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 ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
