Sharpening drill bits by hand

[Monkey_Nuts]

I always used to sharpen bits, by boss would never buy any new one's! He once sent me to the post office to buy one envelope so a drill bit would be a big thing

[gdgrinder]

I always used to sharpen bits, by boss would never buy any new one's! He once sent me to the post office to buy one envelope so a drill bit would be a big thing

The boss think about save the production cost, so when you resharp the used bit, you will make the waster things to be useful.In our workshop, all the people who operate the lathe machine, drilling machine, milling machine kown how to sharp the lathe tool, drill bit,endmills, it is ability for the operate people, but now adays, many people who operate the CNC machine do not know how to sharp the tools, so i think you have the ability to sharp the used tools, it is very good for you and for your company.

[wganders]

Here's the deal! Smaller drills are not worth the effort to sharpen because it's cheaper to buy new ones than try and sharpen them. My rule of thumb is that if it's 1/4", or less, throw it away. If you can afford a Darex Drill Sharpener, good for you because they will sharpen a drill in less than a minute and it will probably cut within .003 of nominal. But, you can get a Drill Dr. for $80 at Home Depot and it does a pretty good job. For larger drills, 3/4 and above, I will use a bench grinder but after I sharpen the drill, I'll take a test cut to make sure it cuts within my tolerance. It's not hard to screw up a drill and make it cut .030 oversize.

Just saying!!!

[handlewanker]

Mostly it is the pride you develop by being a skilled tradesman, and the ability to know your trade.....I resharpen drills down to .5mm (1/32") bacause I know when and how to.

I expect you could make a killing on Ebay if'n you took all your under 6mm drills and auctioned them off in 1KG bundles at 10% of the new price....LOL.

BTW, the ability to resharpen a drill .25mm (.010") off centre is handy when you're drilling materials like copper or alluminium bronze etc, so that the drill will cut .5mm (.020") oversize and not seize up in the hole due to rapid thermal expansion of the work piece and rapid contraction from cooling when the coolant gets down to the drill point.

Also when the edge of the drill right at the corner of the land gets dull and the drill is cutting almost to its size, you will get rapid side wear of the drill flanks if'n the drill edges don't cut enough material to make a hole that will allow freedom for it's diam.

A drill can be made to cut PRECISELY to any diam within reason by grinding off centre a small amount.....grinding dead on centre guarantees flank wear and a prematurely worn out drill which is impossible, without cutting the end off, to renew.
Ian.

[handlewanker]

The last statement is only valid when you drill into metal with one drill, but if'n you subsequently open the hole up with a larger drill you won't get the "variable" hole diam characteristics I mentioned.

You have to know your cutting tools to know what they will do.
Ian.

[wganders]

You guys are giving way too much credit to your labor force! If it's your shop and you don't care where you spend your time then go for it! But, your minimum wage employee will not have the skill level to re-sharpen a drill economically, regardless of size, generally speaking! It ain't goin to happen!

[handlewanker]

Yeah, pay peanuts get monkeys.....if'n you have an unskilled workforce, 'cos it's "cost effective" to not pay them more, (LOL), you need to deskill the equipment to allow for their shortcomings, that's why drill grinders were invented to take the skill out of accurate drill grinding by semi skilled people.
Ian.

[neilw20]

Yep, promotion beyond their level of incompetence.

[Cavi Mike]

I once worked with a gentleman that used a belt-sander to sharpen his drills...

[z369]

I once worked with a gentleman that used a belt-sander to sharpen his drills...

I used to do it all the time, most of the time it was on a grinder but some of the bigger drills wouldn't fit in it, when my machines were running good I would just snag an old cobalt and hit it on the belt sander (they're a little easier to work with)
After a couple years I would look forward to a new drill going out, I would yank it out and grind it by hand or on the grinder, touch it off and 8 times out of 10 it would run twice the amount of parts as a new drill.

[Joe S.]

. . . . I am buying name brand USA made.

Wow, they still sell those ? That's the real kicker, sharpen your old US Made, genuine HSS or some third world crap, which almost cuts and is maybe the marked size. Try drilling stainless with those super duper Chinese cheapies.

I had to laugh, though, the company we support (from inside) had one of their workers borrow our drill doctor to sharpen some of their bits. He did not understand, or likely want to, the subtle nuances and turned the holder the wrong way, causing the bit to sharpen backwards, where the cutting edge was the low side.

