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Messages - wootz

#16
Knife Sharpening / Re: Question for FVB users
April 10, 2020, 09:01:54 AM
Quote from: janeric on April 10, 2020, 07:20:41 AM
Just to clarify things, does the FVB need to be in contact with the body of the T8 when sharpening ordinary knifes?

Please see our video "Grinding and Honing Software for Tormek" https://youtu.be/JjLrG-2iawY - all your questions are answered there.
#17
Quote from: wootz on November 18, 2019, 03:44:58 AM
The working prototype:



Sleeve 1.5mm thick

Inner diameter 11mm
Outer diameter 14mm

Length:
Tormek-7  28mm
Tormek-8  32mm

One Threaded hole M4
Socket set screw M4
Set screw length: Totmek-8 max 4mm; Tormek-7 - any.

Allen key 2mm

My coarse wheel Tormek now runs overclocked to 130 RPM.

... before you ask, we are too busy at the moment to make them for others, maybe in January next year. Check with your local steelworks shop if they can make one for you.

I see on YouTube variations of this approach to speed up Tormek RPM:

Using epoxy (12 years of knife sharpening on the same T-7)
https://www.youtube.com/watch?v=UzqyIMPMQhQ&t=118

Using cloth tape (in German)
https://www.youtube.com/watch?v=-kfVllwWjzI

Using cloth tape and an elastic tube (in German)
https://www.youtube.com/watch?v=0DiHBg8c9r4&t=920s
#18
Quote from: wootz on November 16, 2019, 01:43:07 AM
Tormek-4 owners, please bear with me - the testing is still in progress.

We do not use Tormek-4 in our sharpening workshop, but I've bought a T-4 for the purpose of the testing. Proper testing requires constant diameter of the grinding wheels; since we do not make 200mm CBN wheels I had to order them from WoodTurnersWonders USA, but they say they are on backorder from their factory, ETA 4 weeks.

I will have every grinding and honing regimen tested for T-4 as we've done for T-7 and T-8, and in 2 months the software for T-4 will become as reliable as it is now for T-7/8. For now the result may be playing in both the Grinding Angle Setter and the Frontal Vertical Base applet because of the pure theoretical extrapolation based on the T-4 constants.
T-4 is the last piece in our big revision that is still pending experimental verification... Well, if I can find a SuperGrind 2000 around, I will test it in real sharpening as well.
When ready, I will email the update to Tormek T-4 owners we have on our records. Appreciate your patience.

Tormek T-4 updated software is available as of yesterday.
We've updated both the Grinding Angle Setter and Frontal Vertical Base for Tormek applets in the part of T-4.
Testing has shown that the software works accurately for Tormek T-4.

Please see our YouTube video for how to update your applets:
https://youtu.be/DTq71b033OQ

Cheers,
Vadim
#19
The working prototype:



Sleeve 1.5mm thick

Inner diameter 11mm
Outer diameter 14mm

Length:
Tormek-7  28mm
Tormek-8  32mm

One Threaded hole M4
Socket set screw M4
Set screw length: Totmek-8 max 4mm; Tormek-7 - any.

Allen key 2mm

My coarse wheel Tormek now runs overclocked to 130 RPM.

... before you ask, we are too busy at the moment to make them for others, maybe in January next year. Check with your local steelworks shop if they can make one for you.
#20
Al, New Zealand woodworker & sharpener - twice as sharp as the Gillette razor.
Sharpened on Tormek and honed on paper wheels, using our software



Video how we sharpen Japanese single-bevel knives on Tormek: https://www.youtube.com/watch?v=dhpajIaBW0c
#21
Tormek-4 owners, please bear with me - the testing is still in progress.

We do not use Tormek-4 in our sharpening workshop, but I've bought a T-4 for the purpose of the testing. Proper testing requires constant diameter of the grinding wheels; since we do not make 200mm CBN wheels I had to order them from WoodTurnersWonders USA, but they say they are on backorder from their factory, ETA 4 weeks.

