Sharpening Drill bits.

[artme]

As I understand it drill bits are generally sharpened at 118 degrees (Why don't keyboards have a "degree" symbol? ).

Without going to the expense of buying a Drill Doctor, And given my total lack of ability to freehand sharpen bits, what would be wrong with setting an angle of 59 degrees using a jig to fit the table on my grinder and simply rolling the bit against the wheel while also holding it against the jig.:?:?

[DJ’s Timber]

(Why don't keyboards have a "degree" symbol? ).



Holding down the Alt key on the left or right of the spcebar whilst typing 0176 will give you the ° degree symbol :;

[watson]

or Option 0 on a Mac will give you º

[Dean]

I think you will find 59 degrees will probably produce a fairly ordinary drill bit and will greatly affect the drill bits ability to actually cut. In fact, I'd guess it wouldn't cut at all... Too sharp a point.

Imagine how much research has gone into determining the best angle for the tip to cut the most efficiently and the fastest!

See if you can find yourself a second hand drill doctor perhaps. These things are the best tools for sharpening drill bits.

[mic-d]

I think you will find 59 degrees will probably produce a fairly ordinary drill bit and will greatly affect the drill bits ability to actually cut. In fact, I'd guess it wouldn't cut at all... Too sharp a point.

Imagine how much research has gone into determining the best angle for the tip to cut the most efficiently and the fastest!

See if you can find yourself a second hand drill doctor perhaps. These things are the best tools for sharpening drill bits.

Dean I think Arthur means to bisect the angle enclosed by the tip of the drill, thus presenting the two flutes at 59º to the wheel gives the 118º angle. I haven't gone into the ins and outs of drill angles for a while, but as long as you choose the correct angle and bisect it to set up your jig, I can't see why it will not work.

FWIW, I have had one of these (http://www.multi-sharp.com/index.php?products_id=38&option=com_oscommerce&osMod=product_info) for many years and it does basically what you want to do on the grinder. It is quite an acceptable sharpening system.

Cheers
Michael

[Dean]

Dean I think Arthur means to bisect the angle enclosed by the tip of the drill, thus presenting the two flutes at 59º to the wheel gives the 118º angle. I haven't gone into the ins and outs of drill angles for a while, but as long as you choose the correct angle and bisect it to set up your jig, I can't see why it will not work.

FWIW, I have had one of these (http://www.multi-sharp.com/index.php?products_id=38&option=com_oscommerce&osMod=product_info) for many years and it does basically what you want to do on the grinder. It is quite an acceptable sharpening system.

Cheers
Michael

Umm good point! It's morning and I'm not a morning person, particularly on 4 hours sleep :( You are probably right...
In this case, it could work, but then you would want to get that rolling action right and be equal on both flutes, which is the trickiest part. The drill doctor offers this correct rolling action to make life easier... But heck, if it works, and you can sharpen them accurately, why not :2tsup:

[Batpig]

Dear Artme,

The problem with your proposal is that the angle in question is 118deg only at the axis running across/between the two cutting faces. After that, due to the necessity for the "shoulders" or "heels" of the Bit to fall away at a "relief angle" behind the cutting faces, the 118deg angle gradually increases because the shoulders' surfaces must also angle up and terminate to the same edge up at the tip - even though their starting point is gradually dropping away around the edge of the Bit.

That is why Old-Timers do that funny little jigless "Push and Twist" thing when they are sharpening Drill Bits on a Bench Grinder. A "Drill Doctor" achieves this "compound" action with consistent no-brainer accuracy by using a simple double-cam type of setup that comes into play when you twist its chuck...

Best Wishes,
Batpig.

[Jack E]

At one place I used to work we had a grinder with a groove in the tool rest.
You simply sit the drill bit in the groove and twist as you pushed it into the grinding wheel.
I'm not sure but I am guessing the groove was at 59º, it worked well so I cant see why a similar jig wouldn't.

I now have a Drill Doctor permanently mounted beside my drill press.

This is not a very good pic but it shows the groove in the toolrest. You could do the same thing by cutting a groove with a v-bit in a thick peice of MDF and fixing that to your tool rest.

http://www.woodworkforums.com/attachment.php?attachmentid=102494&stc=1&d=1239748462

[petersemple]

I second Michael with the multi-sharp. I got one from Bunnies a few weeks ago and it's already paid for itself. It is designed to give the correct angle to the flutes and also the correct relief angle behind the cutting edge. Does a useful size range too.

Peter

[artme]

Thanks all!

Multi Sharp sure is less expense than a Drill Doctor.

[wheelinround]

Arthur I recently bought one of these through my daughters work this is the manufacturer http://www.generaltools.com/Products/Original-Drill-Grinding-Attachment__825.aspx

http://www.generaltools.com/Images/woodworking/825L.jpg

I'll find out who they whole sale to I think Gasweld was one Blackwoods and in QLD Tool City??

[Wongdai]

My grinder also has the groove in the toolrest - very handy. The most important thing though is to have the trailing edge lower than the leading edge. I don't know how to explain it better than that - its easier to show than describe.

