How hard is it to sharpen drill bits freehand on a diamond stone or do you need a drill doctor?
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whateg01
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Practice. You would probably have a hard time doing anything other than flat facets by hand but that can still produce a usable drill. Are you just needing to touch up an edge? Or do you have drills that are destroyed that you are trying to salvage?
rooster59
Well-known member
Some people have the touch of a surgeon, some have hands of cement. Relief angle. Give it a go and get back with a full report.
sharpening freehand is a bit of an an art. larger drills are easier than smaller ones .
it's all about the motion and angle you move the drill bit thru the grinder pretty much.
it's all about the motion and angle you move the drill bit thru the grinder pretty much.
whateg01
Well-known member
Also the included angle isn't super critical for general use. But you want both flutes to be the same.
rlitman
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What are you planning on drilling with these sharpened bits? That will tell me if having a sharpening jig matters or not.
Rccrawlerguy
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This. buy yourself a drill bit gauge. Unless your eye-crometer is dialed in perfect, getting the flutes to match will be difficult.
Firebrick43
Well-known member
I find it quite easy to do 118 degree bits 1/4” or larger by hand with a good sharp wheel and a drill bit gauge. Smaller drills take a lot more effort and a magnifier.
I still will use a good drill bit sharpener if I can as they can do split points but even thing if a tip or edge has lots of damage I will grind it back by hand first to save a lot of time
whateg01
Well-known member
Oh, I was thinking of a flat stone, not a diamond wheel. That is easy but I would recommend cbn for hss drills. If you get it hot, as I understand it, diamond will pull carbon from the steel or vise versa.
whateg01
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I would not buy from a Vevor impersonater. That's worse than buying a Mitotuyu mic!
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RoninB4
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-Not the same thing. Knives usually just need a touchup with less metal removed. A twist drill will likely need more metal removed than a flat stone is capable of. Far quicker and easier with a bench grinder.
-You should watch some videos and read some articles before attempting this so you have an idea of what you're doing. The angle isn't really critical provided they match and are of equal length so the tip is in the center. Get one of these, they're cheap and provide a better reference than just eyeballing it. Learn to use this and it's not difficult. Sharpening twist drills smaller than 1/8" is more difficult than larger drills because there's less to see. If I could learn to do this just about anybody can with practice. Ask questions if you have any.
I have been sharpening drill bits since was a teen. Shop class in high school taught us about drill bits and how to sharpen.
Anything under 1/4" I don't bother with and just replace them. And in reality anything up to 1/2" I might sharpen, but will replace after a couple sharpenings. Larger than 1/2 inch I have bits I have had for years and have sharpened many times.
Anything under 1/4" I don't bother with and just replace them. And in reality anything up to 1/2" I might sharpen, but will replace after a couple sharpenings. Larger than 1/2 inch I have bits I have had for years and have sharpened many times.
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whateg01
Well-known member
Why? You can thin the web at the end and eventually you end up with a screw machine length which is great on the mill or lathe.
I do them by hand with a fine wheel on the bench grinder. It's not hard to figure it out but takes some practice.
Once a guy I worked with had a drill doctor out. I told him how I've been doing it and we both sharped one of the same size bit. I can sharpen it faster on the grinder and it cuts faster too.
Once a guy I worked with had a drill doctor out. I told him how I've been doing it and we both sharped one of the same size bit. I can sharpen it faster on the grinder and it cuts faster too.
Firebrick43
Well-known member
dnschmidt
Well-known member
You can't do it with a flat diamond stone. Most use a bench grinder, the round wheel works better than a belt sander, and with some talent and practice larger bits (>1/8") aren't that difficult. My dad was a machinist and taught me how to do it at about 10 years old. The relief angle is the hardest part but with some patience and practice it's not that bad.
cvairwerks
Well-known member
Replacement cost vs time cost is why I don't even touch up anything under about 5/8". I buy the specific sizes, lengths and materials that I use regularly, in bulk. I normally use jobber, 6" and 12" lengths in HSS, cobalt and carbide.
damn you make a good point it doesn’t really make sense to buy a special sharpener and put in effort to sharpen it if I’m just burning out a few small like 1/8” drill bits per year.
i was hoping I could do something quick and easy with the flat diamond stones I already got. But honestly if I’m going to replace anyway I could try it and if I ruin it then I was going to throw them away anyway
rlitman
Well-known member
There's also an economy of scale here. Singular drill bits are expensive, but 5 packs are much less than 5x the cost of 1. If you can narrow down your usage to a few select sizes and then buy those in bulk, then sharpening doesn't pay. I'm probably not sharpening 1/8" bits when I can just get good ones in bulk, but I'll re-sharpen sizes out of my index if I don't have any extras.
whateg01
Well-known member
Economical or not, I sharpen most sizes down to about 3/32, all by hand. I hate throwing away otherwise good tools
How cheap are you buying them? I can sharpen one in less than a minute.
Firebrick43
Well-known member
You can use a jig to sharpen small bits on a stone. I don't know if they are available commercially but there have been several home shop machinist articles about them. Gadgetbuilder.com has this jig
Old Man Roger
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I’ve been using one of these for decades, I think it cost me 20 bucks. Pretty sure you can still get them for close to that price.
Twisted Sid
Well-known member
Not sure how velvo(u)r can sharpen drill bits. It’s pretty soft.
I can sharpen knives and blades pretty good but the times I've tried drill bits by hand, I ended up with dull spoons.
