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+-- Thread: How ro drill round holes in thin sheet metal (/showthread.php?tid=7345437)
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RE: How ro drill round holes in thin sheet metal - Wizard of Oz - 01-04-2019
As odd as it sounds, the drill bit was too sharp.
RE: How ro drill round holes in thin sheet metal - Timberwolf - 01-06-2019
(01-04-2019, 12:11 AM)Wizard of Oz Wrote: As odd as it sounds, the drill bit was too sharp.
RE: How ro drill round holes in thin sheet metal - daddo - 01-06-2019
An old machinists trick. I saw it in an old machinists handbook - don't remember the date- somewhere in the 40's?
If you look at the end of the typical twist bit, you'll notice the very center line (web) that actually doesn't cut the metal and relies on the outer cutting edge to penetrate the metal. The back face of the drill can be ground to allow this dead spot to actually cut, and by relieving the backside some, the drill will cut through instead of push through the thinner material.
I grind a few bits this way for thin material.
You'll also see in the video you posted, that bit is not properly sharpened equally on each side, as it is chipping more on one side- this allows for grabbing the bit and pulling it out of round.
A bullet/split point bit works well for thin material.
RE: How ro drill round holes in thin sheet metal - Phil Thien - 01-06-2019
(01-06-2019, 01:29 PM)daddo Wrote: A bullet/split point bit works well for thin material.
It would be nice if those little drill bit grinders had a setting to sharpen for thin metals.
I've used brad-point bits in a pinch, drilling a very small pilot hole with a split point and then using a brad-point to follow-up. Bit I don't have a good wait to perform brad-point bit sharpening so I'm very hesitant to do this unless it is really going to matter.
RE: How ro drill round holes in thin sheet metal - daddo - 01-06-2019
(01-06-2019, 01:51 PM)Phil Thien Wrote: It would be nice if those little drill bit grinders had a setting to sharpen for thin metals.
I've used brad-point bits in a pinch, drilling a very small pilot hole with a split point and then using a brad-point to follow-up. Bit I don't have a good wait to perform brad-point bit sharpening so I'm very hesitant to do this unless it is really going to matter.
You can get a set of 29 bits at HF for 10 bucks when they're on sale- (expendable bits).
The HF saw blade sharpener works good for quick shaping of bits. I use the diamond blade it comes with to point the bits and sharpen my carbide cutting tools- even sharpen blades and other tools..
A quick touch on the bit is all that is needed.
RE: How ro drill round holes in thin sheet metal - Phil Thien - 01-06-2019
(01-06-2019, 05:10 PM)daddo Wrote: You can get a set of 29 bits at HF for 10 bucks when they're on sale- (expendable bits).
Those are my GOOD bits.
RE: How ro drill round holes in thin sheet metal - Timberwolf - 01-07-2019
(01-06-2019, 01:51 PM)Phil Thien Wrote: It would be nice if those little drill bit grinders had a setting to sharpen for thin metals..........................
I've used brad-point bits in a pinch, drilling a very small pilot hole with a split point and then using a brad-point to follow-up. Bit I don't have a good wait to perform brad-point bit sharpening so I'm very hesitant to do this unless it is really going to matter.
This video will demonstrate how to re-grind a bit for thin metal........My choice of a bit would be one of HSS.
https://www.youtube.com/watch?v=XA8L4L30TyI