Drilling .201 hole 6 inches deep

[mike561h]

I am going to have topeck drill on the mill. TIR is .002 from center. No cnc Lathe

 

Can anyone recommend some good drills for drilling 17-4. I could drill under size and ream.

Starting the hole in is fine, coming out the other end is the problem. I can't chance meeting in the middle and having a step.

[Columbo™]

Try Guhring

 

They got the length and I believe they will cut 17-4

 

Good luck

[?Mark]

Gun drill would be a good option here.

Which 17-4 is it? If it's annealed than gun drill is probably your only option. You just CAN'T break a chip in this material

BTW, we work with it everyday, but nothing that deep.

[mike561h]

Thanks

[Tim Johnson]

Holding that TIR on that length with any kind of drill is going to be a major chore. You might be better off drilling it undersized and wiring it to size.

[Kevangel]

Can you gundrill it and then turn od on a mandrel sort of thing for .002 TIR? (put plugs with centers in each end and turn)

[Kevangel]

forgot...stepped plugs

[ToolMan184]

Im with Tim on this one. I would wire EDM those holes.

[mike561h]

I agree it would be tough to hold tolerance.

I'll give wire EDM a try. At least I can blame it on the wire guy.

[Colin Gilchrist]

.002 TIR? 6" deep...

 

EDM for sure...

[RobertELee]

Yup, hole-pop then wire for sure!

[Josh T™]

Hole popper would be my guess. Our Current will hold that location pretty well. Maybe Wire EDM if you're really worried about size.

 

You may want to check with your customer before going with an EDM process. You are cutting 17-4 and if this is an aerospace or medical application part some customers will not allow the recast surface or commonly know as the "White Layer". We have been back and forth with our materials lab on this issue several times.

 

HTH

Josh