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[How do I?] Setup A Corner Rounding End Mill On Cnc & Gcode?

countryguy

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#1
I am going to make a few things that would benefit from a corner rounding operation on a main plate of Alu 6061. I purchased a 1/8" radius 5/8 OD by .5 shaft Hertel for use on a 1/4 or 3/8 inch Alu plate. I watched several videos on using the manual method via Toms Techn's but cannot find much on the setup for CNC?

I'll play with scrap first w/ some trials but is the general idea to enter the tool as a end mill w/ 5/8" diameter. Use the tool offset setup of my Centroid setup and get the 0 to the top of the part. Take the OD .625 (-) the 1/8" and then (+ )a few "thou" back to stay just above the top of the material (not too deep say's Toms vid to rid burr edges) as my values for Z and X? depths of cut. Say .123? Maybe tell my Cam to run that in 2 passes or stick w/ 1? (a 3 flute cutter device)

Thanks everyone. The 3D printer took a ride w/ the kid for a few weeks. bummer! :) Back to some metal work projects.
 

derf

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#2
Here's what I would do: Using some scrap,set up the cutter and zero the z touching off the top of the part. Go to an outside edge and drop the cutter down to the contact the major diameter with the edge and zero out. Now go into manual mode and start cutting until the radius suits you. Once the radius is correct, take note of the z depth, and the offset of the tool. Once you know what the correct diameter is of the tool on the small end, you can enter it as the diameter. Measuring the tool will get you close, but it may be off a few thou, the way it cuts.
 

JimDawson

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#3
Here's what I would do: Using some scrap,set up the cutter and zero the z touching off the top of the part. Go to an outside edge and drop the cutter down to the contact the major diameter with the edge and zero out. Now go into manual mode and start cutting until the radius suits you. Once the radius is correct, take note of the z depth, and the offset of the tool. Once you know what the correct diameter is of the tool on the small end, you can enter it as the diameter. Measuring the tool will get you close, but it may be off a few thou, the way it cuts.
:+1:

I'll add to what @derf said. Once you have done it a few times, you'll be able to make the offset corrections in you head after measuring the cutter. :)

Also don't get too greedy with the cut, you are presenting a very wide cutting area to the tool bit. Also set your spindle speed for the OD of the cutter.
 
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cs900

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#5
Well the wonderful thing about CNC is you can do it however you like so long as you remember how you did it when you do your programming. I personally use the diameter of the tool created by the vertical tangents of the arc for my tool diameter, and I use the horizontal tangent of the arcs as my "Z zero" reference.

I also run my tool about .005 above the point where it would make a full radius to avoid that nasty shelf/burr as well. I typically do it in 2 passes. 1st pass takes the entire depth, but leaves about .008-.010 stock for the second pass. That's on a much larger radius though, 1/8 you could probably do in a single pass.
 

JimDawson

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#6
Oh and don't forget about corner rounding, carbide tipped, router bits. That's what I use on both steel and aluminum (and wood sometimes ;)). Normally less expensive that HSS corner rounders and available from a lot of different vendors.
 

cs900

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#7
Oh and don't forget about corner rounding, carbide tipped, router bits. That's what I use on both steel and aluminum (and wood sometimes ;)). Normally less expensive that HSS corner rounders and available from a lot of different vendors.
That's what I use as well. They cut like butter in aluminum.
 

countryguy

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#8
welll.. I have 2 cobalt CR end mills coming in.. Grrr... And Jim, I know you posted that before on the router bits! Midnight shopping last nite and I forgot that one. I elected to do purdy' on the new improved plasma machine torch holder.. Grrrr. :eek 2:
I am looking forward to playing.

....and to CS900 - Love to learn! Will take a run on your method too. I'll need to putz around and draw out your way. I'm just not seeing that in my head yet but a Tangent line from an arc I think Fusion360 should do pretty easily to graphically show me. Not getting it just yet. :confused:

You guys are the best!:applause 2: thanks.
CG.
 
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