Aligning 1/2" pre-drilled holes in 3/16th steel sheets

[Troll Hunter]

As in the title.  My holes don't quite line up between the two sheets, and the shapes of the components don't allow me to force them into alignment.  It looks as if I have to extend one layer of holes at least a 1/4"  into oblong slots.  So, what is the easiest way to do this, please?  I have available a number of power tools - drills, oscillating saws, reciprocating saws, angle grinders and a pneumatic impact chisel/hammer.  I have a MIG welder, but no gas burning facility.  I also have a number or round section manual files and a hacksaw.  That's about the limit of my workshop!  

Can any of these be used to reduce the hard grind, literally, of filing by hand to extend nominally round drilled holes into oblong holes?  Are there any specialised bits that can be used in any of my tools? 

Any advice will be gratefully accepted.

Mike

[miketomcat]

Rotary bur in a die grinder or drill works well but you need to keep a good hold as they can wander.

Mike

[Bowie69]

Honestly a round file will get that done quite quickly if it is sharp.

That is, unless you have 100 holes to deal with! 😉

[Stellaghost]

Both of the above will work, but if you have multiple holes to do you could knock up a small jig with a reasonably thick piece of steel /box with a hole drilled in the size you need, then place jig over hole in a position you need to drill and clamp jig this will then hold the drill piece in position to drill a partial hole next to where you need to extend if that makes sense regards Stephen

[Dr Strangeglove]

Depends on how many holes, but you could try running through with smaller drills and work your way up. Then just use a decent washer. If you use 1mm increments, you are less likely to have the drill snatch on you.

[simonr]

8 hours ago, Bowie69 said:

Honestly a round file will get that done quite quickly if it is sharp.

That is, unless you have 100 holes to deal with! 😉

It's a bit gash - but I one adapted a round file to fit in a Jig-Saw.  Worked brilliantly.

I have a die grinder too - but it's almost impossible to steer in the direction you want.

[landroversforever]

I don't like die grinders for this kind of thing as seemingly how careful you are they snag and send themselves round the once smooth hole turning it into some kind of inside out rasp. Nice sharp round/half round file it my go to unless there are more than 10 holes.

I have managed to slot holes with a step drill before... but only works with a decent and sharp one as they can also wander like a die grinder.

[Troll Hunter]

Many thanks, all, for your thoughts and suggestions, but being a lazy git, I like miketomcat's the best:

On 9/8/2021 at 11:02 PM, miketomcat said:

Rotary bur in a die grinder or drill works well but you need to keep a good hold as they can wander.

Mike

I can put my bench mounted pillar drill on the concrete floor of the shop and position the clamped steel components - about 80 lbs -  beneath the drill with a rotary burr fitted.  This should prevent the burr from wandering and keep the holes aligned.  Tomorrow's project, and I'll report back.

I'll also invest in a new round file, or two, just in case the rotary burr doesn't cut the mustard!

Mike

[landroversforever]

Key with minimising the risk of them snagging is not taking too much of a cut.

[steve b]

If the burr doesn't work you could use a 1/2" slot drill milling cutter .

...or one of these ...

Steve

[simonr]

These days, however, I just use a Mag Drill.  It will hold a drill (slot drill, end mill, broach cutter, die) exactly in place.  They are a bit spendy - but you can hire one.

Si

[Stellaghost]

9 minutes ago, simonr said:

These days, however, I just use a Mag Drill.  It will hold a drill (slot drill, end mill, broach cutter, die) exactly in place.  They are a bit spendy - but you can hire one.

Si

Excellent for what needs to be done unfortunately not many have them but you could hire right enough regards Stephen

[FridgeFreezer]

A variation on mike's suggestion is a small rotary burr in a dremel - they work very well but do make excellent tiny incredibly sharp swarf that sticks in you.