[Darth Yoda]

Hi again guys.
Need a bit o' Help. I'm standing in front of a brand new DMTG DV-500 CNC with the Fanuc Oi-MC controller. I've written a couple practice programs and they run fine. Problem is tool heights. The tools stay sky high above the parts. When I try to change the tool heights in the relative window, I get an error of incorrect format.
Right now the machine has this as a work offset. G54 x8.856 Y-73990 Z0.0. This is the actual center of the part I'm playing with. The G54 EXT feild has XYZ all zeros. The actual Relative page has X0.6690 Y-35040 Z-20.5115.
When I jog the machine down to touch the top of my part I get an overtravel alarm with the tool at about .500 above the part. I have read the manual but couldn't understand it.

I guess what I need is a step by step tool height tutorial preferably using 123 blocks as a gage. Anyone willing to help out?

Thanks for the help.
Yoda

[Ed Leeson]

sounds like you have over travelled in you z

[fordav11]

on a Fanuc the over-travel in Z has nothing to do with tool heights or workshifts.
The over-travel alarm means you have hit your physical hard or soft slide limits.
you do not say what part of the machine your are touching when you jog your machine down to touch the part. if it is the nose of the spindle you cant do that. the machine will not go that low. if it is a tool then your tool is too short or your travel soft limits are set incorrectly.
also, generally the Z workshift is not 0. it is usually a minus number and when the machine reads the tool length offset (G43 H1 etc) it will know how far to go to get to the Z0 position.

[Darth Yoda]

I'm trying to bring a 3/8 endmill to the top of the part which is about 1.5 inches above the table. The endmill/toolholder is about 4" from the spindle. It gets about 1/2 inch away then stops. Monday I can send pix if needed to help clarify. BUT the same thing happens with a 3/8 drill bit at 8 inch length.

[Superman]

You have not put up any code to see your programming method, ( you may be leaving out code that applies offsets )

This is my method of setting tools & a work origin
The tool length ( from tool tip to gauge point) is input into that tool's geometry offset page
Work origin (G54-G59) is XYZ distance from machine origin (HOME) to the part origin, ( ie. the value of Z is from the spindle nose to top of part ( usually a -ive number))

The G54 "00" field is a grid shift that gets added to the G54-G59 origins

For your program to take up offsets correctly, a G43 is used with a call-up of a geometry reference number ( tool length should be stored under the same number as the tool number )
ie
G0 G54 X0. Y0. ( rapid to the XY origin of the part )
S1000 M3 ( set & start spindle CW )
G43 H1 Z1. ( rapid the spindle nose distance (G54[Zvalue] minus the H1 stored value ) to 1" above part origin ) ( -ive/+ive values need to be entered with care, signing is critical )

[Darth Yoda]

Superman, there is not a program in the machine. I am trying to set up tool heights by touching the top of the part. The mill Z's out before I can touch it. It is about 1/2 inch high.
Also, the method you describe is exactly how I program. But thanks for the input, it gets me one step closer.

[Jalapena]

There is a limit as to how far the spindle moves down in Z. Sounds to me your machine does not have enough Z-axis stroke to reach the top of your part. You can either get longer tools/tool holders to reach the part or you can add something to raise your part. I made a set of aluminum risers which I often use when parts are too short to mount directly to the table.

[Darth Yoda]

Hi again. The problem I had was a missing Minus sign AND not enough Z travel. Since this is anew machine I ASSUMED it would Z move "close" to the table. But thanks again for the help and replies.