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Messages - tgbto

#526
Quote from: cbwx34 on January 31, 2022, 07:34:24 PM
Quote from: nevertakeadayoff on January 31, 2022, 07:31:11 PM
...
Also, sometimes I change the stone and it wobbles. Sometime it doesn't.

Haven't done it personally, but some users will put a mark on the shaft and on the stone, so when they remove/reinstall it, they can line it up in the same location... to prevent this.

I do that... partially. I always put the stone on the shaft with the label up. I consider the shaft true enough for my tolerances, and I've never seen any sign that it is not on both my T-8s.

But unless we are not talking about the same thing, this solves what I call the stone being "out of round" when it is not put on the machine in the same position it was trued. The wobble is to me a side-to-side movement; one that is due to the stone having some lateral play on the shaft, that got solved for me just by making sure the shaft was all the way in before tightening the nut.

#527
I'd concur with cb : the wheel may get out of round with the diamond plate, though with the small quantity of knives I sharpen it takes a rather long time. Once it starts to be so, there is no coming back and it will only get worse. The truing tool with take care of this.
#528
Knife Sharpening / Re: A small useful 3D printed tool
January 27, 2022, 04:45:25 PM
Nice job !
#529
Knife Sharpening / Re: SJ-250 and deburring
January 27, 2022, 04:43:54 PM
Quote from: cbwx34 on January 27, 2022, 03:49:07 PM
Maybe it's a matter of perspective? 

Maybe, and maybe a question of what it means to "improve" the edge. I have not seen an improvement in BESS scores between SG > SJ > honing or SG > honing. Nor have I seen any reduction in honing time. As a rule, I always start grinding/honing with the handle in my right hand, and finish with the handle in my left hand. So the burr is always on the "good" side for the next step.

The edge is shinier with the SJ though, and I have no means to quantify edge retention between SG > SJ > honing and SG > honing. My guess would be that edge retention is improved with SJ as the edge has less microteeth that will be easily blunted, but I have guessed wrong so many times that I wouldn't bet on it.
#530
They do, yes : they abrade the surface and break down the surface particles in the process. Pretty much the same way the stone grader does.

I have not noticed faster wear from the stones. I did find though, that I had to true the wheel less often.

Just for clarity, I did not invent this process at all, I saw it in one of Wootz's videos on stone grading.
#531
Knife Sharpening / Re: SJ-250 and deburring
January 27, 2022, 12:42:28 PM
In the Tormek presentation video for the SJ, they repeat the claim that there's no need to hone (around 1:00).

There's some kind of a debate in the Advanced Sharpening Class at around 1:11:30. Wolfgang says normally you don't have to hone after the SJ but with some steel varieties you do need to hone very slightly.

So maybe it's a question of steel, but those I experimented with seem fairly standard to me, and I have to hone - not that lightly - to get rid of the burr...
#532
I no longer use the tormek stone grader. I use the diamond plates in the SE-77.

I have the fine plate more or less sitting in the SE-77, and when I need to greade the stone fin I slip the SE-77 onto a horizontally mounted USB (that I don't use much, as I always use the long USB). Then I finish the knife on the stone graded fine, then hone.

Then only do I change the knife and start sharpening it on the stone without grading it coarse. The stone will quickly get back to its ca. 600 grit, in-between state.

#533
I know for most (all?) of my rotary equipment you either have rotary switches (so there is no ambiguity what you need to do at any time to interrupt the power supply) or double push-buttons. In the latter case, the ON and OFF switch work very differently (and the safety manual of the Tormek seems to confirm it is the case with Tormek as well) :
- The ON pushbutton triggers a magnetic switch by powering a solenoïd. This closes two switches that connect mains power to the machine. Once the machine is powered the solenoid remains powered and so power is maintained. Pushing again on the ON switch does basically nothing as the solenoid is already powered.
- The OFF switch interrupts the power supply to the solenoid, so the machine is disconnected from mains

Such switches usually include an overcurrent and/or differential protection as well, so that when the protection is triggered, power is removed from the solenoid, and the machine is turned OFF. I'm not familiar with the "U<" symbol on the switch, my guess would be differential protection.

All in all, you can't have such a switch with a single button as at a moment in time you wouldn't know what pressing on it might do : Is the machine off so i'll turn it on, or is the motor somehow not turning but the machine is powered and i will turn it off ? That plus the fact that if the switch was bistable, you'd keep supplying power to the solenoid, overriding the protection.

#534
Knife Sharpening / Re: How do I get a small knife edge?
January 26, 2022, 08:25:45 AM
Quote from: van on January 25, 2022, 06:06:06 PM
Maybe it should do it in reverse, first at 18 ° dps and then at 14 ° dps to create a small bevel.
Or am I wrong to interpret the question?

If you do it first @18dps then @14dps, you will be working on the edge first, then on the shoulders. It will be very hard to be consistent in doing so, as you'll have to be doing heavy grinding of the shoulders while at the same time making sure you keep a hair-thin 18dps bevel along the edge.

Doing it 14dps first, then a few light strokes @18dps ensures that the edge is ground @18 but not too wide.
#535
Ken, I guess you're referring to my other post about the lexicon.

The idea was not to replace the excellent sources you've listed. As you say, they are many, many of them. The idea was therefore rather to have some kind of a one-stop-shop for members when a question occurs. So that we would not say: for DBS, please look there, for DPS, elsewhere ...
#536
Quote from: highpower on January 24, 2022, 07:38:39 PM
Probably not needed but cheap insurance against further chipping in my mind.

I'm not sure it would be, right ? You will probaly only fill the area which has cracked yet, or else you'd be modifying the internal geometry of the bore, which could in turn skew the wheel.

