On Wednesday 26 October 2016 08:11:18 andy pugh wrote: > On 26 October 2016 at 03:19, Jon Elson <[email protected]> wrote: > > Assuming your home switch is 1 inch from the top (max limit) > > and 4 inches from the bottom (min limit), > > and that the HOME_OFFSET is 0, then you should set the soft > > limits like this : > > MIN_LIMIT = -4.0 > > MAX_LIMIT = 1.0 > > Just one caveat with a system like this: You need to make sure that > the home switch is "true" for the entire range from 0 to +1. Otherwise > a homing command when above the switch will go up away from the > switch, not down towards it.
Or, in my case, if its a tad above the switch trip, which itself is less than half a turn of the screw from the mechanical limit, it can't overpass the switch, but since the switch will be closed, it will refuse the home all until it has been run back down the post far enough to get off the switch. I did have the potential for that problem on TLM but my most recent rework, putting the tapered gibs on it, has now put TLM in the same state as the G0704, in that it cannot move past the switch to clear it now. So that also refuses to do a home all until its manually (keyboard right arrow) moved clear of the switch. Problem solved. The small mill has 2 switches, but they are basicly e-stoppers, to keep it from running the nut off the end of the screw. I tried to use them as home switches too, but couldn't cobble up enough hal quickly so I removed that. So the best I can do on it, is run it to the limit trip, enable the backoff, backoff some fixed amount, and manually home that axis. That fixed backoff however cannot be done without doing all the homes manually at arbitrary positions because it cannot do an mdi move until its homed. Question re small mill switches: If I was to nuke the switches use as limits, and make them home switches (shared), then set the software limits say 100 thou off the switches, can it, if I need to rehome it, ignore the software limits so it can find the switches, which might be beyond the sw limits? OTOH, in that scenario, the switches do act a bit early, unavoidable from the way they are mounted, and I could gain a much needed extra 0.15" of movement and still not be letting balls fall out of the nuts. Ignore the noise, its just me, exercising a rusty old brain by actually thinking. but it needs at least 1 more cup of caffeine yet. :) And I can't remember if the table hits the post, or the safety limit switch on the Y axis first, ISTR it hits the post first. So I'd have to mount another switch to trigger on the post for that to work. That is two switches to be added because there is no switch on the Z either. A project for next spring maybe? Keeps me out of the bars don't cha know. Thanks guys. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ The Command Line: Reinvented for Modern Developers Did the resurgence of CLI tooling catch you by surprise? Reconnect with the command line and become more productive. Learn the new .NET and ASP.NET CLI. Get your free copy! http://sdm.link/telerik _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
