What are my options for axis marks on circles?

[carbidecraters]

Backlash? Thrust bearings? Its on a 1994 3016 and we have gotten backlash marks ever since we had a job that required some serious hoggie..ie pounding! What can I do to correct these axis marks? Id their any hope besides a ballscrew change?

[Neal]

If the marks are at 12,3,6, and 9 o'clock then it is normally a backlash issue. Thrust bearing play can also come into play here. Don't forget to check and adjust gibbs and straps as well. Last but not least verify the servo loop gain and axis balance.

Neal

[carbidecraters]

Neal We tested backlash that was good. Next we tested gibs they were good. Not sure what straps are but the motors and x axis thrust bearing are all tight. How do we verify servo loop gain?

[JR1050]

To verify the loop gain is set correctly,program a long 15" move at 45 dg,back ang forth,and observe the lag on X&Y-should be identical.If not,adjust untill they are the same-Check the maitaince manual for procedure.Make sure the ball screw couplers are tight,often a burned or plugged(if you have brush motors) commutators will cause lines,turn the com on your lathe,while your at it,replace the bearings.Bad thrust bearings are usaually noisy.Check the screw mount for being tight along withn the nut.Fadal in their infinate wisdom makes the bearing mounts from aluminum and doesnt beleive in supporting the screw from both ends.Bad spindle belts will cause a bad finish on circles and angles as will bad bellvilles.Straps are the plates under the axis with the gibbs.If you have turcite coated gibbs,take a big lever and pull the table against the NON- gibb way,then snug the gibb-just snugg.If you have bronze gibbs-which may be an urban mythe on all Fadals except mine,tighten tight,then back 1/3-1/2 turn.Good luck.wanna buy another Fadal?

[Neal]

If you are in Format 1 then add a G8 to the beginning of the program.

Neal

[carbidecraters]

Neal we are in Format 2...now we are getting a C-axis #10 fault when we try to start the spindle. Any insight on this? We dont have a C-axis hooked up and their was never a 4th axis on this particular machine.

[ltmquik]

Originally Posted by carbidecraters Neal we are in Format 2...now we are getting a C-axis #10 fault when we try to start the spindle. Any insight on this? We dont have a C-axis hooked up and their was never a 4th axis on this particular machine.

C-Axis is the spindle orientation. Sounds like a Vector Drive failure. As for the dwell marks on the circles, this is common on all Fadals with the HS88 control. They can be minimized by the procedures indicated before but they will always be there.

[carbidecraters]

I believe part of that post but we have a couple others with the 88hs control that cut a perfect circle and are 14 years old!. The C axis fault was due to a plug that was loose in the servo chassis. (Fixed).

Axis circles...I am at a loss when it comes to tuning servos

[Paul_S]

Try using a G8 for those cuts. And return to G9 when finished with those cuts or in rapied. G8 turns off ramping, the deceleration used for in position check. If that doesn't work have the backlash settings re-adjusted.

The G9 is like the G61 on fanuc controls and works in the block as the G9 on a fanuc control. The G8 is like the G64 milling mode on the fanuc control. Fadal format 2 doesn't reconized G61 or G64 and so G9 and G8 must be used.