Drilling Durbar plate

[Revs1972]

got a job next week that's going to involve drilling and tapping 10mm O/P Durbar plate. The holes will be 14 dia and tapped out for M16 bolts.
The plates have probably been down around 60 years , but look to be in good condition.
Anyone had experience of using a mag drill on the pattern side (no choice, it's got to be this side). Do they stick well ? , or would it be best to take a big chunk of plate to sit the drill on ? Plan on using HMT - TCT cutters to drill the holes , or are we better off using blacksmith drill type bits mounted in the mag drill . Will be using M16 HMT versatap in either the mag drill or impact driver to tap the holes

 

[rory1]

Mag drill will never stick to the tread side, use a piece of flat plate tacked, clamped or somehow fixed to the job.

 

[Revs1972]

Giving the boys a third option.
Drilled and tapped some 100 x 20 Flat bar that they can weld down to the flooring ( last resort ) . These are having M16 threaded bar screwed into them and puddle welded to the bottom. 14 dia TCT cutters make light work of drilling the flatbar and the tap takes seconds to cut.

Couple of plate girders they are working on for me