G50 in a turning program is a speed clamp. The machine accelerates up to the speed you set (G50 S2000) and will not go any faster.
Now before I get arrested by the “Correct Word and Grammar Police” I know it’s not actually a clamp. The truth is it’s just what everybody calls it, so get off my fuckin case.
Black dog his name is Boris
Anyway if I start to call it something else all my CNC mates (and I do have some) will be confused.
Just check me out on LinkedIn. Anyway as I was saying my mates wouldn’t know what the fuck I was on about.
You must program a G50 before each tool and at the beginning of the program for safety reasons which I will explain later.
It’s Modal
G50 is a modal G code (it stays active). If you have a program where you do not want to clamp the speed you must still put the G50 at the beginning of the program (set the clamp to the machines maximum RPM).
Otherwise it may pick up the G50 from the last program and you may not get the RPM you want. It can have the effect of slowing down production because the speed is being restricted and you didn’t realize.
Don’t use someone else’s G50 get your own.
You wouldn’t wear someone else’s dirty pants. (Americans call underpants underwear I think)
These are mine (sorry I din’t get time to wash them).
Historically G50 was used to set the machine datum. This still works so do not put any X or Z figures on this line. You will get some weird shit happening if you do. Oh and you will probably trash your 100 grand machine.
Anyway how to use G50 on a CNC lathe
G50 S2000 (SPEED CLAMP 2000 RPM)
Some G code systems, or depending on parameters, may use G92 instead of G50. This is not very common but it works exactly the same way.
On a Fanuc control they are called A type and B type G codes and depends on machine tool builder. Most of the G codes remain the same but proceed with caution.
It is particularly useful when you are facing a part using G96 (constant surface speed). When the tool reaches the centre of the part the machine will be running at maximum RPM. This could be very dangerous on large or out of balance components. When you set a G50 speed clamp, once the machine reaches the clamped speed it will go no further.
Reset To G54 Fanuc Parameter, altering this parameter will make the control reset back to G54.
If you find it annoying that your control keeps jumping back to G54 when you press reset change this parameter to a 1.
To change parameters you need to go to the setting screen in MDI.
First of all take a deep breath and prepare yourself.
Now put a 1 in the parameter write box.
Reset To G54 Fanuc Parameter 1201
How annoying is it when you press reset on your Fanuc control and suddenly it dumps the work offset. You know your in G55 and it jumps back to G54.
I reminds me of my teenage years when girls used to hit the reset button on me. I didn’t default to G54 or anything just got really pissed off.
One particularly ungrateful girl dumped me after I had spent nearly an hour trying to explain to her about the system variables on a Fanuc Control. I even offered to lend her the Fanuc Manual.
This parameter is quite difficult to find. Now I know I often go on about me not being very bright but it really is true. I often say to customers I’m the one who just reads all the boring shit in the manuals that you can’t be bothered with and that’s really all I do.
It’s actually true although,0000000000000000000000000000000000000000 I do like to think that I have a good way of explaining things in “layman’s terms” as they call it, profanities included.
(sorry the cat sat on my keyboard again)
This is my cat she is called Hagnes, that’s not a typo. Her name was Agnes but as she is an upper class cat I added an H because posh people add H to a lot of words.
They often say words wrong like they say “help” when they mean “elp” it’s no wonder we don’t know what the fuck they are on about.
This is all really hypocritical from the guy who fuckin hates it when people put gratuitous crap on Linkedin that belongs on TikTok or Facebook. I mean do I really care if you had two eggs for your fuckin breakfast or one.
Anyway she did stand on my fuckin keyboard.
The parameter, the parameter oh yes…..
The reason not many people adjust this parameter is because it’s kind of hidden. That means it’s down to people like me who sit reading Fanuc Parameter Manuals when all other adult men are playing Candy Crush or Cyberpunk 2077.
This Is It Folks (1201 bit 7)
This is the Explanation.
Extract from an ancient Fanuc manual dating back to biblical times.
Parameter 1201 bit 6
Always read the small print.
Must admit I didn’t read the little note above until I changed this parameter for one of my victims the other day. It didn’t work. Just altered the one below and Bingo.
This Parameter will Need Changing Too
Phew I need a lie down after that.
This parameter is complicated because it’s all about G code groups. Every G code is in a group it is not something you need to worry too much about until you get on to more advanced Macro Programming.
If you think of it as G codes that you couldn’t have in the same block like G0 G1 G2 and G3.
You can only have one or the other. I mean you couldn’t G0 and G1 together that would be stupid telling the machine to rapid and feed at the same time.
Well…… these are in the same group it’s group 1 actually.
This parameter will reset whatever G code is active in group 14.
Group 14 just happens to be G54 G55 G56 G57 G58 and G59 (your work offsets).
As they are all in the same group (14) only one can be active.
So all it means is when you press reset if the machine was in G55 G56 G57 G58 or G59 it would always default back to G54
Now you know how to reset to G54 by altering a Parameter.
So 1 means don’t reset to G54 and 0 means reset to G54
Here is More Total Confusion
Parameter are listed like this
Parameter bits
I’ve written the bit number below because it can be a bit confusing. There are 8 bits beginning with bit zero. The first one is not bit 1 it’s actually bit zero.
So what’s confusing?
Well for one thing they work from right to left.
The other thing is they start at number zero not number one.
It’s all because they are binary numbers without these you and I would still be winding handles and drinking out of our hands and living in caves.
I’m not gonna go there by the way.
Just One Thing
Oh just one other thing before you go off and cripple your machine forever.
Do yourself a favour take a picture of the screen before you change your parameter.
Make a screen shot if you can.
If you ain’t got a camera then you must have a piece of paper so write it down.
(Oh and get a fuckin camera, you dinosaur, they are very useful you can take pictures of your arse and send them to your mates)
Even better back everything up, on our machine that is.
Thanks
If you have been affected by any of the issues in this post or need CNC Counselling then contact me.
If you want to learn to programme CNC Milling Machines
If you write macro program you will probably know that 500 series variables stay in the machine even when you switch it off.
Unfortunately the 100 series variables don’t stay around. This parameter when changed means these little blighters will retain their values even if you turn off the machine.
Now I don’t want to appear sexist here but sometimes my wife will be awake at night worrying about whether or not she left a gas ring turned on.
Now me I worry about different things I mean how can you compare a gas explosion to a collision on a CNC Machine.
(I really should clean that cooker)
Anyway my point is if you worry about G91 and if you left one active in a program and it causes a collision.
Help is at hand. Now this maybe another piece of useless shit and you might wish you had stayed on Facebook, reading your mates post, ruminating on the benefits of vegan cheese and how you can’t tell the difference. (I have tried and it’s really nice once you get the thought of eating semtex out of your brain).
Don’t set me off about vegans. Just answer one question, if they don’t like meat why do they have to keep banging on “I’ve just eaten this burger and you would think it was real beef”
G90 G0 X0 Y0 G81 G98 Z-20. R1. F100. G91 X50 G91 X10. G91 X20. G91 X30. X100. (This would go back to G90 automatically)
“That’s daft” I hear you say.
Well not really because it means that if you ever forget to switch back to absolute (G90) it doesn’t matter because it never got swapped in the first place.
Every time you want G91 you need to write it in that block of code.
