Drilling clean holes in thin sheet

Drill a pilot hole and cut out with a coping saw? If the inside of the tank is not accessible, make a handle (duct tape?) for the blade so the free end is exposed. Orient the teeth so they cut on the pull stroke.

must the hole be round?

if not, drill a crappy hole with a trist drill and then tear the rest size with good needle nose pliers.

I've opened canned food with needle nose pliers, so I know they can cut such metal pretty nicely.

Another method I have used: drill a pilot hole and enlarge carefully to size with a dremel grinding bit.

Tim Wescott fired this volley in news:-bKdnZ0q6I92qxLSnZ2dnUVZ snipped-for-privacy@web-ster.com:

Tim, A "spur drill" comes to mind, but you don't have one. I might suggest another way, without buying another tool (just yet).

Shorten your step drill. Just grind off the offending length. They're not all that expensive, and you can keep the ground off version for future "shallow-by-wide" drilling projects.

Use a cut-off wheel, or go VERY slowly on a grinder, cooling frequently in water to avoid drawing the temper of the metal.

LLoyd

Lloyd

A 1/2" one-flute countersink may do the job well enough.

You could turn your own one-step drill bit from drill rod. Mill 1/4 to

1/2 off of it with an end mill to get a radial cutting edge. It might drill the can without hardening.

I made an emergency one to open up truck spring u-bolt holes from 1/2" to 5/8", so the kid could get his truck back together and out of my driveway. It was milled half-round and definitely did need to be hardened, twice to get it right.

jsw

Punch the hole with a hollow punch (HF has a set cheap) backed by hardwood. The slight bent edge will just help with soldering.

If it's one hole, I'd use a piece of 1/2 copper or other pipe, a circular dam of putty, and some abrasive, the way you'd drill one or a couple of holes in glass.

Water will work for a lubricant/retaining liquid.

Can you solder the fitting on first and then drill thru it? Art

Ragged hole a bit bigger and solder in a thicker piece with a good hole?

I'm flying electrics myself, would like a gas plane as an occasional luxury though.

Almost, but not quite.

It's a brass ring with 40TPI threads, about 0.4" inner diameter, to clear a clunk weight. (This is like, way gonzo from a model airplane standpoint. But the contest is THIS WEEKEND, and neither the weather nor my work schedule are going to allow test flights. So, I do something that may or may not work, and I may or may not have a spare plane on Saturday).

Drill a 1/2" hole in a brass plate. Solder this to the tank and drill thru it. Unsolder the brass plate and Bob's your uncle. Art

Thank you. I happened to have one, and it made a nice clean round hole

-- just like I wanted. My ass is saved -- for the moment.

It's one of those head-smackingly obvious things in hindsight, isn't it?

I've got all this "wet power" stuff lying around, and '08 through '10 were very bad news for me. So I can't quite swing the investment for the changeover.

But I'd like to -- I'd most certainly like to.

If you have a CNC mill or a rotary table, mill out a circle using a very small end mill.

i

Hey Tim,

i have not read "down" my list here, so maybe you have better suggestions already, but: Get somewthing, a flat washer perhaps, with a hole in it the size you want. Tape it to the tank so it is rigid temporarily. Poke a smallish hole in the tank, and then run a Dremel stone around and around until you are "tracing" the inside of the "washer".

Problen will be cleaning the "swarf" out the tank then.

Good luck. Let us know how you fare at the "contest"?

Brian Laws>I've got a little 3oz fuel tank (model airplane) made out of thin

Only after trying it. See what a multi-flute countersink does on a test piece.

jsw

Is the can curved, or do you have a flat place to drill the hole?

If there is no curve, and you can back up with some wood, I would suggest drilling with a brad point wood drill, which cuts through at the OD first (not counting the centering brad, of course). This will probably dull the bit, but it may be expendable.

If you have two of the Unibits, why not cut off the end of one so you can use the normal one to get up to as far as you can get before the tip touches the other side, and then use the shortened one to complete the hole.

If you could live with 9/32", something like my sheet metal punch pliers (Roper-Whitney No.5) might do. Hmm ... there is another size, the "Model XX", which can go up to 17/32" hole size -- almost all the way there.

Here is their web page, in case you are not familiar with these tools:

For that matter -- do you have the T-handled tapered reamer? It will go up to 1/2" (though it is rather long for your can) and I'm not sure how well it will work in something as thin as your workpiece.

Or -- do you have Greenlee radio chassis punches? They will work well for this, set the punch on the inside with the points set at the apex of the curve, and the die on the outside. You'll probably need about 3/4" to clear the thickness of the die between the ribs of the can.

Good Luck, DoN.

grind a twist drill like the picture in the below url. Test it on another piece of metal.....they work great on sheet metal.

John