Messages

71

General Mach Discussion / Re: Mach 3 showing a rotary file

« on: February 02, 2013, 10:08:55 PM »

Here is a pic of the Toolpath Configuation dialogue box,

Check "A-Rotations Enabled".   This turns on the toolpath view to show rotary toolpaths.

"Use Radius for Feedrate" check-box turns on the Rotary Axis Feedrate Compensation.

Select which is the axis of rotation.

If you want to see the rotary toolpath displayed, then you must designate the rotary axis as "A".    Mach will not display B or C as a rotary toolpath.

"Rotation Radius" DRO on the settings page is poorly named and is used by the toolpath display as well as the feedrate compensation. 

This must be set to the Z axis origin offset.  If the origin is at the centre of rotation, then the correct value (origin offset) is zero.

Greolt

72

Machscreen Screen Designer / Re: Klaus, it hasn't been said for a while, but, THANK YOU for Mach Screen!!

« on: January 29, 2013, 04:49:59 AM »

I use the screen designer and the video plugin very regularly.

It is one thing for a clever person to get enthused and start a project like the screen designer.

It is quite another to keep upgrading and supporting that project over a number of years, all for free!!!!

So I will enthusiastically add my thanks to Klaus.

THANKYOU !!!

73

General Mach Discussion / Re: 4th axis

« on: January 04, 2013, 04:17:52 PM »

You need to use the Rotary Feedrate Compensation feature.

This is a copy of a post that I wrote a while ago.

===============================================================================

All axis move in units per min. With a rotary axis those units are degrees.

So what is 120 ipm on the linear axis (desired speed of the tool in the work), is 120 degrees per min for the rotary.

That 120 degrees per min angular feedrate will make the tool move through the work at a speed dependant on the distance the tool is away from the centre of rotation. (in your case, very slowly)

So Mach has a feature to compensate the rotary axis feedrate, to accommodate differing radius that the tool is cutting at.

It is activated via the Toolpath Setup menu. Check "Use Radius for Feedrate" All the other settings in this box are to do with the toolpath display window.

On the Settings page there are three DROs labelled "Rotation Radius". IMO they would be better labelled "Origin Offset"

They are to tell Mach the distance that the relevant axis (Z in this case) origin, is offset from the centre of rotation. (A axis in this case)

So if you are machining on the outer surface of a 10 unit diameter job and Z axis origin (zero) is set on that outer surface, then the correct value for the "Rotation Radius" DRO is 5. The distance that Z origin is OFFSET from centre of rotation.

If, on the other hand, the Z axis origin is at the centre of rotation (my preferred method for most jobs) then the correct value for "Rotation Radius" DRO is zero. The distance that Z origin is OFFSET from centre of rotation is zero.

Mach takes the Z axis DRO value and the "Rotation Radius" DRO value and adds them together to ascertain at what radius the tool is cutting at any one time. Then compensates the angular feedrate to have the tool move through the material at the desired speed.

Maximum velocity as set in motor tuning is honoured, so that will always be the upper feedrate limit.

Now there is one little "Gotcha". A zero value in the "Rotation Radius" DRO will automatically disable the entire feedrate compensation feature. This is a known bug and is being addressed by Artsoft at this time. Hopefully it will be fixed soon.

The workaround for this, is to use a very small value (eg. 0.001) in the "Rotation Radius" DRO when zero is the correct and desired value. Small enough to have no measurable effect on feedrate, but not zero.

====================================================================================

Regarding the two last paragraphs;

This bug was fixed some versions ago. Not sure exactly when.

Hope that is of some help.

Greolt

74

General Mach Discussion / Re: Mach3 Tool Display "squashed" for 4-axis Gcode??

« on: December 25, 2012, 08:42:25 PM »

Dean

If you are going to be doing 4th axis work it is definitely worth getting a good handle on the Rotary Axis Feedrate Compensation feature.

The following is a copy of some info I posted in the past

====================================================================================

All axis move in units per min. With a rotary axis those units are degrees.

So what is 120 ipm on the linear axis (desired speed of the tool in the work), is 120 degrees per min for the rotary.

