02-10-2014, 11:52 PM
Your RPM is way too high. Often, areas where a cutting torch was used cool off quite quickly. This hardens the steel, if it has any amount of carbon in it. Harder means slower.
Also, carbide doesn't like interrupted cuts. The roughness of the hardened area can cause carbide to chip. 50 thou is a pretty heavy cut for a light machine. (You haven't said what mill you have.)
For that size cutter, try 900 RPM (carbide) or 130 RPM for HSS. Any time it's throwing sparks, stop and change something. Carbide can cut blue or straw-coloured chips, but no glowing ones. If HSS is causing chips to change colour, slow it down.
Also, carbide doesn't like interrupted cuts. The roughness of the hardened area can cause carbide to chip. 50 thou is a pretty heavy cut for a light machine. (You haven't said what mill you have.)
For that size cutter, try 900 RPM (carbide) or 130 RPM for HSS. Any time it's throwing sparks, stop and change something. Carbide can cut blue or straw-coloured chips, but no glowing ones. If HSS is causing chips to change colour, slow it down.
Mike
If you can't get one, make one.
Hawkeye, proud to be a member of MetalworkingFun Forum since Jan 2013.
If you can't get one, make one.
Hawkeye, proud to be a member of MetalworkingFun Forum since Jan 2013.