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« on: April 24, 2010, 12:45:28 PM »
I roughed it out with a .375 carbide wood router bit, then did most of the finish work with a .250 Carbide end mill, and did some detail contour work with a .0938 carbide end mill.
Pocketing and material removal was done at about 30% step over at 20 IPM The small bit was only able to remove about .005 per pass, but the .250 and .375 bits were able to remove .010 per pass.
In order to make the lid fit properly I made its pocket about .004 (plus/minus backlash) larger than the lip it mates too.
(As a note for wood I have found you either need to hand taper or goto about .006 as wood compresses then springs back as it cuts. Different woods will vary.)
I did each process as a seperate operation rather than run it all together. It allowed me to feel more comfortable, and I do not have a tool changer.
Not learned on this particular job, but some folks will tell you a TiN coated bit does not stick to aluminum as bad. I think if that's the case its hardly siginificant. Its much more important to use a sharp mill, and not exceed the chip load of the cutter. I did not use any TiN coated bits for this job. All were carbide.
After I was done I rounded all the sharp edges with some fine grit aluminum oxide paper by hand. I didn't want to make it round, just dull the edge so the recipient would not get cut by it.
I also dressed the inside of the lid where the heart point comes in with a file, and hand guided the cutter to indent the box at the same point so the lid would not hit at that point.
Its not always the case, but often enough you have to do some tweaking to make a work piece come out nice.
Theoretically I could have done the entire piece with the small bit as a single operation, but instead of doing it in a day (5-6 hours machine time) while hanging out in the shop and doing other things it would have taken a couple days.
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