Instructables

How to drill holes in thin steel?

To save me going through the trial and error stage (I can only eat so many Altoids), what is the best way to drill a matrix of neat 5mm holes in the lid of an Altoids tin? Centres will be 12.5mm (1/2") so reasonable gap between. How do you clamp and support the tin without bending it? What drill speed do you use? Centre-punch first? Drill pilot holes? Drill from the inside or outside? I have a bench drill and usual workshop stuff available.

Answer for your queries Clamping and support is tricky for these slightly curved surfaces Drill speed is a function of diameter. Slow always works, though patience is required in small drills ! I wouldn't try and drill a tin can at high speed with a big drill. I'd use a VERY small drill and drill through a piece of perfboard taped onto the part with double sided, then I'd open them up with your 5mm drill. For sheet material like this, I suggest you use a step drill, rather than a twist bit, but if you HAVE to use a twist bit, I'd regrind the cutting edge to bite less aggresively . WIth the perfboard method, You have the benefit of a beautifully regular matrix this way too. Drill from the outside in, then your main burrs are inside, and you should get pretty crisp edges outside. In the past, we've cast wax into the inside of thin shells, to give some backup to the drill, but for 5mm you don't really need to. If you hold the job by hand, drill SLOWLY and at LOW SPEED. I shouldn't advocate this, but if you ARE holding it by hand (and I don't recommend you do :-) ) hold it like you mean it - and be prepared to let go fast. Steve
AndyGadget (author)  steveastrouk5 years ago
Many thanks Steve - The perfboard to get the centres is a brilliant idea. I'd never heard of a step drill bit and now have a set on order as I'm sure they'll be used for a lot of other projects.
(Sorry CM - not this time ;¬)
Dremel high speed Mototool with thin cutting wheel: Square corners obtained instantly in thin metal. I just cut some pretty thick stainless steel with mine. After sawing and eating a Sawsall hacksaw blade in about 5 minutes... So hot teeth its were red, then went away.
AndyGadget (author)  dacarls5 years ago
Ta - I hadn't thought of that. I'll have a go at that.
HTH Only "problem" is a limited depth of cut usually <4mm for any given hole diameter, and I've found they REALLY like a pilot hole, but otherwise step drills are perfect on sheet metal. Steve
AndyGadget (author)  steveastrouk5 years ago
Hi Steve. Step drill arrived today and 3 x 4 matrix drilled - Absolutely BRILLIANT result! The step drill has just been added to my list of 'Things I Never Knew I Needed Until I Got One and Now I Can't Do Without It'.
You'll get full credit for this technique in my next Instructable - Keep an eye out for 'Close Encounters of the Minty Kind'.
Why not post an Instructable on the hole drilling technique? If you don't, I probably will.
Hi Andy, What a good idea. Let me write my first instructable then ! Glad it worked for you. Careful with the speed, and apply a bit of oil and you'll get great tool life. Steve
AndyGadget (author)  steveastrouk5 years ago
I drilled a 1.5mm pilot, then went through with the step bit to 6mm (I couldn't find a 5mm) using slowest drill speed and very light pressure. I didn't think of oiling it. Thinking back to my metalwork lessons, I suppose I should have.

Once I'd done, I went very carefully from the other side using the 8mm step to remove the burr.
Result : Perfectly aligned holes - clean on both sides - no distortion of the lid.
Deburring at low speed is a VERY good idea - I've screwed some parts up by being a bit too fast. For 6mm I'd probably run at around 500 RPM. Steve
AndyGadget (author)  steveastrouk5 years ago
650 is the slowest I can go but it worked OK. My bench drill does 650 to 2600 in 5 steps. Now we've covered circles, how would you go about cutting clean rectangles in an Altoids lid to fit 7 segment displays etc.? Is there some sort of small, hand pressure operated guillotine punch available? (I've googled around and found electric nibblers and square hole drill-bits, but nothing really small and neat.)
Weelllll. You can get hand operated nibblers which can be quite good, but you aren't going to avoid some file work I'm afraid, whatever you do. Qmax punches are available for some squares and rectangles, but they will struggle with very thin sheet. Here at work, I have a press mounted nibbler for larger holes. The best way by hand is to mark the rectangle, then carefully dot punch along the lines, then cut the rough outline, and file to the marks. You need an eyeglass, but look at the punch marks: when you see half a punch mark, you have hit the line. I suppose you want an instructable for that too ;-) HTH Steve
to stop the tin from bending you could shape a piece of wood so it fits perferctly inside the tin so when you go through the tin you will just drill into the wood!!!
Dremel high speed Mototool with thin cutting wheel: Square corners obtained instantly in thin metal. I just cut some pretty thick stainless steel with mine. After sawing and eating a Sawsall hacksaw blade in about 5 minutes... So hot teeth its were red, then went away.
sharlston5 years ago
you could put something inside the tin like a block of wood then drill through the tin and the wood to keep it from bending