Do you sharpen your drill bits? Impetus for the thread being that drilling some holes in mild steel dulled a 1/4" bit, so I went out and bought another one. I should have used oil.
If so, what sort of hobbyist work do you do? I'm assuming this is an essential skill for pro machinists and woodworkers and what not, of which I am certainly not.
I'm still figuring out the opportunity cost*monetary cost/benefit ratio of adding a bench grinder or a Drill Doctor to an already crowded garage and learning how to use it, and if adding another machine to the mix makes sense, if it is worth buying a bench grinder and learning how do sharpen bits manually while enjoying the added versatility that a bench grinder brings, or if I should just get a Drill Doctor and throw the learning curve, inconsistency, the versatility a proper grinder, and my own incompetence under the bus.
That being said, how are Harbor Freight bench grinders compared to pricier options? What is the sweet spot? They all seem to be the same generic induction motor with the spindle coming out both ends and they all probably come out of the same Chinese factory. Perhaps they take the more balanced motors and slap a DeWalt sticker on them? Or are you a satisfied Drill Doctor user? Let's hear it.
>>928815
drill doctor isnt exactly skill-less
you can fuck it up and have lots of inconsistencys
its also a diamond instead of a stone so you can sharpen other things
that being said, its wayyy easier than grinding freehand, also do you have a belt sander? you can just use that
anyways, I use all 3 methods
buy many bits of same size
regrind on grinder
and sharpen on drill doc
buying is easiest, decent drills i can get several of the same size for $5 use oil when drilling
drill doctor is second fav on my list because once you do a bunch it becomes easy as shit to to a lot
grinder takes the most prcatice, but you will have more uses for a grinder than 5x 3/16 drill bits, also a belt sander works as well
so, do all 3 options
dont get home depot drill bits
I had an old machining book with a whole chapter on sharpening drill bits that basically said not to do it. At least not by eye with a grinder. If you are off by just a bit, only one side of the bit will be doing all the drilling. Also having the precis angle is very important for efficiency.
>>928831
>also a belt sander works as well
Ah, thanks for reminding me that I have a belt sander. Well, it's more like a toy belt sander, but it hogs away metal like a champ.
I have a Ken Onion Work Sharp that my wife got me for Christmas a year ago. It gets a blade pretty crazy sharp, but I always preferred using waterstones despite the time it takes. The results from hand sharpening always seemed to be superior and the Work Sharp removes metal so fast it can round off the tip or change the 'belly' of the blade in no time.
Maybe I can adapt my technique for drill bit usage. I'll report back.
>>928815
Yes. I have a jig that bolts onto a standrard bench grinder and my dad has a drill doctor type sharpener as well.
Most cheap drill bits will come from the factory with a shitty grind on them. Change the angle and sharpen them and they work okay.
i'm a hobbyist metal worker.
i can't imagine life without a bench grinder. sharpening drills when they don't cut right is a reflex at this point, i don't even realise i'm doing it unless i go to the grinder and someone's unplugged it.
when a bit snaps it becomes a shorter bit, and eventually a spotting bit, instead of scrap metal. making lockwire holes in hardened bolt heads is brutal for snapping bits.
when you drill grabby metal like brass or lead you can grind a profile that cuts less efficiently.
if you're too cheap to buy an endmill to square out the bottom of a blind hole you can grind a flat face instead of a point.
cheap grinders work fine, it's nicer to use a huge quiet well-balanced machine with loads of horsepower but it's not a hundred bux of nicer.
having a grindstone on one side and a belt sander or wire wheel on the other is great. worklights are great too.
wear your safety shit, and adjust the rest to stay close to the stone as it wears down, or else the grinder will snatch the work down into the gap and mash your fingers into the spinning stone. the guy who taught me drill sharpening had some gnarly scars.
>>928815
>Impetus for the thread being that drilling some holes in mild steel dulled a 1/4" bit,
Many department-store drill bits are shit; all HSS is not created equal.
If you have to drill a lot of thicker steel then buy just the sizes you need from machinist supply places online; they generally work a lot better.
>>928835
>I had an old machining book with a whole chapter on sharpening drill bits that basically said not to do it.
Yea, you can't ever really get them even by hand. Nobody can.
You can get them useful again. And if you double-step drill (say, for a 1/2" hole: drill a 7/16" hole first and then the 1/2") you still get a decent hole even if the drill isn't cutting evenly.
Cheap grinders: the main risk of cheap grinders (and wheels) is grinder wheels exploding from spinning too fast and cracking.
I spent more for a variable-speed grinder--so I can run it at low speeds mostly. I rarely turn it up more than 1/3 of the way.
If you're cheap, you might get a cheapo single-speed grinder ($30) and try it with the $22 Harbor Freight router speed control.
>I'm assuming this is an essential skill for pro machinists
It is.
