How to sharpen a drill with a bench grinder

Sean,

right ON! I have had to show a Euro Engineer how to fix a door knob. ha ha

Cal Poly State University, California.
motto;
"Learn by Doing."

Example;
Do you want to TIG weld, on an engine, from a 1960's Thore Missile,,, ???
yes, one is parked out back.

Not, kidding.

Edwardo
BS Cal Poly Mechanical Design
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Do you anneal the bit after you grind on it? In other words do you heat the bit and then chill it in water after the grinding process? With steel you anneal with heating and quenching, if you don't quench steel after it is heated, it get's softer, thus making your bit less likely to hold it's edge for a long time. Brass is just the opposite, if you heat it and let it cool slowly, it get's harder.

 

Check your bench grinder. Mine has an angled groove in the left wheel guard. Place the bit in the groove and gently twirl as the bit makes contact with the wheel to get the edge even. Works every time.

 

cheers . .. CSULB

 

no . . drill bits are 0-1 tool steel . .. you can dip the end in water to quench it as your grinding it just to stop from burning your fingers which also quenches it at the same time . . . I don't think you're getting the tip anywhere near hot enough to loose the heat treat of the base material.

 

what's a wheel guard?

take a pic . . I never noticed.

 

I use cheap ti coated bits. If I don't reheat with a torch after sharpening the quench in oil my bits will not survive mild steel drilling. Do you have tips to accurately keep the point centered? My biggest problem is I can never keep the point as centered as factory and then my drilled holes are larger than nominal diameter just enough to piss me off.

 

1. buy better bits . .. I have the same sets from 1994 (non coated . . a cheap coated set is another oxymoron . . the coating might as well be gold paint ) . . . you get what you pay for . . I machine mild steel and hot rolled all the time . .. . same is true for taps

2. centering the tip comes with experience . .. it's amazing what you can see by eye . . the shape of the point really amplifies what's going on there.

3. screwing up the diameter enough to piss you off? . .. give me a number and I'll tell you if you're whining . Like I posted before IMO the surface finish from a drill sucks anyway.

cheers

edit: also tell me what application this is that's pissing you off with the oversize hole . .. could just be paralysis by analysis . . . an extra .005" clearance around a bolt doesn't hurt squat!

 

Cheap Ti coated drill bits are good for emergency use on wood,.......... if the wood isn’t too hard.

 

with a fire extinguisher around

BTW . . I'm not saying I can sharpen a drill as good as a professional tool grinder with the proper fixturing . .. but good enough that I never have to shut the shop down or stop a project 'cause of dull drills . . that's why I wanted to share this with you guys . .. . just trying to save a trip to the hardware store when you might already be a bit frustrated.

cheers all . .. off to the Italiano

 

YOU BOZO'S ITS EASY TO SHARPEN A FECKING DRILLL BIT OF ANY SIZE. YOU DONT NEED A STUPID JIG..... HECK IVBE BEEN DOIN IT FOR YEARS WITH JUST A BENCH GRINDER.... I AINT BOUGHT A BIT SINCE!!! SHEITE I EVEN DO EM WHILST THEY ARE STILL IN THE FREEKING CHUCK.... CHUCK. GOD BLESS

 

you don't have to yell

 

Sean,

Do you have a good source of drills at a decent price? I've been using the cheap Ti drills a few times then throw them out.

 

I CAN SHARPEN A DRILL BIT BUT I CANT WORK MY KEYboard

 

Why mess with sharpening?
I go through my number drill index every year, make a list and buy new ones.
Ave $30 / year isn't bad to maintain a perfect set.
My letter drills don't get enough use to have them become dull.
My pc board drills are bought by the dozen and I've plenty of spares.
I don't have fractional sizes.

 

I spent 15 years with a large engineering firm that had an intern program with MIT. I supervised this firms machine shop and managed the manufacturing engineering department. The MIT engineering interns work in my department even though they were mechanical engineers.I taught manufacturing processes, manufacturability studies, dimensioning and tolerancing. I found it was much easier to work with the ones that new nothing than those who had a summer job once that required them to use a drill press. Needless to say these interns were woefully unprepared for actually designing something competitively. I believe this was the first time they actually got a chance to really understand the realities to manufacturing.

John

 

mcmaster carr . .. they only sell industrial grade

Rutlnad Tool/Air Gas have multiple grades . .. buy the better grade

 

I don't really know how it's today because they altered the studies, but when I began my mechanical engineering studies in 1987 it really helped to have completed a practical education prior to the studies. I myself learned ' industrial mechanic ' and then worked on this profession for four years.
Mechanical engineering study took at least 4 years for the fast ones and 5 years for me
During the basic studies during the first 2 years you are trained hard in the basic sciences like higher mathematics, technical mechanic, machine elements, thermodynamics, fluid mechanics, etc., etc.
After this you can choose certain directions, like - for instance - design or manufacturing. I chose manufacturing but work as a designer today.

