Y-axis Backlash after Crashing Brand New Machine

Hello Everyone,

We bought a new Smart SM1365 3 axis CNC mill, with FANUC control, and it is quite a superb machine from what I can tell. The other day we(actually it was me) crashed a part into the side of the machine while setting a tool in the Renishaw tool setter (stupidest mistake I've ever done on a CNC)! It was a long, folded piece of steel rail that I was modifying for a customer. The part was 70 inches long, and when I started the tool length measurement cycle, I thought I had clearance because the side door of the machine was open, but I didn't...

The end of the steel rail slammed into the sheet metal on the side of the machine right next to the door--apparently I didn't realize that the machine table had to move in the y-axis to position the spindle over the tool setter and the steel rail slammed into the side wall of the machine, at an angle (50% rapid moving in x and y simultaneously), and bent the sheet metal on the side of the machine so bad that now I can't even close the side door, and coolant sprays out of the machine when I run it.

I hit E-stop and reset the machine and it still wouldn't let me manually hand jog the part away from the side wall of the machine, oh yeah and the machine had an alarm that I couldn't clear (x-axis thermal overload). So finally I unclamped the steel rail from the four vises that we holding it, and the whole table popped/ jolted back in the opposite direction it was going when it crashed.

I was was worried about fixing the sheet metal, but I didn't think anything would have been damaged too bad because the sheet metal on the machine gave way and it was a relatively soft crash. But now I have backlash in my y-axis... To where it chatters when I'm climb cutting the outside of a circle on stainless steal, it leaves a nasty little transition mark when I'm circle interpolating circular pockets and circular bosses, and what's worse, it doesn't repeat position in the y-axis when I test positioning (x-axis seems to be ok). The y-axis position is out between .001" and .0005" every time I test it!

Can someone give me an idea of what they think the fix will be and how expensive it is? Backlash compensation, new thrust bearings, new ball screw?

I hope this doesn't happen to any of you guys (I've been losing sleep over this ordeal).

Any advise you could share would be greatly appreciated because I need to be able to machine circles on the mill with out having to use a boring bar all the time like on my older machine.

Thanks!

WE

Indicator on spindle against Y surface on table. Get a big handful of grip on the table and shake the Y axis. Indicator should move with the problem so work/indicate along the parts to see what is moving.

I might would give the machine builders techs a call and schedule an appointment.

There may be couplings in the axis that are designed to "give way" when something like this happens. At worst, it could be a thrust bearing. Very doubtful the ballscrew or rails are damaged. I used to work for Doosan and stuff like this would come through the office all the time. Give your dealer/MTB service department a call and schedule an appointment. They may show more mercy on you than you think.

You cannot literally change the clearance in a thrust bearing by crashing it, or you would get noisy bearings, because damaged balls spall actual flakes. More likely, the crash changes the preload because the preload nut was not fully seated from factory. Or, the nut securing the ballscrew into the thrust bearing housing had its threads stretched a wee bit, and it needs to be unstaked and retightened.

Thanks I will try that.

Thanks for the input gents. I have an appointment with a service tech from my dealer on Tuesday. I will let you know what I find out.

Carnage will be found! Nah I hope it's something simple.

A veteran machinist told me that the Y axis servo coupling may have just slipped, so we we removed it and it had some bent torsion disks in it. We ordered a new one ($266), installed it, and adjusted the Y-axis servo backlash. Now the Y-axis repeats position within .0002". We are happy with everything for now. Hopefully this was the final fix. Thanks again for your guys' input!