Sharpening a Weldon style single flute countersink

[hdv]

I noticed my Festool QLS 2-8 CE countersink is in need of sharpening. As I haven't done this before I thought to look it up, but I am getting differing recommendations. Some recommend removing material from the outside with a bench grinder, while others recommend filing the through hole with a diamond file. I know there are some members here that are a lot more knowledgable than I am when it comes to metalworking, so I'd like to ask here: how do you guy sharpen these countersinks?

 

[Packard]

Festool has a USA based sharpening service.  Do they not have the same in Europe?

If not, write to Festool and ask if they have a Festool certified or recommended sharpening service.

Most of the sharpening will be on saw blades, so specify that you are interested in sharpening the countersink.
https://www.woodworkingnetwork.com/...stry-news/festool-launches-sharpening-service

 

[Cheese]

I haven't had the need to resharpen any of my Zeroflute countersinks but the traditional method is to rework the cutting edge of the hole...carefully & minimally. Basically, you're making the hole diameter slightly larger on the non-relieved edge, also known as the cutting edge.

The outer surface can be machined but it's difficult to control unless you have the proper fixture and the proper grinder. To do that properly the countersink would need to be sent out to a tool grinding service as they would be able to maintain the proper relief angle.

 

[rst]

With 44 years of commercial glazing, I’ve had to sharpen mine occasionally.  I use a fine Dremel stone on the inside of the sink.  As with any hole saw sharpening the outside will be problematic

 

[Packard]

Circling around the subject matter, I have a few countersinks.  I frequently get chatter when I countersink a hole. 

I no longer countersink holes; I drill holes in countersinks.

I drill the countersink first.  It never chatters.  It makes an excellent lead-in for the drilled hole. 

None of which helps with locating a European-based sharpening service for the countersink.

Does it pay to sharpen a countersink?  How much does the Festool countersink cost?  I cannot imagine that Festool will handle any sharpening for less than $50.00.  So is it cost-effective to have it sharpened?

Can you chuck this bit in a slow spinning drill in reverse and stretch a narrow band of fine Emory sandpaper across the cutting edge?  It would burnish the cutting edge.  In my mind this will work (but all my great ideas work perfectly in my mind—in the real world?  Not so great.)

Addendum:  Google yielded the cost (American dollars) at $51.00.

What I would do, is go ahead and buy a replacement.  When it arrives, try sharpening the old bit.  Maybe even a fine Arkansas stone over the cutting edge.  If it is just dull and not damaged, it might be as easy as sharpening a knife. 

Note:  What Google did not reveal was, “Is the chamfer bit a solid piece of carbide or high carbon steel?”  If it is carbide, you can forget about sharpening with a stone or Emory cloth.  Do they make diamond sand paper?

I’m still thinking I would replace rather than have professionally sharpened.

 

[kevinculle]

I have an EZE Lap super-fine diamond hone on a "fingerboard" that I use to tune-up Forstner bits, countersinks, etc.  It looks like this:

[attachimg=1]

I lap the flats that form the cutting edge and it works really well.

 

[Packard]

I have an EZE Lap super-fine diamond hone on a "fingerboard" that I use to tune-up Forstner bits, countersinks, etc.  It looks like this:

[attachimg=1]

I lap the flats that form the cutting edge and it works really well.

How much do those diamond boards cost?  What is the size?  Nothing to reference the size in the image.

 

[hdv]

I don't trust my skill enough to grind the outside of the bit. But I think I have a diamond needle file that might fit in the cross hole. I'll go search for it tomorrow. If I find it, I think I will try filing the cutting edge of the hole as [member=44099]Cheese[/member] suggests and see if that makes enough of a difference.

[member=74278]Packard[/member] : I was indeed inclined to just buy a new one. At least that would be less costly than having the bit resharpened. Around here the bit costs about €40. Sharpening would cost €5 more than that, excluding postage. But I'll try the method Cheese suggests first. If I ruin the bit, I can always buy a new one. Trying won't hurt. Who knows, I might even learn something from it. That would be nice.

Oh, before I forget: the reason I need to do this is because I had to deburr 42 holes in aluminium.  After that I noticed that countersunk holes in wood were not as clean as they used to be. At first I thought there might be aluminium stuck to the cutting edge of the bit. But I don't see any when I look at it. That's why I want to try resharpening the bit.

