Never seen one like that before.....Whats the hole for?It's a countersink bit, specifically a zero flute one.
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/133122384955
Never seen one like that before.....Whats the hole for?
incidentally the seller says " best countersink i have never used"...
The hole forms the cutting edge - and yep, best I've ever used too, no chattering!
Dave H. (the other one)
Thought it might but the "deburring" bit made me wonder
Used with little or no pressure in a pillar drill they make a good job of deburring a round hole.Thought it might but the "deburring" bit made me wonder
Same reason a fluted countersink has cutting edges all the way.
Well a fluted countersink has evenly-spaced cutting edges all around, thus even cutting pressure from all points on the circumference. If they had no relief then they would just rub like a badly-sharpened drill bit.
I see the Oxtools vid shows a tiny bit of spiral in the grind. I didn't know that. I wonder if the cheapo ones have it?
Yup the hole is the cutting edge and the chip is ejected through the other end.
Hard to explain but the pointy end isn't actually round, it's kind of offset to relieve the cutting edge.
I've never used one for countersinking rather specifically use them for deburring holes.
They can be sharpened too.
Good video on them and how to sharpen...
Thank you, I did not know that they could be re sharpened.
It is towards the end of the video mate.Daft question
How do you resharpen them?