How do I adjust backlash compensation?

[TheGreenMachine]

First off let me say I've never ran a Fadal, tomorrow I'm going to look at a Fadal and I'm going to run through all movement, tool changes...ect. I also want to take a look at the spindle run out and the backlash at different point on the table to determine how exists and narrow down where its coming from. So my question is how do I access the backlash compensation, I would record the numbers, set them all to zero, then when I'm done checking the backlash I would set them all back to the original numbers.

Also if anyone else has any suggestion on what to look for I'm all ears.

[little bubba]

Saw this one earlier and figured somebody else would pick it up, but since you are looking in the morning..... Took me a while to remember my password.

At the "enter next command line"

BL[enter] will show you the backlash table. X and Y should have 3 #s, Z should have 1. The first # is center of travel, the second left, the third right. They should be in .0001 of an inch. I'm not sure if it changes if its running in metric. So, a '17' is .0017 of compensation, '2' is .0002 of compensation.

There is a command to wipe it out I think, but I don't know what it is.

BL,1,0,0,0 will set X all to zero
BL,2,0,0,0 will set Y all to zero
BL,3,0 will set Z to zero.

Toss the numbers back in place of the zeroes. Middle, left, right, to reset the backlash.

Don't get all flustered on the backlash, Fadal's are notorious for puking the ballscrew thrust bearings. A quick $100 fix per axis, its almost a maintenance item and I keep spares on hand myself. They are also pretty good at loosening up the motor to ballscrew couplings, that can screw your #s up pretty good also, also another cheap fix.

Things to look for and at, the spindle chiller, the fan in it craps out pretty easy. The spindle chiller pump (there should be a gauge on the chiller) bites it pretty easy too. Thats a few $100 there. Not a big deal if they are chugging, but probably a big deal if they are running max RPM all day.

The spindles never sound as nice and smooth as you think they should. Belts and all. Its a unique sound and may sound a bit funky to somebody that hasn't been around them. Don't run it without a toolholder in it, the drawbar can come in contact with the tool change piston. That can make quite the racket.

I'd ask about waylube use. If they are filling it up about once a week, thats about right, if its once every six weeks there is a clog, if its once a day, its a broken line.

[TheGreenMachine]

little bubba, thanks for the reply. I looked at the machine today, its a extremely clean machine and everything worked nicely. I've looked at many machines over the past couple of years and I have never seen a used machine that was kept so clean. With the backlash compensation set to zero the Z axis had .0004, the X had .0015, and the Y had .0065 of backlash obviously their is something other then normal wear on the screw and nut going on with the Y. They happened to have a tech there who use to work for Fadal, I talked to him for a while and he knew these machines inside and out, he said the same thing as you did about the coupler and thrust bearings. In the morning hes going to take a look at the coupler and see if that is causing the excessive back lash. Were pretty confident that new thrust bearings and adjusting the gibs can get this machine much tighter. If all goes well I will be joining all of you on the dark side soon. lol