Drilling Brass

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ddickey

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I was drilling/boring some round brass stock on the lathe. It was Ø .5" first using a pilot drill then a 25/64 bit. It felt like my bit was getting pulled into the work, real choppy like. I think rpm was about 900.
I think it might have been to slow of feed? Suggestions?
 
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I also have some modified drills for brass as suggested, but not all sizes. For small bits that I don't have modified, I put some tension on the tailstock quill lock to reduce the "pull in tendency".

David
 
mikey said:
Skip the pilot drill. Spot it, drill with final size drill and it will go well. Using a pilot drill in brass is asking for grabbing and it just isn't necessary.
Click to expand...
What he said.
If free machining 360 brass just bang it through at the rough diameter after spotting then bore or ream, there is no reason that a small lathe could not push a 1" drill through this material.

This is what Free Machining means.

If you insist on piloting the hole then put some tension on the tailstock ram with the locking screw so that the drill doesn't pull the backlash out and auger into the hole.
 
The drill is being pulled in kind of like the flutes of the drill acting like a thread. It pulverizes its way through and most often you end up with an oversized hole and a ruined part. You can use a regular drill with a drill press or mill that has a ring collar for setting your depth on the quill. As you lower the quill by hand you slowly rotate the threaded depth collar to keep the quill and drill from being sucked down. Your just lowering your stop as you go and on a lathe lock the tailstock somewhat like stated to keep tension.
 
Thanks for the suggestions.
I seldom drill brass so will try no pilot next time before investing in some new bits.
 
I seldom drill brass & bronze as well so I chose not to have a dedicated set of drill bits modified for such.

Like WreckWreck recommended, on the lathe I keep slight on drag on the tailstock ram lock when needed & a firm grip on the handle. On the mill I won't use the quill handle for drilling like usual, I'll use the quill fine feed for drilling for better control as well as slight drag on the quill lock if needed.
 
I've found that drilling copper is much worse than drilling harder types of brass. Some copper will try to suck the drill right out of the chuck. I grind just a touch of negative on the cutting edge (just enough to dull it up a little) as others have suggested and the link from Ron shows the concept well. Then, when I need to cut steel or alloys, I just touch the cutting edge back up. No big deal...

YMMV,
Ted
 
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