Precision Drill Sharpener

[Mark_f]

Hi,

Very nice and well done project! First of all I would like to apologize for my so poor English but I'm French (near Paris…) … Like many of you, I'm tired of junking my "old" drill bits and I plan to realize a drill sharpener as you. That's why I'm a few question for you especially concerning the grinding wheel:

- You use a diamond grinding cup wheel but I think that it is not well suitable for steel (iron seems to chemically react with carbon… Something like that!). I think that CBN wheel (Cubic Boron Nitride) would be more suitable: What is your opinion? What about the prize difference?

- From the operator point of view, the cup rotates (I think) in a clockwise direction. Considering the position of the drill bit, the cup will grind it pulling the cutting edge backward: Is it true? Is it the right direction/process in the case of a diamond grinding wheel? Using common grinding wheels (made with abrasive aggregates), I think that the right direction is when the cutting edge is pulled foreward.

Thanks once again!

Sincerely,

All your points are somewhat valid, but in this instance, in my opinion, it won't really matter very much. I have had no problem with the diamond wheel. A CBN wheel may be better choice but not enough to justify the large price difference.

You are correct about the direction being clockwise. The rotation in this direction is such it tends to keep the chuck pushed against the table while grinding ( which is desirable). The disadvantage is that there could possibly be a slight burr on the edge from the direction of grinding. I have had very little problem with this and when it has occurred , the burr is so thin it can be wiped off with my finger or a fine small stone. Once drills are sharpened on this machine, resharpening is usually grinding only a few thousandths of an inch to touch up the cutting edges. I have seen one built by a fellow with the drill angled up instead of down. This has several advantages in that it is easier to see the ground end and it eliminates any burr. It requires a little re-designing to make the table tilt down instead of up and makes the unit somewhat larger. This would be a good consideration, but the one I built previously works flawlessly, so I just stayed with the same design.

This design has the ability to be changed in many ways and still work well. Many people have built this machine and I don't think there are any two alike. It seems everyone puts their own "twist" on it. The important thing in its success is to keep the concept of how it works . The designer , John Moran, has designed a wonderful machine that is easy to build, simple to use, and makes a precision drill when properly setup. You can visit his website at www.gadgetbuilder.com and read much more about drill sharpening and this machine. John is a brilliant man and shares a lot of great information on his website.

 

[Noufab]

Thank you for your advices and your experience feeback: it's a good starting point for me. Even if it differs from the original version I will think about a design with the drill bit cutting edge up: I'll keep you informed if my project comes to fruition.

Sincerly,

 

[CarlosA]

Very nice. I recently won a SRD grinder on ebay but realized later that it isn`t really ideal for what I want to do. I want to be able to sharpen bits up to 1", and also sharpen reamers and end mills if possible... is that something this setup would do? I am assuming this would handle anything that will fit in a collet - and bonus if the collet is built into the block, so there is rear access for morse taper bits. Most of my bits are morse taper anyway.

What do you think of this multi facet style drill grind as opposed to the typical grind?

 

[Mark_f]

Very nice. I recently won a SRD grinder on ebay but realized later that it isn`t really ideal for what I want to do. I want to be able to sharpen bits up to 1", and also sharpen reamers and end mills if possible... is that something this setup would do? I am assuming this would handle anything that will fit in a collet - and bonus if the collet is built into the block, so there is rear access for morse taper bits. Most of my bits are morse taper anyway.

What do you think of this multi facet style drill grind as opposed to the typical grind?

The four facet drill is so superior to the conical grind, in my opinion there is no comparison.

Now, unless you build a larger unit, it grinds drills up to 1/2". I have made a fixture that does from 1/2" to 1 1/4" that fits on my T&C grinder.

As far as morse taper bits, they can be done on this grinder if the drill is long enough so that the taper is behind the chuck. Ido morse taper bits on my T&C grinder.

 

[CarlosA]

The four facet drill is so superior to the conical grind, in my opinion there is no comparison.

Now, unless you build a larger unit, it grinds drills up to 1/2". I have made a fixture that does from 1/2" to 1 1/4" that fits on my T&C grinder.

As far as morse taper bits, they can be done on this grinder if the drill is long enough so that the taper is behind the chuck. Ido morse taper bits on my T&C grinder.

Thanks for the info. I will give it a shot and flip the SRD. My other plan was to make a collet chuck for the SRD but then comes the indexing setup, small size limitation, and the old school grind ...

As for enlarging this setup - would it be as simple as using larger collets? ER32 or ER40 - I assume the diamond wheel could be the same size, since it is used just on the flat face anyway? Now I realize the diamond wheel would be pretty slow on large bits, so maybe swap out a standard grinding wheel for rough work. Does all of this sound about right?

 

[Mark_f]

Thanks for the info. I will give it a shot and flip the SRD. My other plan was to make a collet chuck for the SRD but then comes the indexing setup, small size limitation, and the old school grind ...

As for enlarging this setup - would it be as simple as using larger collets? ER32 or ER40 - I assume the diamond wheel could be the same size, since it is used just on the flat face anyway? Now I realize the diamond wheel would be pretty slow on large bits, so maybe swap out a standard grinding wheel for rough work. Does all of this sound about right?

Not quite. You would need ER40 collets to go to 1". This would at least double the size of the chuck block, which would mean probably doubling the size of everything. You could use the 4" wheel but would have to make the table wide enough to have both trunnions on the outside of the wheel to be able to have enough travel to sharpen a 1" bit. You would also need to shorten the collet block to be able to do the morse taper bits but that would be easy enough to do. This would be a good project but only worth th investment if you had a lot of big drills to sharpen. The Er40 collets would be to large to use for smaller drills as they would have to hang too far out of the chuck. I can see in my head a way to make a larger version using ER40 and ER20 collets to do any drill up to 1". For me , it would not be worthit as I own drills up to 1" but don't have to sharpen the big ones that often. I just set up the T&C grinder and do a large drill if needed.

 

[Mark_f]

This is a 1" drill I sharpened on my T&C grinder.
It is sharpened with the four facets. It works great. It took about 20 minutes from start to finish to do this large drill, but it should be a long time before I need to do it again. ( this is the first time I sharpened it in two years and I use this one a lot).

This is the simple fixture I made to sharpen drills over 1/2" on my T&C grinder.

 

[CarlosA]

Thank you for the photos, that is a great jig & setup. I especially like the method to align the flutes.

 

[RVJimD]

I probably missed it in one of your posts, but where do I send my dull drill bit for resharpening?

Thanks for the nice project thread!

 

[Mark_f]

I have thought about doing some sharpening for a few folks, but the cost of shipping both ways plus a couple bucks for sharpening and it gets too expensive. But any of you close enough to bring it, I'll sharpen the big bits for you. ( as long as I don't get over run ). I used to sharpen these big drills by hand cause I had no other way, but I can't believe the difference in drilling and hole finish using a properly ground drill.