First Time Milling Steel - Snapped a cutter - HELP!
Today I tried milling a simple part from some 1/4" steel on my recently finished bridgeport interact retrofit. This was the first time I've tried milling anything harder than wood or plastic. I ran the program cutting air first and everything looked fine so I tried again a second time round so it would actually cut something and within a second or two of touching the metal the cutter snapped.
That was the only one I had so decided to call it a day and got some more on order for tomorrow. However even the cheapy end mills are not that cheap so I was hoping to glean some advice from the experts on here to save myself from snapping too many more cutters.
My suspicion is that the breakage was caused either due to a feedrate/spindle speed/cutter size mismatch or due to the way the material was clamped to the machine .. or both. or maybe something else entirely that i didnt even think of.
My setup was with a small piece of 1/4" plate approx 3" x 5" clamped in a vice with about 1/3 of the piece sticking out the side of the vice cause i was cutting from the edge and wanted a bit of clearence from the jaws incase the machine decided to have a funny moment. I'm wondering if maybe even though the vice was done up really tight, that the bit sticking out was enough to cause some deflection which then broke the cutter ?
The cutter itslef was a 0.16" diameter slot drill, spindle speed was 2000 rpm and horisontal feeds were 11ipm. Does this sound about right or was I way off the mark ?
Thinking out loud here, should I have been climb or conventional cutting and if i'd been using the wrong one is that likley to have contributed to the breakage? I'm using a new cam package and I still dont fully understand what i'm doing with it.
Appologies for all the questions and i'm sure I sound like a total noob, but this is a new machine and all my cnc experience up until now has been with softer materials which are a lot more forgiving to the blundering hobbiest. Now trying to cut a bit of mild steel and all of a sudden it seems like I have to be a lot more diligent.
Dom
http://www.ukrobotics.com/projects