Drilling holes in thin material

Just been watching this video by Mark Presling where he shows an interesting trick for drilling thin sheet material. Can't wait to try it out!

Rob

Links to https://www.youtube.com/watch?v=cAGiuXOKKi8

That’s what the old boys used to do with a countersink bit to stop the chatter marks.

A good old trick.

Another trick I have found if you want to open up a hole a tiny amount in even very thin sheet - get an old adjustable reamer and turn all of the cutting flutes around so they form a very shallow taper instead of parallel. It works great, cuts smooth and you get a very round hole of very precise size (if you're careful). You do get slightly tapered sides to the hole but nothing you could measure on thin sheet.

Was shown that in the early 50's at Tech College

Roy

Good link Rob

H

Even with the cloth I would not hold the sheet metal with my hands as shown in the video. You only get one pair of hands and it's better not to rip them to shreds on a drilling machine.

Doug

The traditional material to use for this was a couple of folded pages from the Daily Mirror.

It was mainly used to stop the chatter when trying to open out a hole with a larger drill or with a countersink as posted above.

Good trick. Also, if you are doing a lot of sheetie work, you can sharpen your drill bit as below. These days I just use a step drill for the thin stuff.

Plus 1 for the step drill which will also deburr/chamfer the edges of the hole.

Edited By ega on 24/04/2022 00:05:59

Hello to you all.

just watched that video...I would not recommend that way at all...that’s a surefire way of loosing a finger or life changing cut to hand....what an idiot for putting that online.

when I worked in engineering...the way to drill the sheet metal on a bench drill was to have a bit of plywood and clamp workpiece to it... then drill hole . Safely!

this worked on bench drills ...jig borer tables....even lathe faceplates ...for thin disks.

the good idea was when you had drill through metal..you had wood so you knew when you had drilled through...just deburred afterwards.

Edited By Steve Purkiss on 24/04/2022 08:30:33

Yes indeed. The sheet metal drill illustrated above works best when the sheet metal is on a layer of wood underneath it. The point goes through into the wood and holds the drill centred, then the points more or less trepan the OD of the hole until they break through into the wood.

Yes it’s old hat that video, but not if you havnt had the tip. It works!

but why

does it take such a long video?

the wood block is clamped down, why not clamp the work at the same time? He says don’t hold the piece, then goes and does it!

He's an old guy pottering around in his shed, not a videographer. Tis the nature of much of YouChoob.

I have some special sheet metal drills designed to drill unsupported sheet alloy such as aircraft skins. They drill a perfectly round hole because there is no relief on the outside like normal twist drills which tend to leave triangular lobed holes.

If possible for flat sheets, the sandwich method is best to reduce distortion.

He's a retired teacher, so explains what he's going to do and why, then demonstrates it and finishes with another explanation. Just like any competent trainer, and not the self indulgent Youtubers who don't know when to shut up

I watched his excellent video at 1.25 normal speed.