Elongating holes


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Old 12-14-20, 04:31 AM
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Elongating holes

I have a 1/4" piece of steel with 5/16" holes that I need to elongate by about 1/4". Tool recommendations? Rattail and do it by hand? Is there a blade I can put in a jig saw to hog out the material or a bit for a dremel tool?
 
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Old 12-14-20, 05:07 AM
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Drill a 5/16 inch hole centered 5/32 inch from the existing 5/16 hole and use a flat file to remove remaining metal.
 
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Old 12-14-20, 05:53 AM
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Since you already have 5/16" you really can't drill next to it without making a longer slot. When your drill bit touches the edge of the existing hole the bit will walk and break out into the hole. Going the 5/16" (plus a tiny bit) from the edge of your existing hole as beelzebob recommended will prevent your drill from breaking out into the old hole. Then you can use a file to smooth the sides and make a true slot but it will be about 5/8" long.

If you just need to make slots and it can be in either direction then use a 5/16" drill bit and tip the drill back and forth in the hole. Then you can use a rat tail file to open up the ends of the slot. You can also slot the whole way with a rat tail file but that will be slow. You can also use a grinding bit in a Dremel. Or, a small enough fine tooth blade in a jigsaw. Basically use whatever you've got.
 
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Old 12-14-20, 07:32 AM
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Thanks for the advice, appreciate it very much.
 
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Old 12-14-20, 10:21 AM
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I used a Dremel chain saw sharpening bit to enlarge a 1/4" hole. It took about 2 minutes.
 
 

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