Sharpening drill bits by hand

[gdgrinder]

I have worked in a machine factory for sell work.As to the used drill bit, if you throw it away and to buy the new drill bit, i think it will wasted money, so it is right to use the drill bit grinder to sharp the used drill bit.it is a wise choose.

[DMF_TomB]

i think your drill bit sharpening poll has more to do with

20% cannot sharpen a drill bit
10% do not want to bother as they don't pay for bits
70% can sharpen and care enough to save money by sharpening bits
.
i wonder what your poll would be for machinist who buy their own drill bits with their own money??
.
when i was an apprentice it was expected for the apprentice to sharpen everybody's drill bits. the better they got at it the sooner they was done with it.

[Dualkit]

Mine have to do with size, I used to be able to sharpen down to 1/32 with a loupe and a diamond wheel. Now with shaky hands and bad eyes, nothing smaller than 5/32. I have found many a time my re-grinds last longer than the drills out of the envelope and I am buying name brand USA made.

[handlewanker]

The fact is everyone, if'n you're in production all the time, that is continuous production, to stop and regrind a drill means you are costing the drill grinding against production output.

In actual fact if the machine is auto working, either CNC or peg board auto or just plain cam auto, the setter usually has enough spare time to do that kind of regrind work.

It takes about 1 minute to hand grind accurately the average drill, say a 9mm (3/8") diam jobber drill, but the machine must be kept running all the time and that means some form of auto control.

In the real world the drill just gets changed, and a $30,000 a year toolroom person operates the drill grinder and puts a point on the drill.

The drill grinding is a hidden cost because the toolroom person is probably a lower skilled worker and serves tools at the store window and grinds drills between time.

In UK in the early 70's we employed a young lad from Trinidad, 16 years old, couldn't read a mike' or a drawing, didn't know the angle of an end mill end face or a slot drill helix, but could serve tools at the store window and operate the drill grinder once shown how....wages then about 800 pounds sterling, or at 2 dollars to the pound, about $1600 a year.

Just before I retired, every drill used in the production process had a tool number backed up by a drawing that stated the max and min length size, and as such were only ground in the tool room on a tool grinder by skilled personnel.

When drills became too short to drawing size, (sometimes only 1mm short), they went into a section of the store for reallocation, and when that box became so large they got periodically obsoleted and sold off to dealers for lack of space to store them.

BTW, I regularly regrind drills as small as 1.0mm diam with a hand drill grinding jig I made, (it was commercially available as the Wishbone Drill Grinder) because nothing cuts like a freshly ground drill especially after you've been pushing it a bit, and 1.0mm drills don't cut if they ain't ground right.
Ian.

[Dualkit]

The fact is everyone, if'n you're in production all the time, that is continuous production, to stop and regrind a drill means you are costing the drill grinding against production output.

In actual fact if the machine is auto working, either CNC or peg board auto or just plain cam auto, the setter usually has enough spare time to do that kind of regrind work.

It takes about 1 minute to hand grind accurately the average drill, say a 9mm (3/8") diam jobber drill, but the machine must be kept running all the time and that means some form of auto control.

In the real world the drill just gets changed, and a $30,000 a year toolroom person operates the drill grinder and puts a point on the drill.

The economics work for me. My dulls go in a box. They are on a "to do" list of things to do when everything is running on automatic. No productive time wasted.

[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]

Originally Posted by 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

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.