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how to remove a stubborn screw?

Canadium

Canadium

Ian
I've been trying to dismantle the apron on my old South Bend 9A lathe in order to clean it all up. The gears are jam packed with crud and oil channels are all plugged up. I got it all apart except for the clutch. The clutch has a left hand threaded nut holding a star shaped knob. This nut is notorious apparently because people turn it the wrong way and break it off. So it seems to me that I am turning it the right way for a left hand thread (clockwise) and still I have been unable to loosen it. One complicating factor is that the screw has only a shallow slot so a screwdriver pops out very easily. I've tried heating the knob and hammering on the screw to loosen it without success. Any thoughts on how this stubborn problem can be conquered?

SB9A clutch screw.jpg
 
Hmmm... putting that on my Christmas tree list (only 4 months away LOL).
About how much angular rotation equals 1 thwack? Or is that somehow settable?
 
They are not adjustable. The amount of turn depends on how firmly you hold the driver and how carefully you preload it but even at best I don't think it would exceed 15 degrees. I use them all the time. They do work most of the time. But I broke the head off of a screw that holds the flange on to my back gear belt pulley that way. Don't use it on sintered metal.
 
Other approaches include heating the part with the hole and cooling the stud. Liquid propane is an option if you are no where near flame. But you can also buy a can of freeze at electronics places
 
I guess I should add that when all else fails, (as it might with a stripped flat head screw......) drill off the stud then use a screw extractor. If that doesn't work, fully drill the stud and then re tap. And install a torx screw to replace it with.
 
Another way if impact driver not available and you have any sort of Hyd press. mount your framework on press frame and insert screwdriver bit (just the bit) in slot and lower press hyd rod to just firmly hold the bit in place....now turn the bit with a wrench. Rod pressure will hold the bit from exciting the slot and lots more "turn force" can be put into it.
 
YYCHM said:
You can change the direction of rotation though.
Click to expand...

Yes. That would work for left hand screws. But, I cannot ever imagine using it to deliberately tighten a screw or bolt. I'd go WAY out of my way to put in a torx screw and a proper wrench instead.
 
Eureka! I went and got myself a manual impact driver first thing this morning. Got the screw off right away when I got home! Thanks everyone for your input and great advice! Love this forum!!!
 
Go for you! They are a great tool! Put the hot/cold trick in your trick basket too. Combined with the impact driver, it's the best there is. Just don't hit sintered metal with that thing. Ask me how I know that.....
 
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