How to Hand Sharpen a Twist Drill

[TomG]

Here's another one take wonder on the basics of hand sharpening a twist drill.

Tom

[mikecwik]

Easy as pie! Who cant do that with the same accuracy as a machine?.....(snide sarcasm intended)

[TomG]

I don't know if it's easy as pie Mike, but it's certainly not that difficult. Perhaps the difficult part is presenting the technique in such a way that anyone can figure it out.

Tom

[mikecwik]

I spent a lot of time trying to pick up this skill and even just getting one to cut again isnt easy let alone to make a tip that is anywhere near factory or special made grinder geometry is pretty impossible.

I wish I had access to an optical comparator and knew someone that was really good with free handing them.

[Mayhem]

One of the best things I did was to buy a drill sharpening gage off of eBay. Not only does it allow you check the angle you are grinding but also the length of each cutting edge.

This was about $7. I could probably get a new one cheaper but this one has a bit of history attached. I think the Union Twist Drill Co. no longer exists, as I couldn't find anything with a quick Google search.


  DrillGauge.JPG (Size: 31.73 KB / Downloads: 169)

On the weekend I broke a 3.5mm drill and was able to sharpen it to finish off the job. I'd certainly have to put on the magnifying lenses if I wanted to sharpen anything smaller!

Edited to fix typo

[stevec]

I think I may have posted this before.
   
I believe I picked up a couple at Busy Bee a while back.
I don't think they carry them anymore.

[TomG]

Yeah, I forgot to mention the sharpening gauge alternative. I actually don't use a gauge at all anymore except on larger drills. Getting the geometry correct has sort of become second nature.

Tom

[dallen]

sharpening drill bits by hand is one of them some can and some can't things that I don't do very well. and I've had the dang gauge for about 25 years. So I got me one of them things you bolt on the bench

[Mayhem]

I must be honest and say that I didn't actually watch the video until now, as I was in a rush earlier and (wrongly) assumed it was a link to one of the ubiquitous drill sharpening videos on YouTube. Then I heard a familiar voice and gave the vide due course and attention.

The main issue I have is setting the initial angle on the cutting edge. The back relief isn't a problem but I sometimes wonder how much angle to place on the cutting edge. I roll away from the cutting edge to create the back relief but I may try your method as well.

Thanks for making the video Tom.

[TomG]

(12-17-2012, 08:40 AM)Mayhem Wrote: I must be honest and say that I didn't actually watch the video until now, as I was in a rush earlier and (wrongly) assumed it was a link to one of the ubiquitous drill sharpening videos on YouTube. Then I heard a familiar voice and gave the vide due course and attention.

The main issue I have is setting the initial angle on the cutting edge. The back relief isn't a problem but I sometimes wonder how much angle to place on the cutting edge. I roll away from the cutting edge to create the back relief but I may try your method as well.

Thanks for making the video Tom.

Thanks Darren.

The angle of the point is basically related to the hardness of the material to be cut. Choose a flatter point (135º) for tool steels and stainless and a steeper point for softer materials like mild steel and non ferrous metals. The trade offs are that while a flatter point will dissipate heat more readily it will also be more apt to wander. By the same token, a steeper point will self center, but wear more quickly.

I opted to do the faceted clearance angle just to keep things simple and basic. The rolled back relief is the norm, but takes more skill to get it right.

Tom