Shake-n-break versus impact gun

[Packard V8]

For removing rusted Phillips screws, such as those in the door hinges of older cars, there are those who swear by a air chisel and a shake-n-break. I personally use an impact with a chuck and bit. Sort of the same but different.

For those of you familiar with both, which do you choose and why?

jack vines

 

[mattygee]

They essentially do the same thing, but the impact is quicker if the conditions allow... The shake n break (or screwknocker) is useful for recessed drive screws like Phillips or allen. Particularly in aircraft applications, there is no substitute for a screwknocker when your faced with a 100 or so over torqued screws that have been painted over. Have both in your tool box.

M

 

[The Ratchet Man]

Never saw one of these before. I could of used one of those the other day, and probably still can, but didn't know they existed.

What B&M store would carry these so I can look it over before I buy?

 

[Jagmandave]

An impact is difficult to control as to the speed of rotation of the bit, it seems like it's either all or nothing.....I tried using one just yesterday to get some stuck license plate screws out, didn't work for ****. I wound up getting out the cutting wheel and grinding the heads off.

FWIW, a shake and brake probably wouldn't have worked either in my situation.....the aluminum "rivnuts" were turning with the screws, and even tho I had access to the back to hold them, I couldn't keep them from turning.

How does a steel screw "rust" in an aluminum nut?

 

[EOC_Jason]

Man, now I need to get me one of those and an air hammer...

 

[jrlp]

An impact is difficult to control as to the speed of rotation of the bit, it seems like it's either all or nothing.....I tried using one just yesterday to get some stuck license plate screws out, didn't work for ****. I wound up getting out the cutting wheel and grinding the heads off.

FWIW, a shake and brake probably wouldn't have worked either in my situation.....the aluminum "rivnuts" were turning with the screws, and even tho I had access to the back to hold them, I couldn't keep them from turning.

How does a steel screw "rust" in an aluminum nut?

Galvanic corrosion. Any time 2 different metals are in contact, and water gets between them, they make voltage. Exactly like a battery does, except battery material is designed from the ground up for it. So it's a very small potential, but it happens.

If they ran the steel screw in fast, they could have also caused galling of the rivnut. That's where the bearing face of the nut overheats, melts, and smears on the bolt, but only a few thousanths.

Couldn't get a vice grip on the back of the nut? If you have access to the back, sometimes hitting them from the back with a hammer or pushing against them pushes a thicker section of the nut into the hole, and you can remove the screw normally.

 

[Packard V8]

Thinking about it, is the "screwknocker" pretty much like an old hit-it-with-a-hammer manual impact driver with a side handle and an air hammer head attached?

jack vines

 

[finn]

I bought a Shake-n-Break to loosen some rusted screws on a windshield frame. It failed to do the job so I ended up drilling the screws out.

Quite a disappointment.

I'll try it again, I suppose, but for now it sits in the back of my box next to Bob Villa's Robogrip pliers.

 

[Jagmandave]

Couldn't get a vice grip on the back of the nut? If you have access to the back, sometimes hitting them from the back with a hammer or pushing against them pushes a thicker section of the nut into the hole, and you can remove the screw normally.

I did get a vice grip on the back, but it just broke the rivnut in two, once I had the heads of the screws ground off, I just worked the rivnuts out of the holes and use screws and nuts to attach the new plate. Job done.

That was the problem with using the impact wrench, it wanted to spin the bit so fast it just tore them up.

But I got 'er done, and didn't damage the metal on the decklid, so it's good to go.

 

[mattmankow]

Shake and break is totally different than an impact and screwdriver bit. S&B "impacts" into the screw head, where as the impact and bit "impact" in a turning motion, not putting pressure into the screw. The impact will tend to jump out, stripping the screw. The S&B is impacting the bit into the threads with every blow and you twist out with the handle. The one fault I have found with the S&B is, unless you lower the intake air pressure, when using a REAL air hammer, you will mushroom it into the air hammer. S&B directions say to turn down the pressure, but who does that?
Verdict? They have their place and well worth their $40 tag.
I built my own version by welding an old extension onto an old impact bit with an old ratchet handle welded to that. I'm cheap! And it can handle the impact out of my ph3050, unlike the S&B version.

 

[WVBrady]

Man, now I need to get me one of those and an air hammer...

Make sure that they are compatible. The screw knocker that I got would only fit an aircraft rivet gun, not an ordinary impact gun. However, I was able to grind it to fit. I haven't used mine yet. The screw that I wanted to use it on wouldn't wait for me to grind the tool to fit.

 

[Packard V8]

Shake and break is totally different than an impact and screwdriver bit. S&B "impacts" into the screw head, where as the impact and bit "impact" in a turning motion, not putting pressure into the screw. The impact will tend to jump out, stripping the screw.

No, not exactly. I've removed hundreds of screws with an impact gun and bit without stripping them. The obvious technique is to lean the gun hard into the workpiece. If the bit is a good quality and the screw is also, one of two things will happen. Either it screws out or twists off at the surface of the threads.

So the screwknocker doesn't have any "undo" action of it's own? The operator has to turn out the screw manually?

jack vines

 

[Provincial]

No, not exactly. I've removed hundreds of screws with an impact gun and bit without stripping them. The obvious technique is to lean the gun hard into the workpiece. If the bit is a good quality and the screw is also, one of two things will happen. Either it screws out or twists off at the surface of the threads.

So the screwknocker doesn't have any "undo" action of it's own? The operator has to turn out the screw manually?

jack vines

Or the third result, which is that the bit breaks and skips across the aluminum skin with the jagged edges. BTDT

 

[reptilezs]

Make sure that they are compatible. The screw knocker that I got would only fit an aircraft rivet gun, not an ordinary impact gun. However, I was able to grind it to fit. I haven't used mine yet. The screw that I wanted to use it on wouldn't wait for me to grind the tool to fit.

i bought a screw knocker on ebay and it fit my air hammer just fine. my hammer is a ingersoll rand 121

 

[EOC_Jason]

No, not exactly. I've removed hundreds of screws with an impact gun and bit without stripping them. The obvious technique is to lean the gun hard into the workpiece. If the bit is a good quality and the screw is also, one of two things will happen. Either it screws out or twists off at the surface of the threads.

So the screwknocker doesn't have any "undo" action of it's own? The operator has to turn out the screw manually?

From what I saw / read of the screwkockers, they operate like this: Your air-hammer just keeps pounding away at the screw, while you take the handle / bar of the screwkocker to manually loosen the screw. I would think it would be less prone to stripping out a screw since you are putting the torque and can tell if it's going to slip out or not.

 

[Tavy]

If it's well and truly stuck, air hammer turned down and a screwknocker. Just a bit too much for by hand, impact. The impact tends to slip out or break bits when you really need to hammer on it for an extended time to break it free, while a screwknocker gives you some room to play with it before you break stuff.

PACCAR loves their Phillips head screws everywhere, including in floor pans in Upstate New York. Genius plan really. If they'd use Torx, at least you could break the heads off and deal with it later -- bad ideas? Aluminium nutserts, regular steel bolts, fiberglass cab roof. Don't even touch the drill, it won't end well.

 

[Shadowdog500]

I use something similar for brakes that is made for a regular air chisel.

It removes bleeder screws and those screws in the rotors like nothing.

I put this on my snap on air chisel and everything it touches comes right off.