Cobalt bit brand recommendation please!

Hey everyone, I’m looking for some recommendations for a project I have coming up.

I purchased some step rails for my Jeep Cherokee, and the installation instructions call for a 1/4" bit to drill through the pinch weld (hardened steel).

I’ve been doing some research and it sounds like Cobalt is the recommended bit material, preferrably M42 (8% cobalt). However, I’ve talked to a few other guys that have performed this install and some are saying they went through 6-8 cobalt bits drilling the necessary holes.

I’m looking for a recommendation of a higher quality (brand?) of cobalt bit that will prevent me from needing 6-8 of these. I’m seeing listings on Amazon for Bosch, Irwin, Dewalt, and a few brands I’ve never heard of.

Thanks for your time!

since you’re drilling though a set of pinch welds I recommend getting a set of drill bits. Don’t care which.

Or maybe consider re-sharpening with a bench grinder if you want to work that effort. not sure it’s worth your time.

reasoning - body of modern car is often a high boron content - high tensile strength steel - if steel body. Those pinch welds are often multiple layers at a point - pinched together and then melted and hardened. Thus one of the hardest points in the car body.

Even a extra hard M42 or other machinist level drill bit won’t like that job for long. How many holes do you have to drill? say it’s 10, I’d plan on getting 3 bits and hoping I can cleanily make 3 holes per bit and I would put oil on them

Of brands Irwin hanson is pretty good quality, as is Norseman which is what I’d look for. but I’d give equal look at just getting some common HSS bits in the size I needed and considering them throw aways. Might be cheaper and easier in the long run.

DO you have to drill the 1/4 inch hole and then open it up - or just that size hole? How many?

Thank you for the detailed reply!

I have to drill 8 holes on each side, 16 in total. The size of the hole is 1/4", it does not need opened up.

I found the following listing for M42 1/4" bits on Amazon, however I’ve never heard of any of these brands: “Top Tech Tool” “Champion Cutting Tool 12-Pack”

There are more, “Drill Hog USA 12-Pack” and “Viking Drill and Tool 12-Pack” However my newbie status won’t allow me to post more links. :slight_smile:

We had good luck with the Cleveland brand. I’d recommend a bit with a 135 degree split point and try to keep the pressure consistent to avoid walking and further work hardening,

For hardened steel Champion make what they call Locksmith’s drills for drilling into safes. They are carbide tipped and tend to wander cutting holes that sometimes are out of round. I guess this is OK when all you want to do is get a peek inside and access the locking mechanism.

Better are drills we use to call Die-Maker’s or Die Drills - but they are better suited if chucked in a magnetic drill press - not a hand drill:$smthumb$

Thanks Fred!

I checked out the MSC website, and decided to chat with them to just leverage options. After explaining the material I’m working with, and the goal of 16 holes, they recommended THIS which seems like over-kill.

My original plan was to purchase 8-10 standard bits, and just return what I don’t use. However, if this full carbide bit would do the entire job, maybe it’s not a bad idea. But I’m hesitant to put this entire project onto a single drill bit.

About $10 cheaper at Grainger if you decide to go with the M A Ford bit. I don’t recall that we ever used this style bit - but did use other MA Ford bits. I think their brad point bits for drilling composites worked well for us.

It’s been so long since I’ve used machinist bits but IIRC they don’t like being in a hand dril. IE not made to spin in something like a cordless ______ hand drill.

As far as those other names I know a number of guys in the hangar swear buy those drill hog usa bits - but they do consider them throw away because of cost. But that doesn’t mean you won’t see a guy at the bench grinder re- sharpening one.

+1 on that 135 degree point comment - which BTW helps with the resharpening idea. take your whatever bit and on hole 3 - re square the tip on the bench grinder.

MA ford is good stuff but I thought they only make machinist tooling. I’ve never used a bit like that in a hand drill so I won’t say it won’t work but I don’t think it’s made for that.

How’s the drilling and installation of step rails on your Cherokee? My sister recently acquired a Cherokee as well and looking to get a good step rail. These drilled ones seem to be tougher. I’ll be finishing installing the Smittybilt parts first before working on the rails.


I still haven’t decided! There’s a lot of back-and-forth information. Cobalt vs Carbide, etc. I’ll take the plunge sooner or later.

The step rails I purchased were from Rocky Road Outfitters, they’re essentially the only company making steel step rails that can support the weight of the vehicle. They also offer bull bars that don’t impact approach angle, and some other goodies.

Since they haven’t even shipped yet (they’re made to order) I haven’t been in a massive rush to pick up bits yet.

But, to install the step rails, I’ll remove the lower plastic rocker guards and then need to drill 8 holes on BOTH sides of the car (16 in total). I believe the attachment method is nutzerts, however I know it’s been updated a few times in the last couple of years, so we’ll see once they arrive :slight_smile:

If the attachment requires nutserts you will want the hole to be pretty spot-on conforming t the nutsert specs. Do you have the tool for setting them - or do you plan on using one of the methods using washers like these:

OP - are you talking about their Rock Sliders/Super SLiders or a different product

The “Jeep Cherokee KL Super Sliders”, which are under the Step Rail category. I also opted for the cover panels, since other owners have had some issues with mud and things building up behind them.

The bit where it says it mounts to the subframe - will you have to drill that too?

The body seam attachment does sort of look to be a threaded insert but I wonder if they don’t have access for you to put the bolt in through the back. Good luck with it - looks rather sturdy.

To be honest, I’m not sure what the installation completely involves. I have a friend that has installed the rock rails on his Cherokee, he’ll be advising / guiding me through the whole thing.

I picked up these bits, It’s a 12-pack of M42 Cobalt bits. I figured that 12 should be MORE than enough and I’ve heard some pretty great things about Drill Hog bits online.

I guess we’ll see once they arrive!