[ljaques]

I finally got out to the Green Monster (my home-built CNC router) again today and started feeding in soft limits, home offsets, and auto zeroes. Before setting Home offsets, it didn't back off the limit switches. Now it is. Hurray!

I think (confirm my assumptions, please) that I'm using the upper right quadrant in the Cartesian system for positive X and Y. X home is left, Y home is toward me, Z home is top.
I'm working in inches with 52" X and Y ranges, & a 5" Z range.

In the Motor Home/Softlimits config box, I have
Soft Max 51.00
Soft Min 0.50
Slow Zone 1.00
Home Off. 0.50
Home Neg. Checked
Auto Zero Checked
Speed 20%

in X, Y, and A boxes (Home Neg Xed on A, which is slaved to X).

Pic, far left is home corner. http://tinyurl.com/com9z8g
Pic, I changed Y back to mirror X http://tinyurl.com/d3kdnt8
After saving, I have lost a few thou on the DROs. Curious.

OK, I click the REF all home button and Z goes up, hits the limit switch (home) and backs off less than 1/10 turn, even though the offset is set to half inch. Then Y comes home and backs off about
0.1" with the offset also set to half an inch. Then the gantry goes left, hits the X1 (A axis) limit switch, stops, reverses 1/8" or so, and then moves left again. This is where I get a limit switch error.

Questions: Why is it erroring out? Why the small movement when the offset is listed higher in the soft limits? I had a 0.1" offset at first and it moved the same distance back off the limit switch that it
has with the half inch offset entered there. Why? Is it only moving until it deactivates the switch? (if it's even doing that) With X and A slaved, why isn't it locking one side and doing the other afterward? Can I unplug A and just test the X by itself, then swap and try again? Would this do any good?

I get the same small movement off home on all axes despite settings in the offset of 0.1, 0.5, and 1.0. The Z moves about 19 degrees by my calcs.

The frame is within 1/32" of square, the rails are even from the end, but I just measured about 1/8" difference in the gantry position from side to side. I guess I have a twist somewhere in the gantry. It will flex about an inch while remaining easy to roll down the rails. (2 linear bearings per side, spaced 4" apart)

[ger21]

Go to General Config and make sure Home Slave with Master is NOT checked, then try again.

[ger21]

Sorry, I didn't have time to finish my reply before.

Assuming you have a home switch for both the master and slave axis, then my answer above should get you homing correctly. If not, you may need to modify the homing macro to use RefCombination() to Home the slaved axis.

When homing in Mach3, once the switch is closed, Mach3 backs off just enough to open the switch, and no more.
What Home Offset does, is allow you to tell Mach3 the position of your Home switches, if you want them to be at a position other than zero.
For example, my gantry has about 45" of travel, and I don't want to home it at the zero position (far left), as it would be in the way of loading parts. So, I use a Home Offset of 45 with the switch on the far right. When it homes, it sets the machine coordinates DRO to 45, rather than zero. This places my X zero position at the opposite end from the Home switch.

If you want it to back off the switches more when homing, then you'll need to add some movement commands to the homing macro.

Pages 16&17 of my Screenset manual explain how to move further off the switch, as well as how to use RefCombination().
http://home.comcast.net/~cncwoodwork...0%20Manual.pdf

[ljaques]

Sorry, I didn't have time to finish my reply before.

Not a problem. I didn't see them until all 3 posts had appeared last night.

Assuming you have a home switch for both the master and slave axis, then my answer above should get you homing correctly. If not, you may need to modify the homing macro to use RefCombination() to Home the slaved axis.

Darn, the checkbox is unchecked for home/master slaving. I'll swap the two DB9 connectors and see if it makes any difference in homing. At worst, I'll have to remove that 1/8" skew in my gantry. (Where's my Ford hammer? I need to finesse something...)

When homing in Mach3, once the switch is closed, Mach3 backs off just enough to open the switch, and no more.

OK, the near switch never opens. I think I need to do the X/A cable swap at the Gecko drive and/or finesse something. Maybe instead of the Ford hammer, I can put my little 4T Porta-power to work to de-skew the aluminum frame parts.


[quote=ger21;1191000]What Home Offset does, is allow you to tell Mach3 the position of your Home switches, if you want them to be at a position other than zero.
For example, my gantry has about 45" of travel, and I don't want to home it at the zero position (far left), as it would be in the way of loading parts. So, I use a Home Offset of 45 with the switch on the far right. When it homes, it sets the machine coordinates DRO to 45, rather than zero. This places my X zero position at the opposite end from the Home switch.

OK. I thought that was usually done via the G offsets.


[QUOTE=ger21;1191000]If you want it to back off the switches more when homing, then you'll need to add some movement commands to the homing macro.

I guess it doesn't matter much, if I'm going to be specifying various offsets for different setups. I'm just trying to get a reference point to begin from. I hope the

Pages 16&17 of my Screenset manual explain how to move further off the switch, as well as how to use RefCombination().
http://home.comcast.net/~cncwoodwork...0%20Manual.pdf

I'll have to look into that. Thanks, Gerry.

[ger21]

I'd try using RefCombination() in the macro first.

[LeeWay]

How does one go about editing a macro in Mach3?
I looked through the PDF Ger. Looks good, but I can't simply open that type file.
Thanks.


Ah, Gerry. You already answered that over on the Mach 3 Forum.
Notepad will open it.
Thanks for such a blazing fast answer.