I assume that you are refering to Baxis in you example as it is inline with Y SO your chuck is moving CCw?

Terry that is a B axis toolpath.  To keep the explanation simple, I should have made an A axis example. 

My mistake.  Here is my fix.

Same basic example.  Showing the same conventional direction, but this is an A axis toolpath.

Two pictures of simple profile toolpaths of lettering on a cylinder, displayed my Mach. Showing that Mach follows convention with rotary axis direction.

 I have tried to make them from the same perspective. Included is the 3D compass for reference.

The first is toolpath set to cut correctly with CONVENTIONAL direction of the CHUCK. Displayed in Mach3. You should be able to see the visual display is correct.

The second is toolpath set up to cut correctly with rotary axis direction set up for APPARENT tool tip movement.  Opposite to chuck movement.  As per Terry's argument.

............SO your chuck is moving CCw?

IF so then B positive would be to the right which would be CW tool motion or CCW chuck motion. Facing the chuck. YES?NO?

NOW there IS no real standard for the placement of the chuck on rotarys I know just as many that run it on the left as on the right as A axis. the exception being the B where MOST run it outboard to clear the column (mills).

NOW as to physical Chuck rotatation IF I swap from left to right I must rev the direction of the chuck to maintain toolpath orientation.

This is a perfect example of why I keep banging on about the Right Hand Rule.   

CW and CCW,  "which end is the chuck??"  "Facing the chuck. YES?NO???"  "Is the sun over your left shoulder??" 

The explanation possibilities are endless, as are the opportunities for misunderstanding those type of explanations.

The Right Hand rule simply explains any and all situations.  Stand in front of your machine and do it.

Make a fist with your right hand, thumb extended and pointing in the positive direction of the axis you are interested in. Your fingers curl around in the direction of positive rotation.

I think you guys are basically saying the same thing ... sort of  ... partially  ... but not really.
This was a bit confusing (to this beginner) but forcing myself to allow the Right Hand Rule to trump everything else makes it much more simple to understand.

My biggest hangup was thinking that the axis directions (in relation to the tool-tip vs. work surface) were the same with rotary as they are with their associated linear axis. This is only true with the A axis and it's linear cousin Y. The B axis is opposite of it's linear cousin X.

I say the RH Rule trumps all.
It works in all phases of the moon too.
Thanks for a great discussion,
Russ

My biggest hangup was thinking that the axis directions (in relation to the tool-tip vs. work surface) were the same with rotary as they are with their associated linear axis.

Yeah you just need to forget that idea for rotary axis. 

Just to throw a curly one.  ...... What happens if you are cutting below centre of rotation???

Just stay with the right hand rule.   

  ...... What happens if you are cutting below centre of rotation???

That is only possible when Jupiter is aligned with Mars.

Really though, does Wrapper allow a negative radius ? or can Wrapper even do it ?
Have you done it ? Can you explain how ... briefly ?

Thanks Greg,
Russ

OK folks, I'm going to bed now ... with a headache.
I loaded this Wrapper thingy, really neat.
Simulating here on my laptop.
Used the Write Wizard , produced the attached with 0,0,0,0 where shown.
Noticed in the Wrapper extrema that ALL A moves are Negative.
Then I jogged the A axis and sure enough, the actual rotation of the part is opposite of the RH Rule.
But, it loads, looks and runs just fine and as expected/designed.
I guess all of the switching is done in the sw.
Just a bit confusing again.
Can you verify with yours that the jogging is opposite of the RH Rule ? Or, do I have something wrong here ?
Thanks,
Russ

Then I jogged the A axis and sure enough, the actual rotation of the part is opposite of the RH Rule.
Can you verify with yours that the jogging is opposite of the RH Rule ? Or, do I have something wrong here ?

I am not sure what you are getting at here Russ. 

If you jog in a positive direction, ie, the DRO value is INCREASING, then the chuck, or job, will be turning according to the RH rule.

Your fingers curl around in the direction of positive rotation.

I think where users come unstuck, is expecting it to look, feel and act like a linear axis.  It is not, it is a rotary.


Looking at your pic of your example job in Mach, you can see that it is correct.   I assume you used CNCwrapper.

The fact that it comes out correct in Mach is because both Mach and CNCwrapper both follow convention for rotary direction.  So they match.

This demonstrates the main reason why I think it is worth going with convention.  Compatibility with various CAM software, controllers, etc.  It is just industry standard.

However as I said, if users want to go their own way, then go for it.  You are the user, its up to you.

Hi Greg, and thanks so much for responding.
Yep, using the Wrapper.
All set up in Mach (simulating) as conventional, nothing I can change there .... afaik.
Where you say " ..Mach and Wrapper both follow convention"  is where i agree and that makes it work out properly.
But, this is where I'm at.
A is mounted in line with the x axis on a knee mill. So Y is converted to A.
The Wrapper converts all of the Y+ moves to A- (but in degrees of course).
So, although Mach and Wrapper follow convention in their respective internal conversions, the actual rotation of the A chuck is opposite of the RH rule.
If I set a hotkey for A+, and a Hotkey for A -, when hit they are the opposite of the rh rule (looking at the chuck) but perfect if looking at the relative movement of the tool tip.
It's neat the way it works, but the rh rule appears to indicate the direction of the tool in relation to the work surface, not the actual rotation of the cylindrical axis.
Either way, I see how it works and now know how to implement it.
I could see your apprehension in getting involved with this discussion, but truly appreciate your involvement.
You are a rotary wizard.
Thanks Greg.
Respectfully,
Russ


 

Russ

Still not sure what you mean here

If I set a hotkey for A+, and a Hotkey for A -, when hit they are the opposite of the rh rule (looking at the chuck) but perfect if looking at the relative movement of the tool tip.

If you press the A+ hotkey and the A axis DRO does not go positive (increase in value) then you have the A+ hotkey misassigned

A+ means jog in a positive direction.  DRO increases.

I don't use the Mach standard 1024 screenset.  So I had to load it up to check it out. 

When on the tab fly out, which has on screen jog buttons, I press "4+" button and the A axis DRO increases as expected. 

Does yours not do this?

When on the tab fly out, which has on screen jog buttons, I press "4+" button and the A axis DRO increases as expected. 

Does yours not do this?

Yes, it does. But at the same time, the physical rotation of the A axis is running opposite of the RH rule.

Simply ... if you grab your chuck with your right hand from underneath with your thumb  to the right(x+), then jog A +, the chuck rotates opposite of the rh rule.
Indicating that the tool is moving toward you, opposite as it would with a Y+ move, which would in turn be A +.
it all works, but the finger tips are pointing to the direction of the tool movement, as opposed to the table/surface movement.
It all works as yo  describe, it's just hard to explicitly explain.
Thanks Greg,
Russ