[cygnus x-1]

No offense, but I feel like giving up! You touch off every tool on every different part you run. Any change in the tool or the part requires a change. The machine has no idea where your part is or where you tool is. It does not know the type of tool, the size of the tool, or the length of the tool, or the location and height of the part. Touching off means you are telling it where everything is. Otherwise if you tell the tool to go to Z0. and that is 100mm lower than you piece of material or the table of your machine, it will go and crash through it. It does not know anything. Touch off the tool any time for a different part. If you are running 100 of the same parts with the same material and size, then touch off once. If you run one part then go to a different job or part then touch off all over again.

I used to do it that way, and honestly I found that it sucks. If you run large quantities of parts per setup it might not be so bad but if you change setups a lot it means you are always touching off tools. And it's totally unnecessary.

The better method is to always touch off your tools to a fixed reference point that NEVER changes. It doesn't really matter where this point is, it just needs to be constant. When you load a new tool you set it's offset (to the fixed reference) once and it never changes until you take it out of the machine. Now when you setup a job, you set the work offset to the difference between the fixed reference point and the top of the work. The way I do this is to use my spot drill as a sort of probe, since it's always in the machine and never changes. I know that its offset to the fixed tool reference point is 10.675. So I jog it down to the top of the work (starting from machine Z0) and subtract that value from 10.675. The resulting value is your work offset. It may be positive or negative depending on whether the work is higher or lower than the tool reference point, but as long as you keep the sign it doesn't matter.

The nice thing about this method is that if you break a tool in the middle of a job; you just load a new tool, reset it's offset to the fixed tool reference, and keep going. If you set your tool offsets based on the top of a work piece, once you machine off the top of that work piece you've now lost your reference point. Now if you break a too you have to figure out how to recreate that reference point, or set the new tool to some other area of the part with a known distance from the original work zero. If the part has no flat areas to reference you're screwed and have to start over again. Been there. Done that. Don't want to do it again.


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