Gallery, Projects and General > How do I??
snapped centre drill
Stilldrillin:
--- Quote from: Arbalist on December 07, 2015, 05:10:32 AM --- I should add that unlike some I don't use mine for deburing or countersinking, I use a countersink for that!
--- End quote ---
The reason, they are at a 90* angle is to produce the chamfer. Before the hole is drilled.
The produced spot, is a larger diameter, than the finished hole.......
David.
Arbalist:
I only spot the hole, I don't drill to the full diameter with the spotting drill. For example I only have 6mm and 8mm spotting drills but still use these to "spot" or start holes of any diameter.
kayzed1:
Gents, this i will do in the future as today i found the box with it's 6 spotting drills. As has been said me being new and all that i put them in a draw as i had no idea what they were used for....I do now thanks...i will have a play tomorrow after i have fixed a sack truck for the pub up the road.. :beer:
Lyn. Ow! just had notice my 3phase kit will be here 10th to 12th in the am...so that will be the weekend job.
sparky961:
--- Quote from: awemawson on December 07, 2015, 03:12:07 AM ---Don't forget that if you do cut jobbers drills down to stub drill length, the diameter won't be accurate as drills taper slightly to create clearance. They will cut slightly under size.
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I've known for what seems like forever to measure drill bit diameter near the cutting lips but never realized that there is an intentional and surprisingly large taper as you mention. By large, I'm talking only a thou or two over the length from what I measured. Considering drills are generally only expected to rough your hole this is acceptable.
Thanks for providing that tidbit. I'm sure it will keep me from doing something silly at some future point.
Will_D:
--- Quote from: sparky961 on December 07, 2015, 05:31:40 PM ---are generally only expected to rough out your hole
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Ooohh Matron!
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