I got lucky and got a very slightly used drill dr with all the add on parts and a handy VHS instruction video for cheap a few years ago and it works for me. With that said, sometimes its just easier to buy new bits
Lassen Forge
Well-known member
Start with a drill sharpening guide until you inderstand the angles involved. Once you GOT that, you can sharpen a drill bit no problem. But the angles don't feel natural until ou got it, then they do.
If your intended use is metal working/machinist work to any degree of precision, then you're kidding yourself that you hand grind a drill bit to an acceptable shape and concentricity.
Doesn’t matter if you use a gauge, any asymmetry in the flute angle, the tip, or the relief angle will favor the more aggressive side and give an oversized hole. May be only 0.0005" but that's alot.
Drill Doctor may do a better job but it takes time and patience, and as someone said 1/4" and under just replace.
Drilling holes for deck building ? Doesn't matter.
Doesn’t matter if you use a gauge, any asymmetry in the flute angle, the tip, or the relief angle will favor the more aggressive side and give an oversized hole. May be only 0.0005" but that's alot.
Drill Doctor may do a better job but it takes time and patience, and as someone said 1/4" and under just replace.
Drilling holes for deck building ? Doesn't matter.
whateg01
Well-known member
I guess I should sell the Bridgeport and monarch and take up boating. If I care that much about the size of the hole, I can get a new drill, or better yet, bore or ream to size. Doesn't seem like op is working to tenths on anything.
gahrajmahal
Well-known member
I was taught how to do it on a bench grinder as a teen. If I need a precision hole I will use only a good bit. If I’m boring holes in the frame of your car to install a trailer hitch,I’ll resharpen as many times as I can. Relieving the back side of the spiral to Create a split point is a key skill. Try to find some videos explaining how to accomplish this. Here is a quick jig you can make to get the angles even and correct. Super glue two 1/2” nuts together.
Firebrick43
Well-known member
Never worked in a machine shop that expected drilled holes to be +/- .0005"
Standard tolerances for drilled holes is ten times larger.We reamed, bored, or honed holes with those kinds of tolerances, on really good CNC machines or maybe the SIP jig borer
Machinist Drilling Mechanical Tolerance Capabilities Chart - ANSI Size Drilled Hole Tolerance, ISO Metric Drill Sizes
This chart defines drill manufacturing process capabilities for ANSI size machinist drills. Drilled hole locations and size variations are cumulative of several manufacturing variables. Tool sharpness, accuracy, tool and machine rigidity, machine spindle bearings wear, general quality of...
www.engineersedge.com
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whateg01
Well-known member
(don't tell anyone, but sometimes I need a clearance hole in a piece of metal, and I just grab a drill that looks "about right"!)
For general fabrication that 90% of people are doing, who cares?
Does the bolt fit in the hole? Yes, mission accomplished. I'll often drill the hole a couple sizes bigger so it's easier to line up.
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Never worked in a machine shop that expected drilled holes to be +/- .0005"
We reamed, bored, or honed holes with those kinds of tolerances, on really good CNC machines or maybe the SIP jig borer
If that's true, no sense in having a wire gauge set of drill bits. Perhaps I should throw them out ?
Like I said, if you're doing metal fab, or building a deck or putting plastic anchors in drywall, it doesn't matter.
Flat stones, I'd not bother. I suppose there's a way, but I don't even want to think about it.
Much easier to use a wheel on a bench grinder. Like by a factor of forever.
There'e a muscle memory motion to sharpening drill bits, and once you understand the geometry you're trying to achieve with the cutting edge, It's not terribly difficult to gain that skill.
A few years back I taught my son with a 3/4" drill. It was easy for him to follow the edges and develop the "rotate and lower the end" motion.
FWIW, I have a nice Darex, but 9 out of 10 times I'm on the bench grinder with an 8" wheel. Someone mentioned a drill gauge, get one to help you maintain cutting edge symmetry.
Have fun!
Firebrick43
Well-known member
First, We are talking about drill bits we can resharpen in this thread. Even the shops with CNC cutter grinders inhouse we didn't grind drills in the number gauge sizes. 6mm gun drills was about the smallest and that was because of the how expensive they were.
Second, If you would have read the link I posted, It talks about precision standards and how they relate to the diameter. I didn't just spout it off, I actually linked pertinent information.
Here is a screen shot of Cleaveland/Chicago Latrobe/walter catalog on drill tolerances. The finished diameter of the drill bit itself(not the diameter of hole it makes) has tolerances as large as you claim before it ever even starts drilling a hole.
Third, Few if any one is going to have a chuck on their drill press or mill that will have .0005" runout or less. Maybe an new Albreicht. But in the CNC world that is going to be a shrink fit tool holder or hydraulic like a Shunk.
Fourth, they make reamers that are wire sizes as well. https://www.mcmaster.com/products/reamers/system-of-measurement~wire-gauge/
If you want an accurate small hole, you start with an even smaller hole and ream it to size.
theastronaut
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36 replies later we've argued about .0005" accuracy but no one has linked a relevant YT vid yet.
MarineScott
Well-known member
I've used a drill doctor for 20+ years with satisfaction, and no problems.
ez-duzit
Well-known member
I think you missed the point. Don't expect Youtube to give you all the right answers to every problem.
Though I have machines, such as Drill Doctors, mostly my drills get sharpened by hand on the bench grinder--for one principal reason: to keep the job going. Once you get used to it, hand sharpening is very fast and allows you to complete the job at hand. It's not practical for me to inventory multiples of the same size drills, except for a few small sizes I am likely to use up. The larger sizes, like tap drills for M24 threads, especially in cobalt, are just too expensive to inventory for my 1-man shop. This should equally apply to most home shops.
I drill a lot of stainless steel. On some parts I must resharpen the same expensive drill several times just to complete the job.
