View Full Version : .250 Dia x 22.00 deep ??

09-02-2003, 01:12 PM
I have to put a .250 dia hole thru a part that's 22 inches long. I've heard hole poppers can do this, but haven't seen one.

Anyone done anything like this? Do you know where I can go to get it quoted??


'Rekd teh Long and Deep

09-02-2003, 01:40 PM

Can you gun drill it?

09-02-2003, 01:43 PM
Don't tell me you have to do this on a mill. You'll need a lot of Z to do it. :eek:

I've used a variety of peck drilling techniques to drill deep holes like that in lathe operations. It just takes patience. Undoubtedly, a gundrilling machine would be ideal, but the concentricity of the hole for the full length is never guaranteed. You might have to turn the od concentric after the hole is drilled.

09-02-2003, 01:47 PM
I've looked at hole popping, they don't get big enough. Looks like gun drilling will be the ticket. It's a manifold, so a mismatch at the intersection is ok. (Drilling from each end is ok'd on the print, along with mismatch)

I found another print with a .166 hole 15" deep, ********.


09-02-2003, 02:07 PM
Charge them for your trouble!

09-02-2003, 02:10 PM
So far it's a package deal, 10's of thousands of dollars. I was afraid these 2 items were going to take us past the dollar amount, but it doesn't seem it's going to. I just hate sending work out to other shops when we could do it in-house. We're under a tight schedule and it doesn't leave us much 'recovery' room.


09-02-2003, 03:08 PM
What is hole popping? Is that anything like using an armour piercing round? That would be hella fun to machine holes like that :D

09-02-2003, 03:10 PM
Yeah, but you gotta hit that sucker just right! :D

Hole popping is a method that uses EDM with (I believe) a turning spindle to shoot .012" holes 3" deep.


09-03-2003, 02:35 AM
I've heard about hole popping. The other day i had to drill a 5mm starthole 165mm deep through a piece of titanium. I was allowed 0.5mm runout. I managed to get it right! Took nearly 2 hours to drill that hole....
Yes gun drilling would be my choice.


Jim Estes
02-25-2005, 08:59 AM
I have had to do small water lines in large mold plates, and I don't have a gun drill. I figured out a better way to do it than on my mill. I mounted the plate on my lathe carriage, shimmed it up the the right heigth to drill the hole with the drill mounted in the lathe chuck. I took a long peice of drill rod and welded a drill to the end of it (this id the hard part). I drilled a 13 inch deep hole 0.343 diameter in about 20 minutes. Since then I don't bother doing deep holes any other way. I talked to a friend of mine who used to work at a large shop and he said they used to do large pieces that way all the time. I know this reply is a bit late but maybe someone else has a need for the information.


02-25-2005, 09:24 AM
Easiest way to weld the drill bit to the steel rod is friction welding.
Hold the drill bit in the lathe chuck with about 1/2" of the butt end sticking out, hold your steel rod in the tailstock chuck or if its really long hold in a toolholder keeping the overhang short.
The rod must be lined up with the drill.
Spin the lathe at 2000 RPM and crank the 2 pieces together with some decent force. The instant the joint between the 2 turns into a red molten ball stomp on the brake as hard as you can.
It is often a good idea to take a skim cut off of your new shank but more often-than-not for deepening a hole the runout is acceptable.
Ps. it will most likely be necessary to grind the pressure ridge down that is formed during the welding process.