Impact screwdriver

Firstly (eggs, grandma) is the impact driver set to 'turn' or has it jammed in 'fixed' ?

Is there any reason why there might be a L hand thread ?

Otherwise treat the screw/bolt to some pen oil and heat, and leave for a day and a bigger hammer (a lump hammer may be 'gentler' than an ordinary hammer hit with mucho force.)
 
Not sure the alloy frame would appreciate me trying to heat countersunk ss screws.Personally have found oil a waste of effort unless under ideal conditions. I'm asking if the impact doesn't do it, is it a case of hitting it harder until it does (or bit shatters)
 
vic008 said:
Not sure the alloy frame would appreciate me trying to heat countersunk ss screws.Personally have found oil a waste of effort unless under ideal conditions. I'm asking if the impact doesn't do it, is it a case of hitting it harder until it does (or bit shatters)
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Whilst the alloy frame wouldn’t appreciate an oxy-acetylene torch, you could try a decent wattage soldering iron on the screw head.... Build a little dam of plasticine or blue tack around it and try a pool of penetrating oil to soak in?
Is it a wood screw or a self tapping screw or a machine screw with a nut and washer?
Sarabande is right when he suggests a lump hammer (and checking the rotation of the impact driver!)
 
Maybe see if you can borrow an electric one*. These have the advantage of providing the juddery torque without all the violent hammering so you're less likely to go too far with the force. Make sure you have the correct size bit in an electric one though!

*impact driver, NOT electric screwdriver or electric drill. They work very differently!
 
I would definitely try heat, but gently so as not to damage any coatings or warp the frame.
Alu and SS have different rates of thermal expansion so you can occasionally use this to your advantage. The alu frame will absorb the heat and expand faster than the steel, I have had good success in the past by heating the area around a SS fastener.

If there is too much corrosion, this won't work but in this case i'm not sure there is much that would. In this case you may have to drill the head off the screw and then the remaining thread can be heated with an induction coil which is probably the last chance saloon.
 
My impact driver needs quite a bash however the screw and device must be pretty well supported against the bash. A hammer or mass behind might help. It has a strong spring so not so easy to determine if the bit rotates just by pushing. ol'will
 
Lol, or use a tool that doesn't require a bash! No points will be lost through the use of electricity in 2021!
 
I have never had much success with impact drivers. My yacht had Goiot hatches secured with stainless screws, and I would not even consider hitting an impact driver with the sort of blow needed to start removing the screws. You are much more likely to damage the frame or crack the deck fibreglass. Try other methods. Stainless to aluminium corrosion responds to water soaking better than it does to oil, but its hard to do. It worked for me removing a thoroughly siezed 16mm studs from a large cleat, by leaving it in a bucket of boiling water, replenished several times, but that cannot be achieved with the hatch screws. One method might work for you: Heat applied by putting a hot soldering iron on the screw heads. This method will work and is easiest if they are phillips or pozidrive screws: Drill them the diameter of the screw until the head s come off. After the hatch is off the remainders of the screws will come out fairly easily if gripped with a mole wrench.
 
The manual hit it with a hammer impact drivers seem more sympathetic towards a stubborn screw. The cordless ones just end up shearing the screw head off.
The single most important thing is to have exactly the right size screwdriver bit for the screw. Anything else and it will end up ruining the screw head.
 
Lustyd has it, use a cordless Impact Driver. I have found them invaluable. Any use of a hammer in a fiberglass mounted aluminum frame will result in damage to the surrounds.

Rappey said:
... The cordless ones just end up shearing the screw head off...
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If this is the case, nothing would remove the screw intact.

Given the reaction of SS screws with aluminum, I'd just drill the screw head out and deal with removing the remaining threaded section then re fill the hole with epoxy to re-drill a new screw hole.
 
I had to remove a winch base plate on a mast. Large pz3. I could feel that the cordless one was doing nothing. Broke out the hardly ever used manual impact driver. A few good whacks and the screw came free!
The cordless rotates only. The manual gives a large downwards impact as well as rotating. This can help to break the screw free.
On one job alone I had to remove 154,000 stainless screws and replace.
Some were rounded off, had grit jammed in heads and some even had snapped off screwdriver bits rusted into the heads and quite a few just sheared off.
Became somewhat of an expert removing screws!
All the advice above given is good, the only other thing I would try is a screwdriver/socket setup to allow good leverage and work on clockwise/anticlockwise to try and break it free.
 
I've been using a manual impact driver for 35+ years and I whack it with a lead mallet. It's never failed me and I have never damaged anything. One trick is to make sure you are twisting the screw undone as you whack so the force goes into the turning motion. Use nice grippy gloves and keep adjusting your grip. Stubborn screws usually come free with rapid repeated whacking. Very stubborn ones may need soaking with penetrating oil or PlusGas for a day.
 
ctva said:
Lustyd has it, use a cordless Impact Driver. I have found them invaluable.
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+1!

Not that I’d suggest this for smaller fasteners... but I recently had to revert to my 1/2 drive impact wrench to get the 8mm ss hex machine screws out of the base of our Lewmar 52s, using a 1/2 drive to 1/4 bit adapter.

Nothing else worked... plenty of heat, days of PBlaster doses, manual impact screwdriver with biggest lump hammer, etc.

I was about to ask another yard member to weld a nut on top, before I thought to adapt/try the impact wrench on the fastener itself. It wrecked the hex head, but with hex removal impact bits it actually came out with relatively little fuss (3 or 4 ‘ugga duggas’ and it was free!).

good luck!
 
vic008 said:
Not sure the alloy frame would appreciate me trying to heat countersunk ss screws.Personally have found oil a waste of effort unless under ideal conditions. I'm asking if the impact doesn't do it, is it a case of hitting it harder until it does (or bit shatters)
Click to expand...
With steel into aluminium I've had success pouring kettles full of water over the area. Squirt in a bit of penetrating oil and leave it a while; several kettles full over the course of a day or two. It is amazing how effective this can be!

If it was a small item I might try putting it in the freezer before taking it out and dropping it in a pan of boiling water.

Even if these techniques alone aren't enough to free it completely, I would think it would weaken the bond of the corrosion.
 
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