How To Mill Slots In Steel
Having that leg of the angle iron that you are milling unsupported really isn't the best setup. I'm glad that it worked for you but you should really hold pieces completely.
That formula for calculating spindle speed is wrong too. This is the real formula
- The machinability of steel differs depending on alloying elements, heat treatment and manufacturing process (forged, cast, etc.). In soft, low carbon steels, built-up edge and burr formation on the workpiece are the main issues.
- Your Rotabroach cutter is made of M2 high speed tool steel. That’s not going to be effective with most alloys of stainless stock and is not recommended for hole depths over 1/4″ in mild steel.
Mill slots in machine tool tables, indexing tables, and other workholding surfaces. Undercutting End Mills A fine -point tip cuts lettering and numbering and makes designs in a variety of metals and composites, such as aluminum, fiberglass, and titanium. When performing slot milling, process reliability is extremely important. The chips must be reliably removed from the groove and must not damage the surface. A large number of solid carbide shank cutters and indexable insert side and face mills in various cutting widths and diameters allows a broad range of applications to be covered.
(PI * DIA X RPM) / 12 = SFPM
How To Mill Slots In Steel Hole
Using your formula it says to run a 5/16 inch cutter at 550 RPM which is only 45 SFPM, less than half the speed you should run. You should mill steel at 100 SFPM or more.
I'll mock up a better setup. Ignore the burn holes in the steel. It is the first piece of scrap angle I found laying around. Anyhow, the hold down on the leg keeps it from fluttering around. Chatter is a bad thing when machining.
jmarkwolf
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How To Mill Slots In Steel Knives
I never paid much attention to how many flutes my end mills had, I just purchased what the local Production Tool Supply had on hand. The aluminum didn't seem to care.
I recently needed to cut a 1 -1/16in diameter counter bore 0.125in deep in some angle iron, to accommodate flush mounting some weld studs I fabricated. The only end mill I had was a 2-flute.
It did the job for me, but it 'chattered' to beat the band, even with flooding with oil. It seemed to like a faster feed rate as well.
Can anyone advise 'when and why' to use end mills with various numbers of flutes?