Long Hole Drilling?

[madman]

Heres a tuff one for me at least. 32 inch long stainless Steel 303 material with a inside hole through .360 diameter right through the center. ? Outside Diameter is 1.5 inches. I am stumped how to do this right. Rerhaps centre drill, drill end mill opart way with the same dia e mill as the drill? Weld extension ??? Or? Any tips guys?? Thanx

[tattoomike68]

Weld extension ???

Thats the only way I could do it, they do sell long drills. thats 90+ diameters deep, a deep damn hole. 303 is good stuff and machines nice , 304 would be a real pain.

A turret lathe where you can rapid traverse out of the hole would help and high pressure coolent like 100 psi would help.

I have done 1/8" grease holes 14" deep in 4140 but it did not have to be perfect in the center all the way, just pass grease.

maybe our gunsmith type machinist would have the best advice, they do stuff like that all the time.

[Jim Caudill]

Unless it is a real "non-precision" hole, this is one that I would "sub out" to a gun driller. From my area, I think there are shops in the Akron-Canton area of Ohio that would do this for a reasonable fee. The right shop can do this with their eyes closed and one arm behind their back. For you and I, this could be a real "ball buster".

[tattoomike68]

Unless it is a real "non-precision" hole, this is one that I would "sub out" to a gun driller. From my area, I think there are shops in the Akron-Canton area of Ohio that would do this for a reasonable fee. The right shop can do this with their eyes closed and one arm behind their back. For you and I, this could be a real "ball buster".

Amen, dont kill yourself doing what others do with ease.

[pcarpenter]

One of the other problems that rifle barrel makers deal with is stresses. They can do funny things to a long hole like that if you cut the steel later. More often than not, these holes are not perfectly concentric or even have some curvature to them for that matter...even in a rifle barrel. The key is that the barrel not change shape after the fact or suffer from lots of stresses or the curvature will change as it warms up. Rifle barrels are usually stress relieved before deep hole drilling if I recall correctly. A barrel maker could handle both for you.

Paul