Z Axis Slips

[AntsOftheSky]

Hello, First timer here...

I've recently begun to develop a series of industrial machines with small footprints and high rigidity. I am using the Acorn and the AcornSix as the primary offerings for mills and lathes. One of our prototypes has begun to do interesting things when taking moderate clearing passes in annealed stainless steel -- something it previous chewed through without any issue for hundreds upon hundreds of hours. The cut is 9mm down, 0.6mm load with a 1/4 roughing endmill.

The cut is dragging down as it makes a pass, the Z axis slowly gives way and drops down by a mm or two, slipping downwards as it moves on the X and Y just fine. The cut sounds pretty awful and chatters a bit.

The spindle is a 1.5kw servo, each axis is a 425 oz/in stepper (7 amps). Servo has its own 220v line and everything else is running off a 15 amp 110v line and a 48v power supply. I'm at wits end trying to go through all the options so I've come here. Here's what I've thought thus far.

Physical considerations -- is the ballscrew just too small? (1605) Is it vibrating loose? This seems unlikely or even possible... Gibbs are fine... The head of the mill hasn't changed weight since its begun doing this, and if it has, it's changed less than a pound or two. Its colder now but that's not something that should be this much of an issue, I'd imagine to cause this unless the frigid temperatures really do play this hard.

Electrical considerations -- is the motor too weak? It's a 425oz/in Stepper right now. I'm looking at going up to a 15000-1600oz/in Closed Loop in the immediately future. Is the Z motor losing power as the X and Y motors draw more? If that's so, I'll break out another power supply.

Any help is immediately appreciated, seriously, am trying to figure this out and under constant pressure -- thank you!

[Nigelo]

Please post a current Report.zip from your machine, ideally with hi-def photos of your control cabinet, which will help everyone understand your configuration

[ShawnM]

As for your "physical considerations", how is the Z motor coupled to the ballscrew? What type of coupling? Does it have a keyway? If not, did you use Loctite 648 on the coupling?

And as Nigel pointed out a report is needed to help you further and some detailed pics of the Z axis would also be beneficial.

[tblough]

Is the tool pulling out of the holder?

[AntsOftheSky]

Right now the Z motor is attached with a Rigid coupling, no keyway, clamp style attachments. It's tight and with the amount of slippage this has undergone, the entire thing would have flown out by now.

Tool is not pulling out of the holder, we measured before and after.

Will get report.zip and photos shortly

[cnckeith]

start photo album so we can see what you see and post link here.
here is how.
https://centroidcncforum.com/viewtopic.php?f=60&t=1043

[AntsOftheSky]

figured it out -- massive voltage drop from a bad power supply. The motor was never getting full power and would quit out, mid cut. Also, the X and Y axis gibs needed a little bit of tightening.