News:

Welcome to the Tormek Community. If you previously registered for the discussion board but had not made any posts, your membership may have been purged. Secure your membership in this community by joining in the conversations.

www.tormek.com

Main Menu
Menu

Show posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Show posts Menu

Messages - wootz

#31
Jan, are you implying we do not center blades in knife jigs before grinding? - we always do.
BTW, the Tormek knife jig SVM-45 centers a 2.1 mm blade, not 2.5 mm as you think.
Anyway, the blade thickness behind the edge matters for accurate calculation, even if using a self-centering jig.

Our software update is not only for the sake of the edge angle accuracy, but for better matching the grinding and honing angles to get a sharper edge.
As you guys can see at the http://knifegrinders.com.au/software_testing.htm the BESS Sharpness Tester PT50 showed 60-80 BES for the 12° and 16° edge honed with the Tormek honing paste at the ground angle. This is an improvement over what we observed in the past for the knife steels used in this testing.
#32
Jan, sharpen plate steel 1mm, 2mm and 3mm thick to the same target angle using your script, and you will see difference in the ground angle between all the three.
.
#33
We've completed testing of our updated software, the testing process and results are shown here:
http://knifegrinders.com.au/software_testing.htm

It has been an exhaustive testing. I didn't count, but overall we did near 100 test sharpenings. With the amount of experimental grinding and honing we've done using the Grinding Angle Setter and the Frontal Vertical Base applets, I am confident in the accuracy of our software. Those of your who have a laser protractor will be able to confirm it yourself as we release the update.

It is clear now, that thickness behind the edge is an important parameter that should not be ignored.

The mathematical description of the grinding angle given for Tormek machine by Ton Nillesen in 2013 is using an abstract blade, thin and single-bevel. This is a normal phase in scientific thinking, as we have to abstract from real-world particulars to be able to generalize and describe the reality mathematically. That model did not take into account the thickness behind the edge. Because of that, the formulas give a systematic error for thicker blades, especially double-bevel, as Ton Nillesen explains in his additional booklet in 2018.

Our updated computer algorithm factors in the thickness behind the edge, and specifics of double-bevel edge vs single-bevel. It is more complex, but also more accurate.

This, however, does not make our applets more complex to use.
For our customers who care about the edge angle accuracy, our software gives an accurate tool.
But those of you who prefer simplicity and do not care much about 0.5 degree deviation from the target angle, can simply put number "1" in the "Blade thickness" field for thin knives, and number "2" or "3" for thick knives. I will explain this in the updated manual.

The software is now with our MacBook and mobile apps programmers, and should be released within 2 weeks from today. I will then send the update for Windows, Mac, iPhone/iPad and Android smartphone/tablets to our existing customers free of charge.


#34
Last week a professional sharpener from Europe, who already has several Tormeks, wrote to me that he is looking at a clone only because it runs at 125 RPM, to speed up his sharpening. I must have been thinking about this till the last night I saw this solution in my night dream, actually :)

No slippage of the insert, and no spillage of the water at this speed. In the T7 I could insert a 2.5 mm bushing that increases RPM to near 150, but the T8 takes maximum a 2mm insert.

CORRECTION - there is slippage when the blade is pressed against the wheel. The insert must be fixed on the motor spindle to work. Not as simple as it seemed initially.
#35




You've heard that CBN and diamond wheels grind better than stone wheels, but that is given the pressure on the blade is the same.  Since pressure on CBN and diamond wheels is to be less than on the stone wheel, to see their grinding advantage we need higher RPM.

Generally speaking, with the evolution from stone toCBN and diamond wheels that dissipate heat from grinding very well, the Tormek RPM could be increased to 250 RPM. You will not want that much speed in precision grinding of delicate blades, but for grinding bevels on grossly dull knives and tools or reprofiling you'd love it. So if this ever is going to happen, it better be done with a removable RPM-increasing insert that the user can put on the motor spindle when he needs more intensive grinding.
#36
Quote from: Josu V on October 16, 2019, 08:43:29 PM
One question about honing diamond compounds.

I´m in process with paper wheels. I use an oil based diamond compounds whith leather wheels of Tormek.

https://www.thk.hk/online-cart-dtl.php?cid=38&sid=61&ssid=0&id=498

Any problem to use this compounds in the Razor Sharp Paper wheels?

