Getting rusted snapped screw out of aluminum

OK. So I goofed. Rather than try WD-40 I just tried the brute force method and broke the head off the screws, and they snapped flush with the face of the almuminum. Do I just go at what’s left of them with a drill now, or what?

Since the screw is “rusted” I guess it isn’t aluminum. Depending on the size of the screw a left threaded drill bit should work. If you can find one.

Well you would have done better to just spit on the screws than use WD-40.
If you are very careful screws can be drilled out. A left hand bit would be good because the heat of drilling will help break the offending screw. Good luck and use a penetrating oil next time.

Good luck drilling it out without gouging the aluminum. If you can, you’re a better man than I.

WD-40 is no good as a penetrating oil. In fact, I don’t know what it is good for except that some of the local fishermen spray it on their sturgeon bait.

If you want to have a can of real penetrating oil that works, pick up a can of PB Blaster penetrating catalyst. Available at most hardware, automotive type places.

Unless you can reach the back of the screw and get a visegrip on it, you’ll have to drill it out…and you WILL booger it up. Use a little bit and drill several holes around the broken one until you can get it out, clean up the hole with a big bit and use a new, bigger screw…maybe with a washer to cover the mess.

Pick up an Easy Out extractor. There’s several brands.

Easy Out for ten bucks

here’s one at Sears

Might want to Google Helicoil kits while you’re at it.

I appreciate the advice. I’m not that concerned about scratching the aluminum since it’s inside something and not normally visable, it’s just that it’s not that thick so I’m afraid it will crack if I get too enthusiatic.

Nitric acid is the true nerd solution. It will attack iron but not Al. Precautions are in order if you take this approach.

Interesting, and I have taken chemistry courses so I know basic safety precautions with dangerous stuff
I’m sure there’s someone selling it on eBay, but I thought it was virtually impossible to get lab chemicals in the US, not because it was illegal, but because no one would sell it to you unless you had a real business.

Alum dissolved in water also works, but probably more slowly. Quite a bit safer, though. I dissolved a broken tap in aluminum with this method.

It also makes nice hexagonal crystals if you let the alum solution evaporate.

Short term, a lefthanded drill and an easy-out would be preferred. If you can center punch the broken screw end and align yourself perpendicular to a flat face on the aluminum, your hole will not touch the aluminum. The action of center punching may also break some of the corroded bond between the screw and the aluminum. If the aluminum is something that can flex, even of only slightly (and what can’t?), then flexing it back and forth for a while may also disrupt the bond. Also, heating the entire assembly would help, because the aluminum will expand more than the steel and will increase the gap between them (aluminum has a higher coefficient of thermal expansion).

How big is the aluminum that contains the screw? Are you handy with a drill press?
Do you know any machinists? A machinist will drill that out in no time. If drilled carefully, the existing threads can be preserved, but a helicoil replacement is a great idea.

The aluminum is an about 1 foot square frame, the screws are in the corners so I don’t think I could flex it and there is paint on the outside that needs to be preserved. They’re like #8 screw.

I do know a machinist / metal workers who’s currently restoring another project for me. I own a hand drill but not a drill press.

I do have the proper safety equipement to work with acid left over from my college chemistry class days. I noticed concrete etcher is 15% nitric acid, would that be strong enough? Does an alum solution have to be heated to work, I did some searching and it seems you need to boil it.

It doesn’t need to boil but it should be heated. I’d guesstimate that 150 F would be sufficient. The hotter it is the faster it works, but if you’re in no hurry you can just leave it overnight or whatever. Just make sure the water doesn’t evaporate away.

1 foot square is kinda big as far as common household glassware goes, but maybe you could dip one edge in the solution at a time (using a glass baking dish or some such–over a foot long but less than a foot wide).

This. I do it all the time on the job.

Heating the aluminum may help, if you can. The hole will get wider faster than the steel bolt. Once heated an Easy-Out should work well. Assuming you don’t have to rethread or use a Heli-coil, you should get a fine threaded bolt to replace it, and use oil or Loc-Tite as needed to make it less or more removeable in the future, and protect from corrosion.

The OP said it is a #8 screw which would indicate a sheet metal type screw not a machine screw. So unless he can convert to a machine screw, heli coils are off the table.
#8 is kind of small and I doubt that even with my rather extensive collection of easy out I have one small enough to fit.
If the material is thick enough it could be drilled almost the full depth using a drill press then either use a larger sheet metal screw (#12?) or use a blind hole tap and use a machine screw.

You can carve a slot with a dremmel cutoff blade for a screw driver then jostle the screw around with a hammer and center punch/small chisel till it gets loose enough to unscrew.

Drill it out and use screw extractor best method.