Drill bits for chrome

[spike95]

Hi Guys,
I am having an issue at work. We just got in some new trucks and need to drill holes in the bumpers to mount the license plates. My coworker started trying with his set of Blue Point bits, and wasn’t getting anywhere. I tried with my Milwaukee cobalt bits and some cutting oil. I could barely make a mark. These new Mack bumpers are no joke!
...so I broke down and bought a couple of the nicer Snap On solid cobalt bits thinking that would do the job. Wrong...
Another coworker from our body shop came in with a bit that he said he has had for years, but doesn’t know the make. It went through in about 10-15 seconds. The only marking on the bit was “HSS” and the size, so not a ton of info there...

So I’m trying to figure out what to buy for this purpose. I’ve seen people online talk about carbide, but then also seen it mentioned that they are very brittle and better used in a press than a hand held drill. I would be pissed if I snapped a $35+ bit. Is there another option? Or does anyone have another suggestion better than cobalt?

 

[californiaHank]

I don't think you have to spend $35 for a bit.
There are lots of generic Chinese HSS twist drills with carbide tips for a lot less.

https://www.acehardware.com/departments/tools/power-tool-accessories/drill-bits/2094035

I don't think that carbide tipped bits are any more likely to snap than your cobalt ones. It's just the tips that are hard, not the shanks.

 

[byacey]

Drilling chrome and stainless steel requires a hard steel bit and using a slow cutting speed to prevent work hardening the material as you're trying to drill it. Use cutting oil.

I've been using Molybdenum steel bits that withstand high temperature well. You might want to try these.

 

[byacey]

I don't think you have to spend $35 for a bit.
There are lots of generic Chinese HSS twist drills with carbide tips for a lot less.

https://www.acehardware.com/departments/tools/power-tool-accessories/drill-bits/2094035

I don't think that carbide tipped bits are any more likely to snap than your cobalt ones. It's just the tips that are hard, not the shanks.

The smaller diameter bits ( #66 to # 50) used in the printed circuit board industry are solid carbide, and very brittle.

 

[californiaHank]

The smaller diameter bits ( #66 to # 50) used in the printed circuit board industry are solid carbide, and very brittle.

I'm in Silicon Valley, and toured the driling plant that did the PC boards for the company I worked for. The drilling machines were 20 foot wide and mounted on enormous marble slabs to control vibration. Each machine drilled several large pieces of stock at once, which would be cut into individual PC boards later in the manufacturing process. There were dozens of computer controlled drill heads on each machine, and each head moved to a new pre-programmed location every couple of seconds.

Not exactly the same setup you'd use for hand drilling a few licence plate holes, and completely different bits.

 

[byacey]

I'm in Silicon Valley, and toured the driling plant that did the PC boards for the company I worked for. The drilling machines were 20 foot wide and mounted on enormous marble slabs to control vibration. Each machine drilled several large pieces of stock at once, which would be cut into individual PC boards later in the manufacturing process. There were dozens of computer controlled drill heads on each machine, and each head moved to a new pre-programmed location every couple of seconds.

Not exactly the same setup you'd use for hand drilling a few licence plate holes, and completely different bits.

I can understand the need for the marble slabs. These bits don't take any abuse, and will break if any wobble or lateral force is applied to the bit.

 

[seber]

I'm willing to bet the only important difference in the bits is that the one that worked is sharp and correctly ground.

 

[Steve_P]

By and large most chrome plating is a 3 step process.
First Copper to bind to the metal base, then Nickel which is polished, then Chrome which is actually yellow but the coating is so thin it becomes transparent and acts as a sealer to reveal the polished Nickel layer underneath.

The Chrome layer is very, very thin and a good whack with a center punch that goes to the base metal is what's needed. A 135 degree split point cobalt drill bit will get the job done quickly and won't drift off the center punched mark.

Here's where I get mine.
Scroll down for the Split Point Cobalt bits
https://www.victornet.com/subdepartments/HS-Jobber-Drills---Cobalt/1130.html

.

Not really. Copper is generally only used when needed to fill imperfections and when it will be polished after filling. Like restoring old pitted parts. It is absolutely not necessary to apply a chrome plate. Nickel is yellow. Hexavalent chromium is a beautiful blue. Trivalent chromium is more of a yellow than hex, but prettier than nickel

 

[rsanter]

Die grinder with stone to spot through the Crome and then drill away.

I also like to use solid carbide die grinder pits as drill bits in hard stuff

 

[spike95]

I'm willing to bet the only important difference in the bits is that the one that worked is sharp and correctly ground.

