I guess it is not structural and by the time it is in use, any feint marks will be covered by paint.  You could drill out, very lightly countersink both sides and peen a plug in place (Brass if you like). Then gently heat and apply soft solder (Just to make sure it won’t turn during drilling) clean up and drill 6Ba clearance.

If it were structural, start afresh.

Bob

I have Rotabroach mini cutters down to 6mm and they would be my choice for cutting over the holes to plug the plate. They are good where there is a risk of existing holes deflecting the cutter and far stiffer than a small diameter cutter as they are mounted on a Ø13mm shank. They are designed for making holes in sheet metal up to 6mm thick. You could probably make your own shank to mount one on but even the smallest ones are not cheap. It depends on how much time you have invested into this part and the risk of further problems if a drill or milling cutter wanders.

Martin C

On 22 September 2025 at 16:45 bernard towers Said:

Ill go with Jason on that one

Yes.

Make some big washers and use them to cover up the slots. Unless you need to use the holes for positioning. No one will know!!!

Chris Gunn

On 22 September 2025 at 21:33 Clive Foster Said:

 

In practice, as it’s steel, if I needed a quick fix I’d hit it with the welder. MiG or Stick depending on what I felt like

Clive

Me too, if you have a welder?

Or tap and plug with steel and a dab of 603 as I have some.

With ateel then as we used to say:

”Measure twice, cut once, weld to fit”

That said I think it probably fits into the “do over” category. It’s not large, and the shape is simple. I bet that a new one will take the same time as faffing about to fix the old one, and the end result will be better.

Dave

Drill larger, put in a tight threaded plug with a dab of loctite retainer, re-drill on the correct centre.

Or Silver solder in the plug, then re-drill….

Further to Jasons point about drill wander if using a filler where there is still some overlap between metal and the filled hole.

Realistically it’s best to use an oversize hole so you are only drilling filler.

If overlap is the only way you need a good starter mark and some sort of drill guide.

For the starter mark something better than a pop mark is pretty much essential. For baby stuff I used to like a no 0 centre drill but you have to be very careful of the 1/32″ diameter point. A no 1 is way better but sometimes the 1/8″ point is too big. Nowadays I’ve gone all modern and invested in a couple of spotting drills. Even stiffer than centre drill and much less vulnerable.

Frankly for a job like that I’d not only knock up a bending former but also arrange some form of guide plate for the drill. That sort of narrow flange bend is often not dead flat despite the main shape following the correct bend angle.  The slightly not flat portions are very effective at dragging a small drill off line. Showing it a milling cutter to make the surface flat is always a good idea.

When working on narrow flanges it can be quite difficult to mark hole positions out correctly. I have gear to make it easy but the price performance ratio of mine is such as to be inappropriate for the shopping list until a workshop is well established.

Back in the day making things like ruler holders, scribing blocks et al followed by “finding a nice piece of flat plate glass” to run them on were considered essential ab initio projects for folk just getting started so they could do the necessary marking out.

To be honest in this day and age going direct to a mill fitted with a decent DRO for drilling rather than setting up for traditional making out is probably a better way. Given a bit of thought and engineers low cunning a drill guide can be made in a manner that makes marking out far easier than trying to work direct on the flange.

Those apparently trivial little components can take much more making than it appears at first sight.

Clive