I will have every grinding and honing regimen tested for T-4 as we've done for T-7 and T-8, and in 2 months the software for T-4 will become as reliable as it is now for T-7/8. For now the result may be playing in both the Grinding Angle Setter and the Frontal Vertical Base applet because of the pure theoretical extrapolation based on the T-4 constants.
T-4 is the last piece in our big revision that is still pending experimental verification... Well, if I can find a SuperGrind 2000 around, I will test it in real sharpening as well.
When ready, I will email the update to Tormek T-4 owners we have on our records. Appreciate your patience.
.
#22
Instructions on our software update have been emailed.
If we missed someone, it means we do not have your email on records - please email us a proof of purchase of the original applet, and we will email you a promo code to install the updated applet free of charge.

Feedback from Spain:
#23
At my workshop we sharpened 3 types of blades, under 1mm behind the edge, 2mm and 3mm thick behind the edge,
from 10 to 20 degrees per side, at 1 degree step, registering the actual edge angle vs calculated.

We repeated this grinding into the edge, and grinding with the edge using our Frontal Vertical Base.

This way we collected a set of experimental data.
Looking at these data I saw regularities that I expressed mathematically and included into our computer algorithm.

We then made another round of the above 100 sharpening sessions to confirm the new algorithm on 2 Tormek-8 and 2 Tormek-7 machines, as detailed in the Software Testing on our website http://knifegrinders.com.au/software_testing.htm

Our computer algorithm is the most accurate and the best tested.
This way we've improved matching of the ground angle to the honing angle, and knives sharpened using our updated software and Frontal Vertical Base are sharper than ever. Everyone can now get hair-splitting edge on his Tormek machine.

Jans, you better put aside your pencil, switch off your computer and switch on your Tormek.

Another good news: last week Tormek agreed to supplying us directly with the XB-100 part for our Frontal Vertical Base. The first boxes arrive to Australia in 2 weeks, and we won't have interruptions in production as we used to when we sourcing this part through retailers.
We are also the very first in Australia to get Tormek Extended Universal Support US-430, to supplement our Frontal Vertical Base but not sell individually.
#24
Jans, simply start your Tormek, and set the grinding angle using your formula and _TormekCalc.xlsx.
Grind a single-bevel blade and a double-bevel and observe difference between the resulting edge angle and the calculated.
Then grind 2 double-bevel blades of differing thickness behind the edge and observe difference between the resulting edge angle and the calculated.
Then take the thicker blade and grind it at 20 degrees, and at 12 degrees, and observe how the deviation from the calculated angle increases.

Then you probably will reread Ton's explanation with more understanding.

What Ton does not mention, but I've found out, is that grinding with the wheel rotation goes differently to grinding into the wheel and requires additional mathematics. Therefore, you will see that the angle calculated for the Frontal Vertical Base by _TormekCalc.xlsx deviates from real edge angle even more.

I understand that accepting that may be frustrating to you both, but we have to adjust maths to the real world, the vice versa doesn't work.

#25
Ton Nillesen from Netherlands gave us mathematical description of knife sharpening on Tormek using an abstract model of a thin single-bevel blade.
Jan did a little tweak to Ton's formula, but this does not change the fact that it still describes the abstract thin single-bevel blade.
The _TormekCalc.xlsx by Jan JVH on this forum uses Jan's tweak as well, and still calculates grinding angle as if the blade is single-bevel and thin.

How on earth can this be accurate for a double-bevel blade?! For a thick blade? And especially for a thick double-bevel blade?

Formulas are giving a systematic error that Ton Nillesen explains in his 2018 booklet on page 6; and as Ton has shown, the thicker the blade and the lower the grinding angle, the greater is the error.
Why the 2 Jans persist in denial of what the author of this mathematical model himself says?

I've revamped my computer algorithm to take into account the blade particulars, and now our applets grind correct angle on double-bevel, single-bevel, thick and thin knives.

Grinding Angle Setter for Tormek
Released for Windows, MacBook, iPhones and iPads, and Android phones and tablets.
Details on our website.

