Drilling Deep Hole On Lathe

You can use a gun drill in a lathe. Use a boring bar holder on the tool post and hook up the coolant to the back end. Have to drill a pilot first, but doable. That small a hole leaves a little to the pucker factor, though! In the gun drill, I run .25 bit at about 3500 rpm and 1.5 fpm. Obviously can't do that in the lathe, but.....
 
Paul in OKC said:
You can use a gun drill in a lathe. Use a boring bar holder on the tool post and hook up the coolant to the back end. Have to drill a pilot first, but doable. That small a hole leaves a little to the pucker factor, though! In the gun drill, I run .25 bit at about 3500 rpm and 1.5 fpm. Obviously can't do that in the lathe, but.....
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What kind of coolant and pressure is required for proper operation?
 
Deerslayer said:
That's a great idea! Engage power feed and get er done! In all serious ness it's a great idea for most but I'm pretty tall and more comfortable at tail stock height.
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Please use caution with this! As somebody mentioned when I first posted on the mechanism, the lathe's power feed mechanism has some weak parts (possibly the rack and/or pinion), and you might be asking it to do more than it's capable of. The threading mechanism is probably more robust. But in either case, the drill bit can clog with chips before you're aware of it, and cause some real trouble. I've always used the feed handle, so that I could "feel" what's going on.
 
hman said:
Please use caution with this! As somebody mentioned when I first posted on the mechanism, the lathe's power feed mechanism has some weak parts (possibly the rack and/or pinion), and you might be asking it to do more than it's capable of. The threading mechanism is probably more robust. But in either case, the drill bit can clog with chips before you're aware of it, and cause some real trouble. I've always used the feed handle, so that I could "feel" what's going on.
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I was joking, all be it, it works for some however my power feed moves far to far per rev to be able to do this. I agree with wanting to feel the bit
 
The best source for information is to look up gun barrel drilling these holes are up to 60 inches long and come out within 2 thousands tro.
 
Deerslayer said:
Gun drill would be great if I had the coolant system for it!!
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I i worked in a shop that did a lot of gun drilling on a lathe, they has a set of chance gears to slow down the feed and used a general motors power steering pump for the fluid, i think we did 5000 parts for IBM. the most boreing job i've ever had. pun intended
 
Get used to slow drilling times from the tail stock in a manual lathe.

I made 2 parts yesterday, .749-.750" TGP 304 SS, the slowest feature is a .44" diameter X 12" deep hole on one end that I did in a CNC lathe manually from the tail stock. this took nearly 1 hour for each part using a typical HSS long twist drill. This is for a Company that makes high vacuum machinery used in research labs and semiconductor manufacturing.

I have no clue what this part does, the 12" deep hole has a 1/4 NPT entrance yet is not ported outside of this hole, I can only surmise that a hole is drilled in place once the part is in the assembly.

As a side note, (Rant On) I simply can not fathom why an engineer designing + $100.000.00 equipment controlled by computers would use a 150 year old thread design (NPT), I can not even begin to describe how much I loathe tapered pipe threads (Rant Off).

Happy Weekend
 
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