Need of some "old school" knowledge! - Sharpening bits

[11echo]

I'm a hobbyist machinist! I've been doing this afew years now. Normally I pick up older machines, rebuild them to the best of my ability and try to use them to their extend. Same goes for cutting tools ...ie drill bits. I get old drill bits (usually with a #2 or #3 MT shank) clean them up and try to sharpen them ...per my high school shop training (or what I remember of it). Seem to be semi successful on larger bits (over 3/4" dia.). But I have trouble with the smaller ones (especially below 1/2"dia.) ...primarily because I don't think I know how to deal with the smaller bits. SO can anybody point me to where I could get some info on how to hand grind these and reamer too (I just picked up a number of them too)?
YES I've tried "googling" ...but most of what I'm finding is "Drill Doctor" type machines. I'm looking for old school hand grinding techniques!! THX! ...Mark

[Glenn]

IForgeIron > Blueprints > BP0223 Sharpening Drill Bits

[markb]

I've used these wheels in the med. and finer grits on small bits with the above posted technique

Cratex - Rubberized Abrasives Catalog - Large Straight Wheels

[agsolder]

Lindsay Books-- www.lindsaybks.com-- has many old time machinist texts in their catalog, including some specifically re: drill bits. Their print catalog has much more than the on-line list of goodies.

[R Funk]

I hand grind my drill bits, but do not know how to explain how to do it over the computer....

One of the most important items, outside of patience, precision and good lighting, is a simaltaneous rolling and changing the angle of the drill bit. This step is critical to get the clearance but comes only with practice.

As far as grinding a reamer I know of no way to hand grind a reamer. This is a certain path to ruining a reamer in my opinion.

With a small abrasive stone, for example a 1/4" X 1/4" X 6", you could "stone" the radial face of the cutting edge to get a fresh edge. DO NOT TOUCH the outside diameter of the reamer with the stone. Only the radial face of the cutting edge.

[Erikgem]

The instructions for hand grinding drills were good. I am an old escaped metal shop teacher (now a jeweler) so I keep a few teaching aids. The pdf file can be printed and used in making a home made drill grinding gage. Just cut one out and past it on a piece of sheetmetal with spray adhesive. Cut it out with sheet metal shears. You can cut notches for the graduations with a jewelers saw or just scratch them in. You can then remove the paper or just leave it on till it wears out. The spacing on the graduations doesn't have to be perfect because you are only using them to make the two lips equal length. Don't forget, when grinding, never let the shank of the drill get higher than the point of the drill or you will lose your clearance.
Dave Anderson
Erik jewelry

Drillgage.pdf

[keykeeper]

Erikgem,

That's a very helpful pdf file you provided. Thanks from everyone here.

Also, How about a thread over in the "Introduce Yourself" section of the forum, I'm sure you have loads of metal shop wisdom for us Newbie's here.

Also, your location would be helpful. Just update it in the user control panel.

Welcome to IFI.

-aaron c.

[Daryl]

Drill bits! Don't feel bad about being unable to sharpen them correctly (yet). The shop I work in is filled with mechanics under 30 who seem to only have the ability to create arrow heads with drill bits, or worse. Yes, at Tech School they are all instructed in this arcane art and are passed!!!!!!!!!!!!!!!!!!!!!!!! Strangely, after my days off, my first task in the shop is not to sharpen drill bits, but to make them so they will actually drill a hole. I don't use a gauge or drill doctor or assistant, just a decent, trued grinding stone and a piece of graph paper. The real secret to sharpening drill bits correctly (or anything else worth doing) is to pay attention to what you are doing and to what the result is.
BTW, poor drill bits are a real pet peeve of mine.

[nonjic]

ive only just got the knack of grinding the small fellas (after many years in engineering!) - basically it will cut ok so long as when you eyeball it the cutting edge is the highest point! - if you can do big uns you can do the little ones with practice.

with the small ones, if they have been badly ground I sometimes find it easier to grind them flat, and start from scratch.

Dont let on to you know how to do it, or you end up grinding them for everyone else every 15 mins :)

[LDW]

If you clamp 2 hex nuts together in a vise that will give you a 60 degree angle to work with.

