Wavy finish in pocket

[BenK]

I am cutting a 6061 part that I has several R.125 inside a pocket. The machine is a Makino A66 with a Pro 3 control The problem is that every time I'm cutting in the X+ transitioning to the Y+ direction it leaves a wavy finish. I have tried slowing the RPM and reducing the feed but the result was the same. Any Ideas what it could be?

[Tony35]

we had a similar problem on our A71 pro 3 control

turned out to be a bad X axis ballscrew

[jeff]

How wavy? and is it always in the same direction? Is it only for a certain distance each time?

My Okuma has this issue also, looks similar to chatter, but it's not. and it's less than .0005" imperfection,but it really stands out on aluminum.

[BenK]

It is about the same distance every time and in the same direction every time. It is about .001 to .002.

[Tony35]

you filtering the toolpath?

[BenK]

No filter.

 

 

 

 

N357 G1X.9727

N358 G3X1.0026Y-.2989J.0312

N359 X.705Y.7731I-1.0026J.2989 <----------the first .1 of this ark is one of the wavy spots.

[jeff]

If you have the same issue as I do, the way I get rid of it is to extend the lead off to past the part.

For example if you are machining around a square part on the outside, set the lead out to run past the end of the part.

Wavy lines = gone

[BenK]

Jeff, This is on an internal corner.

[jeff]

Yeah I don't have a fix for that other than multiple finish passes maybe.

[McLaren]

Are you using a 1/4" endmill?

[K2csq7]

Take a pic & post it up

[BenK]

Are you using a 1/4" endmill?

 

3/16 ENDMILL.

[K2csq7]

Whats the D.O.C. ?

[McLaren]

If it's happening on only 1 of the inside corners, and I assume there's at least 4, and they all have the same amount of material left over, then I'd have to guess backlash issue. You could try a different number of flutes though.

[K2csq7]

I have also seen spindle squareness issues affect finishes on certain portions/sides of parts.

When you say "wavy" do you mean like a candy cane spiral wavy (chatter) or does it look like the toolpath has "humps" in it?

[BenK]

Keith, It looks like the toolpath has humps in it. it is happening on all my different D.O.C(from .1 to .625). I have tried changing my rough stock (from .02 to .002) with no difference. now I'm even doing a semi-finish pass.

[Tony35]

what kind of chipload you running? .002? .003? .006?

[BenK]

.002 chipload

[McLaren]

TTIWWOP

[BenK]

TTIWWOP

 

UHH What? I have no clue what you are trying to say there!

[Tony35]

how is the tool runout?

grabbing at straws now

[McLaren]

This Thread Is Worthless With Out Pics! lol

[BenK]

Its running nice and true and its even in a balanced tool holder. Its a 3 flute Benchmark endmill for aluminum, same thing we use on most everything here.

[BenK]

I can't post a picture of this part.

[K2csq7]

I can't post a picture of this part.

How bout a cropped image of the problem area?