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03-14-2010, 08:46 AM #1
Best way for removeing old Flat head machine screws
What are some good ways to remove old stuck flat head machine screws? Any I've tried kerosene as a thin oil and ground screwdrivers and tool metals to match it up as best as i can but this one screw really wants to round out, but the other three came out with little trouble.
03-14-2010, 08:56 AM #2
An impact driver will usually do the trick. In case you don't know, this is typically a tool on which you'd mount a socket with the proper blade in it. To the average guy, its usage may seem a little mysterious because it doesn't look like much
Then you cock it by turning the socket one way or the other (after the first blow, reset it in the only direction it will rotate). Then put the blade on the screw and hit the end of the impact driver handle with a hammer. The action of the hammerblow simultaneously keeps the blade well seated in the screw and turns the socket a partial turn.
03-14-2010, 08:58 AM #3
These work well:
- Harbor Freight Tools - Quality Tools at the Lowest Prices
I'm not endorsing HF, just an example.
03-14-2010, 09:03 AM #4
If impact doesn't work, drill it out with a LEFT-HAND drill bit. Most will just wind out. I rarely have to use an "easy out" when drilling LH.
03-14-2010, 09:04 AM #5
I just weld a hex head bolt to them, wire feed or tig, works great. I used to remove them from the blades of reel type mowers for a golf course, weld the bolt to the first one, remove it and weld both to the next, all 3 to the next and so on. I would somtimes have 10 welded together. I could get 7 1/4 28 flat head cap screws out in less time than it takes to tell about it.
03-14-2010, 09:16 AM #6
Use WD-40. Putting pressure on the screwdriver just hammer it few times. This should work. Using hammer will help you feel how match pressure to put on the screwdriver.
03-14-2010, 09:21 AM #7
try a brace
I've had good luck using a brace with a screw driver mounted in the chuck, they come in different swings, 6-14" 8 and 10 being most common. Usually can get a very good old one for $3-$5 around here. The better ones will grip a round shank but all will grip a hex shank . You can get good downward pressure and if you wiggle the crank back and forth gradually increasing the force counter clockwise usually you have success. Too much torque will break off the screw so go easy and use a lubricant and heat if possible. As mentioned already the impact drivers are godsends.
03-14-2010, 09:26 AM #8
A hammer and center punch works well also. With a center punch mark out near the edge of the head the screw can be rotated by driving the center punch at an angle to force the screw to rotate.
03-14-2010, 09:35 AM #9
I like the brace idea, welding would put some heat into job and loosen things up and impact drivers are certainly a great help. I can imagine the job Moonlight would have otherwise had with his mower screws which spend their lives soaked in grass juice!
You would never get the cross point screws out of a Jap bike aluminium alloy crankcase without an impact driver and they don't have to be expensive to work. Pity they never put a bit of lube on 'em when they put them in.
03-14-2010, 09:36 AM #10
The older metric motorcycle had tons of these buggers. First try the impact driver as suggested already, if no joy, big center punch mark and drill 1/64 smaller than the shank size. This will usually leave the head on you drill bit, or a twist with a screwdriver will break it off. The shank of the screw will usually unscrew with your fingers after your separate the parts.
03-14-2010, 09:44 AM #11
Use one of those screw remover designed to dig into the head of the screw. I can't remember the name for them. if that doesn't work break out the welder.
03-14-2010, 10:04 AM #12
Of course I have an impact driver that I try first, but the vast majority of times I have to use the center punch method. I had bought a pack of five Starrett 1/16" center punches to use because all my others just dulled too quickly. I still have all five and haven't had to resharpen any.
03-14-2010, 11:50 AM #13
First thing to try is to take a piece of bar a bit smaller as the head and give it some good blows with a hammer
In many cases that will do the trick
Peter from Holland
03-14-2010, 02:52 PM #14
Peter, has it right
if the head of the screw is half inch, just use a half in diameter punch
and use a couple of solid hammer blows straight down on the screw.
99 times out of a 100 the screw will come right out.
03-14-2010, 07:16 PM #15
Peter and Bob have it right. I've used that method many times. Works 99.9% of the time.
03-17-2010, 05:23 AM #16
If you can get the part onto a drill press chuck a bit that fits the screw slot then bear down on the screw using the drill press and rotate the chuck by hand to back the screw out. By using the drill press you eliminate the possibility of the bit climbing out of the slot and get plenty of torque from turning the chuck by hand.
03-17-2010, 06:11 AM #17
03-17-2010, 02:49 PM #18
A little lapping compound on the tip helps reduce the tendency of the screwdriver bit to cam out of the slot under torque.
MikeS-54 liked this post
03-17-2010, 02:57 PM #19
03-17-2010, 03:50 PM #20
I second the TIG welder approach. This is the easiest way on the old cars I work on. Attached photo is a cylinder block assembly for a 30 Rolls Royce which someone had broken a few of the water jacket studs. When I got it one was drilled below block level and the other two were at block level. I put a #12 nut over each one, a 1/16" tungsten in the TIG. Drew an arc on the stud and with a fine filler rod built it up and into the nut. When cooled they turned right out. Also works well on head studs in aluminum blocks ie my 36 Rolls.