The Snap On bits I used were brand new and sharp. My coworker’s bits were old and never sharpened.

By and large most chrome plating is a 3 step process.
First Copper to bind to the metal base, then Nickel which is polished, then Chrome which is actually yellow but the coating is so thin it becomes transparent and acts as a sealer to reveal the polished Nickel layer underneath.

The Chrome layer is very, very thin and a good whack with a center punch that goes to the base metal is what's needed. A 135 degree split point cobalt drill bit will get the job done quickly and won't drift off the center punched mark.

Here's where I get mine.
Scroll down for the Split Point Cobalt bits
https://www.victornet.com/subdepartments/HS-Jobber-Drills---Cobalt/1130.html

.

I always use a punch before I start drilling any kind of metal. It was not able to get to the base metal on this bumper.

Drilling chrome and stainless steel requires a hard steel bit and using a slow cutting speed to prevent work hardening the material as you're trying to drill it. Use cutting oil.

I've been using Molybdenum steel bits that withstand high temperature well. You might want to try these.

I also used cutting oil and my drill on low speed. I have not tried Molybdenum though. I will look into those.

 

[spike95]

Die grinder with stone to spot through the Crome and then drill away.

I also like to use solid carbide die grinder pits as drill bits in hard stuff

I do like that idea of starting with a die grinder. I bet that would do the job on this.

Does anyone have any specific bits that they can recommend that are better/harder than Snap On solid cobalt ones?

 

[APEowner]

You shouldn't need anything exotic. Just a good quality bit. I'd start with a short length, Titanium-nitride (TiN) coated, split point bit from McMaster-Carr.

 

[tarbellb]

What size hole are you drilling?

I have a hard time thinking just about any decent bit cant pierce that chrome?

My MO is typically center punch first, grab a 1/8-1/4" stubby bit, then open up with step drill to final size. Lots of pressure, low speed, should do the trick.

 

[spike95]

What size hole are you drilling?

I have a hard time thinking just about any decent bit cant pierce that chrome?

My MO is typically center punch first, grab a 1/8-1/4" stubby bit, then open up with step drill to final size. Lots of pressure, low speed, should do the trick.

I am only trying to get to 1/4” hole. I center punched and then started with a brand new (very first use) 7/64” Snap On bit planning to step up to 1/4. These were the nicest ones they sell on the truck. I have never had an issue getting through anything like this before. I swear it is like trying to drill through a high end tool.

 

[matt_i]

A dremel tool with sanding drum or the woven cutoff wheel would make short work of the chrome plate. Obviously have to be careful to avoid "idiot marks"

Then most any drill bit will work. I like to always start with 1/8 if I'm hand-held drilling. Then work up. Its faster that way. I buy the 1/8" in packs of 12 that way there's a good chance a sharp one is available....treating them like a consumable and not bothering to resharpen. I've mostly used C-L chicago latrobe black oxide for most of my adult life but Precision Twist and Triumph make very nice bits also.

 

[the intimidator]

Another idea would be not drilling threw a nice ne chrome bumber and having rust stains within the year but to build a plate mount that would attach at one of the bumper mount bolts. I know this doesn't help with the original question as to drilling threw chrome but a lot of good ideas already. I'd find an alternative way to mount the plate if they were my trucks! Rust runs on chrome bumpers don't look good imo especially on a new 120-200k truck

 

[Zewnten]

Strange enough when ever I have to drill chrome I use a set of HF step bits with the "titanium" coating, goes right through. Comes in a 3 pack of different stepped bits

 

[theoldwizard1]

Years ago on a car bumper, we used an air hammer and a punch to pierce the metal and get a decent size hole. Finished it with a regular bit

 

[Steiger9]

For what it's worth, I've had very good luck using carbide tipped and solid carbide bits in a hand drill. The ones I have are straight flute. To date I have drilled into a grade 8 bolt, broken extractor, broken torx bit, and an allen head set screw. Haven't exploded a bit yet.

Picked mine up from ebay for under $10 a piece.

 

[tarbellb]

Sounds like it may have gotten work hardened. If thats the case you may want to hit with a abrasive like die grinder/dremel/etc....?

Sometimes its the oddest things that hang us up. Good luck.

 

[CR888]

I'm willing to bet the only important difference in the bits is that the one that worked is sharp and correctly ground.

#metoo

 

[spike95]

#metoo

Once again, the bit that worked was many years old and never sharpened. The bits that did not work were BRAND NEW and never used before.