I learned about removing rusty screws from working on crop dusters. I was taught to use valve grinding compound on the phillips bit because it gives a grip. I have removed hundreds of rusty screws with this method.
I always had a hard time believing it worked until I tried it myself, now its one of the first things I do to a really rusty screw instead of chewing it up first. It really works.
what i usually do if i dso not plan on saving the screw is cut a slot in it with a dremel so that i can use a flathead that is wider than the screw so that it cannot slip unless the head breaks.....
I've also had very good results with an IMPACT DRIVER like this one: http://www.kk.org/cooltools/archives/000723.php I got mine(SnapOn) CHEAP at a Swapmeet
I try the screw if it is clean or only slightly rusty but use the following process otherwise. I use the phillips head as a center guide and drill them out. I drill them the with the recommended tap drill size and re-tap to clean the threads. I spend less time that way than if I tried to fight them out.
DITTO on the impact driver, as mentioned by HemiRambler! If the cross-slots on the screw head aren't boogered already from previous removal attempts, an impact driver will almost ALWAYS back the screw out, as long as it isn't stuck so bad that the shank breaks. It's also a good idea to "shoot" the screw with PB Blaster, or some other good penetrating oil, and allow it to soak in for a few minutes prior to the removal attempt. C'ya - RAY
heat the screw head with a small welding tip on your torch until it;s just orange, they will come loose 99% of the time...
Use a left hand bit slightly smaller than tap size and the screw will often twist right out at some point...I've done that with exhaust manifold bolts with some success.
Another way for any screw, bolt or nut is to tap a sacrificial flat blade screw driver, punch, or chisel at an angle in the direction of rotationon with a hammer on the outside edge.
Try that with a left hand drill bit. Some will back right out when the bit really starts biting into the metal.
hell, i've been wondering what to do with the valve lapping compound i have until i start on the new engine. thanks for the tip!!
I've had very good luck with needle nose vise grips on the head of the screw ( if possible) turn with the vise grips and the screw driver at the same time. Sometimes I've found it justs needs alittle help.
I have used all the methods described and all WILL work. But the EASIEST WAY I HAVE FOUND is to spray / soak with Aerokroil, let it / them sit for a while. Use a 1/2 inch speed handle / apex bit, they will back right out.If you dont have room for the speed handle, use a ratchet.
In the aviation biz we use what's called an"old man" it's just a handle for leverage used with an air hammer,I'm sure there's a more technical term for it,maybe someone on the board might know. Works very well.
'Old Man' 'Screw Knocker' '#%!!*&$##' (if your a dumbass like me and let the web of skin between your fingers get between the bulge on the shank and the nose of the air hammer, without a guard on it) I have been wanting to try the one you take a screw out next to it and anchor the tool so you can lever the apex bit harder into the stubborn screw. Can't seem to find a pic though.
these work great, way better than a impact driver. they are easy to make with an air hammer punch, an all thread nut and 3/8 socket extension to hold a socket w the screwdriver bit. slip on a ratcheting end wrench and hammer away. a soaking w gibbs also helps
works unbelievably well. breaking the flush-head screws loose in the fuel tank inspection covers I use the compound and hammer the screwdriver in with an impact, using a wrench on the screwdriver(on my snap-ons, there's a hex right at the base of the handle). when that doesn't work, we have a bunch of the Craftsman bolt/screw extractors that are amazing. btw, rusty screws tells me you worked on either ag-cats or thrushes, correct? I'm an A&P and work full time mostly with AirTractors.
I use the ball peen hammer trick. Take a ball peen hammer and hit the head of the screw and colapse the phillips groves some. Then take your phillips screw driver and stick it on the screw aligned with the crushed in slots. Give it a wack on the handle with a leather or dead blow hammer. This will seat the screw driver (or impact driver bit) into the screw for a custom fit. The shock also helps break the rust. Turn while pressing down on the hammer. Gets most of them out.
when that doesn't work, we have a bunch of the Craftsman bolt/screw extractors that are amazing. btw, rusty screws tells me you worked on either ag-cats or thrushes, correct? I'm an A&P and work full time mostly with AirTractors.[/quote] I have loads of those screw extractors I used to make em when I was a machinist and would drop em in my pocket everyonce in a while. For research of course.
there are some good ideas here ,if you have air or the tools to do the job with. when you are working on old airplanes on a dirt maintence area you use the simplist item at hand. I learned this back in the 50s . it still works, because some company has put it in solution and its available in a squeeze bottle.It does work. oh yeah I used to get a new bit or screwdriver about once every 6 mos. 1.15 an hr then.
Just take a scrap piece of steel and tack weld it to the head of the screw and use the steel to turn it out.
Sometimes dipping the head of the screwdriver with blue Loctite gives it a little grip too. Too much of an advantage is never a problem!