On Thu, Feb 3, 2011 at 11:13 PM, Viesturs Lācis <viesturs.la...@gmail.com>wrote:
> 2011/2/3 Yi-Shin Li <y...@araisrobo.com>: > > On Thu, Feb 3, 2011 at 2:44 PM, John L. Craddock < > > john.cradd...@xitech.com.au> wrote: > > > >> > >> > -----Original Message----- > >> > > >> > http://www.youtube.com/watch?v=BraEMAu5UkY > >> > Video clip for plasma cutting for 6mm mild steel. It's with > >> > EMC2, a USB based THC/motion interface, and 3Amp/axis > >> > low-cost micro-stepping drivers. > >> > The Plasma Cutter is HYPERTHERM PowerMax 45 with machine > >> > interface. The EMC2 is patched with NURBS motion and S-Curve > >> > velocity profile. > >> > -- > >> > Yishin Li > >> Very interesting Yi-Shin. Can you tell us a bit about the USB THC? I > >> couldn't see any initial height sensing mechanism from the video. > >> Best > >> John C > >> > > > > The prototype machine lacks Z axis sensor for initial height > > probing. Currently, we use manual touch-off for initial height sensing, > > which is quiet inconvenient. We are drafting the mechanical design for > > initial height sensing. Any advice would be appreciated. > > My waterjet machine has ultrasonic sensor that outputs 4-20mA analog > signal, I have microcontroller which converts that to 0-10V analog > signal (please, do not make my mistake and just get a sensor that > outputs 0-10V directly), then comes voltage-to-frequency converter and > then the frequency signal goes to EMC2. In EMC2 there is software > encoder, which takes the frequency as input and outputs some virtual > velocity. EMC2 already has THC module, which compares the velocity > (converted to some virtual volts) and compare it with the volts > requested and adjusts Z position so that actual volts are equal to > requested volts. > I have modified THC module so that: > 1) together with minor tweak in kinematics module Z returns to > original position, when THC is turned off, > 2) there are 2 correction speeds, depending on difference between > actual and requested volts, > 3) I have pyvcp panel with spinbox, in which I can change the value of > requested volts and I also have 2 buttons - one turns THC on and off, > another just freezes current position. Both of them are available "on > live" - when machine is running. So it gives me possibility to > pseudo-jog Z axis, when EMC2 is running code. > > >From hardware point of view You need: > 1) ultrasonic sensor with 0-10V analog signal output. > 2) voltage-to-frequency converter. There are chips available for DIY > designs. Or You can take a look at Mesa thcad board. > > >From software point of view - take existing THC module, try it out and > adjust it to meet Your expectations... > > > Could anyone share sources for cost-effective (cheap) plasma generator? > > Viesturs > > Thanks for your advises. They are very valuable. -Yishin ------------------------------------------------------------------------------ The modern datacenter depends on network connectivity to access resources and provide services. The best practices for maximizing a physical server's connectivity to a physical network are well understood - see how these rules translate into the virtual world? http://p.sf.net/sfu/oracle-sfdevnlfb _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
