Machinists: critique my twist drill sharpening.

6879 Views 65 Replies 23 Participants Last post by fj40guy, Jun 1, 2004

rusted

Discussion Starter · Jan 1, 2004

Ok, I've read and heard about those expensive, fancy, store bought drill sharpeners. Drill Doctor is about the cheapest little thing you can buy. You can get crazy with a CNC twist drill sharpener that will run you $18,000 and cut a twist drill into a miniature mouse dildo.

BTW, we're in the metal shop, so these are not 'drill bits'. You gotta go next door to 'The New Yankee Workshop' to find those. Here in cutting oil land we call them twist drills. Don't ask me why, it's just what I read.

So, being a poor man, and hearing that 'old machinists' could sharpen twist drills on their own, in their sleep, I was of course intrigued.

Newer twist drills have a 'split point' edge. In order to sharpen them using this method, you have to 'thin the web' I don't have this problem since I have the cheapest bits around, so I don't have anything to critique there. I could figure it out I bet.

I put the grinder rest at an angle I figured was conservative.

I measured the cut angle by placing a large bit on the face of the stone and marking the shank resting on the guide with a sharpie.

Only the most precise methods for me!

I eyeballed the edge to get it centered, and I think I did pretty good. The picture I took was with one hand holding it 18" from my body. With two hands it doesn't walk at all. Using a center punch it doesn't walk either of course, and the hole's not egg shaped.

It's not the 'sharpest' thing around, but I drilled 7 or 8 holes, and had no dulling I could tell.

This is the drill I used as a guide:

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rusted

Discussion Starter · #21 · Jan 1, 2004

That's cool, if I ever have a chance I will pick up a used DD 750.

Here's what I did on a hardened lawnmower blade. I'm very very happy with the results. Usually, this would take me all day.

I can go anywhere and do this as well. Sorta like stick welding, I'm glad I learned this before getting accustomed to a DD.

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rusted

Discussion Starter · #22 · Jan 1, 2004

frankenfab said:
The cutting edge (in blue in the picture) should be higher than the trailing edge (in red). I can't tell from your picture if you ground it this way. I bought a Drill Doctor Journeyman 400 and it is well worth the money. I use it all the time.

Yes that's the way it's cut. The adjustment of that angle is what makes the diff between a more aggresive and milder edge. Thank you for confirming that!

mj

· #23 · Jan 1, 2004

thank you
this is good tech
even if you buy a drill doctor it is better to know how to do something correctly

rusted

Discussion Starter · #24 · Jan 1, 2004

ForestCam said:
Well my wheel is shit at the moment (gotta get me a dresser) and even with the small amount of set up with the DD it's faster and easier. My brother went through about 100 old bits he had in a coffee can in about a half hour. Once you getthe hang of it it only takes a few seconds per bit and the biggest plus is on the big bits. Ever pull the it off to check your angle only to put it back against the wheel and fawk it up?:laughing:

No, I'm an expert already, what are you talking about? :flipoff2:

:laughing: Seriously, I'm having very very good results so far.

ForestCam

· #25 · Jan 1, 2004

2

frankenfab said:
I bought a Drill Doctor Journeyman 400 and it is well worth the money. I use it all the time.

Cool beans!

Drill Doctor 750SPK $139.99 w/free shipping @Amazon plus there's a $10 mail in rebate!

Hmmmm...Sleggtools.com has the same model with the left hand chuck added for $10 more....desisions desisions.....

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rusted

Discussion Starter · #26 · Jan 1, 2004 (Edited)

ForestCam said:
Cool beans!

Drill Doctor 750SPK $139.99 w/free shipping @Amazon plus there's a $10 mail in rebate!

Hmmmm...Sleggtools.com has the same model with the left hand chuck added for $10 more....desisions desisions.....

I was contemplating buying a DD, and adding it to my considerable tools list.... as in, this is $140 further away from my T/A 185TSW. Not anymore, this puts me a few weeks closer to my TIG welder! :bounce: :laughing:

As a matter of fact, I haven't seen a DD in use in person, but I've read the tech articles. At this point, I consider one a waste of money and shelf space. I'll qualify that because like I said I haven't used one. But at this point, I don't NEED one!

