Z-Depth; mind of its own?

[ohiwish]

Hey kids, new operator to ShopBot with my high school kids. We are running the PartWorks sample program; flat bottom v-carving. It has the word 'Open' in the middle of an oval. Problem is we set Z to 0, and run the program on 1/2 inch thick medite. Well the z-depth comes in and plunges way below the material, we have to stop it before it completes the plunge into the table. The program code says .150, but is is clearly not. I have experience on the CNC metal mills but the ShopBot stuff is a bit different. We zero'd all axis on the corner, everything seems right, and ideas. . . . .please. . . . . . .

Thanks
Jim
Central Kitsap High

[ken_rychlik]

If you set the material up to zero to the top of the material in partworks, and actually zero to the bed of the machine instead that will mess things up.

[myxpykalix]

Like kenneth says you need to know where your Z zero is located, to the top of the material or top of the table?

If it is located at the top of the material and you want to take a cut .150 deep it will go down .150 into the material

However,
If it is Zero'ed to the table top and you want it to go down .150 and you have a .75 thick piece of material the bit will go down all the way thru the material and down .150 in the table if you don't stop it first!

This is something you need to be aware of when setting up the file to begin with. If i were you i would develop some type of checklist the kids need to follow when creating a file and then prior to starting the file on the bot.

Some of the questions might be:
Where did i set my Zzero when i created the file?

Is my material the same size as the file i created?

Where is my start point in the material (lower left, center?)

Did I Zzero to the top of the material or to the table (check to see if it matches the file before starting)?

Those are a few off the top of my head, i'm sure there are others. I myself still go thru a mental checklist when starting a file.:eek: