Re: [CAD_CAM_EDM_DRO] Shoptask Z-axis - quadralift?

At 02:51 PM 3/5/03 -0000, you wrote:

>a short end mill in a collet. The head is fairly low. Then
>you change to a 17/32 drill bit in a jacobs chuck, and need
>to raise the head by 6" to make the tool change. Do you have
>to touch off each tool after the change, or is there some
>way that the control can do it automagically?

This amounts to having a tool length table. Here's how it worx: CNC
software allows you to jog machine, which you do with each tool in turn, as
part of the setup process. Tools are touched off on ref point and the
machine ccords are stored for each. So tool change position must be farther
from machine than longest tool, probably in your case the drill bit. The
stored coords can include the two horizontal axes also. The coordinates are
stored with tool numbers and when each tool number is called in the
program, the machine should home, allow tool change opportunity, and move
that tool to the reference location. So each vertical tool for example,
starts the same distance above the ref plane; from there it's the
programmer's job to postion it for cutting. For ex, for roughing
rectangular blocks, one might ref the milling tools just outside the rough
stock at clearance hgt and then feed it to the right starting point for
each type of the remaining machining. BTW, the software usually stores
fixture offsets in the same table, and it usually adjusts displayed coords
to the repsective tool tips, so each shows it's tip as zero no matter where
the machine actually is. And when a fixture is called, the fixture coords
are compared to the respective tool offsets, so each tool is displayed at
zero compared to each fixture also. Nice touches include delivering tools
to a settable clearance hgt instead of the actual ref zero, and even also
storing feedrates and/or tool dias in the tool number table.

Regards, Hoyt McKagen


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