MAG Drills - How Precise ?

[Erie Fred]

Thread resurrection.
I am trying to see if a mag drill is available that can straddle a raised welded seam (for example).

Might sound a bit far fetched but a few times recently a hole has needed to be filled with weld. Drilled and finally tapped.
The holes are often in a fixed machine and a SDS drill with cobalt drills is not touching some welded up.holes.

A mag drill was used but a welded seam tipped it so it did not cut square. A shim was used to complete one hole but the others were just not able to be hit centrally and perpendicular with a standard mag drill..

How are you going to tap the hole ?
If it's that hard you need a carbide tipped annular cutter or drill, I've yet to see the same in a tap.

 

[ukracer]

How are you going to tap the hole ?
If it's that hard you need a carbide tipped annular cutter or drill, I've yet to see the same in a tap.

I don't know to be honest.
It's a learning experience in which he needs to learn the best way to.approach a repair.

It's the inconsistency he is trying to get his head round.