47-55.1 Sharpening drill bits

[Matt_50]

I'm tired of buying drill bits. I stopped buying the real cheap ones and I now get farther with what I got but it starts to add up when I need a new one.

So I started looking this up a few minutes ago and I have a bench grinder...

Anyone got any advice to throw in? Are there certain brands or types that aren't worth resharpening or can't be? How many times can you resharpen a drill bit?

Matt

[mongocanfly]

day 1 of machine shop school was drill sharpening...learned to do it by hand all them yrs ago...there are definatly good, better, best of drill bits..buy American if possible...
ive sharpened them all the way down to where theres barely a flute left..sometimes on purpose if I needed to clearance...
a good drill angle gauge will help keep the sides even...there are drill sharpening machines but ive never used one

[MiraclePieCo]

Would you like to offer a how-to for sharpening them?

[rsavage]

I bought a drill doctor a few years ago. Works pretty well. Every so often, I'll spend an afternoon sharpening drills. They never stay sharp for as long as when new though it seems.

[mongocanfly]

really no need for me to put on a how-to...just u-tube it...theres lots of how-to videos on hand sharpening bits....we didn't have u-tube back then though...just a 70yr old man standing over your shoulder hollering at you saying you was doing it wrong...haha

[Matt_50]

I'm wishing I hadn't thrown away so many now... I'll try and sharpen what I have. I guess if I mess it up, I just grind it down and start over lol

[dsraven]

grab a drill gauge and a grinding wheel dresser (so you start out and maintain a flat wheel) and keep a cooling can close by so you don't overheat the bit when grinding. some grinders have a tool rest with the angles built in and some have a groove for the bit to sit in, but if not scribe a line on the tool rest so you keep the angle correct easier. take a look at a new bit so you understand where the cutting edge is and the clearance angle behind that and then use the gauge to keep the angle right and the length of each cutting surface the same length. this part is critical or the drill will make a hole larger than the bit is because the bit won't be centered in the hole it is drilling. to keep the cutting edge as the "high" spot, so it will keep cutting, you will need to grind back from there (clearance angle) but not too much of an angle or the cutting edge bites too hard so it slips in the drill chuck, jams the drill, dulls quickly or breaks anyway the edge. some bits have the back side edge of the flute ground off to keep that clearance angle surface smaller so less chance of the rear edge being a high spot. when sharpening don't twist the bit but rather hold the cutting edge against the wheel and then lower the rear of the bit as you start to grind the clearance angle. some guys will grind the clearance angles first. if you twist the bit when sharpening you will likely contact the wheel with the other cutting edge and grind off the cutting edge of the other side of the bit. try sharpening a really big drill first because it is easier to see the angles and measure the edges.
remember to quench the drills often when grinding so you don't take the temper out of the steel

https://www.amazon.com/grinding-Dril.../dp/B01HW35656

https://www.youtube.com/watch?v=y0SQkzScQk0

[1project2many]

we didn't have u-tube back then though...just a 70yr old man standing over your shoulder hollering at you saying you was doing it wrong

Hmmm. Did we have the same teacher?

I have trouble seeing to sharpen anything smaller than about 3/16" without my reading glasses these days. I can't hand sharpen much below 1/8" with reading glases. I have to rely on Drill Doctor for some of the smaller bits.

Get sharp bits and look closely at how they are ground. The heel must be lower than the lip. The lip needs to be the same length on both sides. Chisel edge should be distinct on larger bits. I usually tell people to get the twist and angle motion down to creat the correct shape then work on getting the lips the same.

[dsraven]

I had a really great metal shop teacher in high school. he showed us all how to sharpen drill, metal lathe bits, all kinds of shop items. for the bits we used large bits, like 1", because they are easier to measure the cutting edges and also easier to see how the clearance angle needs to be ground lower than the leading edge of the cutting edge. it is also harder to grind off too much in a hurry like a smaller bit is. anyway, long story short, when starting out use the biggest dull bit you have to learn on. try some second hand places or garage sales for some cheap bits to practice/learn on. dress the wheel flat first though, and move the drill bit across the face of the wheel as you sharpen it so you don't groove out the wheel and get an uneven surface on the drill bit.
practice makes perfect

[_Ogre]

drill doctor work very well, my neighbor owns one that i have access to. never had much luck sharpening them by hand
you can sharpen a drill down as far as you want/need. flutes need to be deep enough to expel material.

[dsraven]

The further down it gets the thicker the web becomes. That is why you need to grind that part as well to keep it sharp on the end but also so the pilot hole doesnt have to be so big.
Pilot hole should be the size of the drill bit web. Tbat way the drill also stayz in the center of the hole.

[Getter-Done]

I learned from my Grandpa and Daddy years ago.
I could sharpen them pretty good. They got the job done.

Then from a 25 year exp. Shop teacher 10 years ago.
Now I can really sharpen them.
I don't know that I can add much to what has been said above.
Like others have said
1.Keep the grinding wheel flat (dressed)
2.Buy an angle gauge for reference
3. start learning on the bigger twist drills(1/2" and up).
4. Watch video's ( here is 3 good ones) from Tubalcain
1st https://www.youtube.com/watch?v=hJItj_ISurY
2nd https://www.youtube.com/watch?v=rUMTJ9GZIC8
3rd https://www.youtube.com/watch?v=cqn2VPGYA9c
5.a few pictures for reference

[FAKKY]

Originally Posted by _Ogre

drill doctor work very well, my neighbor owns one that i have access to. never had much luck sharpening them by hand
you can sharpen a drill down as far as you want/need. flutes need to be deep enough to expel material.

Thats what I use.

[Matt_50]

Thanks Getter-done.

[mr48chev]

I've always done it by hand and learned in high school from my auto shop teacher, I had a lot of kids watching me sharpen them in the 13 years I taught auto shop but never actually taught them to do it as a formal class.

When I was teaching I use the stone on the Sious valve facing machine as it was a fine stone and easy to control what I was doing.

The main thing besides getting the correct angle and having the sides centered (yes you can grind them off center) is learning to roll them in your fingers while dressing the lands.

I've got an old bench grinder out in the shed that doesn't have enough power to do normal grinding but now I might keep it for drill bits and put a finer stone on it on one side.

I'd suggest practicing on some old clunkers before doing your (good) bits.

[Matt_50]

I dug yup a few bits last night. I have a couple of 1/2 inch bits I'll practice on. I sharpen chisels by hand on stones and only use the bench grinder to clean up a chipped edge.

Is it better to use stones on the workbench or use the bench grinder?

[Getter-Done]

Originally Posted by Matt_50

I dug yup a few bits last night. I have a couple of 1/2 inch bits I'll practice on. I sharpen chisels by hand on stones and only use the bench grinder to clean up a chipped edge.

Is it better to use stones on the workbench or use the bench grinder?

Bench grinder then maybe touch up with the stone

[hogfarm]

After seeing this post I went to my shop and looked at my drill bit collection,well I have a steel box full,I'm not kidding there are thousands.I was a machinist working for the government in the Hydro electric plants for 35 years before I retired,and never sharpened 1 drill bit,always just grabbed a new one.

[1project2many]

hogfarm, you could build art with those bits. Takes much less time than sharpening them all by hand!

[Matt_50]

It sounds like he has way to many.... make art OR put them in a nice box with a stamp on it, send it to Texas...

[1project2many]

[Matt_50]

Lol that's awesome. Artsy stuff would be a good way to practice welding for me.

[hogfarm]

That is a great idea,I'm waiting for the painter to finish the bed on my truck,and I'm in the middle of remodeling the downstairs of my house,using the steampunk decor