In that case, not only won't it prevent a non-epoxied sector to chip, but if there is just a tiny step between your repair and the rest of the bore, wouldn't that precisely give the shaft some purchase to catch on the epoxy and push it outwards, with the risk of creating new cracks ?

#537
Knife Sharpening / Re: How do I get a small knife edge?
January 25, 2022, 10:06:12 AM
Pietje,

I'm not sure what you are referring to by microfase. In case you are referring to the microbevel, that is a short bevel at the very tip of the edge, it can only be made at a HIGHER angle than the main bevel angle.

So you can first grind for 14dps, then increase the angle and grind only a short bevel at 18dps. It is perfectly doable on a Tormek, I'd recommend using a fine grit stone (SG just recently graded fine, SJ or DE-2x0) in order to not grind too much.

sorry if I didn't understand you correctly.
#538
Hello all,

As mentioned a few times, it would be nice if newcomers and oldtimers alike could have a shared reference for many terms we use.

The idea would be to make this a sticky thread, that would be completed/amended as often as necessary.

It would include several sections, one with common abbreviations, one with the list of tormek references as compiled by Rick and others, and possibly if Wolfgang/Sebastien authorize it, a reproduction of the drawing shown during the Advanced Sharpening youtube class, with all blade shapes and terms (bevel, choil, etc.).
It also seems to me it wouldn't be complete without a link to Rich Colvin's sharpening handbook and the Tormek Youtube channel.

What do you think ? Ken, if you think this is inappropriate, feel free to delete ! If not, feel free to reply and I will try to add the to the original post.

Abbreviations








AbbreviationElaborationMeaning/Reference
dpsDegrees Per SideHalf the total bevel angle, or angle between one side of the bevel and the plane of symmetry of the blade
HRCHardness on Rockwell Scale CIndicates the toughness of the blade, its resistance to indentation
BESSBrubacher Edge Sharpness ScaleMeasures the sharpness of the blade at a given point along the blade, at a given instant.
CBNCubic Boron NitrideA synthetic crystal with a hardness second only to diamond

Tormek Jigs/Parts
































ReferenceName
US-105universal support for T-7 & T-8
XB-100Support base (plate and knobs only)
MB-100Multi-Base
USBUniversal support bracket
BGM-100Bench grinder mounting set
SVM-45Knife jig
SVM-140Long (and flexible) knife jig
SVM-00Small knife jig
SVA-170Axe jig
SVS-38Short tool jig
SVD-185Gouge jig (old)
SVD-186Gouge jig
SVS-50Multi jig
SE-76Square edge jig (old)
SE-77Square edge jig
SVX-150Scissors jig
SVD-110Tool rest
SVH-320Planer blade attachment
SVP-80Moulding knife attachment
DBS-22Drill bit sharpening attachment
TT-50Truing tool
SP-650Stone grader
WM-200AngleMaster
TTS-100Turning tool setter
LA-120Profiled leather honing wheels
LA-124Narrow profiled "discs" (leather honing wheels)
RB-180Rotating base
RM-533 Rubber work mat
PA-70Honing Compound
ACC-150Anti-Corrosion Concentrate


Tormek Stones







SG-200/250Original grindstone
SB-250Blackstone silicon grindstone
SJ-200/250Japanese waterstone
DC-200/250Diamond Coarse
DF-250Diamond Fine
DE-250Diamond Extra-fine

Picture with blade shapes/blade terms
To be added ?



Cheers,

Nick.
#539
Knife Sharpening / Re: SJ-250 and deburring
January 23, 2022, 11:15:31 AM
Cb,

I will try to experiment edge trailing. However they also say in one of their advanced classes that edge trailing creates more of a burr, although it prevents from digging into the soft stone.

And when I say it's just for looks, I mean that I haven't noticed any difference in sharpness (BESS or cutting test) nor edge retention (even though I have no CATRA tester to back this up) for any standard knife, whether I polish it on the SJ or not.

I do not have any very high-quality hard-steel western style knives so I don't know it that would make a difference in sharpness or honing time with those. For my standard HRC58-61 CrMoV knives, I even feel it requires MORE honing after a SJ polishing step compared to just the SG graded fine.
#540
Knife Sharpening / Re: How do I get a small knife edge?
January 23, 2022, 10:55:22 AM
Pietje,

The width e of the bevel is a function of three things (as seen on the attached picture):
- The pink blade angle beta (in dps here)
- The red bevel angle alpha (dps)
- The blue distance between the tip of the original thinned blade and the actual tip (d)

The relationship between e, beta, alpha and d can be worked out with a bit of trigonometry, but to make a long story short and get back to your problem, if you want a small e you either have to :
- increase the bevel angle alpha, as shown by the green bevel compared to the orange bevel. This will however only take you so far because you won't be able to get the bevel any thinner than half the blade thickness at that point. Moreover, increasing alpha will make the blade less sharp AND worsen the edge retention. You will only gain in toughness. Plus this will leave part of the current wide bevel visible.
- decrease the distance d. To do so, you have to thin the blade as shown by the dotted line. You can do that over the entire height of the blade, and you will most likely need a belt sander AND a lot of skill. You can also thin the blade more locally, that is grind a primary bevel at a much higher angle than alpha, THEN grind your secondary bevel at alpha. However I'm afraid this defeats your initial purpose of having a very thin bevel.

Keep in mind that the reason blades come out of the factory with a very thin edge is because they are sharpened very close to the original tip of the blade, i.e. with a very short distance d. As you use and sharpen your blade, you will quickly get to a point where the bevel height is significant, especially if you don't feel the burr early on in the process. A new blade will require very little grinding to raise a burr.

I'm afraid once the edge is wide there is not much to be done apart from thinning the blade...

Cheers,

Nick.