Stripped Allen hex head screws

This should be a sticky. Or we need a trick of the trade mechanics section.

I incounter this sometimes. The PO wasn't so gentle or didn't clean out the dirt in the hex head screws or his Allen wrenches were stripped. To remove a stripped out Allen head cap screw on the case or clutch cover I take a flat nosed punch and hammer on the head of the screw and roll the outer metal back in all around the screw head. Then I take the Allen hex head wrench and swage the hex back into the screw head using the hammer. I try to eye ball the orginal hex then swage the wrench into it. I seen this method come out so perfect the screw can be reused. It can happen to anyone of us.

Going to need pictures along with that please

ive done this with plastic Phillips heads wack the top of the screw a few times to refill the star holes and you can get hopefully them out.

or they used a fractional allen vs. a metric one, seen that stupidity regular

If this fails place a nut over the allen head and fill the centre of the nut/recess of the allen head with mig weld and use a wrench to remove offending bolt.

Left hand drill bit and put drill in reverse.

They come right out.

I've had good luck with screw extractors. Just got to drill a pilot hole first... Which can take a while.

If the heads are not recessed, I have used vise grips. Simple & fast

Believe it or not, I have used tooth-paste or valve lapping compound. Put some on the end of the allen wrench to give it a better grip in the damaged allen bolt. Left-handed drill bits work well too!

I have used all of the above methods & many combinations of them together. I call it "using every trick in the book" but it's just overcoming the next obsticle slowing you to your end goal. Remember, heat & penetrant is your best friend. Determination helps.

patience is also very helpful...I used to rush into a teardown and inevitably shag 1 or two screws just purely from brute force mixed with too much hurryup...then your time frame is shagged totally I now approach every fastener with the intent that it will strip, fight to the last man and need the resources of the known universe to get it undone... at least when it goes "crack" straight up and comes out smoothly you feel like you've had a win

It's true. Approach every bolt & nut like it could be the one that stalls the project.

That oughta work

For me I would try everything else before bringing a welder that close to a magnesium case. That is why that would be the last resort. I have no reservation near a cast iron engine I would use my MIG before the TIG in either case. Less heat buildup.

Yup any and all the methods, but cant stress enough how well a left hand drill bit works in extracting screws, sometimes do not even need to use an extractor. The other method not mentioned is to make a small cut or groove in the head with a dremel and use a flat blade screwdriver, but depends on if you have room not to nick the cases. One of the best penetrants I have found is called Freeze-off. Seems like PB blaster but the air in the can chills the screw just enough to crack any oxidation. I have used in alone, or heat the parts first to get extra action. Any autoparts store has it and it works very well.

jimspac, why so apprehensive about allowing a welder close to mag cases? Its not uncommon to see magnesium products welded much less welded next to. I admit that taking the necessary precautions are certainly in order.


Tig Welding Techniques and Welding Magnesium

View: https://www.youtube.com/watch?v=weqTWwaaL0g#t=61

I've welded magnesium and the very first time I had one drop of weld hit the floor on fire. Stupid me I stepped on it and it burst into ten Richard Pryor on flames running across the weld booth floor. I was welding in a box flooded with argon. My point is magnesium can be nasty if it catches on fire. Be careful.

I took on every new welding process as a challenge just to learn it. Once we learn one process we get hungry for more knowledge. Arc welding and mig welding is easy, but TIG welding is an art and takes more talent sometimes. It's all a matter of practice.

Not so much apprehension but I had developed so many mechanical means of dealing with issues like that long before I had welders at my disposal. I first bought my own welders when I started doing welded panel repairs on my various pickup trucks I had. I still use my early experimentation techniques for removing stubborn fasteners to great success. But still if nothing else I know works, then I will bring over the MIG.

But in 35 years of repairing and tinkering, that moment has yet to surface. The only justification for the welder would be if a bolt head was broken off and the end of the bolt is at the case face. This will only happen if there is not access to drill a core hole in the bolt and use a screw extractor. My knowledge indicate that if a welder is hot enough to weld something to the end of the bolt, it is hot enough to melt an aluminum or magnesium adjacent surface to that weld site. And it still takes a very accomplished welder to pull off that scenario.

Ok, so I have not stripped out a screw in a long time as I usually take the approach of thinking every screw will strip, so get the perfect grip, push down, keep things lined up etc. Sure enough after this post I'm working on a Honda CB1100 and of four screws that need to come out, the last one will not budge and strips. And it is the only one of the four you really cant get to without spending an hour dismantling the carbs and intake. After an hour of dismantling finally got it out by slotting the head - otherwise I would have had to pull the whole engine in order to get a drill and extractor on it. Murphy's Law.