Drilling Deep

[ALLtra Mach]

Hey guys.
Need some suggestions on tooling.
I am drilling 5/8 and 3/4 holes in 1/2" A36, then move down thru that hole and drill thru another plate 5" below it. These are weldments, so the plates aren't straight and the drills want to walk.
Does anybody have a good tool for doing this that will keep holes aligned?
I don't want to index the part.
Heres a model.

[laka]

If you could find some long center drills to center drill the bottom holes after the first holes are drilled. And just get a couple long-series HSS drills. That's what I would do anyway.

[fuzzyracing1967]

A eazy way to fix it is to incorparate drill bushings into your fixturing, if you are using a fixture that is . Just a thought.

[ZipSnipe]

Sure , flip it over!

[ALLtra Mach]

If you could find some long center drills to center drill the bottom holes after the first holes are drilled. And just get a couple long-series HSS drills. That's what I would do anyway.

Thats what I am doing now, problem is at that length, with a skewed part, even center drill will walk some, which causes drill to lead off.


And Yes, we are using a fixture, but drill bushings wont help that far above surface.

And if you read my post, I don't want to index the part.

[307startup]

I'm thinking some kind of core-drill or one of those insert-drills used for hogging on a lathe

[neilw20]

I recently was drilling 3/4" holes 36" deep at 1 1/4" IPM with no problems, but your application can't use this technology, but your jig could have a second hardened drill guide just above the second hole.

[ALLtra Mach]

I recently was drilling 3/4" holes 36" deep at 1 1/4" IPM with no problems, but your application can't use this technology, but your jig could have a second hardened drill guide just above the second hole.

Now there's an Idea!
36" deep...sonabgun!!
Lol, That would fall under "can't get there from here!"

[RICHARD ZASTROW]

Neil's method (second drill bushing) will work if it can be included in the fixture. Also, his 3/4" dia. hole 36" deep is entirely possible. I've done .625" dia. hole 28" deep without a gundrill as well. Old farts tricks. lol

Dick Z