End mill for drilling indents?


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Old 02-17-17, 07:13 PM
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End mill for drilling indents?

I'm doing some suspension work on a dirt bike and the seal I need to replace requires drilling out four indentations. The seal is contained in a cap that is screwed into the end of the assembly and held in place by four indents. Last time I worked on this type of fork, I drilled them out using a regular taper ended 9/64 drill bit, but due to the taper I can't drill out as much of a relief as I would like. I was thinking a flat end mill bit would work much better. Is there any reason why I couldn't use such a bit in my drill press? I suppose the most critical thing is that I can keep the workpiece perfectly still while drilling since the bit has no taper? Here's an example: https://www.amazon.com/gp/aw/d/B00NE...NQL&ref=plSrch
 
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Old 02-18-17, 04:19 AM
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The only problem I see is getting it centered.
 
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Old 02-18-17, 04:33 AM
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Like most machining half the job is figuring out a good way to clamp and hold the part. End mills don't have a center so the bit wants to walk especially if it touches one side of the indentation first. If you can securely clamp the cap to the table on your drill press you should be able to use an end mill. Occasionally lift the bit to clear the chips as they don't get carried up and out like a drill bit.
 
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Old 02-18-17, 04:53 AM
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Not sure that I have the right picture in mind, but, if you are trying to cut away more of the lip around the dimple, could you use a larger diameter bit that would not drop into the depression as far?
 
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Old 02-18-17, 04:55 AM
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I have a vise bolted to my drill press, so I should be able to keep it pretty still. Another option would be to use a regular larger diameter bit to get the hole started, then switch to the end mill. That way there would be a wall to guide it/keep it centered.
 
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Old 02-18-17, 04:58 AM
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I can't do that because I would be drilling into the cap's threads. I have to stop as soon as I break through the tube/indent.
 
 

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