End mill in drill press

P

PT Doc

Joined
Dec 24, 2011
Messages
1,298
If I wanted to drill a flat bottomed partial depth hole, could I use an end mill to accomplish this? Any special type. If this is not the right tool, how would I do this? Thanks
 
Sure can...I do it all the time. Just use a regular drill bit of the same size as your end mill to start your hole. Drill deep enough to get the shoulders of the drill bit down into your work and then follow with the end mill. This will keep the mill from walking on you.
Phil
 
txwoodchip said:
Sure can...I do it all the time. Just use a regular drill bit of the same size as your end mill to start your hole. Drill deep enough to get the shoulders of the drill bit down into your work and then follow with the end mill. This will keep the mill from walking on you.
Phil
Click to expand...

Thanks. Number flutes make a difference? This will likely be mild steel.
 
End mills don't plunge very well, the center doesn't cut well and sometimes they get a chip stuck in the center that causes them to wobble around, so you want to drill the tip of your drill bit the full depth of the hole so the mill isn't center cutting all the way down. You probably want a two flute for this. I'd drill slightly under so the endmill can finish the diameter.

The bottom won't be perfectly flat. It will have a bit of a cone sticking out because the bottom of endmills aren't flat.
 
Just make a flat bottomed drill.

Drill like Nathan described above, swap to the flat bottom drill and there you have it.

This way will cost less than an end mill too.

Plus you can move around in number, letter, fractional and metric sizes for very little cash out of pocket.
 
Fellhoelter said:
Just make a flat bottomed drill.

Drill like Nathan described above, swap to the flat bottom drill and there you have it.

This way will cost less than an end mill too.

Plus you can move around in number, letter, fractional and metric sizes for very little cash out of pocket.
Click to expand...

I'm not following what you mean with flat bottomed drill. Can you explain a bit more? Thanks
 
Nathan the Machinist said:
End mills don't plunge very well, the center doesn't cut well and sometimes they get a chip stuck in the center that causes them to wobble around, so you want to drill the tip of your drill bit the full depth of the hole so the mill isn't center cutting all the way down. You probably want a two flute for this. I'd drill slightly under so the endmill can finish the diameter.

The bottom won't be perfectly flat. It will have a bit of a cone sticking out because the bottom of endmills aren't flat.
Click to expand...

Thanks for the explanation of how to make this work. If I was going to try to make a 3/8" tapped hole, I'd drill with 5/16. To accomplish this blind hole using an end mill, you'd recommend less than 5/16" drill, then 5/16 end mill to proper depth. How does one figure out how much depth is needed for the application using 3/8 screws? Thanks
 
PT Doc said:
I'm not following what you mean with flat bottomed drill. Can you explain a bit more? Thanks
Click to expand...

Sure, grind the tip of a drill to resemble a flat bottomed end mill.
180 degrees instead of 118 or 135.

Depth of hole is entirely dependent on application.
Rule of thumb is 1.5x diameter in steel gives you all the strength you can get from a bolt.
 
Fellhoelter said:
Sure, grind the tip of a drill to resemble a flat bottomed end mill.
180 degrees instead of 118 or 135.

Depth of hole is entirely dependent on application.
Rule of thumb is 1.5x diameter in steel gives you all the strength you can get from a bolt.
Click to expand...

Thanks for the clarification. Now how to grind the cobalt bit?
 
A bit off topic, but involves use of endmills in drill press. If you actually attempt milling operations (not plunge cuts), and your drill has a tapered spindle on the chuck, good chance it will work loose.
 
Ptdoc, thanks for bringing this up. I was wondering myself how to make a drill bit flat.

Are you guys saying to just grind the tip down a bit on a regular bit?
 
Yes, just regrind a tip.
Save a couple of dull bits, and use them.
Grind the end flat, put a little relief behind both cutting edges, then go to town.
 
You must log in or register to reply here.
Back
Top