Boring small flat bottem holes?

[mototraxtech]

I need to bore some holes or counter sinks for a 3/8 socket head bolt into some spacer/bushing things. I could get a really small boring bar but would it work to just get a 5/8 end mill and chuck it in my tail stock and then just bore in like a normal drill. Seam like a waste of time to try and bore it out with a boring bar. The dimensions of the hole are 3/8" deep with a 5/8" diameter.

Also if that will work which kind of end mill should I use. There are many kinds and I only know a little about lathes and not alot about milling.


Thanks
Randy Gentry

 

[Light Brite]

I have done this with good success in a lathe. I used a single ended end mill with 4 flutes. It doesn't have to be a center cut mill because you already have a hole in the bushing. With a secure work pc. and tool along with the proper speed and feed and you should have no problem.

Good Luck!

 

[Atlascycle]

Why not just get a counter-bore?

 

[Light Brite]

If a tool is going to be bought for this job, that is the way to go as long as the thru hole is of suitable size for the c'bore.

 

[mototraxtech]

I guess I never heard of a counter bore. Ill look into it!

 

[wquiles]

I have done this with good success in a lathe. I used a single ended end mill with 4 flutes. It doesn't have to be a center cut mill because you already have a hole in the bushing. With a secure work pc. and tool along with the proper speed and feed and you should have no problem.

Good Luck!

+1

That is how I do most of them as well, but I also have some very small boring bars that could work depending on the size of the hole.

 

[precisionworks]

I never heard of a counter bore

They are more correctly referred to as a piloted counterbore, with the pilot (item on the left in photo) fitting into the pilot hole you've drilled through the part. Pilots are available in different sizes & can be turned down on the lathe to any custom size you need.

Using a counterbore is a one step op, and fast. Done in about one tenth the time of using a boring bar.

 

[1917]

end mill, counterbore, boring bar, flat bottom drill will all work.

 

[ejot]

McMaster-Carr P/N 29445A17 is designed to do exactly what you need in one step.

I don't have any that big, but I have #6 - 5/16. They work great!