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Need help smoothing out 4th axis..
« on: August 19, 2014, 05:01:04 AM »
Hey guys,
I have a 4th axis setup and I want to run a pass along the outside of the cylinder to smooth it up.

My post processor (All the ones I have tried) post the surface mill the same way... like this...
( N1 T1 = 3FEM )
N45 G21 G17 G40 G80 G90 G94
N50 G15 H1
N55 G0 X0. Y0. Z20.0
N60 M6 T1
N65 S24000 M03 T1
N70 G00 X-105.0 Y0.
N75 M11
N80 A115.189
N85 H1 Z12.092 M08
N90 G01 Z-2.012 F300.0
N95 X-104.988 Z-2.006 A111.624 F600.0
N100 X-104.968 Z-2.0 A105.89
N105 X-104.938 A97.278
N110 X-104.918 Z-2.003 A91.538
N115 X-104.898 Z-2.014 A85.882
N120 X-104.888 Z-2.0 A83.06
N125 X-104.873 Z-2.019 A78.53
N130 A78.485
N135 X-104.859 Z-2.0 A74.449
N140 X-104.845 Z-2.02 A70.457
N145 X-104.844 A70.412
N150 X-104.829 Z-2.0 A65.837
N155 X-104.816 Z-2.022 A62.115
N160 Z-2.021 A62.07
N165 X-104.799 Z-2.001 A57.226
N170 X-104.786 Z-2.022 A53.639
N175 A53.594
N180 X-104.769 Z-2.001 A48.616
N185 X-104.756 Z-2.022 A45.028
N190 A44.983
N195 X-104.739 Z-2.001 A40.005
N200 X-104.726 Z-2.022 A36.417
N205 A36.372
N210 X-104.709 Z-2.001 A31.394
N215 X-104.697 Z-2.022 A27.896
N220 Z-2.021 A27.851
N225 X-104.679 Z-2.001 A22.783
N230 X-104.668 Z-2.02 A19.599
N235 A19.555

ETC ETC. Problem is... when the code runs, either with rot rollover on, it rolls all the way around for each change in X-location, with it off, it start/stops...start/stops... SLOW AND ANNOYING.

Is there a way to make mach 3 interpret this into one smooth motion?
Re: Need help smoothing out 4th axis..
« Reply #1 on: August 19, 2014, 10:40:57 AM »
Cmon peeps, is my post just all wrong or is this how a 4 axis surface toolpath should look? Anything at all?
Re: Need help smoothing out 4th axis..
« Reply #2 on: August 20, 2014, 12:14:03 PM »
It sounds like you have the Motion Mode in General Config set to Exact Stop. Also, try setting the Rot mode to Ang short Rot on GO.

No, this is not how 4th. axis should work.

Also, have you set the 4th. axis settings in Toolpath Configuration? The rotary axis will not work correctly without the right parameters.

Config Menu; open Toolpath;

Set the Axis of rotation;  check the box "A-Rotations Enabled; set the radius value for the feedrate.


Re: Need help smoothing out 4th axis..
« Reply #3 on: August 21, 2014, 01:50:12 AM »
Hmm, I have those on, still really jerky. My A axis stepper must be geared strangely as its set to 13.33 Steps/per. It turns awefully slow for something that should spin fast. I can get CV mode to make it a bit better but it still seems to want to slow down/speedup between every...single.... line of code.

I see people online not having this issue. maybe my feed/speed is just set improperly in CAM. I have a feeling maybe the feed needs to be up around the 5000mm/min to compensate for the radius?
Re: Need help smoothing out 4th axis..
« Reply #4 on: August 21, 2014, 03:20:39 AM »

If you just jog the rotary axis by itself, does it run smoothly, and go fast and slow according to your feedrate settings?

Set the X axis to 0.00; set the A axis to 0.0 degrees. Do an MDI like G01 X300 A180 F1000.

The two axis should run smoothly in sync, and take about 15 seconds.   
Re: Need help smoothing out 4th axis..
« Reply #5 on: August 21, 2014, 08:03:09 AM »
Yeah runs really smooth. Jogging and that line of code no issue.

It's making parts like a graduated wheel right now, where it has to stop and cut a slot, does it very nicely and accurately, moves between are smooth. As are moves when it slots around the part. However, if don't have 360 rollover checked apparently my post doesn't force it go all the way around and only goe 200 odd degrees. But hey thats just working with the software.

However, any sort of surface mill lets say X0 to X100 where it has to follow a feature is terrible. I do wonder if maybe it's my post? Is there any tried/proven lines of code or a post I could try to that you guys know works well?
Therefor I can test it vs my post and see if it's machine or my CAM.
Thanks for the help thus far.
Re: Need help smoothing out 4th axis..
« Reply #6 on: August 21, 2014, 11:14:34 AM »
Would a video be helpful to show you guys what I mean?