Like mentioned, a practical education really helps and saves two practical semesters, which only those have to serve, who have NO practical education.

Like said; they altered the studies; my profession in german is ' Diplom - Ingenieur', which translates to 'professional engineer' in US-, and ' chartered engineer ' in UK-English.
Nowadays the degrees you can obtain in Germany are globalized and the same like yours. ' Bachelor ' and ' Master of Science '.

Best Regards from Germany

Martin

 

Mechanical Engineering has quite a number of branches, one of which is what we called machine design. I worked for a very well known US chemical company for 27 years and was in the failure analysis and thermal design areas. I was amazed at the wrong paths those with soley practical experience took when it came to solving problems that necessitated theoretical knowledge. One of my areas of expertise was thermal stress. It never failed that when something fatigued due to cyclical thermal stress, field people would gravitate to making it stronger or anchoring it, which in turn are the wrong directions to go. Both practical knowledge as well as theoretical knowledge are needed for a good workable design. Problem is that the practical knowledge types have a tendency to belittle the theoretical types. Years ago we had draftsmen, the practical types who had a lot of shop experience. The engineers did the theoretical work and the calculations while the draftsmen let the engineer know whether the thing could be build at a reasonable cost. Naturally there was much ridicule by the draftsmen over the designs and inexperience of new engineers. Now, the draftsmen have disappeared, replaced by computers and programs. The engineers remain.

Within the company I worked for and in the groups I managed, new engineers were always assigned to work on projects and informally reported to an experienced engineer. This was true whether it was machine design work or analysis work. This lessened rework that is costly.

Mechanical design is but a fraction of mechanical engineering work. A large chunk of mechanical engineering effort goes into the analysis end of things, either upfront studies/design or modifications of existing designs that were done without proper theoretical foundations because they were done by the seat of the pants methods and had failed prematurely. Material is too expensive, consequences are too costly both from monitary and safety standpoints, and time schedules are too demanding to design equipment in chemical plants without a proper theoretical background. And by proper theoretical background, I talking about mathematics which is the basis of mechanical design.

Both practical experience and theoretical aspects of mechanical engineering are needed. However, as time passes and software becomes more sophisticated and intelligent, the practical experience lies more and more with the software.

 

I bought Harbor Freight's 101 piece cobalt drill set a couple of years ago. The only time one of those drills has gotten dull is when I dropped it on the concrete floor. They go thru hard high strength steel, that my TiN coated drills won't touch, like it was Al! The cobalt sets run about 2x the cost of TiN, but are worth it if you're mostly drilling metal.

I do occasionally manage to break one, usually a small size, when drilling that cheap Home Depot Al extrusion that's about as gummy as chewing gum. I buy my replacements from McMaster.

 

Great thread Sean. I learned how to sharpen drills when I was 17 years old, and besides the money you save keeping high quality drills servicable, you learn valuable lessons that cannot be taught in any book. Ive never known ANY aircraft mechanic or any decent automotive mechanic who didnt know how to sharpen a drill, its shop class 101. Why they wouldnt teach that in an enginering school makes no sense at all.

 

drill bits/end mills/cutting tools get dull in proportion to how fast and how hard you run 'em .. . period . .. a POS will last forever if you keep the SFM (surface feet/rpm) low . . just slows down production which is often reflected in the price . .. the load meters are there on CNC's for a reason

whatever works just it's a shame to pimp HF when you're spending all this time to make first rate products/improvements for F cars . . . don't be a sell out for a couple $$$

breaking drill bits in gummy aluminum . .. dude . .. that's telling you something's wrong right there . . . you know what coolant is right?

cheers

 

if I had a gang of engineers working for me and million dollar projects to support all the overhead I'd be all over these software packages . . but unforutnately I'm just a small biz where 10-20% profit doesn't give me a few hundred grand to spend on software and the monthly "maintenance" the crooks charge . . . and I never see the massive development projects with tons of fat to justify the capital outlay (I'll outsource any FEA that I need). . one of these days I'll have no choice but for now I'm getting by . . one of the machines I designed and continue to build is the benchmark for the golf club & ball testing industry for the entire world .. .not F1 by any stretch but it makes me a living.


sounds like you have a nice high paying job with all the benefits in a large corp . .. congrats mate.

cheers

 

Any chance you could put legs on one of those things and I could borrow it for a few days for our upcoming club guest day invitational? I'll provide the outer ware.

 

Totally Agree! That's why I bought a variable-speed drill press that can be adjusted on-the-fly (dial on the front)