Datsun Roadster Forum-311s.org

Are there any special tricks associated with drilling through a chromed component such as a bumper to ensure that the chrome does not chip or peel off? I'm going to be mounting a couple of fog lamps to my bumper and will likely need to drill some mounting holes. Any ideas?

Dave,

If I were you I'd take a piece of duck tape about 2 inches in length and put it down where you plan to drill then take a self loading punch and mark through the duck tape to get your bit started. I would start by making a hole with either a 1/4 or 1/8 drill bit then use the size bit of the bolt you will be using, all of these will help the drill bit from walking on you, resulting in scratched chrome and a string of cuss words,

Good luck let us know how it turns out,

Russell

Hey Dave, I would try a step bit. They work alot like a reamer, give you a truer hole with little or no burr. Not a triangle shaped one like a twist drill can do. Center punch and pilot drill with a twist drill then use the step bit for the final diameter. Hope this helps. Pat Mahoney

Thanks for the tips guys. I've been meaning to pick up one of those step drills for some time now. This looks like a pretty good excuse to do it.

Step drills are great for general blasting through during all types of fabrication, but they can make a pretty nasty hole depending on the style. For cosmetic work, look for a taller one with big gaps between the steps between sizes. Also, practice on a scrap piece of metal and make sure you get what you want...

If you have a die grinder, air grinder, ie a rotary driver capable of >10k rpm, consider purchasing a hole expander tool bit, cost $20-30. It is a common machine tool bit, shaped like an inverted teardrop and used as a cutter. To start, drill a small pilot hole through the sheet metal. With a steady hand and an improvised work rest you can achieve some impressive cutting/grinding operations, holes, slots, even rectangular shapes in sheet thicknesses to .375".

Hope this helps.

Thanks for the info gang! My original plan to mount the fog lamps under the bumper was foiled by ground clearance, or lack there of, issues. I'm reverting to the traditional top of bumper mount, utilizing the existing holes for the bumper over-riders that have long since been ditched. So, no holes to drill for this project.

Dave,

Are the lights too thick to mount in the stock fog light mounting holes? Seems to me that would be a logical place to put them...

They're round. About 6 inches in diameter. The stock location is that set of rectangular cut outs in the front lip, right?

Dave, I believe Sid is talkig about the 2 small holes on the front valance. They are about 1/2 to 5/8 in. in diameter and are just below the grille. There should be stainless caps on them when not being used. I've seen lots of cars with these holes filled in or covered with bondo. There are wires built into the harness to run driving lights but it is better to use relays for this setup... Bill

The only thing I've got below my grille is the bumper! They must have been filled in long ago...

OK, I ended up enlarging the license plate mounting holes on the front bumper and mounting the fog lamps there. I know, it sounds kinds funky, but wait till I post a picture, it looks super cool! Picture the fog lamps on the GT350 Mustang in the movie Gone in 60 Seconds.

Anyway, I did use a step drill bit as Pat suggested. It worked quite well and did not chew up the chrome at all.

Thanks for the ideas, guys!