Trouble drilling holes in M1026 sponsons

[RockHillWill]

I had some bolt holes with an odd pattern at the upper third portion of both sponsons, and was unable to determine what might have been mounted there. I plugged the holes with original plastic inserts, but I did not want to leave them looking like that so I made two dummy 'vent' panels to cover them up. The issue that I had was some difficulty in drilling the holes. I was aware that it would be difficult, but was not prepared for hard it actually was to do. I needed a total of eight 3/8" diameter holes, and managed to drill seven of them, but the last one turned out to noticeably harder to do. I am aware that the aluminum was a hardened alloy (can't find what it actually is?) and it seemed like I may have work hardened this area before I could get the hole drilled thru. I was using a smaller 3/16" bit in an electric drill motor, then re-drilled with the 3/8" drill bit. I was continually sharpening both bits as I went. I eventually finished that hole by turning down a 'zip' wheel to a small diameter and cutting a small 'X', then used a 1/4" bit in an air motor drill.

My question is: What type of aluminum is this? What would be the preferred method of annealing a small area to drill holes? What type of drill bit? and is a high speed air drill motor preferred over a traditional electric drill?

[Urban Camo]

I would guess you have the sponsons with the secondary layer of steel in them.
some refer to them as up armored . Are you sure your sponsons are aluminum?
Let me get this straight. To cover up some factory holes in the sponson you drilled 8 new holes?
There is a couple of things that fit on the right sponson above the antenna.
A mounting plate for the blue force tracker antenna can be found in that area as well as a small socket or pocket that the hold open rod sat in on the newer up armored rear hatches.

[AAVP7]

The original M1026 sponsons were made of steel, and probably even the "basic armor" outer part is some kind of hardened steel.

I also had some "extra" holes in my sponsons, and I welded them shut a few weeks ago, so it´s definitely steel.

But I also needed some new holes (for the hatch safety rod), and those were quite hard to drill. I used a high-quality cobalt-covered drill bit in the end, which worked fine, although I noticed the bits becoming weaker after a while.

[RockHillWill]

I will add the following: I did NOT like the hole patterns, so I covered them up. The local NG armory guys were unable to find a matching component and the holes had an erratic pattern, and I like making metal things with louvers in them.

[RockHillWill]

I still have a lot to learn about these trucks. I have heard that they were aluminum for the most part, other than the hood, and so did not stop to think about it being steel. When I drilled the previous holes, the shavings were all bright colored and looked like aluminum, so I never stopped to think about it being steel. I put a magnet on both sponsons and they were both steel. My question remains the same. What would anyone recommend a method to drill with if I encounter this issue again?

[wooody1]

Were you using high speed steel drill bits or carbide, carbide cuts through multiple items? Of course 3 times the price

Did you drill a pilot holes first as in 1/8?

Heat is the biggest killer of drill bits, slow speed and steady with cutting oil and you can tackle any metal.

Some metals if heated while drilling will actually go harder as you try too drill them,making your drill bits heat up and go blunt

[RockHillWill]

Thanks for your reply Woody1. I am familiar with those thoughts that you brought up, and that was my approach, but I still encountered some difficulty. When I was drilling, the chips were shiney, and I was predisposed to thinking that I was drilling aluminum. Even when drilling the 1/8" starter hole I encountered these problems. The last hole that I drilled, even the 1/8" bit would not go thru, and it appeared to be work hardened. Surprisingly, when I quit using the slower electric drill motor and went to a higher speed air drill motor, it seemed to work better. In hind site, I was using the slower drill motor with high speed drill bits and carbide bits, but the best results seemed to be the higher speed drill and the carbide bits. I'm still puzzled!

[dilvoy]

The roof skin panel, both sponsons, and cargo hatch are heat treated to be hard so you are not seeing something mysterious. Steel rear bumper is the same. I pity anyone wanting to install all those footman loops on an early cargo hatch for the external cargo net. Knew one guy who went through all the trouble and countless drill bits only to find that he put them too far out from the center to be original looking. Needless to say, he didn't drill on that cargo hatch again.

[RockHillWill]

Thanks, George. That sums up my education for that particular question. Prior to buying, all I heard was that the Humvees were aluminum except the hood. I had that so ingrained in my mind that I did not consider heat treated steel, and the drilling chips appeared to look like aluminum. Thanks again.

[wooody1]

A sledge hammer head is heated treated steel, some tools have a higher carbon in their make up subject to there end use, you can still drill through a sledge hammer head with a carbide bit.

Most tools are heat treated, then treated in a bath of oil to cool down and harden off for 15 minutes, I am using tools as an example as they are very hard.

Try some cutting oil you will be surprised with the difference