Fanuc 18i Programming

[jorgehrr]

Hello there

I started to work with a new machine today a big Nakamura TW10 with two turrets. I'm getting to know the programming part.

I usually work with small Miyano Lathes

My problem is:

Transmission Gear Selection Command (M41 - M42)

Why and when this Mcodes are used.

Thank you for any explanation.

Jorge

[bborb]

For smaller chucks and collets, a belt driven spindle performs well from 0 to many thousand RPMs since any cutting doesn't demand a whole lot of horsepower. Now that you've moved up to one of the "bigger boys" and are spinning much heavier iron, horsepower is a larger part of machining. Like a car's transmission, in low range (1st gear) you can pull much larger loads but max speed is limited. With your car in third gear, you wouldn't be able to take off with much power but your max speed is much higher.
As for your lathe, you need to find out the RPM range for M41, and the RPM range for M42. M41 is low range and M42 is high range. Now that you're spinning larger parts, its critical you learn to convert surface feet per minute to revolutions per minute, and convert revolutions per minute to surface feet per minute.
Say you're turning some tough steel that requires 350 surface feet per minute and the diameter you're turning is 10 inches. The actual RPM's will be about 140 RPM so you'll want to command:
_
G97 S140 M41
M03
--
or
--
G50 S375
G96 S350 M41
M03
_

You'll also want to include a G50 (max spindle speed) so the RPM's won't go so high it'll throw the part out of the chuck.
This is a whole new ballgame so don't be afraid to hit emergency stop at ANYTIME.
Always be aware of what spindle range you're in for safety.

[jorgehrr]

Thanks man.

I couldn't hope for a better explanation.

And...yes, the first thing I look for was the emergency shut off. (LOL)

Thank you again

Jorge

[maximusek]

Hi jorgehrr

This time is my turn to write something. First in Nakamura tw-10 M41 means also c-axis disconnected or they call it spindle mode. To engage c-axis U have to use M91. Second g50 with g96 is useful but...yes, there is always but if diameter of bar stock is lot less than 1" g97 is enough, don't waste time. The third problem is Y-axis knock. Right now I'm fighting with this **** and either machine is ****ed up or my program is a piece of crap (in my opinion answer b is correct). During turning Y-axis can be blocked (M470 pin IN), for some reason machine drives me crazy when I try to do something - spindle just stops during transfer, no alarm message, nothing - so please keep it in mind.

to moderator, sorry for my language but this machine made me very angry that day

[jorgehrr]

I sure will.

Thank you very much.

Jorge