That 120 degrees per min angular feedrate will make the tool move through the work at a speed dependant on the distance the tool is away from the centre of rotation. (in your case, very slowly)

So Mach has a feature to compensate the rotary axis feedrate, to accommodate differing radius that the tool is cutting at.

It is activated via the Toolpath Setup menu. Check "Use Radius for Feedrate" All the other settings in this box are to do with the toolpath display window.

On the Settings page there are three DROs labelled "Rotation Radius". IMO they would be better labelled "Origin Offset"

They are to tell Mach the distance that the relevant axis (Z in this case) origin, is offset from the centre of rotation. (A axis in this case)

So if you are machining on the outer surface of a 10 unit diameter job and Z axis origin (zero) is set on that outer surface, then the correct value for the "Rotation Radius" DRO is 5. The distance that Z origin is OFFSET from centre of rotation.

If, on the other hand, the Z axis origin is at the centre of rotation (my preferred method for most jobs) then the correct value for "Rotation Radius" DRO is zero. The distance that Z origin is OFFSET from centre of rotation is zero.

Mach takes the Z axis DRO value and the "Rotation Radius" DRO value and adds them together to ascertain at what radius the tool is cutting at any one time. Then compensates the angular feedrate to have the tool move through the material at the desired speed.

Maximum velocity as set in motor tuning is honoured, so that will always be the upper feedrate limit.

Now there is one little "Gotcha". A zero value in the "Rotation Radius" DRO will automatically disable the entire feedrate compensation feature. This is a known bug and is being addressed by Artsoft at this time. Hopefully it will be fixed soon.

The workaround for this, is to use a very small value (eg. 0.001) in the "Rotation Radius" DRO when zero is the correct and desired value. Small enough to have no measurable effect on feedrate, but not zero.

=====================================================================================

The issue mentioned in the last two paragraphs was fixed in a later version of Mach3. I don't remember when.

Hope this is of some help.

Greolt

75

General Mach Discussion / Re: Mach3 Tool Display "squashed" for 4-axis Gcode??

« on: December 25, 2012, 04:54:57 AM »

Rather than "Rotation Radius"  I prefer the term "Origin Offset"

The value that should be entered in to the Rotation Radius DRO is the distance that the Z axis origin is offset from the centre of A axis rotation.

In your case the origin is at the centre of rotation, or the origin is NOT offset at all.  So the correct value is zero.

Often users will have the Z axis origin at the outer circumference of the job.  In this case the Rotation Radius (or origin offset) would be the distance the origin is offset from centre.

Mach needs to know this offset so as to display the toolpath correctly.  It is also used to determine the Rotary Axis Feedrate Compensation, but that is another topic.

Greolt

76

General Mach Discussion / Re: 4 axis Job Display problem

« on: November 24, 2012, 07:19:22 PM »

The 1 Inch version shows the ring correctly.  The od of the ring was 2 inches.   The "A"  Rotation Diameter in the Settings screen was set to 1.00

If the DROs on the settings page are labelled "Rotation Diameter" then you are using an old Mach version.   

There was substantial problems with Feedrate Compensation and display of 4th axis toolpaths.  These were addressed three years ago. 

See this entry from the changelog;

Dec 23/2009
Release 3.042.033
-- Fix for - scale and IJK arc commands
-- Spindle speed register expanded for computers over 3GHz (they where reading - speed)
-- Rotational feed correction fixed for moves with Z axis !=0
-- Rotational Dia feed changed to Radius rather then Dia


If this is the case I recommend updating Mach.    The fixes will be good for your 4th axis work if nothing else.

77

General Mach Discussion / Re: 4 axis Job Display problem

« on: November 24, 2012, 03:18:27 PM »

Had another look to make doubly sure, the R is backwards.

78

General Mach Discussion / Re: 4 axis Job Display problem

« on: November 21, 2012, 06:49:01 PM »

There are basically three things that must be done to get a rotary axis toolpath to display correctly in the toolpath view.

