Drilling copper

[russell]

Hi all,

Had a bad evening last night. I started drilling my boiler for riveting on the firebox extensions and and after eight holes in a strap and three in the boiler shell I had broken both of my 3/32 drills. I have just ordered some from England but have to wait a week or so for delivery.

Copper seems to be an awful material to drill small holes in. It is soft but the swarf coming off is work hardened and it grabs the drill which then breaks. I have read that you must not use any lubricant when machining boilers as it can contaminate the surface and make silver soldering difficult. Is this true?

Any suggestions to save my new drills when they arrive?

Regards,
Russell.

[ron]

Hi Russell
Not really sure why you're having a problem, I drilled mine dry with a cheap 3/32" drill in the B & D without problems, the copper does tend to pull the drill through, the only thing I can suggest is try doing it with a hand drill to see if it helps. The best lubricant I've found for copper is neat washing up liquid which I can't see causing a problem, certainly it hasn't caused me any so far in my short career as a coppersmith!
Ron

[havoc]

What is wrong with using a 2.4mm drill? As you are in France, that should be easier to find than 3/32" and the 0.02mm difference...

[russell]

Can't find 2.4 mm here. Nearest is 2.5 which is a bit loose with a 3/32 rivet.

I'll try washing up liquid Ron. I can't see that being a problem as it is used when mixing flux.

Thanks,
Russell.

[ron]

Hi Russell
If it's a bit loose it isn't all that important, just bash the rivet and the silver solder will fill it up. I don't really think you need a lubricant, try using less pressure when you're drilling and try and avoid letting the bit getting pulled in.
Ron

[brozier]

Hiya,

I bought a pack of 20 of 2mm drills for not much - I pilot drill all the 3/32" rivet holes with these (broke a few!) and then follow up with the 3/32 drill which I haven't broken so far.

This was drilling steel but I guess the you'll get the same results with copper.

I'd of thought one of the big French DIY sheds (LeRoy Merlin etc) would do packs of 2mm drills it's a size that is easy to break

Cheers
Bryan

[Nexuas]

Having an over sized hole in boiler making is a good thing, as it gives somewhere for the solder to go. I would suggest that all side stays should be a rattle fit rather than tight, as the solder will flow and penetrate rather than just covering the surface.

[circlip]

If you haven't already drilled them russell, when your new drills arrive, cut one or two down and regrind so that there is only about 5mm of twist left, in effect making them into "stub" type drills. It's the length of flute that allows them to whip when drilling thin plates. If you're contemplating a lot of riveting you could keep a set of rivet size specials. Regards Ian.

[russell]

My drill grinding jig only goes down to about 1/8 in. I'll have a go freehand but my eyesight isn't what it once was. Isn't the fact that the web is thicker near the end of the flutes a problem?

A couple of drills arrived in the post today so I will see if I can break those tomorrow!

Russell.