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Messages - tgbto

#1
Knife Sharpening / Re: Besoin d'aides
November 07, 2024, 09:04:55 AM
In a nutshell, the OP says they can't get a knife close to sharp with their T4 that came with an out-of-round wheel that they trued afterwards. I suggest more/more careful honing, preferably with a MB-102.

===

Xav,

Sans avoir le détail de ta technique il va être assez compliqué de t'aider. Notamment, quel angle choisis tu, et comment règles tu la hauteur de la barre de support ?
Ceci dit, si tu arrives à lever un morfil de chaque côté de la lame, la technique de meulage est OK, et il faut regarder du côté du démorfilage. D'expérience, la Tormek peut créer des morfils qui prennent beaucoup de temps à enlever, en particulier avec un démorfilage à main levée.

Mes deux conseils pour voir :
- Passer *beaucoup* de temps à démorfiler, et choisir l'angle en commençant avec un angle trop faible, et en allant jusqu'à sentir et entendre que la roue en cuir "gratte" sur la lame, et que des petits morceaux de déchets grisâtres se détachent (mélange de pâte à polir et de métal).
- Acheter une MB-102 si tu ne l'as pas déjà, voire un KS-123. Cela permet de contrôler l'angle de démorfilage, et d'être plus efficace sans risquer d'arrondir le tranchant en démorfilant. Démorfiler à l'angle d'affûtage + 2 degrés est un bon point de départ.

Tu peux également, si tu as une ponceuse à bande avec une bande de démorfilage, essayer de meuler sur la tormek et de démorfiler sur la ponceuse, pour confirmer que c'est bien le démorfilage à la Tormek qui est problématique.

J'espère que ça t'aidera.
#2
As far as I am concerned, I use the SB mainly for HSS drills.

The SB works a charm for those, and I prefer it to diamond wheels because I don't have to worry about pressure (which I have a harder time adjusting with the drill jig than with the knife jig).

It does tend to glaze a bit, but the "Wootz maneuver" with a coarse diamond stone quickly restores it to a duly aggressive surface. I have only trued it once and slightly so since I own it.
#3
Hello Philip,

In terms of tools, I would advise the following :
 - A KJ-45 knife jig
 - A KS-123 angle setter, as you mention, so wheel diameter will not be an issue
 - A USB-420 long support bar. It is not only useful for long knives, but also for medium knives where you want some leeway in terms of clamping position in the jig
 - A MB-102 that will allow you to control the angle easily when honing (or grinding edge trailing, more on that further down)
 - If you want to refine the edge, or make it coarser, two (non Tormek) diamond plates for grading the SG wheel coarse or fine, they will help grade the stone faster, while staying true longer than when using the SP-650. You will use the SE-77 tool that comes with the Tormek for this. The longer the plates the better.

Regarding heel to tip or tip to heel, definitely heel to tip. You need control when dealing with the tip and you will notice quickly that control is harder to get when you're just laying the knife down on the stone. As for the change of angle at the tip, there is no short answer : if you care about looks, you'll probably let the contact point ride up the wheel on most knives, if you want a consistent angle you will rotate the jig so the tip stays in the same place. Practice (and a sharpie) will help you chose your course of action for every knife. You won't get "six sigma", hardware-constrained repeatability for this.

Now regarding the diamond stone, I have two of them and never use them for knives. I don't like the feedback compared to the SG wheel, the scratch pattern is not as even, and they require more fussing around than the Sg stone (they are more fragile, and ACC Anticorrosion concentrate is almost mandatory). Diamond stones shine in my opinion for carbide tools or very hard steels, or when a flat grind is mandatory.

If by stropping you mean stropping on a separate leather strop after honing, it will most probably increase sharpness (if done properly) for the first few hours or the first few strokes. Only you can tell if that is important to you, I personally aim for edge retention rather than initial sharpness. And my experience is that an ungraded SG-250 followed by careful honing are the best time/performance compromise.

#5
There are still a few who might think the T1 is an expensive honing station, or that it uses quite a bit of real estate in a kitchen.

For those, a fine ceramic rod with an angle guide will go a long way towards keeping T8-garage-sharpened knives in good condition.
#6
Maybe a different view on just the following topic :

Quote from: John Hancock Sr on October 15, 2024, 11:44:16 PMIf you buy the SG- which I recommend strongly, this will do almost everything you need, then also get the SP-650 grader to grade between fine and coarse.

