On Tue, 2009-05-05 at 03:26 -0500, forget color wrote: ... snip > I'm thinking really simple and crude, at least for the first pass. > The idea is to have some wells in fixed locations on the cutting bed. > Each well would hold an upright paintbrush. I can use xyz gcode to > drive the machine so that it's over one of these brush wells. I would > then send a command to open the gripper, move the open gripper over > the brush handle, close the gripper, lift the brush out, and move on. > > For a gripper, it just needs to be something that would hold a light > brush. So I'm thinking a pull solenoid that will open a spring-closed > gripper of some kind. I haven't explored this part at all yet. But > like I said, crude is ok as long as it can pick up a brush and hold it > firmly.
I don't think solenoids have a lot of pull at the beginning of their stroke. You might consider using a small motor with a coarse screw and nut arranged as a linear actuator. If the screw thread is coarse enough, the spring could close the gripper when the motor turns off, or you could drive the motor in the open and close directions with an h-bridge. http://en.wikipedia.org/wiki/H-bridge > > Once I've got something crude under my belt, and a CNC working, and a > firm understanding of basic gcode and whatever else I'll need to learn > to get this far, then I'll refine and/or rebuild. > > thanks! > fg Sorry about that, I guess you did describe what you wanted a while ago. I also realize that there are more rack type changers than I thought. http://www.youtube.com/watch?v=RzR6L3lEXdM http://www.youtube.com/results?search_type=&search_query=cnc+tool +changer (short URL) http://alturl.com/jdbk The G540 manual: http://www.geckodrive.com/upload/G540%20REV3%20MANUAL.pdf indicates that the parallel port control signal for OUTPUT1 is at parallel port pin 17, and for OUTPUT2 at pin 1. In your EMC2 configuration file, for example your_cnc.hal, you will need to load the parallel port driver by adding a line. ... loadrt hal_parport cfg="0x0378" ... The 0x0378 is the address location for your parallel port. Ports built into your mother board will most likely use the address of 0x0378 for the first port, 0x0278 for the second. Parallel ports on PCI cards get assigned when the PC boots up, so you won't know what address is used until it gets assigned. See: http://www.linuxcnc.org/docview/html//hal_drivers.html http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?NetMos The driver has a collection of functions that become available when the driver is loaded. You can use a function from a driver by assigning it to a thread. A thread is a list of functions that get executed every x nano or milliseconds. Below is an example of the entry needed to read and write the pins on the parallel port every time the base thread runs: ... # read inputs first addf parport.0.read base-thread 1 # The 1 at the end places this function at the beginning of the run list # write outputs last addf parport.0.write base-thread -1 # -1 places this function at the end of the run list ... The functions provide software pins that can be connected together with signals. Below is an example of connecting the Coolant button on the AXIS screen to the parallel port pin 14. ... net FloodOn iocontrol.0.coolant-flood parport.1.pin-14-out ... So when you click on the Flood button in AXIS or put an M8 in your g-code, pin 14 will go from 0 Volts to 5 Volts. An M9 or clicking flood again, will turn pin 14 off. Since there is no gripper button or M code, you can use the motion digital out function: ... net g540out1 motion.digital-out-00 parport.0.pin-17-out ... Then control it with g-code M64P0 for On and M65P0 for Off. So for a tool rack system, the g-code might look something like: G0 X -1.000 G0 Y 5.000 (Rapid close to tool pocket 1) M64P0 (Open gripper, Pin 17 On) F50 G1 X -1.5 (Place gripper around tool) M65P0 (Close gripper, Pin 17 Off) G1 X -1.000 (remove tool from pocket) G0 X 4.000 Y 2.5000 (Go to first brush stroke) etc, I have probably left some details out, but this should give you an idea of what's involved. I noticed my pen plotter uses a mechanical toggle for the gripper so if it is closed, pushing it in a pocket, opens it and releases the pen. With this design you can avoid the electronic gripper setup above, but the mechanics are more complex. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
