Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: SScnc on October 28, 2012, 12:53:28 PM

Title: Backlash Comp Thud...
Post by: SScnc on October 28, 2012, 12:53:28 PM
Has anyone successfully managed to get backlash comp to not make a THUD sounds every time it changes directions? It's leaving tooling marks in my circular pockets at the 4 quadrants. Currently my settings are .005 shuttle, 30% backlash speed.

Please help
Title: Re: Backlash Comp Thud...
Post by: Hood on October 29, 2012, 04:16:13 AM
Never used backlash but this is what Rich reckons works well.
 "The max velocity is 50% of where your steppers will start to skip"
 "Set the shuttle Wheel setting in configuration to .0050  to .050"
 "Backlash speed"

One thing however is you may have more backlash dialed in than you actually have and thus Mach is overcompensating and causing a grab as it takes up the backlash and more.

Title: Re: Backlash Comp Thud...
Post by: RICH on October 29, 2012, 06:19:58 AM
I  never experienced the THUD you describe with my machines but have seen it happen on another users system.
He was running over 100 IPM along with about 0.1" of backlash. On change of direction you could hear when the backlash was taken out. Slowing down the max velocity in tuning and setting shuttle to to something lower ( try .05). Play with the settings and see if you can reduce the impact.

Note that the axis is stopping and then reversing very quickly and all that energy has to go somewhere....and in this case it
is thrown right back into the screw. How well the axis system reacts to backlash  can be affected by how the backlash is
implemented and would think it can start to vary with higher forces i echo what Hood said.

Anything that changes the cutting action of the tool, in this case backlash comp, will affect the cutting continuity and is reflected in the finish.

No perfect answer and every machine will behave a little differently,