Boring help

[Maplehead]

Hi All
I am trying to do a simple cut. I just need to bore into a 3/4” brass rod at a 1/16” depth. The hole needs to be 5/8” wide.
No boring bars/bits that I have will work for this on my micro lathe so I bought a 5/8” end mill. The chuck turns in the correct direction, meaning into the cutting side of the end mill, but no matter how fast or slow gthe chuck is going, or hos slow I feed the end mill into the stock, the lathe keeps faulting and shutting off.
How the heck do I make this simple cut?
I’d do it on my mill but I have nothing to hold that 5/8” shaft end mill.

 

[T Bredehoft]

Make a small boring bar from an old broken tap, Drill the first hole 1/4 diameter, 1/16 deep. then bore it with your boring bar, .025 at at time. You've got time, haven't you?

 

[tweinke]

Drill a hole to your desired depth and use a 2 flute smaller end mill as a boring bar. I would think a 5/8 end mill might take a bit more power then you have available. Someone more knowledgeable will hopefully chime in soon though.

 

[Chipper5783]

You are cutting a wide face - all the way across, and probably too fast. Why not use about a 1/4" end mill clamped to your cross slide (tool holder). Small end mills work fine as a boring bar - you just position the one cutting edge up. Start with a pilot hole as big as you can get (since it is only 0.62" deep, the pilot hole will probably only be about a 1/8" diameter - but that saves you the center cutting).

Of course for brass - you could grind up a piece of HSS to make a small boring bar (even just a broken off tap, repurposed).

You guys are too fast for me - I didn't see the other replies.

 

[mikey]

If I had to cut that hole and I didn't want to use a boring bar then I think I would use a knife tool to plunge into the center and face out to get the required ID. I could probably cut a 1/16" deep hole, 5/8" ID with a flat bottom in the time it took to type this.

 

[Mitch Alsup]

Some end mills are center cutting, some are not.
Center cutting end mills are like 180º nose angle drills.
Non center cutting end mills will not drill.

 

[Maplehead]

Thanks All
I never thought to use a little end mill. That worked pretty good. Job done. Thanks again.

 

[tweinke]

Glad to hear it worked out for you! Sometimes a guy just needs to be pointed a different direction to cause them to think outside the box.

 

[ericc]

Yaay. Good to hear that you are successful. Remember that for small lathes, the cutting edge of the tool cannot have more than a small fraction of an inch contact with the part. If you are using a large end mill (or drill bit), you have to grind away all contact area in from the edge. I've made several boring bars from junk broken tools, and they kind of work (well enough to get the job done). Then, someone sold me a new Criterion boring bar. Wow!!! Money does make a difference. There is a lot to learn by looking at a commercial tool. Not those cheap Chinese brazed carbide bars. They are worse than any broken drill bit.

 

[kd4gij]

Glad you got er done. Since I got my present job I have come to realize why they call it boring.