Jim Fleig - CNC Services wrote: >Hi Peter, Hi Stephen, > >Thank you very much for your answers. > > Sure (from me anyway :) )
>The goal is to retrofit a knee mill (Hurco KM3P) in very good mechanical >condition with the original servo amplifiers (analog signal, + / - 10 vdc) >and then cut 3D gcode output from a MicroSoft (please keep the booing in the >backround) based CAM software. The user must be able to connect to the >MicroSoft network (Centroid is currently Linux based and I connected the >customer's machine to the MicroSoft network by following Centroid's >instructions) to download files (most preferable) or load the gcode onto a >thumb drive and walk the program to the EMC control, load, setup part zero >and tools and run. > > Either networking or sneakernet will work fine. There is also the ability to remotely monitor (or operate) the machine if you want it. >This application is very blocks per second intensive. Spending money on a >faster CPU or dual CPU's would be weighed against the benefits of the >ability to mill faster. The Hurco, prior to the control dying, would >average 25 ipm. If after retrofitting it would average 50 - 60 ipm this >would be a substantial increase. I really don't think it will do much >better than that because it is a dove tail saddle. Consistently higher >feedrates would require linear ways. The Centroid retrofitted mill that >averages 60 ipm has a dovetail saddle. > > You should do some throughput tests with any candidate software and evaluate the results as needed. You can try EMC2 by downloading the liveCD and running from it, or for a better test you can install it to a hard drive. You should modify one of the stock configs (in the sim directory, since those don't need any special hardware to be present) so it has the correct acceleration and velocity limits for the Hurco. This will give you a feel for how fast EMC2 can do block processing. If the tolerances for these parts are reasonable, you can also set G64P<tolerance> to combine multiple blocks into single moves. I believe that Jon Elson did some block processing speed experiments, and came up with some few hundred blocks/second issue rate. I don't know if that was with G64P- or not. If you can do say 500 blocks/second, that's 30000/minute, so wach only needs to be 0.0015 or so to get to the speed range you're looking for. This is assuming that block processing speed is the limiting factor, not servo acceleration or something else. >Any recommendations for a fast motherboard? Fast motion control board? >Approach to configuring the system? > > A couple of things: 1) You will need a PCI board for high servo cycle rates. There are several parallel-port-connected devices, but the I/O is too slow to support very fast servo cycles. At the moment, I'd recommend a Mesa card <http://www.mesanet.com>. 2) The realtime kernel we ship by default does not support multiple CPUs (which includes multiple CPU cores). There is someone working on making an SMP RT kernel right now, and there is an older experimental one that has worked for me on another system. 3) There has been a report that this motherboard <http://www.newegg.com/Product/Product.aspx?Item=N82E16813157141> peforms quite well on the latency test provided with EMC2. You can get a dual-core CPU if kernel support becomes less of an issue. I don't know if 3 or more cores will help much, but two should. The EMC realtime layer will automatically use the highest core found if there is more than one, so there would be a split between the realtime and userspace code with two cores. I'm not sure how many user processes are involved in getting a command out of a file and down to the realtime system though, so more than two might not be of much benefit. This is a place where you may need to do some experimentation, if the performance of a relatively fast PC with one or two cores isn't fast enough for you. >If this goal can be achieved on a par with a Centroid system (the best I >have seen so far for 3D milling on knee mills but I haven't seen everything) >then I have a customer ready to give it a try. > > Great. Let us know if you need help testing EMC2 for your application. - Steve ------------------------------------------------------------------------------ Create and Deploy Rich Internet Apps outside the browser with Adobe(R)AIR(TM) software. With Adobe AIR, Ajax developers can use existing skills and code to build responsive, highly engaging applications that combine the power of local resources and data with the reach of the web. Download the Adobe AIR SDK and Ajax docs to start building applications today-http://p.sf.net/sfu/adobe-com _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