Regards

The THK diamond paste is what we use on paper wheels, good enough and not expensive.
#37
Quote from: Josu V on October 15, 2019, 09:46:22 PM
In first place, thank yoy for your work.

I will be alert for possible update for IOS app.
Please...  if necessary, I will buy a high magnification glasses in order to can see the app in my smart phone.  ;D
I always use my smart phone to calculate grinding and honing measures and find very interesting an update of the smart phone app.

Regards

;D
Not to worry, Josu. We are blessed to have the best mobile apps programmer, he should be able to solve it with an extra screen for the additional settings. I haven't thought much about it yet as we are in the early stages of the upgrade. I only wanted to say that as I myself program for Windows, the computer-based applet will be ready first; others will follow.
#38
Knife Sharpening / Grinding software upgrade is coming
October 15, 2019, 08:42:11 AM
NEED FOR UPGRADE
In its current form, our software sets an accurate grinding angle for resharpening a knife with established bevels at the existing edge angle.
E.g. you resharpen a 15 degrees per side (dps) knife to the same 15 dps.

However, when grinding new bevels, sharpening a grossly dull knife or a knife blank gives an edge angle differing from the calculated target by 0.5-1.5 degree. The thicker is the blade behind the edge, and the lower is the new edge angle, the greater is the difference.

To complicate it further, when sharpening on a coarse wheel, you may get a higher than the calculated angle simply because the jig projection shortens as you grind off the apex and raise the burr.

For example, when you resharpen a thin kitchen knife on a fine wheel to the same edge angle as this knife already has, you get the edge angle within 0.1 degree of the angle calculated by our software. But when you sharpen a thick hunting knife on a coarse wheel, you get an edge angle by 0.5 degree higher if sharpened at the original edge angle, and by up to 1.5 degree higher if reprofiled to a lower angle.

If you have a laser protractor, observing how the edge angle changes in the process of shaping bevels gives a better understanding of what I am writing here.

NEW INTERFACE
The new interface has additional parameters in its "Blade" section, to address the above and improve accuracy.



STATUS
I've coded the computer algorithm and currently testing in sharpening blades of varying thickness.
The calculations are along the lines of the explanation given by Ton Nillesen in 2018 on the page 6 of his additional booklet that can be downloaded from our website http://knifegrinders.com.au/Manuals/Grinding_Angle_Adjustment_Booklet_2018.pdf

The blade position on the grinding wheel changes as the sharpening progresses, gradually lowering as the edge apex travels the distance of the blade thickness behind the edge, as shown on the following schema:


This downwards shift of the blade and the knife jig it is clamped in increases in the duller edge, the thicker blade, the coarser grinding wheel, and the lower grinding angle. If not corrected, the actual grinding angle will be differing from the target.

As I am happy with my testing, we will prepare an upgrade, first of the computer-based applications, Windows PC and MacBook, and email an upgraded download to our over 1000 customers.

I am not as sure about the mobile applets, though. iPad and tablets are no problem and we will sure upgrade them and find a way to deliver to our existing customers, but the phone screen may be too small to accommodate the additional settings.

We will also upgrade our Frontal Vertical Base software with these advanced settings. But again, the phone applets are a problem, as they hardly take even the current FVB interface.

As we all understand, this is not only about the edge angle accuracy, but for better matching the grinding and honing angle to get a sharper edge.

We will also have to update the applet manuals and our webpage with the new information.
Overall, we need about 1 month to complete this upgrade, and appreciate your patience.

Cheers, Vadim
#39
Michael from Denmark, a professional sharpener, employing our software for Tormek in his business, has shared his sharpness BESS scores.
His sharpening equipment includes 2 Tormeks with all grinding wheels imaginable, and a half-speed buffer with 2 slotted paper wheels for deburring, our FVB and PPC, a BESS sharpness tester, and a laser protractor. He is sharpening for restaurants in the Copenhagen airport and his area, households, scouts etc.




Numbers in his notebook are sharpness of the knives in BESS, for comparison a new utility knife blade scores 150-200, and a disposable shaving razor under 50.
At the top are his notes on the wheels diameter, and Universal Support height for grinding and paper wheels for the knife jig set at 130mm, as calculated by our software.

