[metalmansteve]

Not really a mastercam problem but thought I'd ask here since I use mastercam to program.

How do you deal with vibration marks on the interior corners of a pocket where you're hanging a small tool out.

What strategies have worked for you?

I'm currently working on a part with 1.75" deep pockets with internal corner radius' of .125"

For shallow pockets, using a smaller size end mill works well, but when going 7xD I need to use the beefiest tool available and going down to a 3/16 tool doesn't see feasible....but maybe it is...I haven't tried.

I guess this isn't limited to inside corners but that's where vibration is most prevalent.

Thanks for the input.

[christinandavid]

The vibration is caused by the massive increase in radial cutter engagement in the corner. You could either drill/plunge the corners out first, or mill each corner in multiple passes, gradually decreasing the corner radius each time. You would also have to use multiple axial cuts as opposed to a single cut at finish depth.

If you have a 5 axis machine, angle the part so that only the end of the cutter is in contact with the part and that will have the same effect.

All these strategies are more time consuming I'm afraid....

DP

[txcncman]

The vibration is caused by the massive increase in radial cutter engagement in the corner. You could either drill/plunge the corners out first, or mill each corner in multiple passes, gradually decreasing the corner radius each time. You would also have to use multiple axial cuts as opposed to a single cut at finish depth.

If you have a 5 axis machine, angle the part so that only the end of the cutter is in contact with the part and that will have the same effect.

All these strategies are more time consuming I'm afraid....

DP

+1

Also try necked down tools with minimal flute lengths. Sometimes you can get away with depth cuts with minimal steps showing.

[Matt@RFR]

Reduced Shank 3/16 3 Flute End Mill Finisher 3.5 long X .157 Shank MariTool

These tools work really well for stuff like this. I like them for finishing, but they work just as well for roughing. Leave .004 - .006 or so for this tool to finish, step it down around .300" and feed it at .0008 - .0009 IPT and you'll be happy.

There's just no way to stop chatter in the corners other than a smaller tool.

[Superman]

The vibration is caused by the massive increase in radial cutter engagement in the corner. You could either drill/plunge the corners out first, or mill each corner in multiple passes, gradually decreasing the corner radius each time. You would also have to use multiple axial cuts as opposed to a single cut at finish depth.

If you have a 5 axis machine, angle the part so that only the end of the cutter is in contact with the part and that will have the same effect.

All these strategies are more time consuming I'm afraid....

DP

Another suggestion to add to this one

- rough the shape as you normally would
- fit larger rads ( say R1/2 ) on the finishing contour's internal corners, to keep the larger tool ( say a 5/8" cutter) away from them, this machining should not add any time, speeds / feeds can be quite reasonable
- finish the corners as previous described ( plunge out with a 1/4" cutter-use a peck cycle to eliminate deflection ), then contour with a 3/16" using depth cuts ( say 0.080" depths) , ( these are the added time operations )