.
Well, it is correct if it the tools are cutting upside-down. In that case it is a rolled-over configuration, where the operator really should be standing on his head on the other side. Or you could consider it a front-turret machine that fell over backwards.
Wrong again. Whether the tool is upside down or not (the original question put by the OP) is totally irrelevant with regards to TRN Compensation. Use all LH OD Turning tools on the Back Turret (insert facing up) and feeding towards the Spindle to the Left, its still G42. That's already been covered in this Thread by others, but I guess you missed that.
Oh for sure, for sure ! My inch, your inch, Jorge's inch, why make them the same ? Let's go farther ! Pounds, kilograms, feet, miles, who cares what the standard is ? We can each have our own ! I'm going to go outside and drive on the left side now, and stop at green lights because standards are meaningless ! Whoopee !Machine configuration doesn't need to follow the Cartesian system, it's not the law.
The discussion (as it developed) was right hand rule. G41-G42 is dependent on tool-right and tool-left, according to the path it is taking. Upside-down and rightside up are supplemental to the left-right question.Wrong again. Whether the tool is upside down or not (the original question put by the OP) is totally irrelevant with regards to TRN Compensation.
Angel knows Fanuc very well but that is not the entire world. There are dangers in a monoculture. If you want to be a sheep, have at it. Stick your nose up the wooly ass in front of you and follow along ...Mtndew said:It's amazing that someone is arguing with you. You're one of the most knowledgeable people on this forum in my time here.
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