drilling in copper????

T

Terry_Dodson

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Jul 10, 2002
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I was trying to drill a 1/16" hole thru a piece of copper that is 1/4" thick by 1" wide. I am trying to drill the hole on the 1/4" side and go about 3/4" thru for a pin to go thru the tang. The botton of the 1/4" side is flat and the piece is square, i am setting the flat 1/4" end on the flat table of my drill press (cheap $39 from Harbor Freight). i am using 1/16" cobalt bits. I got the hole started and about 3/16" deep when my first bit broke. OK i said i still have another, and this is only copper, so i put in my 2nd bit and started. It got about 1/16" deeper, then it broke. OK i said, i must be applying too much pressure, so i put in my last 1/16" bit and started again. and it broke. Is there a trick to drilling pin holes in copper or is it because i am tring to drill 3/4" deep? Is there a better bit than cobalt for copper?
 
are you using any sort of lubricant?

Copper is soft but very tough. Because it is soft it builds up very easily on a cutting tool and siezes up and goodbye drill bit. Cobalt bits are good Terry but you need a lubricant, any oil will do and keep the rpm on the low side, lower than you would use on steel. The bit has got to be sharp too. If you do not have oil try some dish washing liquid.
Hope this helps.

Mike
 
OK, thanks, I will try tommorrow after i get some new bits, i do have some some cutting fluid but didn't think i would need it on copper.
 
Another thing, drill in short bursts, do not keep a constant pressure, drill a bit and then withdraw the bit to break the twirly shaving, and make sure the lubricant gets into the hole. It siezes on the sides of the bit too. Take your time and be careful when you break through the bottom too, let up on the pressure.

Mike
 
Lots of non-ferrous metals like copper, sterling silver, and gold like to get gummy and break drill bits. They also get hot very quickly. Just use the advice from the abore mentioned responses.
 
A little trick I was taught by a machinest is:

If ya dont have any cutting fluid just cover the drill bit with some crisco and you can put some on the piece you are drilling.

This works great and isnt as messy as fluids,works great when milling things like aluminum and other non ferrous metals..

Just had to add my 2 cents.
Bruce
 
Hmm, the smell of heated crisco should be less offensive than the smell of heated oil too......:D
 
The other thing to watch out for is that copper will work harden while drilling...I have drilled holes and then went to cut a slot for a guard with a jewlers saw....you can sure tell where the copper got hard from drilling.
If thats the case just heat it with a torch to cherry red and then quench in water.
Mace
 
did you buy your drill bits at harbor fright also? good drill bits are a must...
 
I have to add here that a standard factory sharpened drill is the WRONG GRIND for copper-brass-bronze etc. A sharp drill will want to grap and suck the drill bit down into the material - abruptly ! Completely grind a FLAT yes I said a FLAT on the drilling face of the drill. It is hard to put in words but flatten the cutting edge of the drill bit and it will drill much better for you . If the drill sounds like it is scraping & chattering then you probably adjusted the grind correctly. Trust me on this one and you wont break any more drills in brass-bronze-copper materials.When you break thru it wont want to suck the handle out of your hands or launch the vice the part is in either or make a swelled out ring around the drilled hole btm.
 
Thanks guys.

Bruce that sounds like something i will try ( i already quench in veggie oil) :D , do you have to reapply the crisco while drilling (i am drilling down about 3/4").

David is that making it kinda like an end cutter mill bit? How far up the pointy part do the drill bit needs to be flattened?

Iky, yes i got 2 of the bits from harbor freight and one from lowes. I have drilled hardened steel with the cobalt bits from harbor freight before just fine. But got one from Lowes just in case. These would just all of a sudden break, probably because i was drilling dry, never thought about using the cutting fluid on the copper.
 
David, I have to disagree about the flat on the cutting edge.
You normally do this only for free cutting brass.
You will rub and clog like crazy if you do that with copper.:confused:

I stick to my guns on this one. Sharp drill bit with plenty of cutting oil.

