Ready Steady Eddy

[JAZZCNC]

Sorry my friend, but that is not correct. I didn't think so when I read it, so I just went out to the garage to check. My machine has a lot of flex, so I can easily rack the gantry one way or the other. I have dampers on my steppers, so with the power off, I can move one side by turning the dampers.

First I moved the master side about 3mm away from home, then powered up the machine, and homed the X axis. The slave axis hits the switch, and backs off, while the master keeps moving to it's switch, then it backs off.

Next, I moved the slave side 3mm farther from home. This time, the master hits the switch, and backs off, while the slave keeps moving.

Each side of the gantry (master and slave) move independently to their own switches. For all practical purposes, they are not slaved during homing.

To be honest Gerry I wasn't 100% sure my self it worked like I said and couldn't can't check as I don't have slaved motors on my machine. Last machine I setup that used slaved motors was several weeks ago and was using the ESS but I'm sure that stopped both motors and backed off then moved slave.? Thou I'd have to check again to be 100%. I don't ever use PP so can't check if it works differant to Motion control cards but I will on next slaved machine I'm building just out of curiosity. Previous machine also used Motion control card but that was Russian PLCM and thought that did the same but again can't be 100%.? Esp as it happens so fast and with gantry being square so hard to see.!

But more the point was they work together to square the gantry and like as been said if the gantry's setup square to start with and switches located at same point it's a seamless operation and very little twisting forces applied if correctly setup.

Edit: One other thing for clarity for others (Gerry knows this ).? The speed at which you home makes a big difference to accuracy and how far it over shoots then as to backoff. Thick of it as driving wheels upto a line in your car.! At fast speed chances are you'll over shoot further then have to back up more to put wheels on line. Same principle go slower and chances are you'll hit the line ever time with little to no over shoot.

[Ger21]

Homing in motion controllers is done differently than with the parallel port, so you may be correct with the SS. I know it's taken several years for Greg to get slaved homing to work correctly with the SS.

[EddyCurrent]

Bruce,

This is the circuit as it is on the machine.

[JAZZCNC]

Homing in motion controllers is done differently than with the parallel port, so you may be correct with the SS. I know it's taken several years for Greg to get slaved homing to work correctly with the SS.

Going back a little here to homing but was looking thru Mach manual today and noticed this in the Homing/limits section.

"When a Reference operation is performed, then the axes will run together until the final part of referencing, which
is moving just off the Home switches. Here they will move so that each stops the same distance off its
own switch. Referencing will therefore correct any racking (i.e. out of squareness) of the gantry, which
might have occurred when the machine was switched off or because of lost steps."

So they do a mixture of both really has they are slaved upto point it's backing OFF the Switch.!! Tonight Just checked on machine that is using PLCM-E3 and it works just like this. . . . . . Just thought this might clear any confussion.

[EddyCurrent]

So after that bit of RTFM, here's how I would set up the homing switches;

Assuming 2 home switches used on X

1. One switch can be mounted in a fixed position while the other switch needs to be + and - adjustable in the X direction.
2. Using some form of measuring equipment e.g. large T square, set both switches square to the X axis.
3. Carry out a homing operation of the machine then using the same measuring apparatus as in step 2. check squareness of the gantry to X axis
4. If the gantry is not square then move the adjustable home switch by the required amount and in the required direction.
5. Repeat steps 3 and 4 until the gantry is square to the X axis.

[Clive S]

Eddy Spot on, simples, can't just remember if the slave needs to be the adjustable one. I drilled some holes down the x and y then put dowels in then the square against the dowels. then readjusted the switch and tried again. ..Clive