Supergper

· #27 · Jan 1, 2004

rusted said:
I was contemplating buying a DD, and adding it to my considerable tools list.... as in, this is $140 further away from my T/A 185TSW. Not anymore, this puts me a few weeks closer to my TIG welder! :bounce: :laughing:

As a matter of fact, I haven't seen a DD in use in person, but I've read the tech articles. At this point, I consider one a waste of money and shelf space. I'll qualify that because like I said I haven't used one. But at this point, I don't NEED one!

the only reason you say you dont NEED a DD is cause you have never used one...once you use one you will agree with everyone else that has and say its a must

I love mine...get a perfect edge without heating the bit and I can choose what angle I want...and if I want to sharpen split points then I can do that...I wouldn;t go without a DD

toryranger

· #28 · Jan 1, 2004

flattening the drill point for harder material is a fairly standard thing to do. Watch that the two flutes of the drill are the same lenth when you resharpen it, if they aren't the drill will cut oversize. This can make a difference if you are trying to get a close tolerance hole or drilling for a tapped hole. I was a machinest for 30 yrs and preferred to hand sharpen almost all drills rather then use a machine. On a drill the face of the flute is what is actually cutting, not the end so the Tin coating is still on it. It isn't as good as a fully coated drill but still better then one that isn't coated. A good alternative to tin coat drills is to get cobalt drills.

ForestCam

· #29 · Jan 1, 2004

rusted said:
I was contemplating buying a DD, and adding it to my considerable tools list.... as in, this is $140 further away from my T/A 185TSW. Not anymore, this puts me a few weeks closer to my TIG welder! :bounce: :laughing:

Damn you for thinking logically! *putting my adapter money away*:flipoff2:

rusted

Discussion Starter · #30 · Jan 1, 2004

toryranger said:
flattening the drill point for harder material is a fairly standard thing to do. Watch that the two flutes of the drill are the same lenth when you resharpen it, if they aren't the drill will cut oversize. This can make a difference if you are trying to get a close tolerance hole or drilling for a tapped hole. I was a machinest for 30 yrs and preferred to hand sharpen almost all drills rather then use a machine. On a drill the face of the flute is what is actually cutting, not the end so the Tin coating is still on it. It isn't as good as a fully coated drill but still better then one that isn't coated. A good alternative to tin coat drills is to get cobalt drills.

Thank you! That totally confirms what I found, in my 'secret' paragraph. As long as you get them both the same, the hole will be perfectly round, and so tight the twist drill will actually 'pop' out when you pull it out.

I've heard like you say: Machinists would rather sharpen their own than use a machine, unless it was neccessary. That's where I want to be!

Now getting catalogs is a dangerous thing. I don't know jack about the machinery world, but I'm learning! I learned you can just get sick with this drill sharpening, and that the DD is an amazing little device to put split points on drills for $140!

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rusted

Discussion Starter · #31 · Jan 1, 2004 (Edited)

Supergper said:
the only reason you say you dont NEED a DD is cause you have never used one...once you use one you will agree with everyone else that has and say its a must

I love mine...get a perfect edge without heating the bit and I can choose what angle I want...and if I want to sharpen split points then I can do that...I wouldn;t go without a DD

Nope, don't need it. I just drilled a hole and tapped it out, just to see. No problem. If I'm having a problem with precision above that, I'll go buy a brand-new bit.

PBB, home of Bling-bling, get all the best, every tool for every possible application

:flipoff2:

It's funny that the old hands got by without all the crap that is supposedly 'necessary' if you listen to this forum.

*edit* Besides that, this thread is about bench grinder twist drill sharpening, not an ad for the Drill Doctor, thanks. BillaVista already wrote an excellent article about the Drill Doctor here. I can't imagine you have much to add besides testimonials, which don't belong in the tech forum but in Chit-chat. :flipoff2: So thanky anyway.

ForestCam

· #32 · Jan 1, 2004

rusted said:
It's funny that the old hands got by without all the crap that is supposedly 'necessary' if you listen to this forum.

