Adjusting backlash on VF-OE

[eddie]

Help! I need info., directions or direction to directions on how to adjust backlash compensation on a Haas VF-OE mill. I just started this job and all of the literature for this machine is lost. Any help would be appreciated.

[wms]

Eddie,

That's kind of a tall order.

It is set under the parameters, for every .500 inch of travel for each axis.

I have to ask why you need to do this as I have rarely seen one that need to be set to anything other than the factory setting.

If your ball screws or ball cars are worn then this would compensate. But it is rare that these wear much, unless the way lube is not getting to them. But it can happen.

If you are seeing back lash, I would look at the thrust packs on the ball screws. Or at the flex coupler between the servos and the ball screws. Most back lash is normally attributed to the thrust packs. These are field replaceable and not to hard to do.

It depends on the year as to the different style thrust packs.

Just what I've seen over the years.

[helix77]

IF ITS AN OLDER CONTROL AND YOU ARE FEEDING REAL FAST SOMETIMES IT WILL DO WIERD STUFF
BECAUSE ITS MOVING FASTER THAN IT CAN CALCULATE--- BUT ,IT IS ODD TO SEE BACK LASH

IF YOU REPLACE THE THRUST PACKS ITS PROBABLY A GOOD IDEA TO HAVE HAAS COME OUT AND RUN A BALL BAR JUST TO BE SAFE

[HareBall]

I realize this is an old post, but I just found this forum and could use a little help myself.
I work for a company that uses various machine to work ceramics. We have to be able to set the backlash on all of our machines, bvoth Haas and Fadals. The manual for the Fadals is very straight forward, the Haas leaves a lot to be desired. I also need to set the backlash on one of ours, but can't make heads nor tails of the manual.
In respose to the 1st reply to the original poster, if you you run ceramics everything needs to be set on these things from time to time.
HareBall

[HuFlungDung]

I tweaked my Haas backlash settings a tiny bit. Chances are good that there is already some minute backlash settings already in the factory setup, its not like the machines come out with no backlash, that would mean they are perfect If you get a ballbar done, it would be interesting to see if the tech actually goes in and sets all the backlash settings to zero, to find out what the machine is really like

So in the X parameters screen, there is a setting for X backlash. A similar setting is available in the other axis. The actual amount of the adjustment would be in encoder counts. If you look farther up the screen, you might see something like "X Ratio steps/unit = 138718" Do not change this!. Just look at it
This means that one encoder count is .0000072" or quite tiny. That means it would take approxiamately a 14 encoder count adjustment to remove .0001" of backlash. My machine now has a backlash setting of 64 in X.

If the error is gross, I'd be looking, as WMS stated, at other things in the system. Or, if the backlash amount changes again in a few days use, same thing.

[HareBall]

What I was saying above is that we have a real need to set this. Ceramics are very abrasive and they get into everything. Changing ballscrews is just about an every week thing. We go through sealkits for the through spindle coolant like they are water. In fact, we don't get a warranty on the mechanical parts of the machines because of the type of stuff we machine. We do no metal working at all. I would say that we change out ballscrews about once a year in each machine. After all, you can use a ceramic block to sharpen a knife. Then you add the diamond dust from the cooling... You get the picture.

[HuFlungDung]

Wow, that is awful!
Is there nothing you can do to improve the machine life, such as rubber bellows (instead of steel waycovers), positive air pressure (box in the underside of the table and force clean air from the back), etc?

[HareBall]

We use rubber sleeves on the Y axis, but the others pretty much are just the way covers doing the repeling. The ceramic dust goes anywhere the coolant can get. We have one machine right now that the gibs (sp?) can't be adjusted anymore. It has about .005" play from side-to-side in the Y axis. We will have to tear it down to the frame and send it out to be refurbished. The ones running coolant are bad enough, but we have some that run dry to rough shape the part before they are fired in the kiln. They stay full of dry ceramic dust almost always.