Destroying end mills... not sure why?

[Steve Seebold]

At 5100 RPM, you would even burn up carbide end mills. I would run a 4 flute carbide end mill at about 1,000 RPM and 12 IPM, .100 DOC .100 WOC.

I get pretty aggressive with my machine and I don't use G-Wizard.

All I use is carbide end mills (even on aluminum). I don't think I even own a HSS end mill

[daniellyall]

best thing to do get A good speed and feed chart or program a highly recomend chart or program in the long run you will save a lot of money take a stab in the dark of what you are cutting is a masive wast of money and time do the simple test`s most have been said in this thread.magnet, file, hacksaw and a grinder will tale you a lot. been there done that wasted cutters and time.

[victorofga]

the picture you posted... looking very much as a welded buildup you try to mill..
HSS mill regardles of speed wont work..

you need a carbide mill that designed for cast iron.. small passes, and patiency.... the material itself looking very much of the machined surface likely a springsteel..
reason i mentioning the cast iron, because those carbides standing more the dynamic forces..

[wtopace]

Cordvision, there are multiple things at play, but the two main ones are variable tooth offset and coatings. The variable tooth offset means that on a 4 flute cutter at least one of the flutes will be out of time. Meaning that not all of the teeth are 90° apart on a 4 flute endmill. This stabilizes the cutter preventing cutting edge damage allowing more agressive feed rate. The coatings today are just out of this world. The coating protects the front of the cutting ege from the heat generated during cutting. That in combination of the high feed rate puts the heat in the chip which gets ejected.
Another technology that is finally coming into its own is micro edge prep. Basically the cutting edge is hone by one of several means. This eliminates the micro crevices in the cutting edge that start to immediately break down the tool.

I know this is a lot high tech nonsense for the average joe with a cnc router but some of the priciples still apply. Especially the shallow step over. This will reduce the force on the machine in all applications.




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Just wanted to clarify that a Tormach PCNC1100 isn't a CNC router and doesn't have a super high speed spindle, 5100 RPM is the max. It is also decently rigid for a small CNC machine.

1100 Personal CNC Mill | Tormach Has Affordable CNC Milling Machines

[tmarks11]

When I run Gwizard, I get 2400rpm, and 6.3ipm. That's on "aggressive" Doesn't sound too bad to my novice ears?

It all depends what kind of steel you chose in your calculation. Steel ranges from 60-200 sfm depending on hardness. Using the basic calculations I mentioned above, that gives you an rpm range of 960 - 3200 rpm.