[Jocko 58]

The best way to sharpen any drill is lots of practice, when i first started my trade as an apprentice tool maker in the 70's i was given a box of blunt drills and told to sharpen them. The old saying pratice makes perfect.
With reams tool and cutter grinder is the only thing i know of to sharpen them
Oz cheers

[arftist]

This is a difficult skill to aquire. I use a vertical belt sander instead of a bench grinder (though I can sharpen bits using a benchgrinder or a handheld grinder or sander. The starting angle, both vertical and horizontal is critical. In the vertical axis, the bit must be less than 90 degrees(perpendicular) to the cutting surface. In horizontal axis, while less important unless cutting extremely hard metal, the replication of the original grind is the goal. Until one has an intuitive feel for this, it may be helpful to use a new bit to judge the horizontal axis, with a 118 degree ancle being the goal in most cases. Once the correct starting angles are acheived, one would proceed to gently thrust the cutting edge against the abrasive surface, starting with the lip or cutting edge exactly perpendicular to the direction of travel of the abrasive surface. Imediately upon cutting action taking effect, one must begin to twist the bit in a clockwise motion(if right handed) and at the same time, decrease the horizontal angle as well as the vertical angle, The complex rolling motion mentioned above. Always repeat the same action to both cutting lips with the goal being to keep them the same length and angle. Visualy inspect the point after each series of sharpening in case corrective steps are nessasary. A visual inpection will indicate that the lip is the highest point, when the bit is held verticaly, with the point up, and the edge of the lip is nearest one, and the point away. This is the clearence mentioned above. At the same time, check the angle as well as the length of the lips. No bit can be considered sharp until the lip extends fully to the side or "lands" of the bit. Since this is where wear or chips occur most frequently, often much otherwise good surface must be removed before the corners are truly restored. After grinding, a few quick honing strokes with a smooth or fine sharpening stone will prolong the life further. Please note that severely shortened bits will be thicker at the center or "point", requireing an additional operation known as "thinning the point", which I an not covering here.

[Charlotte]

I don't mean to start an big debate but my Audels manual recommends 135 deg for drilling hard steel and alloys. What brought it to my attention was that I just bought a titanium nitride coated drill in an extended length. When I opened the package I noticed that the included angle was marked as 135 deg.

Checking Audels Machine shop manual it recommeds 118 for general purpose and 135 for hard steel. I know that all my cobalt drills are at 135 deg.

Edited May 2, 2009 by Charlotte
spellin

[saintjohnbarleycorn]

IForgeIron > Blueprints > BP0223 Sharpening Drill Bits

I am having a hard time finding this one, it doesn't link for me and when I look in the blueprints it stops a 200, I know I am missing something here. thanks for any help. kevin

[matt87]

I am having a hard time finding this one, it doesn't link for me and when I look in the blueprints it stops a 200, I know I am missing something here. thanks for any help. kevin

The blueprints above the 200 series and below the 1000 series are currently not available, apparently to do with a technical issue. Glenn, Andrew and the rest of the IFI team are working on the issue and it will be resolved 'shortly'.

[arftist]

I don't mean to start an big debate but my Audels manual recommends 135 deg for drilling hard steel and alloys. What brought it to my attention was that I just bought a titanium nitride coated drill in an extended length. When I opened the package I noticed that the included angle was marked as 135 deg.

Checking Audels Machine shop manual it recommeds 118 for general purpose and 135 for hard steel. I know that all my cobalt drills are at 135 deg.

Nothing to debate. 118 is adquate for most metals including 304-347s.s,titanium,and anealed tool steels. For harder metals, a 135 degree angle (and special knowledge) is recomended.

[Carl Richardson]

I don't know if you still want some help for sharpening the bits, but after you grind them down, try using a buffing compound on a scrap of rough leather and it might help sharpen them a bit, It worked on my brace and bit and many of the knives i sharpen

[Swamptroll]

I don't mean to start an big debate but my Audels manual recommends 135 deg for drilling hard steel and alloys. What brought it to my attention was that I just bought a titanium nitride coated drill in an extended length. When I opened the package I noticed that the included angle was marked as 135 deg.

Checking Audels Machine shop manual it recommeds 118 for general purpose and 135 for hard steel. I know that all my cobalt drills are at 135 deg.

The manual is correct. Another help is to thin the web after they are sharpened

[ThomasPowers]

I've picked up a couple of old industrial arts textbooks that cover a lot of stuff like this in a basic way. Handy things to have around and usually dirt cheap on the used book market.