Thread: How will I sharpen these tricky little suckers?

Originally Posted by FenceFurniture

Good on you Paul, thanks for that - I'll check it after I get some food down me neck. Have a look at the CBN wheel that Ray was talking about on fleabay.

Brett

I had a look at Ray's suggestion. It could be interesting with that tapered edge and certainly worth consideration. two small problems. The hole is rather large for an arbor if you are planing on inserting it in an electric drill. Not impossible as I have already done it with a diamond cup disc which I use for sharpening tungsten carbide circular saws.

I am currently waiting for this to arrive as it has more clearance for multi tooth saws:

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I had planed to put up a post to show how I sharpen them at a later date.

The second problem, as with my diamond cups, is that you can't put a radius on the edges. I think you must do that for your colt drills or be prpeared to slightly alter the shape.

I like Ray's link and will bookmark that.

Regards
Paul

These were initially ground on a T&C grinder (or production version) with a thin profiled wheel. It may be possible to fit a thin white wheel to a bench grinder and match the geometry. If you have a quality rest it may be possible to freehand grind them VERY carefully in this case. A T&C grinder would definitely be the way to go though. If expensive it may be worthwhile sending them out for sharpening.

Pete

Pete, they are not what I would call expensive (certainly not the smaller dias), but nor are they cheap. The biggest problem is replacing them. There are only 13 out of 478 part numbers available locally (and they are expensive, surprisingly), and getting them out of the German factory is painful to say the very least.

To give you an idea:
3mm $2.26
10mm $7.55
16mm $21.65 (currently biggest available).

Certainly not worth freighting back to Germany for a regrind every now and then, but a little painful to throw away (yes you could grind them to a normal twist, but there are plenty of good qual twists available and how many 10mm twists do you really need - 1).

I've had an idea, and it's not (necessarily) directed at RayG, as I know he does the forumites stacks of underpaid favours already. Is there someone with a T&C grinder who could do these when a batch became ready (from the 2000 or 3000 drills that will be amongst us all)? Paid work of course. At least 10c per grind

Where this might become very relevant is with a new drill that I want Colt to make. It's a specialist 3/4" Dog 'ole drill with a RotaStop eccentric shank and laser rings every 10mm up the flutes for knowing your depth. Being RotaStop compatible means that extensions can be used with it (the main function ot RotaStop). There are so many bench builds happening these days, and nobody wants to go through Groggy's Swiss cheese grief (don't think the poor bugger will ever live that down, not if I can help it anyway). He essentially drilled through around 6 metres of old tough Jarrah.

The point being that this drill (if it's produced) will be pretty exxy because of the short run of 10-20 bits, and a re-grind every now and then will be critically important. I imagine that 6 metres of Jarrah would have an effect on HSS M2, particularly with the amount of heat from a 3/4" bit going in 100mm. Get it sharpened, and then sell it to the next Cheese Maker.

Search around for a W point drill grinder. I have a feeling that Darex made a drill grinder at one stage that could this type of drill.

Michael

Brett, you shouldn't need to send them back to Germany for sharpening, I'd expect any sharpening service worth their salt here would have the capability of sharpening these, it's just that I can pretty much guarantee it wouldn't be 10 cents each

If you decide to have a go yourself, keep in mind that just because a surface is ground doesn't mean that it will need to be reground when sharpening. If a "touch up" is all that is needed, you should only need to touch up one of the cutting surfaces. If you have a badly worn one it should be obvious where the metal will need to be removed. All bets are off if damaged however.

Another thing to consider is to approach it from afresh. Even though you provided excellent photographs, there's nothing like holding something in one's hand and figuring it out. Just to throw something out there, you can see from the grind marks how it was originally ground. But it may be possible to get something like a Dremel tool, make up some form of lap, and lap the surfaces 90 degrees in the other direction. i'm not sure if that makes sense, but what I'm getting at is that instead of a large profiled wheel rotating North/South, use a small cylindrical wheel rotating East/West. Woodworking bits will be much more tolerant compared to metal working bits in terms of uneven cutting edges, and if you only lap off enough to resharpen it may get a little more life out of them before replacement is needed.

Just a thought and different perspective to consider.

Pete

There's no need to get all excited over sharpening these drills. I shape and sharpen these drills with ease. The biggest I have so far sharpened is 5/8" and the smallest is 3/16". These were shaped/sharpened using an 8" wheel, 60 grit. The face of the wheel can be cut to an angle of about 10 or 15 degrees if you need to. I only shape the wheel angle if I need to grind smaller than 6mm and even then I don't usually bother.

The smallest drill I have sharpened is 0.0312". This was sharpened with a diamond hone fitted with a flat diamond impregnated steel strip about 1 1/2" x 13/16" glued to a coloured plastic handle. It was shaped as a standard twist drill. It was essential that these small drills cut to dia.+0.001" maximum. It was much better if they cut to dia.+0.0005"

The diamond point as seen on the drill is so shaped to remove the chisel point that is left after shaping the "swallow tail" ends of the flutes. I sharpen all my drills by hand and guage them for size and shape only by "eye".

The Swallow Tail drills are the perfect drill for drilling holes in thin brass or steel shim. Knock the rake off with the grinder or the diamond hone if drilling brass shim. You will be amazed at how easy it is to drill the shim, how safely the drill cuts and how the hole is perfectly sized.

