A new magic wiggler WAS Re: [CAD_CAM_EDM_DRO] Locating already drilled holes
Posted by
Rick Dulas
on 2000-10-10 07:32:05 UTC
Howdy! This is a variation on the bullnose theme. How 'bout using a
Unibit? That stepped drill bit used for cutting sheet metal, electrical
boxes, etc. The one I have steps from 1/8" to 7/8" by 1/16ths. and there
is a chamfer between steps for those awkard sizes.
As another option, consider removing the human from the operation. We
have a machine which is capable of moving under its own power and
responding to external inputs. Using human-operated jog buttons to line
something up just introduces more degrees of freedom and more potential
error. If these inputs are instead derived from error terms generated by
some centering device, we have reduced the degrees of freedom of the
system, and hopefully reduced the locating error.
Imagine a 3" piece of 1/4" drillrod standing vertically and associated*
with the existing hole in the work. This is the target. Imagine a
"Finder" to go into the mill's toolholder. A 1/4" to 1/2" shank turning
into a 3" piece of 1" stainless thick-walled tube. The operator moves
the table/work/target until it is under the finder, then lowers the
spindle until the target is encased by the finder. The operator hits the
"FIND" button on the control system, the system hunts and settles and it
is done. Magic? Of course.
Inside the finder are 3 sets of LED transmitter/receiver pairs arranged
orthogonally. A pair each for the X, Y, and Z axis. Each set of LEDs for
each axis, straddle the "target" rod and shine across it, thus
generating an error term if the rod is not dead center between the LEDs.
The difference in output of the 2 X receivers is sent to the system
control, which in turn will move the table along the X axis until the
error is eliminated or within some acceptable limit. The same happen for
the Y and the Z axes. Why not, you can now locate that hole in all 3
axes. How do you pick up an edge? Get a piece of drill rod that is half
ground away. Set it on the edge of the work, and go to town.
I can hear it now. "This only works when the target is vertical." This
is true, so you put a second set of LEDs on each axis and now the
control system will not only compensate for the lean, but tell you how
much and which direction your target is tilting, if you ask. <G>
Just some thoughts on the existential question of "Where am I".
Rick Dulas
Ian Wright wrote:
Unibit? That stepped drill bit used for cutting sheet metal, electrical
boxes, etc. The one I have steps from 1/8" to 7/8" by 1/16ths. and there
is a chamfer between steps for those awkard sizes.
As another option, consider removing the human from the operation. We
have a machine which is capable of moving under its own power and
responding to external inputs. Using human-operated jog buttons to line
something up just introduces more degrees of freedom and more potential
error. If these inputs are instead derived from error terms generated by
some centering device, we have reduced the degrees of freedom of the
system, and hopefully reduced the locating error.
Imagine a 3" piece of 1/4" drillrod standing vertically and associated*
with the existing hole in the work. This is the target. Imagine a
"Finder" to go into the mill's toolholder. A 1/4" to 1/2" shank turning
into a 3" piece of 1" stainless thick-walled tube. The operator moves
the table/work/target until it is under the finder, then lowers the
spindle until the target is encased by the finder. The operator hits the
"FIND" button on the control system, the system hunts and settles and it
is done. Magic? Of course.
Inside the finder are 3 sets of LED transmitter/receiver pairs arranged
orthogonally. A pair each for the X, Y, and Z axis. Each set of LEDs for
each axis, straddle the "target" rod and shine across it, thus
generating an error term if the rod is not dead center between the LEDs.
The difference in output of the 2 X receivers is sent to the system
control, which in turn will move the table along the X axis until the
error is eliminated or within some acceptable limit. The same happen for
the Y and the Z axes. Why not, you can now locate that hole in all 3
axes. How do you pick up an edge? Get a piece of drill rod that is half
ground away. Set it on the edge of the work, and go to town.
I can hear it now. "This only works when the target is vertical." This
is true, so you put a second set of LEDs on each axis and now the
control system will not only compensate for the lean, but tell you how
much and which direction your target is tilting, if you ask. <G>
Just some thoughts on the existential question of "Where am I".
Rick Dulas
Ian Wright wrote:
> HI,[Non-text portions of this message have been removed]
>
> My method would be to turn a small length of bar stack to the hole
> diameter
> and, at the same setting, turn the end to an accurate point
Discussion Thread
Rick Dulas
2000-10-10 07:32:05 UTC
A new magic wiggler WAS Re: [CAD_CAM_EDM_DRO] Locating already drilled holes