I would concur with @MerryMadMick : I never use the SP-650 for grading, and only from time to time to round out the edges of the wheel. The SE-77 jig with a couple diamond stones is a better investment in my opinion. Plus the OP mentioned sharpening woodworking tools so they will probably have a SE-77 anyway.

And just a word of advice on grading with diamond plates and the SE-77 : while it is definitely more controlled and efficient than grading with the SP-650, and while it is true that it will keep the wheel (much more) parallel to the USB than using the SP-650 freehand, it can (and probably will) make the stone run out of round by accentuating the low spots. The solution to that is to have a MB-102/FVB and rest the diamond plate on the FUSB as well, in order to keep a constant radius.
#7
As for chisels and plane blades, especially if you are getting started with the Tormek, I'd recommend not altering the angle for the moment, as they often come with a factory angle that's tailored to their intended use. Resetting the angle can be time consuming especially when making it more acute on those massive blades.

And when trying to reproduce an angle, the "sharpie method" where you blacken the bevel, then use the microadjust nut to reach the angle where you remove the sharpie completely, is your friend. You can use the WM-200 AngleMaster to guesstimate the angle and roughly set the USB height.

Try to keep two things in mind :
- It is better to reach your desired angle by adjusting the USB height upward (so going from a lower angle to a higher one). It avoids backlash and makes the adjustment smoother.
- On large chisels, which will most likely have a flat grind to begin with, what you're trying to achieve with the sharpie method is to remove as much ink as possible *while still hitting the apex* of the chisel. If you remove ink in the middle you are not sharpening the apex, and if you remove too little ink at the APEX you're increasing the apex angle.

Hope it is clear, happy sharpening !
#8
General Tormek Questions / Re: KS-123 For Chisels
October 11, 2024, 08:23:52 AM
Quote from: John Hancock Sr on October 11, 2024, 02:57:42 AM
Quote from: tgbto on October 04, 2024, 03:04:11 PMSo you'd have to measure the protrusion distance ...

Even then it would not be accurate since the jig is specifically designed to use with the knife jigs which center lines are sitting a specific distance above the bar. I have not checked but if the Square Edge jig is a different distance above the bar then the geometry will be out.

Correct ! My bad.
#9
General Tormek Questions / Re: KS-123 For Chisels
October 10, 2024, 08:14:05 AM
In addition, as a general rule, edge leading tends to avoid creating a thin, fragile burr that can get torn off when honing, messing up the apex.

The only downsides to edge leading that I can think of are :
- more aggressive at the APEX, but then also more efficient
- higher risk of "catching", but that won't happen with jigs that are fixed wrt the support bar.
#10
General Tormek Questions / Re: KS-123 For Chisels
October 07, 2024, 08:05:24 AM
Fortunately nobody mentioned the lack of adjustability of the KJ in this thread, let alone complained about it ^^
#11
Anyway, here's what I just did as an empirical accelerated test:

I 3D-printed a one-sided 20° flat bevel, as wide as the SG-250 wheel, out of white PLA filament. It's a soft plastic that will be ground easily. You can see it in the first pic.

I sharpied it black as is customary, checked that the angle when against the far stop was correct, then ground it with one-second strokes, up and down, until all sharpie marks were gone (mostly), see second pic. I used a digital metronome, and tried to have even pressure.

I then painted it black again, then rubbed it against a #2000 diamond plate, and guess what, it is concave/hollow at the apex, hollow again at the shoulder, and convexish (or should I say, less hollow ?) in between.

As mentioned somewhere else, physics are stubborn, and they like continuity, such as when an equilibrium results in a concave shape, small displacements around this equilibrium will seldom turn that into a convex shape. It is easy to understand that if you spend more time against the stops, then you grind more, so the result is more hollow at the stops.

Now if we take one step back and think of what we do with our Tormeks :
1) With a typical kitchen knife ground with the KJ, using this "convexishing" technique, you will get a bevel that is hollow at the apex and round out the shoulder, then grind the side of the blade. But honestly, who really cares about concavity on a typical kitchen knife.
2) With a knife with a large primary bevel, the result will depend on where the shoulder of said primary bevel with sit when the KJ rests against the near stop.
 2a) If you move past the shoulder before reaching the near stop, refer to the above.
 2b) If you don't, you will either have this double-hollowed shape, or a completely hollow shape depending on how slowly you move in between stops. This shape will however have less of a concavity in the middle compared to when grinding the traditional way. But the same concavity at the ends.
3) With an axe ground with the latest jig, well no actual difference with 2a above, you'll just take more time to reach this result if the axe is convex to start with.

