Hi every1, Thank you for all the response to my question. So this is a very active community. As our ERP system we have chosen ADempiere (http://www.adempiere.com). There we have a very active community, too (and we are an active part of it ;-) ). I know how valuable such a community is for an OpenSource project is, or how valuable the community makes the project.
I took a look to the link Andre' posted. Yes, I guess that's the way. Actually 10 points per inch is more than enough. Now we are using a point distance of about 30-40mm, with a good result. But I have one question regarding the collection of the data: To measure the points I think it would be necessary to save the axis positions on a trigger pulse. The Datron machines do the probing with a tip. It moves down and if it touches the material it sends out a puls. And to make it precise the latching should happen with a very short delay (the z-axis is still moving at this moment). I guess it's the same problem you have with the measurement of the tool length. So is there a functionality for this? Could it be done in user space? BTW: The sensor tip Datron uses is sensitive in all three dimensions. So you could also use it to determine the position of a breakout - a nice feature. -Kai Kenneth Lerman schrieb: > One possible solution to the probing issue is to write a special > kinematics that interfaces with probing. With the kinematics turned off, > probe the sheet at the desired resolution. A special (new) command would > write the X, Y, Z coordinates of each probed point to the kinematics. > > When the kinematics is turned on, it would then provide a Z axis > correction for each point based on interpolation of the table that was > generated during probing. This should be pretty straight forward to do. > > My first approach would be to do most of the work in user space. The > user space code would collect the probe data. It would then generate a > table in a form most usable by the kinematics code. The table would then > be read into a shared memory region where it could be accessed by the > kinematics code. To make this fast, I would probably use a table with a > uniform grid, say 10 points per inch. (Kai, would that be fine enough?) > > For a 20 inch x 30 inch panel (600 square inches), that would require > 60,000 points. Storing a real number for each is only a quarter of a > megabyte. That's reasonably small by today's standards. A 100 points per > inch would require about 24 meg. That's still not unreasonable. > > The kinematics are a simple change to trivkins to add or subtract the > Z-axis correction from the target value based on the X and Y locations. > My guess is that it would take about a week for someone who had done a > kins before and who knew what he was doing. Allow a month for someone > who is new to the game. > > Ken > > Kai Schaeffer wrote: > >> Andre' Blanchard schrieb: >> >>>> Why would it run out of lines? It should always have a buffer >>>> of interpreted G-code to read ahead. I did some experiments >>>> with the relatively new G64 Pxxxx command to set the allowable >>>> tolerance during contouring. I was doing 588 blocks of G-code a >>>> second, and that seemed to be limited by the feedrate I had set >>>> and acceleration limits for the machine, not the CPU. This was >>>> on a 600 MHz Pentium III, so much faster hardware is available. >>>> >>>> >>> It kind of sounds like the current system may be running multiple machines >>> off one computer, some type of drip feed DNC. >>> >>> >> No, one computer per machine. But the software they have right now is >> ... let's say not perfectly optimized.;-). So it could happen from time >> to time on the older machines with older PCs. >> >> But we just had another case were it happened: We milled a gear which >> was defined over DXF file with a lot of small lines (some thousand). So >> the radius compensation took a while (some seconds). >> >> >> >>>>>>> - Measurement of the surface for a Z-correction >>>>>>> >>>>>>> >>>>>>> >>>>>> probing? >>>>>> >>>>>> >>>>>> >>>>> At the beginning of each program we measure the Z-profile of the surface >>>>> of the sheet. This profile is used to correct the position of the Z-axis >>>>> to get a precise cutting depth. >>>>> >>>>> >>>>> >>>> EMC currently doesn't have a feature like that. I suspect it >>>> could be done, but it wouldn't be trivial. >>>> >>>> >>> May be easier to run an EMC program to probe the surface and store the data >>> in a file. >>> Run an offline program to appliy the probe data to the part program. >>> Then run the modified part program in EMC. >>> >>> >> I am not sure. Let's say you have a movement over the whole sheet. How >> could you correct it if you have a little buckle in the middle? >> >> I would say it should be a layer somewhere between the vector generation >> and the hardware. What does "it wouldn't be trivial" mean in man-months? >> >> Regards, >> Kai >> >> >> > > ------------------------------------------------------------------------- > Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! > Studies have shown that voting for your favorite open source project, > along with a healthy diet, reduces your potential for chronic lameness > and boredom. Vote Now at http://www.sourceforge.net/community/cca08 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Schaeffer AG Dipl.-Phys. Kai Schaeffer Vorstand Nahmitzer Damm 32 Tel. +49-30-8058695-25 12277 Berlin FAX: +49-30-8058695-33 http://www.schaeffer-ag.de HRB 93611 B, Amtsgericht Berlin Charlottenburg Vorstand: Jörg Schaeffer, Kai Schaeffer Aufsichtsrat: Dieter Kersten (Vorsitzender) ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
