[murray66]

Hi everyone,
I'm new to the Milltronics forum. Wondering if anyone can help. I have a 1999 MB-19 with Centurion 6 controller. I'm getting poor "choppy" surface finishes in softer materials like aluminum and copper. But harder materials like steel and tool steel surface finishes are pretty good. The spindle bearings are just replaced and brand new. Same situation. Any ideas?

Thanks in advance for any help.

[bborb]

Use an indicator and check your backlash in X and Y axis. Also, with the machine in E-stop turn the X and then the Y ballscrews by hand..... they should "feel" smooth as you turn them. Let us know what you find.

[jpawelk]

Using an indicator check the runnout of the spindle itself. Possilby the spindle may not be tight enough.

[murray66]

Thanks you guys for your replies. I have checked both the backlash and spindle runout. They are both good. Although the ballscrew backlash does vary somewhat when checked at 6 different locations throughout the x,y, travels, I have adusted the ballscrew compensation where I do the majority of my machining (in the middle of the x,y travels). The spindle bearings I can only assume are preloaded correctly with the factory precision ground spacers between the upper and lower bearing sets creating the preload. Just keep in mind as a reminder, soft materials crappy finish, harder materials good finish. I'm thinking of changing my belts, maybe very worn and creating harmonics or vibrations when under very little cutting forces then any "slop" taken up when under higher cutting forces. Any thoughts?

Thanks again...

[Tomorrow_man]

Hi,

I use a MB-19, it was a tool show demo machine in 2000 or 2001.

You don't say what grades of aluminum or copper you are cutting or speeds and feeds, but it sounds like you are 'pushing' the material. Try more RPM's and a little lower feedrate. Also use coolant or spray some CRC or WD40 on the cut.

If I can find some photos I took of surface milling I'll post them.
The MB-19 is a great machine and can produce good finishes.

TM