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Offline BR549

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Re: 4th axis setup
« Reply #30 on: June 16, 2011, 12:17:56 AM »
OK so in  nut shell IF your Z is above 0 it runs off the Zheight and IF your Z is below 0 it runs off the DRO values.

COOL, I ll have to test it again, (;-) TP

Offline Greolt

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Re: 4th axis setup
« Reply #31 on: June 16, 2011, 12:32:07 AM »
It always uses both values.  Adds them together.

Greg
Re: 4th axis setup
« Reply #32 on: June 16, 2011, 01:31:27 PM »
Thank you Greolt, I did not realize the z axis value would effect the feed rate, mine was set at +6.8 when I ran my test file.
Set it back to 0.0 and a axis flew!
now I think I understand cncwrapper better too.

Thanks again,

Richard

Offline Katoh

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Re: 4th axis setup
« Reply #33 on: June 17, 2011, 01:39:38 AM »
lgr
I have sent you a pm. hope it helps.
Cheers
Katoh

Offline BR549

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Re: 4th axis setup
« Reply #34 on: June 17, 2011, 05:24:26 PM »
HI Greg IS there any instructions for the new radius comp . It acts backwards here witheverything I try.When it needs to slow down it speeds up.

If I turn off comp it is constant rotation like it should but I can't  figure a combo to make work correctly.

HELP, (;-)TP

Offline Greolt

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Re: 4th axis setup
« Reply #35 on: June 21, 2011, 05:57:39 AM »
Sorry for slow reply.   Elderly Mother is in hospital for emergency heart operation.


The documentation as far as I can find is scant.  The web site includes the following,

Using Mach3 Mill pdf for version 1.84+.
Section 6.2.2.7 mentions "Diameter/Radius correction" but it is vague and does
not explain its use. No explanation that this is an offset value.

Mach3 Install and Config Guide pdf
Has no mention of this feature.

Greg

Offline BR549

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Re: 4th axis setup
« Reply #36 on: June 21, 2011, 06:29:36 PM »
OK  ;D Maybe Brian can explain how it is suppose to work ????

thanks (;-) TP

Offline Greolt

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Re: 4th axis setup
« Reply #37 on: June 21, 2011, 06:48:22 PM »
Here is a copy of an explanation I wrote somewhere else,

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

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.

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

The last bit about the zero value disabling the feature has been mostly fixed in the dev version, but does apply to the lockdown version.

Hope this is of some help.

Greg
Re: 4th axis setup
« Reply #38 on: April 26, 2012, 07:49:55 PM »
Need Help!!!   ???

First sorry for my english!

I also have some problems with Setup the 4th Axis.

I also use RhinoCam to calculate the Toolpath for Mach.  Every time i use the 4th Axis Operation (roughing, ect.) , the Output of PP write the negative ,,A,, - Values.  The simulation of Rhino the workpiece turn cw and mach will turn it ccw. I try to change the entries in the PP, but the result is everytime the same. the axis in mach turn different to Rhino, cause the output have negative A- Values.
The changed entries in the PP of RC have no reaction. ( manually entrie for cw = ,, -,, for ccw,, +,, )
 
If i use the indexing axis and mill the workpiece step by step (mill first plane, turn 90, mill second plane, turn,....) the PP will accept my entries in the PP for ccw and cw  turn. ( but different direction, ccw ,,-,, and cw ,,+,,) .
result of them is an wrong workpiece. My test file was an turbo wheel with backward blades. the blades at the sheet are right dir.. on the mach screen are left.  i try to change the stepper setup, but this is not the problem. i can do i want, the simulation in RC , the toolpath in Mach and the direktion of axis are not the same. i canĀ“t put it in the same way.
 i have no idea.  ???

Please Help!
 Rudi

Offline Greolt

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Re: 4th axis setup
« Reply #39 on: April 26, 2012, 09:33:35 PM »
Rudi

Mach will only display rotary axis toolpath if it is designated "A" (not B or C)

And will only display it correctly if the rotary direction is per convention.    Some users like to have a rotary axis turn in the opposite direction to convention.  Don't know why.

Conventional direction is as described in the Right Hand Rule.  See Pic.

Greolt