#12
I'd slap myself for those pesky SAVE/POSt buttons when editing...

#13
Quote from: tgbto on October 04, 2024, 02:54:41 PM
Quote from: iSharpen on October 01, 2024, 07:16:34 PMI can tell it's convex because of it's shape. It might not come through on the video but it's definitely rounded.

Hey Baz.

There is no question that the edge is rounded in the area that's away from the apex. But I really don't see how a convex wheel will grind a convex apex. In the same way a flat stone can grind a convex bevel with a flat  apex, a convex wheel may grind a convex bevel but there will be a transition to a concave apex at some point. And the wheel will have the tendency to dig into the material, ie make it more concave than it actually is, whereas the flat benchstone will guarantee that you always remove material in at worst a tangential fashion. Plus the benchstone tends to wear in a fashion that makes it concave, enhancing this phenomenon.

Going back and forth in between the stops kind of blends this into the shape of the blade that is most often naturally convex, which is why you see convexity (for now, and "far away" from the apex). You can think of a more extreme situation with a much bigger blade and/or a much smaller wheel, and you will easily see that you're naturally concaving the bevel, albeit much faster.

That happens pretty much in the same way that the natural tendency of most sharpening devices, being narrower than the blades they sharpen, is to make blades concave. Fighting this natural tendency is something we all know is part of sharpening skills. But we know it's something that needs to be fought constantly, and to that end we use the fact that the Tormek wheel is flat(ish) along the edge axis.

Grinding knives on the shoulder of the wheel is a sure way to eventually grind nice hollow sections. So is grinding the bevel on a round stone.
#14
General Tormek Questions / Re: KS-123 For Chisels
October 04, 2024, 03:04:11 PM
Quote from: Huang on October 04, 2024, 05:45:46 AMI have a fickle relationship with my K8. The KS-123 is a game changer for knife setup, I just ordered one, but have not been able to actually touch one. I'm thinking why can I not use it for chisels and other tools?

For one, the KS-123 can be used because you can position it next to the knife while it is being held by the jig and still measure the protusion distance (because obviously the knife is wider that the jig). For tools such as chisels, the jig being wider than the tool, you can't use it in such a fashion.

So you'd have to measure the protrusion distance, recreate it with a KG/SVM jig and a straight piece of metal to actually use the KS-123 the way it is intended. Quite tedious if you ask me. The AngleMaster is much more suitable for those one-beveled, large tools. Oh, and calculators always work, as long as you can measure a protrusion distance, and USB-stone distance.
#15
Quote from: iSharpen on October 01, 2024, 07:16:34 PMI can tell it's convex because of it's shape. It might not come through on the video but it's definitely rounded.

Hey Baz.

There is no question that the edge is rounded in the area that's away from the apex. But I really don't see how a convex wheel will grind a convex apex. In the same way a flat stone can grind a convex bevel with a flat  apex, a convex wheel may grind a convex bevel but there will be a transition to a concave apex at some point. And the wheel will have the tendency to dig into the material, ie make it more concave than it actually is, whereas the flat benchstone will guarantee that you always remove material in at worst a tangential fashion. Plus the benchstone tends to wear in a fashion that makes it concave, enhancing this phenomenon.

Going back and forth in between the stops kind of blends this into the shape of the blade that is most often naturally convex, which is why you see convexity (for now, and "far away" from the apex). You can think of a more extreme situation with a much bigger blade and/or a much smaller wheel, and you will easily see that you're naturally concaving the bevel, albeit much faster.

That happens pretty much in the same way that the natural tendency of most sharpening devices, being narrower than the blades they sharpen, is to make blades concave. Fighting this natural tendency is something we all know is part of sharpening skills. But we know it's something that needs to be fought constantly, and to that end we use the fact that the Tormek wheel is flat(ish) along the edge axis.

Grinding knives on the shoulder of the wheel is a sure way to eventually grind nice hollow sections. So is grinding the bevel along a round stone.