Also, alt-248 will also give the ° symbol. :p

[eddie the eagle]

As I understand it drill bits are generally sharpened at 118 degrees (Why don't keyboards have a "degree" symbol? ).

Without going to the expense of buying a Drill Doctor, And given my total lack of ability to freehand sharpen bits, what would be wrong with setting an angle of 59 degrees using a jig to fit the table on my grinder and simply rolling the bit against the wheel while also holding it against the jig.:?:?

Degree symbol = Hold down the 'alt' key and type in 0176 on the Number Pad (not the numerals above the letters.) Either that, or cut & paste the required symbol.

Here's a list of codes for the other common symbols.
http://www.ascii.cl/htmlcodes.htm


° ± ¼ ½ ¾ €, etc...

Cheers,

eddie

[Tankstand]

If you can get your hands on a brand new drill bit, say 10mm or larger. You can practice the motion required to sharpen a drill by rubbing (With the grinder unplugged) the drill bit against the grinding wheel. Start with the cutting edge horizontal and you'll soon get the hang of the twisting / lifting action required. Practice, practice, practice. In TAFE it was called "Off Hand Grinding"

[specialist]

I wouldn't be so concerned with having the precise angles as the following scans show there are a number of differing configurations that you can have and still cut very well.

All that I would stress is that the cutting edges are as close the same length as possible and that they have enough clearance.

I have been sharpening freehand for 25 years, drills from 3mm to 65mm with good results. They have to be pretty good to drill steel.

Just practice the two plane twisting motion and you will get the hang of it.

links to full sized jpgs
angle gauge http://www.mediafire.com/file/j2idtdxmldx/angle gauge.jpg

drill point geometry http://www.mediafire.com/file/mnwmjtyyz4r/drill point geometry.jpg

drill point sharpening http://www.mediafire.com/file/trhmyoo1k1h/drill point sharpening.jpg


hope this helps

Robert

[pjt]

I agree with specialist, I don't get too hung up on the exact angles, specially when free hand drill sharpening, the 2 most important things to look for is the cutting edge to be sharp and it must have clearance behind it to cut (to bite into the matl being cut), as for any cutting tool.
With a chisel it can be ground at 25° or 30° and both will cut, one has advantages over the other.
If I want an exact hole (as best I can get with a drill bit) I will sharpen using guages to ensure equal lip lengths and equal angles where required, it will still be freehand sharpening, just a bit more care taken to get it right and it will be the twist and rotate thing.
Peter

[AUSSIE]

I second Michael with the multi-sharp. I got one from Bunnies a few weeks ago and it's already paid for itself. It is designed to give the correct angle to the flutes and also the correct relief angle behind the cutting edge. Does a useful size range too.

Peter
Peter.
How much was the Multi Sharp at bunnys please.Also do you think you will need to get replacement stones?

[Sparkiekosten]

I have just purchased a drill doctor 500X and got a free set of metric drills with it from $390.00 from an AIS catalogue.

http://www.aisnational.com.au/viewcataloguepage.asp?page=1&storeid=20&id=33
The drill set is an el cheapo 19 piece metric set but it certainly helps to have around. :D It goes from 1mm to 10mm in .5mm steps.
Anyway the first thing I did was sharpen all my existing drill bits...........who wouldn't :p
I must say from having tried to do it the old fashioned way by hand on a grinder but the drill doctor is a winner.

I had about 25 drill bits to put through it and a majority were hand sharpened so it was a bit of work to remove the old angles and whatnot but it did it nicely.
It took me about 2 hours to sharpen them. If they had not been stuffed by yours truly I would have finished in a lot less time.
I know $390.00 seems like a lot of money but for the piece of mind I am glad I did spend it.
:2tsup:

[Grahame Collins]

what would be wrong with setting an angle of 59 degrees using a jig to fit the table on my grinder and simply rolling the bit against the wheel while also holding it against the jig.:?:?


The angle of 59 degrees included would produce a totally crap cut as it is too acute and will jam even if given clearance explained below.

The method that you propose will produce no clearance behind the cutting edges.
Without clearance the area following the cutting edges will rub on the metal being cut and friction and heat will occurr.
Shortly thereafter your drill point will burn and lose its temper,stuffing your drill bit.

Free hand drill sharpening is not rocket science.Im not a genius and even I can manage it.


Mark an angle of 59 degrees on the grinder tool plate out to the left.This will provoide an included angle of 118 degrees.

I am right handed and will describe the process for a right hander.

Line the side of the drill parallel with the line .

Rotate the cutting edge until horizontal with the wheel face about the same level as the grinder shaft.

Touch the cutting edge, rotate the drill bit about a 1/3 , and at the same time drop the rear of the piece down.Too much rotation will cause damage to the other face as it will hit the stone at the wrong alignment.

Do the same to the other cutting face and ensure both cutting edges are the same angle and length.


Practice with a bucket of old blunt drills,taking care to cool frequenntly.

Grahame