Anyway, you be the judge Terry. Good luck. Let us know how it pans out.:D
 
Terry,I just touch the cutting edge on the grinding wheel (usually on the sideof the wheel) and just put a small flat (maybe .020-.030) wide on the cutting edge.Nothing drastic .Miden,I'm just going from my experience here.Quite a few years back I worked in a small mold shop(one of many) and we would periodically get a job in (10-20 at a time) that was 660 Bronze.They were called "rockers" the piece ended up to be about .625 x 1.25 x .75. It was a very "fussy" job that almost everyone hated to do-guess who always got it.660 is , I think , over 80 % copper , but in my opinion not a "gummy" material.You could get a pretty nice crisp chip.It would suck a toolgrinder sharpened tool right out of your hands if you weren't careful.The job also had (2) .312 reamed holes in it that I learned how to grind the drill on to successfully get through without any trouble.The grind technique I told Terry about is just my personal experience.I don't claim to know everything about machining-- in fact I don't think guys in the Mold Making/Machining trade ever stop learning.I am adamant about being able to accept "constructive criticism" & welcome it.Terry,I will try to post a pic to show some detail on the grind in the next hour or so.Miden,I will accept your method and put it in my notes.I have been writing down formulas,notes,speeds&feeds etc. for 26 yrs.,and your tips are appreciated & documented-Thanks and I'll try your way again.Please don't take this the wrong way as we are all learning-always!!
 
David, I have spent about the same amount of time in tool and die shops.
This is not said as a challenge or "so there". Yes, I agree, we never stop learning, I am in polymer extrusion now and there certainly is not a day that goes by in which I do not learn something, sometimes from unlikely people.

If you say you did this with the drills and it worked then I believe you unconditionally, after all, you have the first hand experience and we both know all those books and charts are but guidelines.
I have only found this to work on "free cutting" brass and bronze though, otherwise it certainly rips the drill in.

The average brass contains about 60% copper and 40% zinc. "Free cutting" brass has some lead thrown in too, at the expense of some of the zinc, I think. Much easier to machine but you have to watch it, as you know.
I have worked a bit with straight copper too and have found it necessary to have sharp tools and plenty of oil or it packs onto even an end mill or a lathe tool with nasty consequences.
I too have an open mind sir, few things are more offensive than wise-ass "my way is the only good way" types which we encounter far too often in the engineering world.
As for getting the lousy jobs..I seem to land them too but I am sure you will agree, we are the guys that learn.
Now if I can just get that darned grind at the ricasso right....
Nice talking to you and I have noted your info too.:thumbup:

Uh, you still there Terry?:D

Sorry we kinda hijacked your thread but as long as we all learn.....and it is pertaining to knifemaking.....
Hope you get your holes drilled okay.

Mike
 
Miden,I think we will get along just fine as we share the same philosophy when it comes to learning & keeping the mind open to learning.My way or the highway--I usually go the highway route:D Terry,here is a POOR pic of a drill I just touched up so you can see what I'm talking about.Like miden said,make sure you use the "peck" method to evacuate chips & heat. Coolant is also a good idea or air to evac chips too.The grind on the drill bit is actually just a small land,after looking at it I would say more like .010-.020 wide.Just enough to take the "grabby sharp edge off.Try it ,it may work good for you.I not positive but I wouldn't be a bit suprised to see Higgy chime in hear with his support or antipathy for my method.Anyway here is the pic-good luck to you.Please let us know the outcome.Like I said if it sounds horrible and like it is scraping , you probably did my version of the recommended grind correctly.:)

BTW, If it is hard to see,it is the shiney silver land on the drill tip.Of course grind both cutting edges.
 
Hi and thanks for the different techniques to try. :D I saw no hijacking, this thread was about ways to dirll in copper. One thing i do think i need to mention is that when i was drilling it dry, i would not get chips, i got 2 long threads of copper going all the way up the grooves of the drill bit. I did just get back with some more drill bits and will try later tonight, might even try a couple of ways since i now have a piece of copper to test with since the last cobalt bit broke off square at the top of the hole. Know anyways to get that out, since i cant drill thru it?
 
Depends how badly it is stuck in the copper, it is probably siezed up.

Looks like you may have to mark it down to experience Terry.

I posted one earlier but then I realized that you could not go through so it was not much good.
Hence the edit.

Mike
 
I just tried the flat tipped drill bit thing David talked about and using crisco like Bruce said. All i can say is wow that drilled much easier that dry drilling. :D I drilled 3/4" in no time, going a bit pulling it out to clean it and i put a little more crisco on the bit a couple times.

Miden, yep i am chucking this one up to experience, even after i drilled the 3/4" hole thru the side and drilled my mole for the tang i noticed i missed center of the bigger hole, so much for eye-balling it. But at least i have a cople more pieces of that copper so it was a good learning experience. I guess i could drill all the way thru but i figured once i stick the pin in and glue up the handle i didnt ever want to have to take it apart. Do you think i should drill all the way thru just in case?
 
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