Learning to Program CNC Turning Center

[Farmer]

I am trying to teach myself how to program and operate a Turning Center. It has a Fanuc 0TD control. I am having trouble with a seemingly simple problem. How do I position workpiece in the chuck so the same length is sticking out to be machined on each workpiece in a multi piece run. On a manual lathe I would just use a ruler, set the piece X from the face of the chuck, touch the face with the tool and set the trav-a-dial to 0, or face and then set the dial. On the CNC, should I bring down a tool and slide the part to the tool then clamp the chuck? Seems to me there should be a better way. What am I missing? Could I use the workpiece shift codes, say G54? Build my program using the face of the chuck as Z0, set my part with a ruler, then shift my program Z+ the length of the workpiece? If so, what would the lines in the program look like to make this happen? I have the Fanuc Programming Manual for the control, but this country boy can't seem to get his mind around the section dealing with the G50's group of codes.

[Al_The_Man]

On the CNC, should I bring down a tool and slide the part to the tool then clamp the chuck? .

I have used this method in the past, would'nt that be quicker than using the rule method?
Al

[Farmer]

Thanks for the response Al. Yes, it would probably be just as fast to touch the part to the tool for the first end. However, after machining the first end the part gets flipped and the other end gets machined. I am struggling with how to touch the part to the tool on the second end that is not faced, and ending up with a part that is finished to the proper length overall. If I use the face of the chuck as Z0, face and machine the first end, flip the part, put the finished end against the face of the chuck, or space it away from the face of the chuck a known amount with a gage block, then I would know exactly how long my part will be when it is finished. Am I missing something simple?

[Al_The_Man]

The problem is one of referencing the part, on a mill of course you use a jig or a stop on the table.
One method I have seen if it is a through hole chuck, is to make a stop rod that can be mounted on the back of the thru hole and slides in far enough to butt your part to.
Al

[mrainey]

Can't you just bore some jaws with a step to locate the end of the part? The face of the step would be Z0. Program the first side by adding a stock value to all your Z coordinates, so the finished front face of the first side would have a program Z value of the overall length of the part plus something to leave for cleaning up the second side. The front face of the second side would have a program Z value equal to the finished overall length of your part.

Added bonus - the step will prevent the part from pushing back in the jaws when you're taking a roughing cut.

[Farmer]

Thanks for the responses. I have decided to program like Al suggested on the first end, touch the part to the tool. Then do something like mrainey and Al suggested for the second end. I won't bore jaws for this run, since it is only 10 parts, but instead will just use a gage block to space the part from the face. I will do another set of tool offsets and run the 2nd end as a seperate secondary operation.

Does anyone know of a manual for CNC Programming that is written in a way that is understandable? The Fanuc Manual will leave you "mumbling" to yourself in an unrecognizable language!

[mrainey]

Look at:
www.betatechnical.com
www.cncci.com

[rpellegrim]

There are bar pullers you can purchase Through US Shop Tools.
You program it to pull the bar for you.
You can program the machine to come up and set a dead stop to pull the work piece up against.
You can purchase soft jaws and counterbore them to fit your part.
(if slug matl)

[rpellegrim]

Check HAAS, they have great manuals for thier SL series lathes

[TEXASLEADH]

"Check HAAS, they have great manuals for thier SL series lathes"

IT'S VERY WELL WRITTEN.
IT'S ONLINE.
AND BEST OF ALL ITS FREE.

[quammi]

got a link to haas?

[TEXASLEADH]

http://www.haascnc.com/custserv_updates.asp#reference

http://www.haascnc.com/custserv_training.asp#custserv