I referenced this forum several times before trying drilling on my own and thought I would update for other beginners with a quick summary of my various successes of test cuts drilling 1/4" holes though 3/4" thick MDF:
- Using 2-flute flat endmill. Straight plunge: Not recommended! I knew this was probably dumb for all the reasons above, but figured I’d try it anyway since the sled template nearly “drilled” holes for the brick holding bolts. As everyone says above- the Z-axis is too slow and router bits don’t clear sawdust up the flute well. Friction started burning the wood & ruined bit. Probably could’ve started a fire if not well attended.
- Using 2-flute flat endmill and pecking 0.15" at a time. Worked fine. I assisted with vacuum of chip removal. Con: took about 5 minutes to make one hole. I’d use this again if I had < 3 holes to do to prevent having to do a tool change.
- Used a tool change with 1/4" drill bit and 0.25" pecking. ONLY USE HIGH SPEED STEEL bits, cheapo bits are not made for high RPM of the router. I used a titanium coated Irwin Kit. This drilled very well, but I would highly recommend getting a machine length bit because this jobber bit was too long and I ran out of Z-axis travel on clearance height between holes. Also, was off about 1/32" in Y-direction after tool change (kept sled attached). I can live with that but maybe you can’t. Q: anybody find good collet reducers to hold metric size drills?
- Use a 2-flute endmill to create a 0.2" deep “spot face” cut only, then hand-drill the rest when the part is finished. This is the fastest method, but would recommend a pointed router bit so that your drill bit tip can hold center.
Also: I used Fusion 360 to generate my gcode. Ground Control did pause and ask for tool change automatically, but I could not change the Z-axis zero height unless the program was stopped. So I noted the line in code, stopped and re-zero’d and re-started from the line in code. That works about the same as making two different programs.