On Tue, 30 May 2017 03:51:01 +0100 Luke Kenneth Casson Leighton <[email protected]> wrote:
> --- > crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68 > > > On Mon, May 29, 2017 at 3:44 PM, <[email protected]> wrote: > > On Fri, 19 May 2017 01:42:52 +0100 > > Luke Kenneth Casson Leighton <[email protected]> wrote: > >> > >> On Fri, May 19, 2017 at 12:35 AM, Neil Jansen <[email protected]> > >> wrote: > > <snip> > >> now, neil, this is the kind of speed at which an arduino 2560 *cannot > >> cope*, and, also, where the design flaws inherent in RAMPS - using > >> prototyping Evaluation Boards (polulu-style drivers) - start to show > >> up. > > Could you be more specific? Why can't the arduino cope? > > there are more experienced people who know the precise details. > bottom line: an 8-bit 16 mhz processor is simply not fast enough to be > able to send the data to the stepper motors in a way that they will > remain properly synchronised. > > example: X axis gets changed direction/speed, and Y needs to be > changed at the exact same time. but because it takes e.g. 50uS (0.05 > ms) to get round the "compute" loop, the print head has moved on (say) > 0.2mm in that time, it's going so fast, so X and Y are no longer > properly synchronised. > > only by going to a 32-bit processor running at say 100mhz can you get > the timing synchronisation back. I understand now. I thought that the arduino was faster... > >> david crocket (dc42) has specifically designed the duet series so > >> that you can consider exceeding PWM rates of 150 khz, which is what > >> you need if you want to sustain 500mm/sec for example (and do not > >> want problems to occur at speeds well below that). > > Link? > > google it please. This looks like it: http://forums.reprap.org/read.php?147,33082,471483 > >> also i forgot to mention that i've been using the E3Dv6 "volcano" > >> which, when you use a 0.5 to 0.8mm nozzle can easily do flow rates of > >> something mad like.... 200c^3/min - particularly when combined with > >> the huge 40:1 gearing of the flex3drive which can *accurately* > >> deliver the kinds of torque needed. the volcano basically turns the > >> heat chamber round, so that the heat area is 20mm long instead of > >> the usual 10mm. > > Torque for what? > > Again, maybe a link would help us stay on the same page. > > google them, please. i have a lot else to take care of. <snip> I thought you were waiting for the PCBs to get done (which was going to take another week I think), and had nothing better to do than play with that oh-so-giggly-and-fun little girl in the youtube vids? Thanks, David _______________________________________________ arm-netbook mailing list [email protected] http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook Send large attachments to [email protected]
