Drilling flat bottom holes with a flat end mill

[toolsRme]

I have a descent floor model Drill Press but unfortunately I do not own a Milling Machine. I do however have a bunch of brand new (very old stock) double end Flat End Mills that I can't see why they could not be used in a Drill Press to drill flat bottomed holes. Is there anything I do not get here or is it OK to use these End Mills in a Drill Press for the purpose of what I am intending to do? I DO understand NOT to use the Drill Press as a Mill to side cut - this would be strictly for flat bottom holes.

 

[f150skidoo]

I don't see why you couldn't do what you want with the end mill. As long as your not putting any lateral load on the quill, which you said your not you will be fine.

 

[zebrabeefj40]

The bottoms of end mills are not actually flat. Lay a straight edge across a mill to see what I mean...

Nick

 

[rsanter]

If you try that the end mill will likly walk and jump around before beginning to bite into the metal. The bearings and the quill bore are just not tight enough to do that.

How to do it....
Drill a pilot hole or use a center drill(better)
Enlarge to a a size just under the size of the end mill and almost as deep as you need
Then use the end mill to finish the hole

Bob

 

[astroracer]

Be sure the end mills you have are "center cutting". If they aren't they will not "drill" a hole. Your best bet in any fashion is to do as Bob said. Pre-drill to just shy of your target depth then use the end mill to clean it out.
Mark

 

[EdT]

You may find that the end mill will make a hole a bit bigger than it's nominal size. The reason, I think, is unlike a drill bit, the end mill flutes are designed to cut on the sides and any eccentricity, wobble , loose bearings etc. will cause the sides of the end mill to cut resulting in an oversized hole. May not matter, but test on something that doesn't matter first. Also, with double ended cutters you may find that they won't go far enough into the chuck to get a good grip on the round part of the cutter.

 

[buildyourown]

It will work, kinda.
Be sure to clamp your work. Otherwise it will wobble really bad and your hole wont be round and you may chuck the work across the room.
Drilling a starter hole will help a lot.
The other issue is having the other end of the tool dig into the drill chuck. Most chucks dont have enough depth for this to work.

 

[zkling]

You'd be better off grinding a flat bottom drill bit.

 

[ClappedOutBport]

Yeah, that will work fine. You want a two flute endmill, and it must be center cutting.

 

[Jim Johnstone]

Another vote for pre drill first and them flat it with the end mill. Done this dozens of times.

 

[MushCreek]

Definitely pre-drill with a regular drill bit first. Even in a milling machine, an end mill will not like trying to drill a hole. I prefer to make a flat-bottom drill bit, but again, you must first drill with a regular drill bit.

 

[toolsRme]

Thanks for all the responses. So I played around with a double flute center cut end mill today and like most said, it tends to walk a bit unless everything is clamped very tightly. I do agree that the best way is to drill an undersized hole and then finish with the end mill.

I inherited a bunch of them (new old stock - probably from the 50's and 60's) still in their cardboard tubes from my Dad when he passed away 5 years ago, but until now I have never tried to use them. I believe that they are all 1/2" and under and for the rare occasion that I do need a flat bottom hole, I'll pre-drill almost to size and finish off with the End Mill.

 

[mike13u]

First, what is the material that you need these flat bottom holes in?

 

[APEowner]

Since you've done it already you can see what the challenge is. Drill presses aren't really ridged enough for plunge cuts with end mills but you can make it work. I'll throw in one extra word of caution. If your drill press has a chuck with a tapered mount the vibrations can loosen it creating an exciting but dangerous situation.

 

[strike a poser]

I've done this before and all responses so far are good to follow. The only other thing I can suggest is to take a cut off wheel and remove one of the cutter ends at the end of the flutes in the middle to ensure the chuck will get full engagement of the end mill on the solid round surface of the shank.

 

[toolsRme]

I was thinking mostly about Steel and Aluminum but there are times I would use them on Hard wood too.