Part cut out

[Pysiek]

I start this thread here since a lot of people here owns LMS milling machine.
I would like to cut out a part out of solid piece of 6061 aluminum 3/8" thk. What is the best tool to do that? And what settings?
Please check the picture for reference. The groove on the picture is where the tool should cut.

[photomankc]

The part is the center portion I take it? If so, you may want to leave holding tabs on the flat faces to keep it from vibrating and getting ruined as it drops away. Hopefully you are using software that has that feature. It's a bear to have to add them manually. Also I usually try to open the slot to 150% of the cutter width as I go to keep from have a chip-binding mess in the slot. Depends on what you software allows but say it's a 1/4" slot I'll specify a 3/8" cut-width so it opens that trench up as it works it's way down. I find it's better to have a sizable final cut depth too. Don't leave a tin-foil layer for the last pass, having a 1/16" or more to cut into in the last means the material helps keep it stable and I get less chatter till the very end.

Holding tabs though.... they really help but they mean some manual finishing work is needed after you break it loose.

[Pysiek]

photomankc thanks for the reply. and the holding tabs are great idea. When you say that you try to open the slot to 150% of the width of tool you mean that I need to make two passes on the same height?

[photomankc]

When you say that you try to open the slot to 150% of the width of tool you mean that I need to make two passes on the same height?

Correct. I try not make the tool fight through a full-width, deep slot just to profile a part. It makes one full-width pass, then a second pass at the same height that's ~50% width. This way the chips from the deeper passes have more space to get clear of the tool.

[Pysiek]

okay thanks. one more question. how do I mill a hole with helical motion?

[photomankc]

Your CAM package has to support it. Looks like you are using Vetric. If you have Cut2D then it's not supported, nor is setting a cut width. The V-Carve package might. CamBam, which I use, has an operation for "SpiralDrilling" which is quite nice. Saves a tool change for larger holes.

[LongRat]

If you just want to use helical interpolation to make a round hole with an endmill, that's easy. You just use G02 or G03 and include a z component with it. The machine will describe an arc with G02 (or G03 in the other direction). Adding the Z value in there will synchronize a change in height (Z) of the tool with the end of the arc move. Play around with it a bit.

[photomankc]

Good to know. I probably should have thought of that because motion is always coordinated for the all axis in motion. I didn't have much luck programming arcs by hand though so I much prefer an expensive CAM that can do it for me. I'm lazy, which is largely why I have a CNC machine

[Pysiek]

I use USBTOCNC software. But most of the parts I draw in inventor 3D. I have to check the CAMBAM software. What I've heard a lot of people are using it.

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