Another tool table offset question

Hello I am brand new to this forum. First thanks to all for the infp on this site and all of the work in developing EMC. I have a Hardinge Chnc II lathe that I am going to retrofit with emc. On thing that really makes me question my plan is the ability to make tool wear compensation offsets while running parts on the machine.

I come from a commercial cnc (Fanuc and Yasnac) background where making these wear offsets is perhaps the most used feature on the control.

Normal process would be make a part, measure part features, make an offset to correct for variation between actual and desired diameter (in a lathe setting) (due to heat, tool wear, or variations in the touch off procedure)

This procedure is repeated dozens of times during a run of parts.

Would running something like this be at all practical in EMC?

If I update and press the reload tool table at what point exactly will my new values take effect? Would it be the next time the tool is called? The next time the (Gcode) program is started at the beginning? Or would you have to completely restart EMC?

Can the table be modified while running a part program?





Thanks for your time.

Justin

If you have not take a look here
www.linuxcnc.org/component/option,com_ku...,11163/lang,english/
and
www.linuxcnc.org/component/option,com_ku...,11761/lang,english/

Rick G

I don't think EMC supports FANUC style geometry and wear offset. But to make sure I understand what you mean, with indexabe tooling, you currently enter the geometry offset, then use the wear offset as the tool dulls. Then after an insert change the wear is reset to 0 and only the geometry is in effect?

Thats how my O-T works, but I actually just use it as John has described. I never use the wear function.

Thanks for all the replies and links. I will read through them.


Yes, what I would like to be able to replicate, if possible, is the Fanuc style Geometry and Wear offset system. When you first put in the tool and touch it off those numbers go into geometry and any adjustments due to tool wear or temperature changes in the machine would be done in wear. Typically the numbers in wear are pretty small .010" or less and yes, you can zero it when changing sides on a carbide insert and that normally gets you close. Basically the geometry is the absolute value telling the control where the tool tip is and the wear is an incremental offset to the geometry numbers.

It seems that the EMC style of offsets only uses what Fanuc calls Geometry and all changes must be made to this.

The nice thing about having a different offset system for making small adjustments is that it is really easy to see if you inputed a number incorrectly, say .100" instead of .010" therefore avoiding more trouble.


Say you a running 100 parts, and after 10 parts you measure the last one and notice that the bore size is .001 low, to fix this would you add this number to the value in your tool table or use the touch off function? And in each case when would the offset be applied? The next time you ran the Gcode program? Or the next time it calls the tool up? I guess this might depend on how far emc looks ahead to calculate its moves.

Also can you edit the tool table while emc is in the middle of running parts?

Tonight I will just run EMC in a simulation mode and see how it behaves.

Thanks for all the help.

Is any work being done to include wear offsets or assignable offsets in Linux CNC. We finally made our first test cut on a Cincinnati Milacron Turning Center and I was actually surprised that there is no provision for small offset changes without changing the fixed or geometry offset. I believe in the machine tool world the ability to make small incremental changes to the x or z axis without changing the fixed offset is invaluable. I see that this thread is over a year old and maybe there is something else that I have missed looking for a way to add this feature.