Instructional video Software for Tormek >>

Frontal Vertical Base applet
Currently under review by Google Play and Apple Store. Will be released next week.

As soon as the FVB applet is released, I will email users of our software instructions on how to update both the Grinding Angle Setter and the FVB software free of charge.
... just in a few days...
#26
Jan, I knew you would be faulting the method because you are in denial of the fact that the blade thickness behind the edge must be factored into the calculation.

We've done a 100 of test sharpenings for last weeks to make our Grinding Angle Setter and the Frontal Vertical Base applets accurate. We do it for our customers, not for fun. Our updated software release is coming in 10-14 days. You then can get our updated applet, and see to yourself how well it works, not by your abstract estimation, but in actual sharpening.
#27
Quote from: Jan on October 22, 2019, 01:07:19 PM
I have shaped several blanks into blades without observing differences between the desired and sharpened bevel angle provided that the projection length has not been shortened during blank sharpening.

I use my Excel script to calculate the distance between the USB and the wheel surface. My script works without approximations.

Jan

I did trial sharpening by Jan's formula / JVH _TormekCalc.xlsx with a knife 2.5 mm thick at the spine - the results:



If you have a laser protractor, you can see to yourself that neither Jan's formula nor _TormekCalc.xlsx by JVH grind to the exact angle, and the thicker the blade, the greater is deviation from the target.

While our updated Grinding Angle Setter and the FVB applet grind exact angle, as I've shown in the testing results.
#28
Quote from: Dutchman on October 22, 2019, 09:55:33 AM
Thank you for mentioning the source :)

Ton, I believe in credit where it is due.
Your name is in the Acknowledgements of my book

#29
A word on home-made FVBs.
4 months ago we started CNC machining the FVB base, and have tolerances tight.
If your self-made FVB does not have the base of the same thickness as ours or legs in the wrong position, you will be getting less accurate results, and all the man-hours we've put into this software improvement will be wasted as you will not be getting better deburring and sharpness with it.
I'll be stopping making custom applets for home-made FVBs because of that, because formulas by themselves will never match the algorithm fine-tuned to our particular FVB make.
#30
Quote from: smurfs on October 23, 2019, 05:33:50 PM
Hi Vadim,

Could the angle issue simply be due to the reduction in the jig projection length during grinding, as illustrated in the schema diagram in your initial post? If it is would it not be better to recheck the projection after each grinding step in your sharpening procedure, and if necessary return to the initial projection length using the adjustable stop? Perhaps such a tweak is all that is needed to ensure the target edge angle is always maintained.

Or may be I've missed something and it is not as straightforward as I think  :-\

Andrew

I wish it were that simple.
What we've been doing for the last 2 weeks - grouped knives by blade thickness behind the edge: under 1mm, near 2mm and near 3mm, and sharpened each group from 10 to 20 degrees at 1-2 degree step, on two T8 and two T7 machines, in the standard position and edge-trailing using our Frontal Vertical Base.
The laser protractor numbers tell us that the ground angle we get depends on 4 factors: the angle, the thickness behind the edge, whether the blade is double-bevel or single-bevel, and whether the grinding is done edge-leading or edge-trailing.

Our formulas now factor in the difference between the double-bevel and single-bevel blade, and the blade thickness behind the edge. It is not the same as the thickness at the spine, so has nothing to do with modifying the knife jig to center the blades better. You can have a blade 5 mm thick at the spine but thin behind the edge. But of course, you still have to center the blade in the jig as practical.

The new computer algorithm in our software not only has formulas that factor in the blade thickness, but also follows the experimental numbers we've obtained for each edge angle from 10 to 20, ground edge-leading vs edge-trailing, to grind the correct target angle no matter what.
We've made a big change from a pure theoretical algorithm to the one fine-tuned by 100 of experimental sharpenings. This makes the match to the honing angle perfect. At the end of the day, all the man-hours we've put into this improvement are to better the deburring and sharpness.