For the OCD like myself, the one machine I work with that has a factory pot for feed override, is a pain to twiddle the knob to get the control to show exactly 100% on the screen. It's always a little over or under. I would very much prefer an encoder. Just because you have an encoder knob doesn't mean you can't have a graphic on the knob like the photo you showed. You just need to use an encoder with a fine enough count to get the resolution you want in the sweep area you'll use.
Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -----Original Message----- From: Les Newell <les.new...@fastmail.co.uk> Sent: Friday, October 26, 2018 7:53 AM To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Feed/Rapid override physical knob selection I use pots on all of my machines. Generally I have 3 pots, FRO, maximum feed and spindle override. The ADC is provided by an Arduino which controls all of my front panel buttons and talks to LCNC via Modbus over USB. I did put the code on the wiki many years ago but I just did a search and couldn't find it again. There do appear to be a few other Arduino Modbus examples out there. Doing it this way, my front panel just needs one USB cable going back to the control computer. This page <https://dereenigne.org/arduino/arduino-modbus-rtu-adc/> shows a simple Arduino example that reads analog inputs and spits them out over modbus. The MB2HAL module will handle the LinuxCNC side. > too many pots don't have an absolute zero, and they can creep the > machine if left enabled. I can't say I have experienced any issues with creep. I have had pots fail but if you use decent quality plastic track pots they last a very long time. I find it quite handy being able to tell at a glance what your feed rate override/spindle override etc is, no matter what LinuxCNC is doing at the time. The only issue I have seen is that it can be a pain to get the pots initially synchronized. Halui seems to ignore pots until the first time you move them. Les On 26/10/2018 09:25, Gene Heskett wrote: > Generally a Potentiometer, which will need an A/D in the interface to > read it. With an activate pushbutton so they time out. Do that in > your hal file. > > Why? too many pots don't have an absolute zero, and they can creep the > machine if left enabled. One of the reasons I prefer the encoder, it > has receivers built into the mesa cards making the encoder simpler to > hack up the hal to use them, the machine stops dead when the dial > stops turning (might be some windup it has to use up first if you've > spun the dial too fast, so be ready to spin it the other way when its > going to run into something) and I still time it out in about a minute > after its last use. Safety, safety. > > I use the encoder to set the jog size per count, all done in the hal > file, display the size of the jog per click in the axis gui using > pyvcp, a pusbutton enables that and the encoder dial is enabled when > the button is released, and a one shot to shut it all off about a > minute after the last "jog" move. > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
