Problems drilling my copper busbar

[sduser]

I finally pickup some material (1/8" cork gasket material) to place between my cells for padding and built my battery today. I cut the busbar and rounded the edges with an angle grinder, but am having a hard time drilling the holes. I have broken 3 drill bits so far, and two of the broken bits I am unable to extract from the bar. I am using a battery powered hand drill.

The bar is C110 copper (I believe) and is 1/8" x 3/4".

How is everyone drilling their homemade copper busbar?

Another question, what is the best way to extract the broken bits? Should I scrap the piece and start over?

Thanks all.

 

[Supervstech]

Copper bar is breaking bits? Odd.. copper is very soft. What size hole are you trying to drill?

 

[sduser]

Trying to drill small pilot holes at first before going larger. Broke a 1/16", 5/64" and 3/32".

I am using these bits:

SHOCKWAVE Impact Duty™ RED HELIX™ Titanium Drill Bit Set - 23PC | Milwaukee Tool

The MILWAUKEE® 23PC SHOCKWAVE™ RED HELIX™ Titanium Drill Bit Set has QUAD EDGE™ tips that stay sharper longer. It offers 5X life vs. black oxide drill bits.

www.milwaukeetool.com

the reviews are pretty bad and mention broken bits. I'll try another type. Any suggestions?

Anything magic about drilling these bars?

 

[GXMnow]

Copper can be "Sticky" and grab the bit, especially right as it starts to pop out the far side. You need to use a good sharp bit, use some oil or even grease on the surface you are drilling, and go a bit slower. Using a hand held drill is not idea, but with care it will go through. If you can, clamp the bar to a solid object, like in a vice, or clamp it to a table. It can also help to have a block of wood clamped to the back side. That will make the hole cleaner and can reduce the bit biting as it pokes through. If your drill has a torque limiter clutch, dial it down a bit. If the bit snags, it is better to have the clutch slip than to snap another bit. Then just use reverse to back it out and you can try again. Once it does bite, it will tend to want to do it again, so leave the drill in reverse for a few seconds and apply pressure, and it may flatten the ridge a bit so you can go back to forward and start drilling again.

As for getting a broken bit out after one snaps... Did it make it out the other side at all? even a little dimple? If so, try a hammer on the tip of the bit on the back side. Not real hard, but enough to deform where it has bit in, then try to screw it out. If it is flush or below the surface, and didn't come out the other side, it may never come out. If it is a larger bit, under the surface, and not going through, you can try using a punch and a hammer to crack the bit into small pieces, but it can be futile.

 

[sduser]

Thanks for the reply. I'll try some different bits, adjust the clutch and try again with some lube.

I think I'll just scrap the ones with the broken bit in them. I only need three and it's not hard to start over. Just don't want to keep breaking bits.

 

[Forbisher]

Thanks for the reply. I'll try some different bits, adjust the clutch and try again with some lube.

I think I'll just scrap the ones with the broken bit in them. I only need three and it's not hard to start over. Just don't want to keep breaking bits.

What size holes do you need?
Try a good quality step bit with 1/16" steps.
Use lube.
Flip the bar to drill the finished hole from the other side.

 

[sduser]

Forget the size, for a M4 screw. I think 3/16"?

Good idea on the step bit. I have a couple but have to check the sizes.

 

[Forbisher]

Forget the size, for a M4 screw. I think 3/16"?

Good idea on the step bit. I have a couple but have to check the sizes.

Lol You can use the messed up bar for some practice holes.
Step bits cut great on sticky soft material like acrylic and aluminum.

 

[HRTKD]

I was breaking bit when drilling into my RV trailer's frame. That's some tough steel. Some of the bits were fairly new, so being sharp wasn't the problem. I finally admitted that my bits weren't up to the job and bought new ones. The new ones are Cobalt. So far I'm very pleased with them. No breaks and they cut very fast. Here is a link to the bits I bought:

Drill America - DWD29J-CO-PC 29 Piece M35 Cobalt Drill Bit Set in Round Case (1/16" - 1/2" X 64ths), DWDCO Series: Amazon.com: Industrial & Scientific

Drill America - DWD29J-CO-PC 29 Piece M35 Cobalt Drill Bit Set in Round Case (1/16" - 1/2" X 64ths), DWDCO Series: Amazon.com: Industrial & Scientific

www.amazon.com

Lubricant has been mentioned a few times in this thread. It's important to use some to keep the bit cool. I call it cutting fluid. It does work. If I'm drilling something that I can't use the bottle of cutting fluid on (I'm drilling UP into something) then I use WD-40. It's better than nothing, just don't get it too hot or you might see the magic flame. This is the cutting fluid I use that was recommended to me by a number of people:

https://www.amazon.com/gp/product/B003X3ZKXI

Here is a Project Farm video that reviews various cutting fluids:

 

[Supervstech]

Hilarious, and informative...

 

[heavy-impact]

Flip your buss bar and start on the other side. Soft materials require a higher drill speed and it's best to not drill too deep at once. Only drill about 1/8" deep over and over until you reach the desired depth. A drill press is much easier to work with.

 

[Craig]

I think you should just start with the size of bit you need. Those smaller buts break easily.

 

[softdown]

Is this a dream? Breaking Milwaukee bits in copper bar? This should not happen. Copper is one of the easiest materials to drill. Lead being a little easier.

Should be able to poke a hole in copper with morning wood. Ok - that was a bit extreme but the point stands.

 

[heavy-impact]

Is this a dream? Breaking Milwaukee bits in copper bar? This should not happen. Copper is one of the easiest materials to drill. Lead being a little easier.
Should be able to poke a hole in copper with morning wood. Ok - that was a bit extreme but the point stands.

The smaller drill bits especially cobalt ones is soft material break easy. This usually comes from pressing too hard and wobbling around while using a hand drill.

 

[HRTKD]

The smaller drill bits especially cobalt ones is soft material break easy. This usually comes from pressing too hard and wobbling around while using a hand drill.

None of my cobalt bits have broken. Are you sure you weren't using Nobalt bits?

 

[heavy-impact]

None of my cobalt bits have broken. Are you sure you weren't using Nobalt bits?

I did say they must break I simply explained why. I have a machine shop and understand the subject fully.

 

[mapguy525]

I did say they must break I simply explained why. I have a machine shop and understand the subject fully.

Totally agree - Tool quality and operating conditions dictate tool life and quality of work. Operating conditions includes user skill and knowledge handling all the pieces of the puzzle.

 

[sduser]

Thanks everyone. Got the holes drilled.

I suspect the smaller bits were a little dull, I was pressing too hard and my technique wasn't very good.

This time I stated with a new 1/8" bit to start the hole, then switched to a 3/16" step bit to finish. RPMs were very low to allow the cutting edge to cut away the metal and allow the shavings to exit through the reliefs. I also positioned by body to keep the drill straight and applied pressure on the back of the drill inline with the bit instead of the handle which would put a bit of a lean on the bit. I was able to extract the broken bits in the process as well. win-win.