Work offset with CB

[kvom]

I have a current project where I needed to drill a common hole pattern around 4 different other holes in a casting where these 4 hole coords weren't fixed by the plans.  It occured to me to use work offsets for each hole and run the single g-code on each.  So I measured the center of each hole as 0,0 using a different work offset.  Then I typed G54, run program, G55 run program.  Not something one needs every day as with CB one rarely needs work offset.

The distance in X,Y between a pair of holes is also determined this way.

[EddyCurrent]

Good idea until you run out of offsets 

Another way would be to use "Machining Origin" at Part level.

[Garyhlucas]

You can call G54, G55 in your program so it changes automatically and you don't forget.  Using Origin in Part works if you know the origin when programming where G54 can be set while machining with no code change.  They both work.

[dave benson]

HI Kvom

For jobs like this, you should wrap up the Gcode for the bolt hole pattern in a subroutine (programmed in incremental mode). The Idea being that you move to a existing hole centre in absolute mode (or indicate it in) and call the sub
which is written in incremental mode to do the bolt hole pattern. The sub returns to abs mode before ending then
move to next hole (or indicate it in) call sub, rinse and repeat. This is a very powerful and handy way to do this kind
of work.
This is how we were taught to do it in college.

Dave

[kvom]

I had to do only 4 holes in 2 sides of the part.  Having a simple program to run while standing at the mill was the goal.  Now I could have done each hole individually;  I needed to find the hole center using an edge finder.  By using work offsets I could do both without losing the first's coords.  Having done so, I saw no need to modify my simple CB for drilling the 4 additional holes.

I thought making this post might alert some others about using work offsets for similar simple tasks.  Obviously if I knew the coords of the holes in advance I'd just have done it all in CB.

[EddyCurrent]

I thought making this post might alert some others about using work offsets for similar simple tasks. 

It certainly did, but because we all have different experiences and knowledge and we like to pass some of that on, it was only natural that alternative ideas would also be presented. 

[Bubba]

It certainly did, but because we all have different experiences and knowledge and we like to pass some of that on, it was only natural that alternative ideas would also be presented. 
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+1 

[Bob La Londe]

Work offsets can be very handy.  I used to use them all the time to cut two identical parts in two vises on the table.  For multiple parts though I often use fixture plates that allow for holding 6 to 12 parts at a time.  I have a 2D model of each fixture plate, and a X,Y 0,0 point in the model and machined into the plate.  Using either duplicate geometry, or nesting (or often both) I place the positions on the fixture plate in CAD.  Every time I load a particular fixture plate and zero to it, its the same.  I know that's more of a production method, but it is very handy.