On Tuesday 14 July 2020 12:18:30 Les Newell wrote: > On 14/07/2020 15:28, Reinhard wrote: > > The machine moves (assuming it does not have absolute > > encoders that are battery buffered) toward the home switch until the > > switch signals contact. That's the axis origin - and I thought, this > > is what the word "home"-position means. > > With any professional cnc I know about it is the case. > > Obviously not with linuxcnc :( > > Referencing is simply a way for the machine to identify it's position > in space. Where the home switches are positioned is immaterial. They > just say 'you are here'. It is up to the machine integrator to decide > where the axis 0 is. > > > So if linuxcnc has different behaviour, it is far from being > > flexible. It's just crap! Crap from people that don't know machine > > behaviour. > > You can set up LCNC to use the home switch exactly as you describe. > You can define your axis zero to be anywhere you like. > > > No programmer will ever use machine-coordinates (G53) - only in case > > of trouble or for maintenance. > > Nope. G53 is pretty common. For example on a lot of machines Z0 is the > highest point the Z axis can move. G53G0Z0 will give the maximum > possible Z clearance without needing to know about any offsets. > > On my router for instance my parking sequence is: > G53G0Z0 > G53G0x1250Y1300 > > > And that a user needs to use negative tool offsets is bullshit. > > Tool offsets are added to the commanded position, just like any other > control. They specify the position of the tip of the tool relative to > some standardized reference position. For instance on a mill the > reference may be the tool holder gauge line. On a mill or router you > are very unlikely to need negative tool offsets. If you do, the > problem is to do with how you have your work or fixture offsets set > up. > > On a lathe however there are some situations where you would need > negative offsets. For instance if you are using a lathe with two tool > posts on one X axis. Everything will be negative for the tool post > behind the spindle centre line. Some lathe controllers have have > compensation built in for this but AFAIK LCNC does not. > > > Its very poor, that there are so many weird workarounds in linuxcnc > > caused by ignorance, lack of knowledge or misunderstanding :( > > It strikes me that in this case the lack of understanding is on your > part, not the LCNC authors. > > Les > I have to agree. Haveing a home_offset, conbined with logic that runs it toward the switch position is extremely handy if one sets up his switch activation so its never released if travel continues in the direction that closed the switch. On both of my lathes the switch is a bit left of center of the travel, so issueing a home, the switch is first checked and if closed it drives the carriage to the right in search of the switch opening. If open, the carriage is right of the switch so it knows to move left to find it. So at the least, you don't have to manually move the machine to where you know the switch is open before starting to home it. It just goes in the right direction to find the switch autmatically. Its called usability.
Whats not to like about that? > > > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