Well if believe everything you read here as being nessesary you'd cut your upper shock mounts off and go with Fords when doing a SAS instead of leaving them and using your IFS shocks.

toryranger

· #33 · Jan 1, 2004 (Edited)

About 1/2 way down this web site http://www.machine-tools.org.uk/guide1.html there is a great section on hand sharpening drills. The drill sharpening gage shown is a great tool, It helps a lot to make sure the 2 flutes are the same angle and lenth, I got mine from Starrett years ago, general makes one that is cheaper and might be found in a hardware store or sears.
http://www.jdrtool.com/
http://catalog.starrett.com/catalog/catalog/groupf.asp?groupid=211
http://www.artstuff.net/multi_use_rule_and_gauge.htm

EDIT: Yup I'm a noob on PBB but I sure can search

rusted

Discussion Starter · #34 · Jan 1, 2004

toryranger said:
About 1/2 way down this web site http://www.machine-tools.org.uk/guide1.html there is a great section on hand sharpening drills. The drill sharpening gage shown is a great tool, It helps a lot to make sure the 2 flutes are the same angle and lenth, I got mine from Starrett years ago, general makes one that is cheaper and might be found in a hardware store or sears.
http://www.jdrtool.com/
http://catalog.starrett.com/catalog/catalog/groupf.asp?groupid=211
http://www.artstuff.net/multi_use_rule_and_gauge.htm

EDIT: Yup I'm a noob on PBB but I sure can search

Wow thanks! That's the kind of stuff I was looking for!

Who cares about being a newbie. I'm not a newbie and I don't know shit. There's a lot of 'Rock Gods' (

) around here I wouldn't trust with a C-clamp.

BEAR

· #35 · Jan 1, 2004

This post couldnt have come at a better time, I just recieved a box full of my late grandfathers bits.

Ive been sharpening my own bits for years but not with great consistency, that link will help alot!:beer:

BillaVista

· #36 · Jan 1, 2004

Noticed some talk of "precision".

Just a note (and I *think* any machinist will tell you this) that any twist drill is just a rough hole cutter at best - and that any real precision hole should be crafted by drilling undersize and reaming to final fit.

As I understand it anyway.

mjs408

· #37 · Jan 1, 2004

Drills are a rough fit, most are going to drill oversize by a few thousands, less if you use a pilot, if you want it exact you have to ream or bore it.

Toyota_Jim

· #38 · Jan 1, 2004

the way i lernt to sharpen drills goes like this

hold the bit at an angle of 118* or 135*, er somewhere close in my case.
then hold it in the middle of the wheel, in line with the shaft.
angle the end that goes in the chuck down 10-15*. then you can push it to the wheel, then holding the angles move it up the wheel to take metal off the trailing end.

i just do it on the face or the side of the wheel any more. i can do little bits with one hand.

ill never use a DD again. piece of shit.
i sat in front of the movie that comes with it and fucked up a couple good bits.

rusted

Discussion Starter · #39 · Jan 1, 2004

BillaVista said:
Noticed some talk of "precision".

Just a note (and I *think* any machinist will tell you this) that any twist drill is just a rough hole cutter at best - and that any real precision hole should be crafted by drilling undersize and reaming to final fit.

As I understand it anyway.

You know, that's what I was going to suggest for those concerned about close tolerances and not having a fancy drill sharpening machine. Thanks for confirming that method.

Here's a basic outline of what's happening, and there is a LOT of tech info on this available on the web.

Another thing us garage fabricators could use is a store-bought twist drill for the important holes. We don't need machine tolerances for most of the work we do. So you could rough in the holes with one of your hand-sharpened drills, then use a store-bought bit to bring it up to spec. We usually want things to have a bolt in them, so they need to be oversized in most cases, but that's getting into real fastener tech, outside the scope of this thread.

Thanks Bill!

Azzy2000

· #40 · Jan 2, 2004

This is a great thread... lots of good info. I went and re-sharpened my 1/2" bit a few minutes ago on the bench grinder and it is cutting like nothing ive seen before, better than when it was new. It wasnt a high price bit to begin with :laughing:

... anyways, thanks for the info!

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