1.  Designate the rotary axis as "A"   No matter if technically the rotary is B or C,  it must be called A.  Mach will only display A axis correctly.

2.  Set the axis of rotation in "Toolpath Configuration"  and check  "A Rotations Enable"

3.  Have the correct value in  "Rotation Radius" on the settings page.

If you are, for example engraving, on the outer diameter of a  4" cylinder and the Z axis origin is on that outer circumference, then the correct value would be 2.  Z axis origin is offset 2"

If you are doing the same but the Z axis origin is at the centre of rotation, then the correct value would be zero.  The value is whatever the Z axis origin is offset from centre of rotation.


In your previous jobs, which never displayed correctly, I guess you had the Z axis origin at the outer diameter but neglected to enter the offset value. This would compress the displayed toolpath.

On this one occasion that the display looked correct, most likely you set the Z axis origin at centre of rotation.

79

General Mach Discussion / Re: 4 axis Job Display problem

« on: November 21, 2012, 05:00:08 AM »

Hard to know what you are expecting but here is a screen shot of it loaded into Mach.  With the settings as shown in pic.

2D screen shots are always hard to post a meaningful picture of.  You really need to be able to twiddle the 3D view to get a idead of what you are looking at.

Looks to me that you have the Z axis origin at the centre of rotation.  If this is correct then "Rotation Radius" setting should be zero.  (should be called origin offset)

Another thing is the "R" is backwards.  Most likely explanation is that you have the rotary axis not turning in the conventional direction.  Otherwise Mach would display it correctly.  (Mach follows conventional axis direction)


EDIT:  Upon re-reading your original post, my guess is that you have an incorrect value in "Rotation Radius" and that is why you are seeing a compressed toolpath view.

80

General Mach Discussion / Re: A axis problem with Sherline and Gecko 540

« on: May 20, 2012, 04:10:10 PM »

You need to use the "Rotary axis feedrate compensation" feature.

The following is a copy of a post I made some time ago about this feature.

===================================================================

All axis move in units per min.   With a rotary axis those units are degrees.

So what is 60 ipm on the linear axis (desired speed of the tool in the work), is 60 degrees per min for the rotary.

That 60 degrees per min angular feedrate will make the tool move through the work at a speed dependant on the distance the tool is away from the centre of rotation. (in your case, very slowly)

So Mach has a feature to compensate the rotary axis feedrate, to accommodate differing radius that the tool is cutting at.

It is activated via the Toolpath Setup menu.   Check "Use Radius for Feedrate"  All the other settings in this box are to do with the toolpath display window.

On the Settings page there are three DROs labelled "Rotation Radius".  IMO they would be better labelled "Rotation Radius Offset"

They are to tell Mach the distance that the relevant axis origin (Z in this case) is offset from the centre of rotation.  (A axis in this case)

So if you are machining on the outer surface of a 10 unit diameter job and Z axis origin (zero) is set on that outer surface, then the correct value for the "Rotation Radius Offset" DRO is 5.  The distance that Z origin is OFFSET from centre of rotation.

If, on the other hand, the Z axis origin is at the centre of rotation (my preferred method for most jobs) then the correct value for "Rotation Radius Offset" DRO is zero.  The distance that Z origin is OFFSET from centre of rotation is zero.

Mach takes the Z axis DRO value and the "Rotation Offset Radius" DRO value and adds them together to ascertain at what radius the tool is cutting at any one time.  Then compensates the angular feedrate to have the tool move through the material at the desired speed.

Maximum velocity as set in motor tuning is honoured, so that will always be the upper feedrate limit.

Now there is one little "Gotcha".   A zero value in the "Rotation Radius Offset" DRO will automatically disable the entire feedrate compensation feature.  This is a known bug and is being addressed by Artsoft at this time.  Hopefully it will be fixed soon.

The workaround for this, is to use a very small value (eg. 0.001) in the "Rotation Radius Offset" DRO when zero is the correct and desired value.  Small enough to have no measurable effect on feedrate, but not zero.

=================================================================================================

Note that the issue referred to in the last two lines has been addressed but I forget which version this was done.

Hope this helps,

Greolt