Rick M (in 13PTg.77157$ email@example.com) said:
| "Morris Dovey" wrote
| Snip of some very good advice
|| It would not be difficult to move your sliding jig with one or a
|| pair of micro-steppers and set up the jig to clamp while in motion
|| and release at extremes of movement. That would allow the operator
|| to drop the block into the jig and press a pair of buttons (one
|| for each hand), then reach for the next block while the cut is
|| being made. You should be able to feed the block past the cutter
|| at 3-4 in/sec (180-240 ft/min). Once the cut block has been
|| dropped, the jig can be retrieved at a still higher speed. You'd
|| need a PC (an old, recycled 386 would probably do) and a stepper
|| controller to drive the motors. Using steppers makes it easy to
|| control feed speed and acceleration/deceleration of the fixture.
| Hey Morris,
| This job is easily handled by a servo motor system. The one I'm
| thinking about is a stepper motor with an integral controller. This
| controller can be PC controlled, or you can program it to perform
| the very functions you describe. With four digital input/output
| lines, and one analog input line, you can (a) start sequence with
| two switches in series. This drops a shield, forces a clamp to
| close, start the spindle, and after a brief (programmed) delay,
| starts moving. When it hits the end-limit switch, it shuts off the
| spindle, releases the clamp (allowing the part to drop), and after
| another brief (programmed) delay, returns the carriage to the home
| position (set by the "home" switch). The analog input port can be
| used to set the travel speed, and you have the last output to
| either serve as a clamp release, or other function you may desire.
Sounds good. I think I'd leave the spindle running and only power it
down if the operator failed to initiate a cycle within some timeout
period - say ten or fifteen seconds.
| I used 3-stack 34 size motors from Intelligent Motion Systems
| (http://www.imshome.com/mdriveplus_overview.html ) for the assembly
| line battery tester; I was moving 45-60 pounds of fixtures on two
| axis and needed the torque. We used acme screw rod and nut to move,
| and used turned, ground, polished rod on linear bearings for low
| friction directional control.
Also sounds good to me. I used essentially the same linear motion
control approach with the JBot; but found a threadless lead screw and
follower (DAGS: Rohlix) that I think I may like better.
| Hope this helps ... with this approach, it's more mechanical than
| electrical. You will, of course, have to provide a power supply for
| the motor, and will need an RS-422/485 interface (available from
| IMS as well) to program and/or control the motor. Nice thing about
| the 422 comms, you can daisychain a pile of motors on one comms
| line (I had 14 steppers running at once in direct comms mode with
| no issues).
Does help. Even nicer aspect of the 422 I/F is that it's pretty much
immune to shop electrical noise over long runs.
I think perhaps you should be offering Tom a proposal. :-)
DeSoto, Iowa USA