[Joe S.]

I always used to sharpen bits, by boss would never buy any new one's! He once sent me to the post office to buy one envelope so a drill bit would be a big thing

Ha Ha Ha does he buy 2 ply and split it into 2 rolls too?

[Dan342]

nice work thanks for sharing!

[uli12us]

I often have the problem, that a new drillbit don't makes round holes, they are triangular, only resharpening can get a round hole. The other problem is, whats with coated drills, they cost a lot more then the simple ones. Or whats with the extra long drills, I don't think you have many of those expensive tools, that you can throw away or give it the toolgrinder after use. Sometimes I grind a drill a little bit excentric, to get a little bit larger hole for a rollertap in the range of #1 or #2. And I regrind 2 or 3 flute millbits as well. Often enough they have only wear at the last mm. If you shorten it to this, the tool works like new.

[neilw20]

Want to drill a round hole in thin sheet with a big drill?
Aircraft sheetmetal technique.
Drill a pilot hole (to keep you on center) or a DEEP center pop.
Fold a pice of rag over on itself three to five times.
Drill through the rag. The rag acts a guide and stops the triangle wobble.
Works with a business card folded four times too.
A little practice and all holes will be round.
A 25mm hole in 1/2mm sheet is quite practical.
The bigger the hole, the more rag.
You only want a pilot hole about the size of the cross point on the big drill.
Much easier if you are drilling into a piece of wood.

SAFETY: Clamp, or at least use strong leather gloves or hold the sheet with vice grips.

[handlewanker]

Uli12us.......Words fail me....but I'd only comment and say, if you learned the trade properly right at the beginning you wouldn't be posting the problems you have.

Never in my whole life have I heard the term "millbit" used.
Ian.

[uli12us]

@handlewanker: Sorry, I'm from germany and don't often need english, so I don't know always the right word for some things. I think you have understand me anyway.

The reason for triangular holes is the reduced chisel edge, if I grind it down, up to the normal size, the hole is round. The same problem you can have, if you drill a small pilot hole.

@neilw20:

For a round hole in thin sheet I grind my drill similiar to a wooddrill. The middle part of the drill makes a short pilot hole and the outer Diameter makes the complete hole. The drill should be a little hollow to the center, that only the outer circle cut at first moment. These drills you can buy for removing of the weldingpoints in carparts.

For all the massproductionfanatics. Not every1 works around the clock on the same parts, If you need only 5 parts or so, much of your time you will need to make your machine ready for the next part. And the changing of the tool with new parameter input will last as long as a regrind of the drill.

[neilw20]

uli12us,

Been there, done all those things.
Try the rag and paper. You might never do a special grind, ever again!

My father taught me that 50 years ago. A lost art?

[handlewanker]

uli12us, no problem, you speak better English than I speak German.....at least we can understand you, Ja!

Incidently, anyone who drills holes of a fairly large size in sheet metal is asking for trouble.......punching is better, but only if'n you can mount the die on the other side of the metal.....usually a chassis punch works for that.

Supposing you had to drill a 25mm hole in some 1.5mm sheet metal, and you didn't have a hole saw of the right size......I would mark out the hole circle and drill a seies of 3mm holes inside the circle, finally finishing the hole with a die grinder or at worst a half round file, OK for a few holes......all roads lead to Rome.

BTW, you can drill a neat hole in sheetmetal with an end mill.....(not a slot drill).

The end mill with 4 flutes is ground on the end with the centre sloping inwards slightly and so starts the cut on the periphery of the endmill, similar to a trepanning operation.......clamp the sheet metal firmly as the endmill does not have the self centreing property of a 2 flute pointed drill bit.

You can trepanne holes from about 12mm diam upwards, or use a hole saw.

A boring head in a mill or drill with the right shaped tool in the boring bar can cut a precise hole in sheet metal by trepanning to a precise size, and is infinately adjustable......clamp the metal firmly.....repeat cuts can easily be made to enlarge the hole if the size is down, something you can't do with a drilled, trepanned, holesawed or punched hole method, and you can do multiple holes precisely to size in one hit with ease.....use a "sticky pin" to find the centre of each hole if multiple holes are required.
Ian.

[underthetire]

I just give it to the sheet metal shop, comes out perfect every time off the laser


Back to the original topic, yes I sharpen by hand at home, 135 deg split point. At work I toss it and get a new one.