Constant Velocity problem with 4th axis

[Tiwanacote]

Hi!!! When I use 3 axis everything goes good and not jerk movements and vibrations appear using "Constant Velocity" for angles > 170°. When I use rotary axis and Z axis working at the same time it goes bad, It seems to be working with "exact stop" setting. ¿What is the problem?? I tried to change 4th acceleration settings and nothing got better.

Regards
Tiwanacote

[SpaceCat]

Hi, Same problem as I have... Any idees ?

/R

[Tiwanacote]

I pasted what Mach support answered me
Tiwanacote

----- Original Message -----
From: Maxi Bertotto
To: support@machsupport.com
Sent: Friday, March 19, 2010 9:28 PM
Subject: Question

Mach takes the 4th axis into account for CV mode ?

Thank you!!


Hello Maxi,
 
Yes, it should...  ;-)
 
Thanks,
 
scott
--
Scott Nichols
License Manager
www.machsupport.com
 

[HimyKabibble]

I believe you may be seeing the effects of a long-standing bug in Mach3.  If you have two axes in-motion, and then transition to a 3-axis move, the acceleration setting of that third axis will be ignored, and it will be expected (more like required) to accelerate at the same rate as X/Y.  This can be easily demonstrated by setting your Z axis accleration to a very low value, as compared to X and Y, then doing a move that transitions to a helical move in X/Y/Z.  The Z axis will lose position at the entry to the 3-axis move.  This is a known problem, and will be fixed someday, but it's not high on the priority list.  This gave me fits when my mill was capable of 3-- IPM on X & Y, but only 50 IPM on Z.  At present, the only work-around is to run in Exact Stop mode.  It would not surprise me a bit if there were a related problem occurring when moving a rotary axis in concert with linear axes.

Regards,
Ray L.

[Tiwanacote]

Thank you for your info Ray!