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Old 25-06-2009, 02:23 PM
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Hawkeye Hawkeye is offline
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Re: Derby Cover & License Plate Holder

Quote:
Originally Posted by Limey_Dave View Post
I suspect you may have started with too large a bit,with a 1/4" derby cover screw you only need around 3mm,this would have hopefuly left enough slot to pop the heads off and leave some "trunk" to remove the screw.
The screws are Grade 8 so quite hard to start with but a Dormer,Osbourne,etc drill idealy tin coated and ground flute.
The Makita although HSS was prob a Jobber Drill that are disposable and not the best for accurate work.
If you use 3mm you need min speed of 1100 RPM but main thing is to keep it cutting not rubbing.
If you have a second pair of hands fill a squeeze bottle with water and just dribble it on the cutting area. Should be coolant but water is better than nothing at all.
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