Messages

51

General Mach Discussion / Re: hand held controllers ?

« on: December 11, 2013, 07:39:06 PM »

There are many pendants around. 

I happen to have this one and am very happy with it.

http://cncpendant.ru/en.html

It is based on the Shuttle Pro type action, which I had before.   But the Shuttle Pro is meant for desktop work and is a bit fragile.

This is a much more robust implementation.

I much prefer the Shuttle Pro MPG type action rather than a genuine MPG.

It also has more button options.

52

General Mach Discussion / Re: Constant Velocity problem with rotary 4th Axis

« on: November 07, 2013, 06:00:13 PM »

Some years ago I remember Art saying that CV does not really work with a rotary axis.

His suggestion at the time was try to set the acceleration of the rotary to as close as possible to the other axis.

When you have very different steps per unit settings, I don't know exactly what that means.

Never got any more info on this.

I set the G's to somewhat match and that worked for me.   I get good CV on 4th axis work.

You might want to play around with that.

Greolt

53

G-Code, CAD, and CAM discussions / Re: 4 th Axis problem

« on: October 25, 2013, 06:23:39 PM »

IF you set it to ZERO it turns OFF the function.

I thought that bug had been fixed.

I have a brain running that automatically puts a very small value in if zero is entered, so that is why I no longer notice it.

54

G-Code, CAD, and CAM discussions / Re: 4 th Axis problem

« on: October 25, 2013, 03:54:17 AM »

What Terry said is correct.  Just need to add;

The DRO would be better labelled "Origin Offset"  (or something like that)

If you have the Z origin set at the outer circumference of the part, then enter the radius.

If you have the Z origin at the centre of rotation, then the correct DRO setting would be zero. (zero offset)

Whatever the Z origin is offset from the centre of rotation, is the correct value.

Mach adds this setting to whatever the Z DRO is, to determine what the Z axis feedrate compensation should be, at any given time.

55

General Mach Discussion / Re: Help with 4th rotating axis

« on: June 10, 2013, 05:49:42 AM »

Better to designate the slaved axis as B or C

This leaves A designator for the 4th axis.

Mach3 will only visually display a rotary toolpath if it is A

56

Mach Screens / Re: reversing "A" axis rotation on toolpath display?

« on: March 30, 2013, 05:45:02 PM »

You're too gracious Russ.

I should have heeded my own advise and left it alone some half dozen posts ago. 

Greolt

57

Mach Screens / Re: reversing "A" axis rotation on toolpath display?

« on: March 29, 2013, 01:24:22 AM »

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

Well if you want the rotary to follow convention, always my preference, then you need to reverse the axis direction so that it DOES rotate according to the RH rule.

This is done by toggling the "reverse" check box in the homing menu.  But you know that already.

Greolt

58

Mach Screens / Re: reversing "A" axis rotation on toolpath display?

« on: March 29, 2013, 12:00:25 AM »

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?

59

Mach Screens / Re: reversing "A" axis rotation on toolpath display?

« on: March 28, 2013, 10:26:07 PM »

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.

60

Mach Screens / Re: reversing "A" axis rotation on toolpath display?

« on: March 27, 2013, 10:34:29 PM »

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.