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JeffG
02-15-2008, 08:28 AM
I'd like to be able to sharpen morse taper drill bits. I know that the "old hands" did this free-hand, but I havn't mastered that technique - I seem to end up with bits that cut on one lip only. Anyone have plans for a grinding jig that would accomodate bits up to 2"?
Thanks,
Jeff

Carld
02-15-2008, 10:45 AM
It is not that hard to make. Use a piece of angle iron for a V holder for the drills. You may have to design it so you can put different length V's for the short to long drill flutes. You lay drill body in the V and stop the end of the taper with an adjustable stop.

There are drill sharpeners for large and small taper drills already on the market. The last place I worked had a large drill grinder of the type. It was adjustable in two planes but don't have to be.

BobWarfield
02-15-2008, 11:29 AM
Jeff, Amazon has Drill Doctor 750's on sale for half price: $99

Failing that, I have a couple of resources.

First, try:

http://bbs.homeshopmachinist.net/showthread.php?t=22131&page=3&highlight=mcgyver+drill

That walks you through commercial (and many would say slightly better) alternatives to the drill doctor.

Second, on this page:

http://www.thewarfields.com/cnccookbook/CCWishListFutures.htm

There are pictures of McGyver's drill sharpening rig, links to his articles here, and links to some other drill sharpeners.

Cheers,

BW

JoeFin
02-15-2008, 11:30 AM
Depends on what type of grinder you plan to sharpen the drills on.

If it is the typical bench grinder style the woo, flutter, and wobble of the grinding wheel might make it difficult regardless of what type holder you are using.

The craftsman style drill bit sharpening fixtures should be easy to duplicate and if you want photos of one let me know and Iíll post a few for you. Pursuing perfecting the Good Oíl Hand technique might be a better choice if you are lacking a T&C or surface grinder. Larger drills are easier then small bits and you have to go in thinking the drill bit is a throw away and you have nothing to lose by trying. After a while youíll develop the eye and touch to keep the center point and relief angle smooth and even

Been doing it for years and years now and I touch up bits all the time. Funny thing is every so often I get an edge that cuts better then new

Scishopguy
02-15-2008, 12:42 PM
Jeff....It is not as hard as it sounds. Like JoeFin says, larger bits are a little easier than smaller ones. Something that will help you learn the technique is a drill sharpening gage. Looks kind of like a hockey stick and has scale markings on the short arm. The angle is set and you try to match it and check each flute with the scale to be sure that you don't get one longer than the other. You will want to dress the grinding wheel before you start and make sure you keep it from getting a groove or rounded edge. Other than that, you just need to swing the bit in an arc similar to what the swing arm style grinders do. A little practice and you will be doing it like a pro.

best regards,

J Tiers
02-16-2008, 12:31 AM
The Drill Quack won't get close to a 2" drill....... the more expensive version accepts only up to a 3/4".

Larry Backer
02-16-2008, 01:40 AM
This is the way I was taught. Set your adjustment table, or guard whatever you want to call it to 0 degrees, it should be at the center of your grinding wheel. Take a brand new 5/16 to 3/8 bit and lay it on the guard table, (grinder Off) the lip should be paralell to the table, swing the bit to your left 60 degrees. Push the bit in till the lip touches the wheel, the angle of the lip should match perfectly with the wheel so there is no gaps. Take your sharpie and make a line along the side of the bit on the table guard, now you will return to the same angle everytime. When you push the bit into the wheel the lip should just touch the cutting edge, this is where the hand eye cordination comes in. You should be holding the front of the bit with your right thumb and index finger and the rear of the bit with your left thumb and index finger. As you see the first sparks you should push down and in with your left hand( because the bit is laying on the guard it will make the front rise up) and slightly roll to the right with your right hand. Do one side and then always roll the bit over and due the next side. The trick is to keep the angle and make sure the cutting edge meets the wheel at the same time and then you have to be pushing down with the left hand and rolling with the right. Practice with a new bit and the (grinder off) until it feels natural. Then take a dull bit and have at it. It works best to start with a medium size bit. Sometimes a bit is chiped but you still have to do one side and then roll over and do the other otherwise you will have uneven sides. This works for me I hope it helps somebody to get the hang of it. After enough practice you won't need a guard or a mark to make a nice bit out of even a broken bit. With a broken bit you will need a drill bit gage though.

Larry

GKman
02-16-2008, 07:51 AM
You can already sharpen one so it drills on one side? What do you need us for?

But seriously folks:

Matthew J. Russel wrote what looks like a master's thesis on the subject in Home Shop Machinist Sept/Oct 2007. At the end was his design for a sharpening gig. A very nice tool and not difficult to scale up. Basically it holds the drill very accurately (parallel to two sides and edges) in a diamond shaped hole through a rectangular block. (No you don't need a diamond shaped drill :cool: ) The drill can then be sharpened on the disk of a cheap bench disk/belt sander. It provides a split point and it is surprising how easy it is to alternate sharpening the four facets to center the point of the "pyramid".

I didn't fully understand the design or want to spend the time building a complete one until I verified its value. I made a simple version just for 1/4" drills to try first. Block, hole, setscrew. Works great and made a friend for life of the neighborhood body man who drills out spot welds all day. Building a full version is on my to-do.

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