On Tue, Feb 22, 2022 at 9:14 AM John Dammeyer <jo...@autoartisans.com> wrote:
> Thanks Martin, > His question and the subsequent discussion on the MACH group has morphed > in now discussions on whether to use closed loop steppers and ethercat. > Not sure why everyone is so fond of leadshine closed loop steppers but > what do I know. I like my AC servos. > The answer is price. A closed loop stepper is not really stepping. The motor is run by an FOC controller and measured with a rotary encoders. The step/direction interface is kept. So the system is as easy to interface as a stepper but has performance characteristics like your A/C servo but at about $100 per axis. The closed-loop stepper's disadvantage is they come only in limited sized and power > > A decade or more ago it was MACH3 and the ESS or USB smooth stepper or the > EMC as it was then called. Now it seems there are a lot more CNC solutions > around and the number of people even considering LCNC seems to have > dropped. When the typical machinist sees an under $300 turn-key solution on Amazon that has an LCD touch screen and is all wired up with software and a place to connect the motors. Then he hears about LCNC where you first need to locate an antique computer with a parallel port then test it with a latency test then install a modified version of Linux, and only then can he begin to edit config files. He goes for the $300 turn-key system. Here is the "competition" amazon.com/DDCSV3-1-Upgrade-Stand-alone-Controller... <https://www.amazon.com/DDCSV3-1-Upgrade-Stand-alone-Controller-Engraver/dp/B07SR854D1/ref=pd_sbs_5/139-3455477-1339233?pd_rd_w=oXb8b&pf_rd_p=dfec2022-428d-4b18-a6d4-8f791333a139&pf_rd_r=XC1A6X2PEV1N61AZWS5C&pd_rd_r=62aa4f06-4bb7-45db-9de9-6bf67f0f4072&pd_rd_wg=sRlvK&pd_rd_i=B07SR854D1&psc=1> I think it should be clear why it is attractive. It is very much the polar opposite of what LCNC is. > > > I'm also surprised there isn't some sort of teaching module ready to go > for LCNC although again, really, how many even want something like that. > > > Much as Brian Barker might want to create a module the ultimate issue > isn't the starting point but support a year or so later. Without sales to > support the work that only one client wanted that may leave him hi and > dry. At least a DIY LCNC solution is always open source with more than one > clever person ready to help. > That is the big advantage of open source. But the problem is running it on an antique computer using a modified OS and having to hand-wire everything yourself scares off 99% of potential users. I think if you could buy a packaged LCNC machine that came inside a closed box with an LCD touchscreen and it booted up when you applied power and if you could sell it at under $500 and offer tech support and warranty, then LCNC would "take off". The box would still be "hackable" by the 1% who wanted to mess with Linux and config files but for most uses that would not even know there was a Linux PC inside. > > And since there are versions of the MESA that close the loop for servo > control on each axis I'd think that a training version with servos would be > pretty easy. But again I may be simplifying all this. > What is the total cost per axis for the motor size that is typically used? This is what people look at. Closed loop steppers seem to the be best and lowest cost solution for a certain range of power that is needed for smaller CNC routers. _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
