Weird problem.
I have 4 axis BP all Geckos and Breakout board. Mach 2.

Now I mainly cut screw machine cams on my machine using the rotary table. I have cut several hundred of em so I know all works great normally.
Now last night, I was milling away on my last cam of the set and when she got up to the larger radius it started "taking off". By that I mean its like someone put in a F200 or almost G0. There went that carbide end mill.

Since then, I have not been able to figure out why. The arc rises all work perfect and the dwell cuts (rotary A cuts without an X rise or fall) run smoothly.
Its only when the A axis movement is bigger like 15° rotation and the X axis movement is like .0025".
Now these movements are very common  in my line of work. Just generation on the screw machine parts. I have cut hundreds of these.

Prog below..........
(S1038   )         
(  TOOL 5 Cam )         
(STAR SJ-8R)         
                  
G90                  
G1     Z0            F100   
G1   A20.            F200   
G1   A0      X   1.112   F80   
G1   Z-2.5            F100   
G1   Z-2.650            F5   
M01                  
Z-2.800            F3   
Z   -2.960   F2         
Z   -3.020   F1         
G91                  
G1               F40                     
N   99   A   25   X   1.0685   
N   518   A   19.42   X   0.0024   
N   520   A   15.76   X   0.0048   
N   522   A   12.75   X   0.0843   
N   524   A   47.42         
N   88   A   20   X   -1.16   
N   599   A   219.65                           
                  
            G90      
            G1 Z0  F100      
            G1A380X3.5F200      
            G0 A360      
            G92 A0      
            M30      

Any help will be greatly appreciated.

                  

You know, its like the feed rate is following the rotary only and ignors the X axis......

Yes, I am in G94 feed per min.

I did the Dia setting in "Settings" under A but it did not make a bit of diff and I shouldnt have to do that. I never use that unless I am in
CV mode.

Hmmmmm       still playing with it....

More info...............

I go in MDI

I do a G91

G1 A 20 X .020 F40---all moves like I am used to and looks fine.

then
G1 A20 X .010 F40-----All moves faster, kind of pushing it for my work

then

G1 A20 X.005 40------And now she takes off like G00

So the smaller the increment in X the faster the feed moves. So its like .......well, I dunno

I can't find any settings that refere to this. I sure as hell didn't change anything. If it aint broke.....well you guys know.

I understand that Mach 3 is a little more sympathetic to those of us that use 4 axis setups. Is that true?

Hi, Escowizard

I don't understand why, if you haven't changed anything this would happen, is this a larger dia. than before.

Try putting F-speeds in the lines of code giving you problems.

I think A-axis takes over F-speed, maybe reducing your A-axis Vel setting and adjusting your F-speed will solve this.

Just some thought's, Chip

You may be on to something Chip.

I have two machines, One at day job and one at home. The home machine is much more robust and can handle faster feeds without missing steps and the one at day job is tired and easily misses steps so I do have the velocity slowed up quite a bit on that one.

This particular configuration of movements may not have run very often or may not have been as close in dims on my home machine or may have been in such a small area that it was not noticed. Having two or more movements that small on the X and the degs of 15 or so is not overly common.

I will tweak the velocity down on my rotary and try it.   I really appreciate your input.
Art had told me a year or so ago that Mach 3 would be a little more 4 axis (Rotary) friendly and the graphics would be more accurate on the rotary side. Has that evolved in Mach 3 ?

I am thinking about upgrading if it would be a benefit in my cam cutting.

I just started playing around with the demo on an off line PC.

Your thoughts?

Update
Nope, didn't work.
I tweaked the Vel to almost flatline @ 1.344 and thats down from 9.128
I also pulled back the Accel to 22.12 and that was @ 106.68

Ran it through the prog and I cant see any noticeable diff. hmmmm

Its only when I am making very small X movements and several or a dozen or do degrees.

If it was one or two degs then you don't have it burst out in a race. lol

I have always had problems with herky jerky movements when doing a very fine generation on the cam. Like making a cam that would give me a .010 radius on a .020 dia screw machine part.

Its like 15 steps so you can see it is like 15 incremental movements of a degree or so or less and X movements in the tenths.

I cut the cam as normal and then run CV with a 300. dia setting in "settings" and this usually slows it down enough so I don't get steps on the cam. Like mini stairs. I even have to take a pass without removing anything to clean up vibration mark. All very fine.

The problem with doing CV is it does it on the whole cam. Takes an hour or so just to do 360° Normally its a 20 minute cut.

I tried in the past to just put in the CV G code where I wanted it to be used but the prog reads the whole thing ahead of time so it jumps right into CV from the beginning.

Hmmmmm

I have 4 axis BP all Geckos and Breakout board. Mach 2.

Why haven't you updated to Mach 3?

Brett

Hi, Escowizard

Sorry should have commented on Mach3, while I haven't used Mach2 other than fire-it-up to help others, still haven't figured out activation

of 4th axis go figure!

I think you would like Mach3 allot as Art stated,  Rotational view is really nice.

Need a computer around 1000 Mhz, have run it on a 600 Mhz though.

Ive got a 4th axis running also, havent done mutch with it except "air cut" some gear teath.

If I can Help let me now.

Thanks, Chip
 

The only reason I haven't upgraded is "if it ain't broke"  well you know.

It was not available when I got into Mach 2.

I am not one to have the latest, fastest or newest. I do what I need or think I need.........I think I need Mach 3.   lol

I will try it out this weekend. Maybe this prob is trying to tell me something.

Hi, Escowizard

Thy will co-exist and the license is good for both, I understand the If it ain't broke, for sure.

Thanks, Chip