Thought I shared since I started one a while back beginning this year. I'm making engine bracket swap kits using 1/4" 1018cr.

Both 4 v. flute from maritool. Both stickout are less than 1" enough to clear my fixture 1/4" bolt head.

3/6" - DOC 0.028", 2000rpm, 10.5ipm
1/4" - DOC 0.045", 2000rpm, 12.8ipm (might tray .068" next time, I backed out).

As someone mention "Rigidity!" Workpiece and fixture plate is everything.

I do stock 2 flute also but they are not my main cutters (slotting/plunging holes in steel and aluminum uses). Less three flute also as I use my tormach 17mm and 25mm center cutters.

4 flute works wonder and they are only $15 at maritools vs $8 for a two flute.

1018cr tigs right up with a wipe.