Michael is very innovative, and we learn a lot from each other; later he may share with us all his method of sharpening serrated knives on grinding wheels of his own design.

An excerpt from his correspondence:
"I am in the process of contacting a teacher at the chiefs school here in Copenhagen that teaches for the chef degree and other kitchen personal...
My goal is to talk and show how knives also can be sharpened and what they should look for when having someone else to sharpen knives - a sharpening service. I have tested one other knife sharpening service to see how there result was - and as my wife said when she looked at the finished knives we got back - "Have they been sharpened?" - was her reaction to the result. She has also tried other sharpening services at work - with bad results too there. So I thought it could be fun to teach these up-coming chiefs to be more quality minded for getting their knives sharp."


Next is another page from his notebook with BESS sharpness numbers for his workload. Impressive, considering that <= 50 BESS is the shaving razor sharpness.
Michael writes:
"I've done a full workflow of sharpening 14 straight knives for a client using 4 Tormek wheels, and 2 paper wheels with 5,0 and 0,5 diamond paste on them and supports. For the fun of it and to see how well the sharpening went I measured all 14 knives. The more I measured the merrier I got. Have a look at the attached.
I just needed to share this with you to tell that following all your sharpening guidelines really pays of to follow! Thank you again for all the efforts you have used to improve the sharpening..."


#40
The latest 4th edition of the Knife Deburring book is now in a downloadable PDF available on our website, it is not free but is priced less thanks to its digital format. Hopefully this will help to spread the knowledge better than through the printed books.
You do not have to pay twice for the new edition of the book: customers, who earlier bought the 3rd edition of our printed book or Kindle, and also want the PDF of the 4th edition, please email us for free download link. Thank you for your everlasting support!

#41
Knife Sharpening / Re: How to use chromium oxide paste
September 23, 2019, 03:47:13 AM
Chromium Oxide is no way an alternative to the Tormek honing paste, no. Chromium oxide on a 2nd leather wheel is used for edge refining AFTER the edge has been deburred on the 1st wheel with the Tormek honing paste PA-70.
This extra step of honing is for high-end knives. We finish on chromium oxide to clean up the deburred areas on the edge from any weak metal left after the burr breakout to get an "ideal" apex that will stay keen for longer.
#42
Knife Sharpening / Re: How to use chromium oxide paste
September 23, 2019, 12:59:02 AM
Hi Torben,

Using the Tormek oil the way you did is absolutely OK.
But the thick layer of chromium oxide may round the edge. The rightly applied should look like a leather "painted green", not like a layer on the leather.
You simply need to scrape off the excess of the chromium oxide paste by passing the spine of a knife across the rotating wheel, press the blade near perpendicular to the wheel.
After that, as you start doing your knives, you will see that the edge on the first couple of knives may not come out as sharp as it will on the following knives - the thinner the chromium oxide, the better the result. So do not reapply it too often, only once in 4-6 months.
#43
Knife Sharpening / Re: Jig setting knife block
September 19, 2019, 05:05:57 AM
Rudolf from Austria sent us a photo of his jig-setting block:

#44
Knife Sharpening / Re: FVB applet trouble
September 17, 2019, 05:47:53 AM
Thank you for the photos TJ. I've checked our records, and see that you have Tormek T-8, so your calculations and setup are correct.
With a narrow blade like this, you need to thin away ends of the SVM-45 clamps as it is simply too thick - see how I've done, I ground them on a bench grinder:

#45
Knife Sharpening / Best BESS score by edge angle
September 16, 2019, 01:13:45 PM
This is for people who use our software Grinding Angle Setter for Tormek and also have the BESS sharpness tester.

You must have noticed that a 20 dps and 15 dps edge never scores on the sharpness tester as well as the 12 dps, let alone 10 dps edge, despite showing the same keenness in the hanging hair test.
Many a man on this forum put true razor edge on the knives, so can you confirm my observations that the razor sharp edge will score:

10 dps edge near 50 BESS;
12 dps edge 50-70 BESS;
15 dps edge 70-90 BESS; and
20 dps edge near 110-150 BESS.

I am looking for confirmation from others of this "best score by edge angle" pattern.