 

[Cheese]

I don't trust my skill enough to grind the outside of the bit. But I think I have a diamond needle file that might fit in the cross hole. I'll go search for it tomorrow. If I find it, I think I will try filing the cutting edge of the hole as [member=44099]Cheese[/member] suggests and see if that makes enough of a difference.

[member=74278]Packard[/member] : I was indeed inclined to just buy a new one. At least that would be less costly than having the bit resharpened. Around here the bit costs about €40. Sharpening would cost €5 more than that, excluding postage. But I'll try the method Cheese suggests first. If I ruin the bit, I can always buy a new one. Trying won't hurt. Who knows, I might even learn something from it. That would be nice.

Oh, before I forget: the reason I need to do this is because I had to deburr 42 holes in aluminium.  After that I noticed that countersunk holes in wood were not as clean as they used to be. At first I thought there might be aluminium stuck to the cutting edge of the bit. But I don't see any when I look at it. That's why I want to try resharpening the bit.

Hey [member=66485]hdv[/member] ...FWIW...the Festool zero flute countersink is made from high speed steel (HSS) and is especially prone to prematurely dulling when used on aluminum. I learned the hard way... [sad]

A better solution is to use the Festool countersinks for wood only and then pick up a set of KEO countersinks to use on aluminum. The KEO items are machined from cobalt and will give a 10x-20x longer life when used on aluminum.

For those interested, here's 2 photos of the relief angles on a Festool & a KEO zero flute countersink. The line on the RH side of the cutter is the beginning of the grind line and the mark on LH side of the cutter is the end of the grind line, this very shallow helix defines the relief cut into each countersink on the outside diameter. This is why you don't want to mess around with modifying the outside diameter...it can muck things up. Better to just clean up the hole ID without rounding over any edges...keep all edges as sharp as possible but remove the thin wire burr that's produced after stoning the edge. It's not as obvious on the Festool item because the OD is smaller and therefore the draft is less.

The 3rd photo is just a shot of the KEO cobalt countersink.

[attachimg=1]

[attachimg=2]

[attachimg=3]

 

[hdv]

[member=44099]Cheese[/member] : yeah, I noticed. It seems I have learned the same lesson as you now.  [embarassed]

I saw your earlier posts about the Keo countersinks, but I never found them here in Europe. I guess I'll have to find other cobalt coated single flute countersinks. I suspect Alpen with have them too. I have some 4040 profile projects coming up where I could use a good countersink for aluminium.

 

[Packard]

My countersink looks like this:

What is the advantage of the circular design cutter?  I just looked on Amazon and they show cobalt bits but no carbide bits.  I wonder why.

I just ordered a drill/chamfer combination bit in carbide for #4 screws (smallest standard size wood screw I can find).  It is arriving on Friday. 

The bit I pictured above is the one that chatters on me.  Of late, I am cutting the chamfer first and then drilling the hole.  No chatter that way. 

So what’s the story on the circular design cutter on the Festool chamfer bit.

Note to OP:  If the Festool bit is not carbide, you can probably sharpen it with and Arkansas stone or a carborundum sharpener.

NOTE:  I am rather surprised that aluminum (a very soft metal) would have much effect on the cobalt bit (a very hard metal).  I’m going to google that for an explanation. 

 

[kevinculle]

That diamond hone is about 3/4" wide by 5" long with the hone area being about 2" long.  The thickness is maybe 1/8" to 3/16" in the hone area and it fits into the slots of a conventional Forstner bit.  Here's a better pic, I think I paid about $10 for it.

[attachimg=1]

 

[Packard]

That diamond hone is about 3/4" wide by 5" long with the hone area being about 2" long.  The thickness is maybe 1/8" to 3/16" in the hone area and it fits into the slots of a conventional Forstner bit.  Here's a better pic, I think I paid about $10 for it.

[attachimg=1]

Interesting.  I have some carbide bits.  None are dull at the moment.  But I will keep it is mind.

Google has yielded some interesting results. 

The preferred cutter for aluminum is cobalt. 

Aluminum shares a characteristic with stainless steel.  When it gets hot, it will weld itself onto the cutter.  So your cutter might not be dull, but might have aluminum welded onto the edge.

I would guess that adding a countersink to a steel hole would quickly “wear” away any aluminum residue.  I think it is worth a try.

