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Reversing x-axis

bmink72

Plastic
Joined
Jul 8, 2006
Location
Kenosha, WI
I have a '90 mori AL-2B with a Yasnac LX-3 control. The machine originally came with the x-axis reversed from a normal lathe. Thus, X minus makes the part bigger. Does anyone know if there's a parameter that will reverse the axis?
 
I kant hep with your Q, but can I ask another?

I have heard of this issue before on this machine - is the +/ - an issue only in incremental? I assume that 35mm is still a whole number?

No sig line here:
Ox
 
The axis is always reversed. Even the buttons on the control show it going the opposite direction. When programming a 5" dia. you have to tell it X-5.0. My electronics guy said he can reverse the wiring, but he said some controls have a parameter that will reverse it without having to touch the wiring.
 
Reversing the X axis

To properly reverse the X axis on a Mori, you need to reverse the pulse coder feedback signals and also the armature wires to the X axis motor.

Reversing the armature wires is pretty easy (the DC current to the motor), but reversing the X pulse coder requires that you swap 2 pairs of wires in the pulse coder cable. If you reverse the armature without reversing the pulse coder feedback (or vice-versa), the motor will simply "run-away" to the limit switch, so do this carefully. Sometimes, there are 4 armature wires in a single cable, two of them are + and two of them are -, so you have to reverse both the + wires with both of the - wires.

In the pulse coder cable, you have an "A" pulse and a "Not A" pulse (the opposite polarity to the "A" pulse). You also have a "B" pulse and a "Not B" pulse and a "Zero" pulse and a "Not Zero" pulse. The zero pulse is the 1-pulse per rev signal used for zero-return.
Swapping the "A" pulse with the "B" pulse and swapping the "Not A" pulse for the "Not B" pulse should do the trick. There's no need to swap the zero pulse signals because they will be the same regardless of which direction you're going.

After swapping the armature leads and the pulse coder signals, the motor will run in the opposite direction when you press the "+X" jog button. The feedback must agree with the motor armature. If everything is done right, the position display will still show a + motion when you press the +X jog button, but the servo will run the opposite direction.

NOTE: Most Yasnacs and Fanucs do not have "Tach generators" in the motors. Instead, they use the pulse coder feedback to generate a tach signal. If your machine has pulse coders in the motors, then you don't have tachs to worrry about. If your pulse coder is OUTSIDE the motor, then you will have a little tach-generator inside the motor. If this is the case, you'll have to reverse the tach leads as well.

After all this is done, you will have to find the parameters that determine the DIRECTION of zero-return. This parameter just tells the control if you are going to zero-return the axis in the PLUS or the MINUS direction. Your machine is probably set to MINUS, and it must be changed to PLUS, otherwise when you try to zero-retun the X axis, it won't see the cam-operated zero-return switch correctly.

Good luck!
 
To properly reverse the X axis on a Mori, you need to reverse the pulse coder feedback signals and also the armature wires to the X axis motor.

Reversing the armature wires is pretty easy (the DC current to the motor), but reversing the X pulse coder requires that you swap 2 pairs of wires in the pulse coder cable. If you reverse the armature without reversing the pulse coder feedback (or vice-versa), the motor will simply "run-away" to the limit switch, so do this carefully. Sometimes, there are 4 armature wires in a single cable, two of them are + and two of them are -, so you have to reverse both the + wires with both of the - wires.

The odd thing I noticed in the manual is that although it shows the encoder connections for either shaft direction looking into the shaft.
I could not see any difference between the two encoder hook ups, unless this is a typo.
I am suprised they do not simply do it with a parameter bit command, 1/-1 like Fanuc & Mits etc.
Also it shows AC servo with hall feed back, normally If the armature phases are reversed I would expect a hall swap also?
M.
 
Reversing the axis

I'm not familiar with the latest controls, but reversing the pulse coder feedback and reversing the armature wires was how we always did things back at General Numeric in the 70s' and 80's (boy, I'm getting old!).

There may be parameters to reverse an axis on the newer CNCs with digital servos, but I wouldn't know about that. It does seem to be the logical way to do it. I know that the older Fanuc and Yasnac controls didn't have a parameter to reverse the axes. The only parameter that I know of on those controls was to reverse the zero-return direction.

Those Mori's always came with the X axis reversed. That made it necessary to program G02 and G03 backwards from other machines, and also G41 and G42 for tool nose radius comp. I think that all dated back to the design of the Mori rear-mounted tool turrets, which held the tools "upside down" so the cutting forces were pushing the X slide against the ways, rather than trying to lift the slide off the ways. The spindle ran backwards too (M03 and M04 were reversed)

In a way, it's logical because there is an "imaginary" Y axis, which is perpendicular to the X and Z axes. To keep the machine in a conventional "Right-hand" coordinate system, where +X is your thumb, +Y is your index finger, and +Z is your second finger, the X axis had to be backwards and operate on the negative side of zero. The machine's coordinate system looks normal if you're laying in the chip pan looking up at the tool. Mori thought it was more important to follow the "Right-hand" rule rather than to make the machine operate like everyone else's.

Lots of customers wanted us to reverse their Moris just because it was different from their Mazaks and Okumas, but that gives them a "Left hand" coordinate system when using that rear turret.
 
I'm pretty sure that's what my electronics guy said he'd have to do if I couldn't find a parameter to reverse it. Was just hoping I didn't have to call him in.
 
In the pulse coder cable, you have an "A" pulse and a "Not A" pulse (the opposite polarity to the "A" pulse). You also have a "B" pulse and a "Not B" pulse and a "Zero" pulse and a "Not Zero" pulse. The zero pulse is the 1-pulse per rev signal used for zero-return.
Swapping the "A" pulse with the "B" pulse and swapping the "Not A" pulse for the "Not B" pulse should do the trick. There's no need to swap the zero pulse signals because they will be the same regardless of which direction you're going.


Just did this to a spindle drive this summer (no Z pulse of course on that) werks fine! (Haven't chased a thread yet tho. ???)
 








 
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