Drilling Out Screw

I broke off both of the rusted screws holding my shower overflow plate on. I was able to back out the first one using a vicegrips but the other one broke off too short.
I cut it flat then tried to drill it out with a 3/32 bit but it sliped. Now I have a dip started in the center plus another grove down to the side. Do you need to apply a lot of pressure when you drill out a screw? How do you keep the bit centered? -- Bob Simon remove both "x"s from domain for private replies
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"I cut it flat then tried to drill it out with a 3/32 bit but it sliped. Now I have a dip started in the center plus another grove down to the side. Do you need to apply a lot of pressure when you drill out a screw? How do you keep the bit centered? "
This is always tricky. You need to start with a small center punch to make an indent dead center before drilling. It takes a moderate amount of pressure. Too much and you'll break off the small drill bit. And you pretty much have one shot at it. If you go off course and bugger it up, then you're in more trouble.
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On 17 Nov 2005 10:29:30 -0800, snipped-for-privacy@optonline.net wrote:

Yes, I broke my cobalt bit and, as you say, may have bugger'ed it up. I'm hoping that with a new bit and (hopefully) a steadier hand I'll be able to get back on track. -- Bob Simon remove both "x"s from domain for private replies
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If the screw location allows for a little off center, and you drill it a little "off" get a tap and retap it, or get a self tapping screw. Another trick, drill a larger hole, like 1/4". Assuming its brass, get a brass nut with the proper thread, and JB weld the nut to the rear of the hole. Allow to dry for 24 hours or more. If the pipe flange is very rare, or costly, take it to a machine shop that has a drill press. They will probably charge you $5 to $10 bucks, but they will get it out precise. A drill press is so much more steady than a hand drill.
Mark
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I need a little more help with this project. After successfully drilling out the center of a broken off screw, I thought the hard part was over. Apparently not.
Then I used a screw extractor to try to remove what was left of the screw. I used steady even pressure on the T-bar handle but the extractor bit twisted off in the screw.
1) How should I have done this differently so the extractor would have removed the screw without breaking.
2) Is there any hope of removing the extractor now? Bob
wrote:

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In your place I should ask the maker of the extractor tool whether his tool was designed to be stronger than or weaker than the screws it was to extract.
Prospects of removal do not look good. The original screw presumably has a a right-hand thread and the extractor was designed to use a left-hand thread. The effort you use to get the extractor tool out of the screw is likely to make the screw itself tighter, not looser.
--
Don Phillipson
Carlsbad Springs
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Bob Simon wrote:

You probably used too small a drill and too small an extractor. If they are small you have to be very careful to not put ANY side pressure on the drill or the extractor. The best bet when they screw is very small is just drill the whole think out and recut the threads for a larger size.
In your case you are screwed. Time to cut your losses and just get another part or just use one screw to hold the plate on.
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On Sun, 20 Nov 2005 22:16:01 GMT, "George E. Cawthon"

Thank you for your advice. Before I give up entirely on removing the extractor bit (and the original screw) I wonder if a high speed drill and diamond-tipped cutting bit might work. I've been wanting an excuse to buy a Dremel kit (or equivalent) anyway, just never had a specific need for one until now.
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wrote:

no.
if you take it to a machine shop, they can use a mill to get it out. it might cost you more to fix it than replace it though.
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It is possible to do this with diamond or carbide tools but it is not nearly as easy as it might seem. A rotary tool with a grinding type stone does no cutting at the center. Hard drills have edges that are very brittle and easily broken if not cutting steadily against a smooth surface. Hand holding the tool gets difficult as the bit contacts the work and tries to fling the tool sideways. The bit tries to move away from the hard extractor and into the softer metal around it. It is your decision and there is not much to lose in trying it if you are careful not to get something in your eye or otherwise hurt yourself. You will at least gain experience. [I always try to repair unrepairable things just to see if I can or to learn why I can't! :>)] Don Young
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Bob Simon wrote:

I think they are made to break off, leaving you no choice but to buy a new "whatever". If everything around the broke off extractor is metal you can heat up the extractor till it is red hot and let it cool a little then try drilling it out. The heat will take the temper out of the extractor.
--
JerryD(upstateNY)



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Bob...I feel for ya!
I did this very repair this weekend...and like you chased alternatives all over the place. My resolution was to take the wall access cover off, remove and replace the upper assembly...finally life is good.
My problem started when I tried to drill the screws out, and of course the brass is much softer than the screws, and the new holes drifted off center, too much to recover. The correct drill for 1/4 NC tap is I believe a number 7....yup bought them too!
BTW -- a local hardware store sold the upper assembly (brass) for $40, where as the BORG sold the whole brass assembly including gaskets, washers, nuts and all for $30. Replaced the upper half...now all the lower half is left over. They also have plastic assemblies for about half that.
Best of luck to you...
Darwin
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