In the early 1970s, before it went out of business, Farberware was a customer of mine.  I got a tour of their plant.  I found it interesting that they were deep drawing the pots over phosphor bronze tooling instead of steel tooling.  The engineer explained that after a single deep draw over steel, the stainless steel would weld tiny bits onto the tooling.  So all subsequent pieces would have deep scratches in them.  That is called “galling”.  The bronze can be made as hard as steel and does not gall with stainless.

When asked why they don’t use bronze more often, he explained that to get bronze that hard, you end up with a very brittle material.  The large cross sections in the deep draw pot tooling would not shatter.

As a very young salesman I got away with asking way too many questions and all these people were keen to educate me.  I would not have been able to ask all those questions as a more experienced salesman.  I must have been a pain in the ass.  (I probably still am.)

 

[Cheese]

[member=66485]hdv[/member]
I purchased mine from MSC, a metal working supply house over here. In the States, Travers Tool as well as Zoro also offers them for sale.

Amazon could also be a good option for you. They offer both 4-piece and 5-piece sets.
https://www.amazon.com/KEO-53518-Si...395096516&hydadcr=14868_13390424&keywords=keo+countersink+set&qid=1734531193&sr=8-5
https://www.amazon.com/KEO-53519-Si...395096516&hydadcr=14868_13390424&keywords=keo+countersink+set&qid=1734531193&sr=8-8

And finally, here's a page from the KEO brochure that will allow you to enquire about local availability by referencing the part number. If the 4040 project involves a ton of countersunk holes, you may want to consider the TiN coated versions.

[attachimg=1]

 

[Cheese]

My countersink looks like this:

What is the advantage of the circular design cutter?  I just looked on Amazon and they show cobalt bits but no carbide bits.  I wonder why.

I just ordered a drill/chamfer combination bit in carbide for #4 screws (smallest standard size wood screw I can find).  It is arriving on Friday. 

The bit I pictured above is the one that chatters on me.  Of late, I am cutting the chamfer first and then drilling the hole.  No chatter that way. 

So what’s the story on the circular design cutter on the Festool chamfer bit.

Packard, if the countersink is chattering, slow down the speed, that usually helps bigly.  [smile]

For hand held use or small drill press use (I'd guess 99% of us use a small drill press), the zero flute or single flute countersinks will give the best results. Multiple flute countersinks are really designed to be used on large machine tools that will hold the work piece and the countersink firmly in place and allow NO movement. They're designed for large production tools running at production speeds.

I understand why you're using your countersink as a drill bit but it wasn't designed to be used in that manner. If you drill the through-hole first, then the countersink doesn't have to remove much material relative to its diameter. You'll also notice longer countersink life as a result.

I'd approach this issue by drilling the through-hole first and then using a zero flute or single flute countersink at a very slow speed to create the countersink. Lubrication always helps the cause and I prefer IPA for working with aluminum ONLY.

I probably own 20-25 countersinks and all are zero flute or single flute (M.A. Ford) models. The only multiple flute countersink I own is a 6 flute carbide model that I use to countersink holes on cementitious based materials.

 

[Packard]

I believe that I have my bench top drill press at the slowest pulley setting.  I will check when I get home. 

The extra wear on the bit by countersinking first is on the section of the bit that would normally not be used at all.  So I don’t see the wear as an issue.

 

[hdv]

[member=44099]Cheese[/member] : I discovered today that Fisch has HSS CO5 single fluted countersinks in their product range. I do trust that brand and it is easily available around here. I am going to try that one, I think. If that proves to be no success, I will try the Alpen countersink.

I tried filing the QLS with a diamond needle file. That went surprisingly well. The bit has definitely seen better days, but it does countersink without leaving frills again. Thanks for the suggestion!

 

[hdv]

[member=74278]Packard[/member] : in addition to what Cheese wrote, I found that even at slow speeds fluted countersinks are almost impossible to keep from chattering in wood where the difference in hardness between late wood and early wood is significant. The Weldon style bits have more of a cutting stroke and will shear the wood more cleanly because of that. I do have traditional countersinks from Bohrcraft, and they are good, but in wood I always will choose a single flute over multiple flutes. It certainly might be due to a lack of proper technique on my side, but for me they just give better results.

 

[Packard]

You know, this is one of the “simple” things that I just go out and buy without too much thought.

Thinking about things can have remarkable results.  So, I may have to give this some thought.