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Hwacheon 21hs Lathe - Fanuc 18T - Machine Homing

TheBigLebowski

Aluminum
Joined
Sep 9, 2018
I purchased a new to me cnc lathe (hwacheon HiEco 21hs with a Fanuc 18t) back in September. Before moving it I had the batteries in the control replaced, so its possible a parameter was lost at this time.

I am just now getting around to setting the machine up. On power up, the machine's absolute position is shown as a value that wouldn't be possible (as in its outside of the machines total travel). This would be an issue if the machine had absolute encoders, but looking at parameter 1815, I don't think it does.

The Z axis Zero Point and X axis Zero Point lights are both flashing. (which leads me to believe there should a homing procedure)

So what am I missing? is there an obvious button I am not seeing to home the machine, or is it something else?

Unfortunately, I don't have a manual for this specific machine, though I do have the manuals for the fanuc 18 control.

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To start with, zero out the EXT machine offset. This should normally be at zero 99% of the time. While you're at it, zero out all the other work offsets too.

There should be a ZRT or ZRN or Zero Return button. Hit that then press and hold X+ and then Z+ until the carriage makes it's way home and stops.

If you have Absolute Encoders and the batteries are missing, then that's a whole other deal. Go to Machine Tool Repair.com and they have a whole list of how to zero a Fanuc machine with encoders by setting the 1815 parameters.

Here's a link

Zero return procedure and gridshift parameter setting on Fanuc CNC controls


If your machine has Incremental encoders, you might have to hold down P and CANCEL at startup, and re-zero return the machine from there. A machine like that has to be Zero Returned at every power on. Though P CANCEL is not needed every time.
 
To start with, zero out the EXT machine offset. This should normally be at zero 99% of the time. While you're at it, zero out all the other work offsets too.

There should be a ZRT or ZRN or Zero Return button. Hit that then press and hold X+ and then Z+ until the carriage makes it's way home and stops.

If you have Absolute Encoders and the batteries are missing, then that's a whole other deal. Go to Machine Tool Repair.com and they have a whole list of how to zero a Fanuc machine with encoders by setting the 1815 parameters.

Here's a link

Zero return procedure and gridshift parameter setting on Fanuc CNC controls


If your machine has Incremental encoders, you might have to hold down P and CANCEL at startup, and re-zero return the machine from there. A machine like that has to be Zero Returned at every power on. Though P CANCEL is not needed every time.

Appreciate the help, There is a zero return button on the control I just wasn't seeing it. Machine was set up to be re homed every restart or when the estop is triggered.

Do you by chance know of a parameter that will make it so you cannot jog past the software limit? On the RoboCut I previously ran (18i Control), it was configured so that jogging would stop right at the soft limit. On this lathe I can jog into the soft limit and throw an alarm.
 
If this is an Incremental machine, I'm thinking you won't even have software limits. Home Position and over-travel protection are usually done with physical trip dogs. You'll have Deceleration Dogs on one end and Over-travel dogs on both ends.

If you're worried about over-traveling while jogging just do what I do, albeit on an Absolute machine. I put it in Zero Return mode when I want to rapid the carriage out of the way. That keeps me from going too far and setting an alarm. Not sure if you'll get that benefit on an Incremental machine. You might notice the deceleration and quickly remove your finger off the button.

There's typically a Data or Keep Relay setting where you can have the machine either zero Return with a single push of the X+ and Z+ buttons, or, you have to hold the buttons in the whole time. Single push might be a little dangerous on a lathe. Especially in Z if you have a sub spindle sitting there. You'd really have to set a habit of always X+ first before Z+.
 
If this is an Incremental machine, I'm thinking you won't even have software limits. Home Position and over-travel protection are usually done with physical trip dogs. You'll have Deceleration Dogs on one end and Over-travel dogs on both ends.

If you're worried about over-traveling while jogging just do what I do, albeit on an Absolute machine. I put it in Zero Return mode when I want to rapid the carriage out of the way. That keeps me from going too far and setting an alarm. Not sure if you'll get that benefit on an Incremental machine. You might notice the deceleration and quickly remove your finger off the button.

There's typically a Data or Keep Relay setting where you can have the machine either zero Return with a single push of the X+ and Z+ buttons, or, you have to hold the buttons in the whole time. Single push might be a little dangerous on a lathe. Especially in Z if you have a sub spindle sitting there. You'd really have to set a habit of always X+ first before Z+.

Definitely has Incremental encoders on it. It looks like the soft limits are active after the machine is homed. Jogging to far before homing trips a physical limit switch. Jogging to far after homing trips a software limit and throws a 500 alarm. Not the end of the world, but it does require resetting the alarm and rehoming the axis.

I am going to take a deeper dive into the manuals and see what settings I can find in relation to software limits. I know beyond a shadow of a doubt that the RoboCut I worked on physically would not jog beyond the soft limit, it would stop right on it, though it did have abs encoders and scales. If I find a parameter for that setting I will post it here.
 
There is a user defined inhibit zone that can be setup on Fanuc mills and lathes to prevent movement into what might be dangerous areas. Keeps people from crashing into chucks, rotary tables and the likes. Sorry, right now for the life of me I can't think of the Fanuc term for it. It's possible your other machine has that zone setup just inside the soft limits. Note this function like a lot of Fanuc ones is an option on some machines. I'm not positive whether entering this zone sets an alarm of not but if not this might solve your problem.

Again... jogging with the Zero Return button on is one way to do it. That usually moves at a rapid rate. At least on my incremental mill it does. Right up to the decel dogs anyway.
 
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