Van Norman Flywheel Grinder Uneven Grinding Force Problem

An occasional complaint for both the FG5000 and FG10000 Model Flywheel Grinders is that while grinding, the motor will "drop" or feed in aggressively all by itself.  There are four possible reasons for this behavior...

1) Backlash at the Handwheel (rare) - this is caused by a worn key or keyway at the handwheel.  Either the key or the part with the area where the key fits into (keyway) will require replacement.  Also the bear hug nut that is a Ny-loc thread used on the power column units only sometimes backs off it's adjustment.  It will need to be readjusted and loc-tite added to help it retain the adjustment.

2) Feed Nut out of Adjustment (most common) - perform the split brass feed nut adjustment procedure.  Make sure that the feed screw threads are lubricated with the correct lubricant.


a) Power Column Procedure - Lower Column to the lowest point. While raising the column, tighten   the  hex-key  screw  in  the  top  of  the  leadscrew  nut.  Listen  to  the   power  column  motor  while  tightening  the  leadscrew  nut  until  you   hear the motor begin to strain. Stop raising the column and back off   the  hex-key  screw  one  quarter  turn.  Your  leadscrew  nut  is  now  properly adjusted.

b) Manual Column Procedure -  For Manual Column Machines, lower the column to the lowest point.  While  raising  the  column  using  the  hand  wheel  also  tighten  the  leadscrew nut as described above for the power column. When the  leadscrew nut has been adjusted to the point that significant drag  occurs, back the leadscrew nut hex-key screw one quarter turn.

Note: Do not attempt to reposition the hex-key wrench while the power column is moving. Instead, lower the column again then reposition the hex-key wrench and begin raising and tightening again. After installing a new leadscrew nut you may need to repeat this process several times until the nut is properly adjusted.

3) Burrs or Scores in the Guide Rods (rare) - the head of the adjustment bolt may be gouging or digging into the guide rod which causes the column to hang up at the burr and then abruptly "drop".  The burr should be removed and if severe, the rod or rods will require replacement.

4) Worn Feed Screw  - the feed screw threads may be worn.  Check the condition of the threads and replace if needed.  If you replace the feed screw, the best practice is to replace the nut and the key also. 

As always, if this information does not solve your problem you can call 800-553-5953 for assistance from Irontite during normal business hours.