How To Make A Flat Bottom Hole

[EdK]

What's the best way to make the flat bottom hole as shown in the sketch below? It's the 1/4" x 3/4" hole that needs to be flat.

Thanks,
Ed

   

[sasquatch]

What the heck are you building ?

[Sunset Machine]

I'd like to see that too, maybe a plug pressed in from the left or pre-drill and grind up a drill bit for a couple of guesses. Luck out and find a counterbore that would fit? This one is $25.

http://www.travers.com/product.asp?eapro...%2F4%22%27

[dallen]

endmill

[EdK]

(12-13-2012, 08:30 AM)Sunset Machine Wrote: Luck out and find a counterbore that would fit?

I was also thinking of a counterbore but haven't taken the time to look for one. It might be my best option.

Ed

[EdK]

(12-13-2012, 08:46 AM)dallen Wrote: endmill

I'd be concerned that the end mill would grab the part and tear it out of the vise. The material is aluminum which gets kind of grumpy when trying to do a plunge cut like that. I'd probably end up snapping off the 1/4" end mill and not only ruin the end mill but the part and my day.

Ed

[EdK]

I'm making a work stop for my mill vise.

Ed

   

[rleete]

(12-13-2012, 09:23 AM)EdK Wrote:

(12-13-2012, 08:46 AM)dallen Wrote: endmill

I'd be concerned that the end mill would grab the part and tear it out of the vise. The material is aluminum which gets kind of grumpy when trying to do a plunge cut like that. I'd probably end up snapping off the 1/4" end mill and not only ruin the end mill but the part and my day.

Ed

Drill it out (about 7/32" diameter), and get close to depth. The end mill is just for the finish cut. Much less wandering, grabbing and chattering. Of course, you need to peck it, just like drilling. Use WD-40 liberally as lube for better finish and less buildup on the mill.

[f350ca]

I wouldn't hesitate to do that with an end mill. Two flute if it was a blind hole, but you can drill through with the 0.17 then ream with a 2 or 4 flute. Can't see that coming out of the vice.

[dallen]

the way that's drawn, looks like to me that only one side of the clamp is going to actually do any clamping, or am I missing something. ?