A curious comparison between me (the beginner) and you (the pros)

Maplehead said:
Can anybody further extrapolate on that "scale"? My assumption is that its harder than the steel underneath. If so then why wouldn't I want to take shallower cuts with it than what you all say, a deeper cut? Not wrapping my head around that one.
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Mill scale is simply what steel does when hot rolled; the water, air, and other lubricants in the plant and the nature of steel simply cause this scale to "happen". IT is not rust (although it forms in the same way and from the same reactions, but the hot steel being {rolled, formed, welded, ground, ...} is hot so it stays in the annealed state during processing, hot steel is converted into iron oxide with slightly different chemistry than rust on a steel's surface.

The important thing about mill scale is to get the cutting point under it--the cutting point at the end of the end mill is the a) most used, b) weakest portion of the EM. You want the tip of the EM to be under cutting normal steel, while the side edge is dealing with the mill scale. The mill scale would come off with the steel it is bound to if you could cut the top 0.010 off the steel surface without touching the rest of the steel with the tool. {but we can't}
 
jwmay said:
Not a clue. Oh wait..I'm not a pro. But on a good day, with the wind blowing in the right direction, at low tide, facing a rising sun, with a coffee on the bench, and both my good eyes....
Nope. I still don't know.
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"both good eyes" is the problem. One of them needs to be squinted, sometimes both. And add standing on one foot. Supposedly which one doesn't matter, I seem to have better luck with the left. I'm right handed, but the right leg is wobbly.

To the OP, a few of us are real pros, but for the most part we're AmDamateurs. Some use the rules of thumb passed down from "old timers". Others, like me, tinker with speeds and feeds until it looks right on "test" (scrap) pieces then mount the work. Work finish is important, but the machines are dangerous too. Machine finish has many factors, not the least is relative size difference between the work and the machine. I use a small mill, an Atlas benchtop. (MF-C) I don't try anything larger than two inches or so.

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Are you chrome plating these pieces after machining? Unplated steel will rust like crazy on a guitar from sweat and salt
Stainless would be a better choice but of course it's more expensive and harder to machine
-Mark
 
Hey, I don't know how you sand it, but I find filing sometimes to be faster than sanding, unless you have a beast of a machine.
I find a nice file start with roughing passes, then draw filing will leave a sweet finish.

Now if you are using a power sander 6x48 and a nice belt you can do some sanding fast, but often not as accurate as a file..

But both work... I do a lot of file work when I want a super finish. It was the way they did it in the old days... I figure it's still valid.
 
Maplehead said:
Can anybody further extrapolate on that "scale"? My assumption is that its harder than the steel underneath. If so then why wouldn't I want to take shallower cuts with it than what you all say, a deeper cut? Not wrapping my head around that one.
Click to expand...
Like others have said, having the carbide get "below" the scale will save your cutting edges. It is actually quite shocking how much carbide can handle IF you have a solid setup AND the machine has HP to make the cut.
Just for fun, take a look at this video and how much he takes off on a cut while testing some "cheap" carbide inserts from Banggood.
Also, David has an excellent book regarding inserts... Introduction to Indexible Tooling for the Metal Lathe
 
Nickel plating
Hand sanding
966 lbs/1.5HP
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