Drilling problems with a 9a

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brandon428

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H-M Supporter - Silver Member
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Have a South Bend 9a that I mainly use for turning work from the headstock. I have no problem turning 1/16"+ steel per pass -- so plenty strong. However, I went to drill some holes in the end of a 3/4" rod to turn a piece on center, and I'm having a heck of a time getting holes that don't require a lot of force and end up breaking my bits. I have Keo's, so I'm not working with cheap bits.

If I put a dead center in my headstock and tailstock, and use a magnifying glass, they look in alignment. So even if I'm slightly out, it shouldn't be enough to cause any issues.

I've tried both using my Jacobs 14N chuck and countersunk collet holders. When I use the chuck, it moves slightly up and away when I hit the bar with the bit, but the collet stays steady. I can't get any play by hand. My tailstock does seem worn, but again, can't imagine that could be causing such a problem.

Any idea what could be going on?
 
how big a hole?
if you are drilling a large hole, are you pilot drilling it first.
the center of the bit really doesn't bite in.
What kind of material?
Stainless 304 is a ***** to drill if you work harden it. So if you are rubbing, you can forget about it.
 
I'm just talking about a #2 or #3 center drill. I have trouble getting up to the countersink.

12L14 and 1018 steel.
 
bad center drills? turning the wrong way?

those are easy metals to machine.. Hard to believe a 2 or 3 would give you that much of a problem.
is your rpm high enough? those little guys require speed to cut.
 
Exactly my thought on the metal.

I only have 6 speeds, so I'm limited to 680 RPM, though I've been drilling at 392 (middle in normal gear). You think that's fast enough?
 
Is your tailstock aligned? Or are the adjustment screws loose? Is your tailstock worn and below center? That's what I'd check first.
 
pineyfolks said:
Is your tailstock aligned? Or are the adjustment screws loose? Is your tailstock worn and below center? That's what I'd check first.
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It's aligned by eye with a magnifying glass as I said, but I'm having trouble drilling a hole for a test bar to get it any better. Unless you have suggestions for how I could check alignment without one.
 
brandon428 said:
Exactly my thought on the metal.

I only have 6 speeds, so I'm limited to 680 RPM, though I've been drilling at 392 (middle in normal gear). You think that's fast enough?
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That should be more than enough speed for a #2 or #3 center drill. That's about the top speed for my Seneca Falls lathe, and I use it for drilling all the time.
My bet is a dull drill. Use the same drill in the drill press or mill on a piece of flat stock to see how it performs there. If you get the same results you know it's the problem.

Are you facing the part in the lathe before trying to center drill it? If the surface isn't flat the drill will try to skate to the side. That will make the drill hard to start and eventually break it.

As an FYI my bench style drill press has 5 speeds. The lowest is 380 and the highest is 2250. I drill anything from 1/16" to 1/2" at the lowest speed and it always works fine.. For the bigger stuff I go to the floor model. It can go down to 60 rpm. It's supposed to be capable of drilling a 1 1/4" hole in mild steel, but I've never gone over 1"
 
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I agree on the dull bit, if you have a drill press or mill try the bit there.
my SB9 is 750.. but 650 is good enough.
I don't believe the facing, or off center is your issue. you said you are already getting a hole, just can't go deep.

BTW instead of visually seeing if the points line up, try a ruler between points. it will quickly tell you if it's off. My eyes just can't seem to get those points easily lined up... I find it hard.
 
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