Not easy to do. I never could do a good job at it and, I'd use a drill sharpener or just replace it. I've known people that could do a great job sharpening by hand. They were skilled machinists or pro tool sharpeners that knew the geometry well.
I have hundreds of drills I'm constantly sharpening. One of the biggest killers is stainless steel.
All I use is an angle grinder. The trick ive found is rather than concentrate on grinding the lead in edge on the drill tip, only touch this lightly and sharpen by following the flute spiral with the grinder to sharpen to a point.
>>928815
>I'm assuming this is an essential skill for pro machinists and woodworkers and what not, of which I am certainly not.
Pro machinists don't sharpen drills by hand, ever. They buy drills in bulk, use them until they're dull and then put them into the "resharpen" bin. When the bin is full, they send them to a sharpening service.
The Drill Doctor is made by a company named Darex that makes much better industrial models.
The *cheapest* Darex V-390 is around $1500 and pros mostly say it works way better than the Drill Doctor. Even so, it is their "light duty" model. The -normal- model is around $3500.
A big complaint with the Drill Doctor is that it is only really god for very light grinding use. It clogs up with grinding dust and then doesn't work accurately. The Darex models don't have this problem.
>>928851
I probably do my sharpening in the most shitty way possible for drill bits. I leave the twist bit in the drill, and run in backwards against running WS or belt sand or sometimes shitty sharpening stone I have.
Brings it back from DULL to slightly dull.
Downside is it's hard to keep a consistent angle, so not as efficient, but >>928835 both sides are the same because drill spinning, and different angles are more efficient depending on material. eg. soft wood can do like 88 degree point, but you want like a 130 for harder metals.
So eh, don't really care about standard angle as long as it's close.
If I was going to do it right, I'd do that to regrind/sharpen (probably with jig to hold drill angle, if I cared), then grind back a relief by hand on WS or belt sander, so I would know I couldn't fuck up the edge symmetry at all or end up with a belly behind the cutting point.
Please lmk if horrifying or brilliant, I can't decide.
>>929296
>>929296
>both sides are the same because drill spinning,
not exactly, you have to be careful here and apply even pressure because it will wander easy
but yeah when im feeling lazy at home i just hone it a bit with an EDM stone or something and get it a little better
>>928835
yes and no
you are technically right
if op were running a production factory, then yes to all of it.
even if the drill isnt cutting evenly, you will still have a hole good enough for bolt clearance
if you need a hole to be more accurate than a hand sharpened 1/4'' drill bit , then maybe should use a .250'' reamer instead
The best thing you can do is to buy bits from something like Norseman or Chicago Latrobe and learn how to sharpen, or at least find a good sharpening service.
>>928815
You can get a drill doctor but they are usually for general purpose.
Good drill bits are always worth the investment. Platinum drill bits are top tier, kobalt bits are pretty good too, try to avoid offshore ones. When drilling into metal always try and use a pilot bit (a smaller diameter bit to start the hole after you have center punched where you want to drill into).
Now if you want to use a grinder to get that that desired angle use an unused bit as somewhat of a guide to have you hold what angle you want at. Remember to intermittently quench the bit as you sharpen the bit with a grinder so you don't overheat the bit and destroy characteristics of the bit. Also a drill gauge will help so you have the same distant on both sides of the bit.
>>929348
same distance on both sides of the center.*
>>929187
And iirc the industrial models use carbon tungstide instead of diamonds, since diamonds dissolve in iron.
I used to work maintenance at a facility with no budget, so I got real good at sharpening bits. With a few tools and a MAPP torch, I could rough grind, file, heat, quench, temper, and stone a bit in about 10 minutes. I even learned how to change the tip geometry for different materials.
Not that I'd recommend for the average DIY'er. I was a hobbyist blacksmith for a long time before, and have strong metalworking skills. For most people, just buying new bits and replacing them is more economical because of the high cost in time.
Also, I wouldn't put much stock in things like Drill Doctor or whatever. Without heat treating the bit, it's going to soften, and you'll be resharpening it with every other 2x4 it goes through.
I have a reasonably-sized disc-type grinder, and I could not live without the ability to sharpen drill bits. It takes me about a minute to sharpen one, and I'm good at it down to about 2mm. for less diameter, I take a cutting disc at my dremel. Works equally well. With a bit of practice, they are almost as good as new, and certainly always better than before sharpening. It's also not hard to learn, I could teach anyone in 10min or so. If in doubt, have a fresh 10mm drill bit as a model nearby to check if the angles are about right.
PS, are those pretty titanium nitride-coated bits REALLY any better than your typical black-oxide bits? If it's just a coating, then comeon.
I mean, I can understand that cobalt bits hold up better because the alloy itself is different, but yeah.
>>928835
>A whole chapter on sharpening drill bits that basically said not to do it
What is the name of this machining book that has whole chapters outlining shit that you are basically not suppose to do?
I've enjoyed using 400/800 grit sandpaper for sharpening chisels and such
