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IndustryArena Forum > Metalworking Machines > Fadal > Leveling stock using 4th axis and probe

# Thread: Leveling stock using 4th axis and probe

1. ## Leveling stock using 4th axis and probe

Can anyone help with any "simple" methods of leveling stock in Y axis terms, that is chucked in the A axis ...... using touch probe outputs/findings ?? Perhaps a better way to put it is - how do you relate -Y axis touch probe Z output and a +Y axis touch probe Z output ..... so you can turn that into how many degrees to A axis needs to travel so -Y and +Y Z level is equal ??

2. ## Re: Leveling stock using 4th axis and probe

I have re-read the above post and think it may be a confusing/overly complicated way of explaining the problem and I'm relatively new to the CNC game .... so I'll try another way.

I am trying to tram stock (an existing part) that is mounted to the A axis .... using outputs from a touch probe. I need to incorporate this into a program so the machine can probe the parts Z height and then tram the part via the A axis.

I have tried to do this manually by jogging an equal distance either side of Y 0.0 and writing down the Z heights of each side .... then splitting the difference between the Z heights .... jogging the probe up/down to that point .... then jogging the A axis till it touches.
That "manual" method gets the tram close .... but there is still quite a difference when repeating the same jog/probing process to check it is trammed. I think this is most likely caused by parts height above the A axis rotational center (around 9 inches) which would mean the surface I'm trying to tram, is moving in both Y and Z terms when the A axis is moved ??

There must be a method to calculating the A axis rotation required .... but I can't dig up any knowledge/routines to making it work.
Any help appreiated

3. ## Re: Leveling stock using 4th axis and probe

Wouldn't that be arctan(Zdiff/Ydist)? Ydist is the distance between the two probing points (centered at Y=0), Zdiff is the difference between the probe readings in those points.

4. ## Re: Leveling stock using 4th axis and probe

It been a LONG time since I was at school but doing a search on arctan I think you might be on the right track. Looking at a definition of what arctan is, I am probably getting the error as I'm not doing the first touch at Y 0.0 ??
The method I was trying was equal distance from Y 0.0 ... e.g Y -2.0 & Y 2.0 . Does that make sense to anyone ?

5. ## Re: Leveling stock using 4th axis and probe

Originally Posted by Cfin
The method I was trying was equal distance from Y 0.0 ... e.g Y -2.0 & Y 2.0 . Does that make sense to anyone ?
The arc tangent formula should be correct for any two points, assuming the stock is flat. For instance, if your probe touches at (Y=3, Z=-0.07) and (Y=5, Z=-0.05), then the stock is tilted

arctan ((-0.05-(-0.07)/(5-3)) = arctan (0.02/2) = 0.57 degrees. That's the amount you must rotate the A axis to align the stock with the XY plane.

If my math is wrong (which is entirely possible), please correct me.

6. ## Re: Leveling stock using 4th axis and probe

Ok, I can understand that and think I have my head around it now. This is probably a dumb question but I'll ask it anyway .... I assume for this to work correctly Z0 would need to be set to the A axis center line height?

7. ## Re: Leveling stock using 4th axis and probe

Originally Posted by Cfin
Ok, I can understand that and think I have my head around it now. This is probably a dumb question but I'll ask it anyway .... I assume for this to work correctly Z0 would need to be set to the A axis center line height?
No, Z0 does not matter. The formula will give you the same answer no matter where your Z0 is.

8. ## Re: Leveling stock using 4th axis and probe

Yes that makes sense to me now. Thank you very much for your help !!

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10. ## Re: Leveling stock using 4th axis and probe

Use the "find center point" probe option in the setup menu. It does the math for you. As for automating it to a touch probe with a fadal controller I have no idea.