Ideas needed: techniques to reduce Z axis slop:

Hi Guys,
I have a backlash issue in my Z axis and here's the background:
Its a Bridgeport CNC Series II with a 2:1 pulley reduction from the stepper to the knee driveshaft.
The shaft then goes into 2:1 ratio 45degree bevel gears at the Z ballscrew and gives an a total
ratio of 4:1. It seems that the bevel gears are the problem as they have some slop between
meshing the teeth. If I reduce the air assist on the table to force the ballscrew to have some
pre-load or tension, then the stepper has to work harder and my top speed goes down.

I've tried a first attempt at shimming the bevel gears to force them together to mesh tighter, but don't
really like this solution. Any ideas what I can do? This seems like a bad design choice to use non-helical
gears here.

Thanks for any ideas,
Lee

WHY DON'T YOU LIKE THE IDEA OF SHIMMING THE BEVEL GEARS TO TAKE UP WEAR???? THATS HOW WE DO IT ALL THE TIME ON OUR 4-SLIDES. THEY RUN 24HRS A DAY 6 DAYS A WEEK.

Thanks for your reply Chad. I now agree that it is a good way to fix it. I found out 2 ways to help also, I was going to make a spring tension mech. to force them together, and found too that I was running my knee air assist pressure alittle to high. If I lower
it, there's more back force from the ballscrew that acts like an antibacklash, but makes the stepper work harder. -Lee