Deep drilling with thin drill bit in 4140 on Lathe

[Lplates]

Hey Guys,
As the post says, I need to drill 10 parts, with a 1.6mm drill bit, to a depth of (ideally) 10 mm.
Is an ejection punch hole that meets another reamed hole on the other side.
AAAaaannnddd snappy snap snap snap. Usually right at about 5-8mm.
Feeds and speeds seem ok, the lathe tailstock is perfectly aligned, I need some old timer wisdom to help me survive this. I'm loosing my mind.
I realise a bunch of people are going to say "This isn't hard." But man I'm bashing my head against the wall.
Am I retracting too often, should I peck drill it... ughg.
Carbide seems to be going a lot better and HSS seems to be garbage. Any hints or tips speak now! Yes it has to be 4140
Thanks
LPlates

 

[Scruffy887]

6 to 8 x D? 10 parts? And breaking at 3-4 x D? Sounds like a bit of chip sensitivity. I have (and would use) a sensitive drill adaptor with a drill that small, and only 10 parts is not a big deal. Not so easy to feel drill pressure with tailstock drilling with that size drill.

 

[MaxPrairie]

Here you go.

https://youtu.be/PqU5wS0J4MU

 

[Mtndew]

If you're doing this on a lathe then you most likely can't get the rpm's needed to do it properly.
I suggest tiny pecks with full retract to get the chips out and flood the hell out of it.
Spin it as fast as you can, but feed it on the slower side.
4140 is gravy, your problem is the depth. Do you have thru coolant available?

 

[MaxPrairie]

If you're doing this on a lathe then you most likely can't get the rpm's needed to do it properly.
I suggest tiny pecks with full retract to get the chips out and flood the hell out of it.
Spin it as fast as you can, but feed it on the slower side.
4140 is gravy, your problem is the depth. Do you have thru coolant available?

Sounds to me like he is doing this on a manual lathe. I think if he watched the video I posted his stress will float away. I don't see this a being too difficult however. I have drilled holes half the diameter and double the depth before with no issues. Drill was an ATOM 0.029 and worked great. 5 thou pecks at 0.0004 feed per rev I believe. Somewhere in there, it was 6 years ago but I know material was 17-4 H900.

 

[Lplates]

Here you go.

https://youtu.be/PqU5wS0J4MU

Thank you so much, worked so well I made another slightly bigger one too! Cheers!

 

[dgfoster]

Did you end up using carbide or HSS bits. I had a job drilling a bunch of .017 holes 5/8” into steel a few years ago. I used a sensitive drill chuck, continuous air/lube blast on the bit, pecked as fast as I could and found HSS performed much better than carbide. Like any spiral drill, the chip curled out nicely with continuous feed until I was 5 diameters deep. If I didn’t start pecking at that point, the flutes loaded, friction welded, and snap. No issues though with tap, tap, tap fast pecking. I started out trying, without success, with a standard small fixed chuck in the tail stock. No way…

Had I been aware of the simple adaptor shown in the above excellent video, I would not have bought a sensitive chuck, though it is convenient.

Denis

 

[howieranger]

Just an FYI even Amazon lists a sensitive drill adapter with chuck for $42 (I have no idea of the quality) or $400.00+ from MSC