How To Regrind Drill Bits Using a Quorn Tool & Cutter Grinder

In this video we demonstrate the process of precision drill grinding with conical flank relief on a shop-made Quorn tool and cutter grinder.

References:
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About Chronova Engineering Ltd:
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Credits:
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Filming: Alastair Godfrey
Editing & voiceover: Mike Godfrey

[kroon]

I used to do this back at tech college, along with cylindrical and flat grinding.
Loved the precision of the work

[DK-vxzc]

Thank you for creating this video!! Very interesting indeed. A bit fiddly in setup, but excellent results. I suppose once you get used to the setting up, it goes smoothly. Very precise results. Drills perfectly.. Rivals some very expensive drill grinding equipment.

[ParaBellum]

Excellent! I was taught to sharpen drills manually, and the activities of offsetting the bit and rotating it about an imaginary conical path (i.e., how I was taught) seem similar to the way this device works. Though I say so myself, I'm pretty good at sharpening drills, but it's fair to say that while mine cut holes through metal, they can't be as accurate as machine-ground bits.

[jme]

Thank you for taking the time to showcase the Quorn T&C ! It jas been on my dream project list for a few years and this is an inspiring example👍

[forrestaddy]

Very clear tutorial for that particular machine.

I'd raise a separate issue: that drill has been accurately ground on the cutting edges but not properly sharpened.

Note the worn margin lands adjacent to the corner intersection. While this drill would perform adequately in soft steel, aluminum, or brass, production drilling in tougher or harder materials would not go too well. The worn land has in effect a forward taper that will tend to wedge against the walls.

The worn margins chafe against and work harden the hole walls resulting in heat, short tool life, poor finish, and possibly siezing.

That worn drill should have been rough ground back at least 3mm to clean undamaged margins then sharpened.

[MrUltraworld]

When I entered machinist school in the mid 70's, one of the first things we learned was how to sharpen a drill bit. Nearly 50 yrs on, I can sharpen a drill with my eyes closed. Seriously.

[thomasbyg]

All elements in a well conceived and executed production. So well done! Thank you.

[ramonching]

Fantastic grind! The two chips came out simultaneously. 👍👍👍

[iiredeyeiiredeye]

Brilliant machine. lovely grind...almost feel like I've wasted 35 years perfecting this by hand.

[gangleweed]

Now all we need is a Quorn cutter grinder., it is a it tedious think I'll stick to hand grinding drills like I've always like the video, very clear instructions for anyone who also has a D bit grinder.

[davidjames]

Looks great well built, not sure I would have the commitment and patience to build that, setting up is also rather difficult it seems.

[andrewdolinskiatcarpathian]

Very interesting and informative. Thank you for sharing. 👏👏👍😀

[valkman]

It's lovely that these guys refer to each other as doctors and misters ... like someone need emphasize how sophisticated the people behind these home shop projects are. Just tell Jack designed it and let the end product speak for itself.

[shanemeyer]

I’d really love to build and own a universal tool grinder but sadly I don’t think my small Sherline lathe and mill are capable to making the parts for this, maybe one day I’ll see one on the market place and make the purchase. Absolutely fantastic content as always from this channel

[deths]

Now I see why my manual grinding technique makes my bits feel duller. I put all my work in the tip edges and didnt think the relief would need to be cleaned up too.

[AkilaRodrigo-sk]

where I can purchase above type of magnifier ?

[FCleff]

Thank you for publishing this video. Will you be discussing how to calculate the axial and radial offsets for any given drill size? I've watched this beautiful video several times and I would like to try this technique on my QUORN using my version of Professor D.H. Chaddock's (designer of the original QUORN) "Setting Micrometer" to set the axial and radial offsets. My version can do axial and radial offsets up to 1" but I have no idea how to do the calculation for a specific drill size.
Thanks again.
F.C.

[eegaugh]

I think I saw that J Hugel died recently. I would have liked to witness a discussion between him and Professor Chaddock!
Thank you for making his drill-grinding process more intelligible. I note that you are using an extended mounting bar for the work-holder.

[micmike]

Yes, enjoyed the setup. Keep wondering if there is a simpler way?

[speenlmar]

Believe me a decent manual grinding gives very useable results.