If you can measure the output signal with a scope I would do that. You need to know what the SS is seeing. Have you tried swapping  two of your sensors to see if the problem moves with them?

Swapping is out of the question, too destructive ! I have a vellman scope, never used it much, will see what I can get it to tell me today.

Did you solve this, Don? If so, or not, I'd be interested in hearing!

I achieved slight change by tweaking the settings, consistantly at .002" now. I'll have to live with it for the time being !

What actually happens on your setup?

On mine, I have an issue on "Z", but I've attributed it to the heavy knee even though it's balanced with gas springs. It homes at the bottom fine, but then sometimes the switch trips into estop again. With Z homing first, of course, if it does it I have to stop, reset and jog off, then manually home X and Y. I have optical limits and they only back off .001 or less to get off the switch and I'm thinking sometimes it settles. I have tried different shaped vanes to trip, thicker, thinner, etc. I've milled the edges so they're sharp and square. It seems it's so close, ON the switch, OFF the switch, that once in a while the Z settles .0002 and trips the switch in and out. It's actually seen flickering on the diagnostics screen!

When I saw this thread I thought, hmmmm? I've tried all the things you've tried except changing to 4khz or anything. I'm at 1khz and have never changed it. Our issues are probably different, however.

thosj
 It certainly sounds like it could be the axis settleing back in your case, you could if you wished have it move off the Z limit by a small amount right after it homes and hopefully that would prevent it happening.
 Try this in your Ref All button if you like, usual warning applies with my VB, have your hand near the E-Stop the first time you try

DoButton( 24 )
While IsMoving()
Sleep 10
Wend
Code("G53G0Z-1")
While IsMoving()
Sleep 10
Wend
DoButton( 23 )
DoButton( 22 )

Oh also you may need to change the Z-1 to Z1, depending on the way your knee is set up, I would think however Z-1 would be correct.

Hood

Oh, hey, that sounds cool. I asked somewhere the other day if there was a way to do just that, got no reply, but someone probably thought I meant a normal Mach setting.

I'm a new Mach user, just building my machine. Can you give me a brief description of how to "Try this in your Ref All button". I have no clue, but like all the rest of this, I will know once I try it!! Do I have to use some screen editor or something? Looking forward to this!!

Could I also change the order the axes ref by doing like DoButton (23) above the DoButton (24) or something? I need to look into all this VB stuff after I get over being overwhelmed with the build. Almost done.

Thanks.

Some of the buttons on the Mach screen are VB buttons, ie they contain code, you can make your own VB buttons in Screen4 and put your own custom code in them to do specific tasks.
 The RefAll button is a VB button and to edit it you go to the Operator menu then down to Edit VB Buttons, you will then see all the VB buttons flashing, click on the Ref All button and it will open the editor and you just alter the code in there then save.
 Yes you can alter the order of homing just like you were thinking by altering which DoButton is first, second, third etc. Usually though you want the Z to home first as it moves the tool out of the way so the next axes can home safely.

Hood

This sounds like info I have been looking for. I've slowed down the movements to a point which allows me to watch the DRO change. With the Z and Y axis I can see where it trips, zero's, then changes to approx .008" and then backs out to zero. On the X axis however it changes to a smaller number about .006" then backs out to zero which is .002" inside limit trip zone. I'll have to re read what you suggest above and have a look see as I have believed all along that it is doing what it is told to do ! I suspect that I may have picked up something from one of the new not ready versions of Mach I tried.

OK, I got lost in a real big hurry ! I did as you mentioned above and opened the ref all button and then the ref x button. They are very similar and only refer to other buttons and that is where I get lost. So, that means without more learning and specific info I had better leave that well enough unchanged ! from what I've seen tho it sounds like the prg'd command is not telling the routine to back out enough or to back out till it sees the switch open for the X axis. As it is I can't prove anything either way !