Have a go at it. It is not hard to do. A good 10x magnifier is pretty much essential when sharpening the small drills. You can change to a white wheel, 100 grit and it does make a big difference to get the shape correct.

Originally Posted by FenceFurniture

<snip>
Where this might become very relevant is with a new drill that I want Colt to make. It's a specialist 3/4" Dog 'ole drill with a RotaStop eccentric shank and laser rings every 10mm up the flutes for knowing your depth. Being RotaStop compatible means that extensions can be used with it (the main function ot RotaStop). .
<snip>

Hi Brett,

Don't they already make one? Colt MaxiCut Plus Forstner Bit with Lip & Spur Drill Center Point

Or are you thinking of something different?

Regards
Ray

Hi Ray, something different, just a straight Brad Point because the forstner would have to be withdrawn repeatedly during one hole to remove the chips all the time. The forstner cuts just fine except for the chip removal in a deep vertical hole. It would be ok of course if you wanted to drill from underneath the bench

Have discussed a Dog 'ole drill with Groggy and he would prefer a Scotch pattern Auger, and Colt could do one (they think) but it would not be made by them (they sub out some work). One has to pick and choose with Colt - the stuff that they do exclusively is as good as it gets, but some of the other stuff is either 100% not done by them or somewhere in between. I really can't imagine a Brad Point or Forstner being any better than the Colts. Also, a Scotch pattern is not standard issue for them so there would be a part reinvention of the wheel etc. I haven't used a 5* FCE (Brad) bigger than 12mm (although I have a 16mm in the air as we speak) but I think it will do a pretty good job of chip removal, perhaps having to withdraw, in Catholic fashion, maybe 3-5 times per hole rather than possibly 10-15 or more with a forstner.

Btw, that HSS forstner is fairly new and also untried by me. It's mainly for shoulder drilling and steep angle holes, hence the adjustable brad pilot. I've got a couple of them in the air as well. Not a great deal of use for blind holes because of the pilot (don't know how short the pilot can be made yet). The standard forstner is High Alloy of excellent quality and does a very good job of deep boring, as long as you don't expect quick results in gnarly red gum etc. rsser did a deep boring review, thinking that they were HSS (because I originally mislead him, deliberately of course) and managed to blue the cutting wings a little bit. He was a little disturbed. That's when I put him straight about the alloy, and he "dipped his lid" to the quality of the alloy, saying he probably would have eased back a little (it was a very nasty piece of Red Gum). That review also shows the great value of the RotaStop system.

Originally Posted by FenceFurniture

The forstner cuts just fine except for the chip removal in a deep vertical hole. It would be ok of course if you wanted to drill from underneath the bench

Chip removal can be a problem, but your shop vacuum cleaner with a suitable nozzle may sove this problem, at least partially.

Regards
Paul

Yes Paul, but it's a fair old hassle when your doing the Swiss cheese style, like Groggy's bench. Doing just a few would be ok. Actually, I've tried that with a semi-deep bore and you still have to put a chop stick (rsser technique on the lathe) or something in to unclog the chips after about 30-40mm in. Essentially, whilst the maxicut forstners do have excellent chip clearance, that's only when doing shallower holes.

Boring deep holes requires a *very* strong vacuum or a twist in the drill to remove the waste from the hole. Once you get past the 50-75mm point the forstners simply jam and compact waste behind the cutter unless you continuously lift and clear the waste from the hole. This results in a rougher than necessary hole as it is difficult to remove and reinsert the bit in exactly the same plane each time. The clogging also increases the heat at the cutting edges.

This is why the augers are the superior bit for deeper cutting (and have been for aeons).

If you really wanted to get excited and you are drilling an a lathe, couldnt you fit a small steel pipe to the shank of the drill and feed compressed air into the hole just behind the "head" of the drill? That way the vaccum would do a much better job. (if you wanted to get really excited you could drill a hole in the "head"(?) of the drill and have the compressed air on the face, might even help to cool the drill a little.

Stuart

Yes Stu, great minds and all that.....I had considered that, and suggested it to rsser, bit it's starting to get a bit cluttered, and if you do want to withdraw the bit for inspection or whatever, it gets a bit complicated. Furthermore, Ern has a thing about the Vac sound (some frequencies can really aggravate certain ears, and I guess a vac is one of them for Ern).

Originally Posted by Groggy

Boring deep holes requires a *very* strong vacuum or a twist in the drill to remove the waste from the hole. Once you get past the 50-75mm point the forstners simply jam and compact waste behind the cutter unless you continuously lift and clear the waste from the hole. This results in a rougher than necessary hole as it is difficult to remove and reinsert the bit in exactly the same plane each time. The clogging also increases the heat at the cutting edges.

This is why the augers are the superior bit for deeper cutting (and have been for aeons).

You can trust this guy's opinion - he's plenty experienced!

Groggy, I've been meaning to ask you: now that you've settled into your bench and used it in dozens of different ways (because of it's incredible functionality) if you had your time over would you still have the same number of holes, or perhaps less? I'm sure that the ability to be able to put a clamp head onto any given square centimetre is very useful indeed because wherever the job is on the bench it can be clamped, but have you had frustrations with far too many choices of exit strategy for a rolling screw or similar?