Unwinding 4th Axis

[EZ3PUTT]

We have 2 Mori Seiki SV-500 verticle mills with Tsudakoma rotary attachments. Whenever we do 4th axis work they always position in the same direction. If the job requires it the 4th may go around numerous times to machine parts as required. At the end of the program the 4th will unwind all of the rotations it has accumulated while machining the part. It will also accumulate

rotational moves for anything past 1 revolution.

Example - if the 4th axis makes 2 full revolutions the control now displays 720°.

I have searched for some info here but see none or have overlooked it. What i would like to know is how to make the 4th take the shortest path, how to get around the "unwinding" at the end of the program and whether or not it can display actual positions instead of accumulated positions,

instead of 1 and a quarter rotations displayed as 450° can it display as 90°.

Using V8.1 with a modified MPFAN post.

[robk]

jadkins,

 

I can't remember off the top of my head, but I believe it's either in your PLC switch page, or Control Paramater page of the machine control. All you have to do is turn the switch to "shortest path".

 

Rob

[Rekd™]

Try using incremental moves, with positive and negative instead of always going positive with absolute.

 

'Rekd teh ice cold Absolute, mmm

[crazy^millman]

Well I would contact my Machine Builder and ask them about a parameter change to do that. I get around limits that ours have by programming any moves over 1080 degrees in A buy taking the difference of the travel in x divided by a number to make it come out right. Requires a little bit of math but you can not post any incremental or absolute moves longer than that on the A axis with a Fadal. I have not taking the time play with the post to get it to do it have only had one job so far that I ran in that problem.

 

I really think it is an control issue and would contact my reseller or Mori Seki directly to see what they say. It may also depending on the age of the machine be something that is a qurek of the Machine.

 

 

Crazy millman

[mayday]

all else fails rehome the axis,should reset the counter

[Guest CNC Apps Guy 1]

G0 G91 G28 A0.

 

Doesn't work????

[iowajim62]

jadkins,

This is from our hacked-up mpfan for A-55 Makinos,

 

quote:

---

index : 3 #Use index positioning 0=No,1=Direction M-Codes,2=Signed

#3=Controler takes shortest path

---

This code is found in the Debugging section of the post. Don't know if it will help but you can add it to your post after you backup your orig post and try posting some code and go from there.

HTH

[robk]

Just checked the machine control-- It's a PLC Switch called "Short Cut RT". This control is a Meldas so the name of your switch might be different. That's all I have for you. Good luck

 

Rob

[crazy^millman]

Well you could always make it G92 A0 after 360 degrees and get the screen to do right.

 

Crazy Millman

[crazy^millman]

Well you could always make it G92 A0 after 360 degrees and get the screen to do right.

 

Crazy Millman