This knife jig aid is not for every knife, but yet for the larger portion of knives, which profile is a normal sweeping curve, like most hunting and cook's knives, sheepsfoot and wharncliffe knives.
For this type of knives, the movement to keep the blade on the stone must be axial to the shaft of the knife jig.
Any shifting other than vertical results in uneven bevel.
I use a 1/2 inch shaft locking collar, locked at 12mm from the jig stop (the flat black plastic part), to ensure the jig slides on the Universal Support perpendicular to the stone, vertically rocking on its axis following the blade taper, and not shifting horizontally (or you may say not shifting laterally or forwards/backwards).
I have it on the jig at all times, and when I sharpen a blade of a different profile, e.g. curved etc, I unlock the collar and slide it away.
(http://home.exetel.com.au/dropbox/locking_collar1.JPG)
I like it
Make that two likes.
Ken
That might be a good solution - will give it at try.
Rolf
Rolf, if you do, the Universal Support weld will need some filing for the collar to slide past, as in the picture, just be careful not to nick the horizontal bar (I did it with a Dremel).
(http://home.exetel.com.au/dropbox/US.JPG)
It is funny to remember how I came to it. My 9 year old son wanted to sharpen his kids' bowie himself on Tormek, and I thought how to make it fool-proof, or child-proof for this case.
Added the collar, set his bowie in the jig, and let him do it, and his first grind on Tormek gave a perfectly even bevel.
It also helps with S-shaped knives: with the adjustable stop at the concave trough, I lock the collar at the convex crest, getting an extra reference point to maintain the S-blade in the same line of contact as I sharpen it.
Quote from: wootz on May 25, 2016, 12:54:45 AM
Added the collar, set his bowie in the jig, and let him do it, and his first grind on Tormek gave a perfectly even bevel.
I'm a big fan of letting kids do these kinds of things. Learning at a young age embeds skills in a way that has no substitute. I liken it to spreading mulch on a garden.
Nice image, Herman. We need to allow our children (and now grandchildren) to grow in skill and creativity.
Ken
ps That creative growth should not be limited to the young. :)
My eldest granddaughter, who is now 13 years old, has lively interest in some affairs of the Tormek forum. She already knows many of you by name (e.g. Ken, Herman, Steve, Wootz, Elden, Rob, Stig ...) and she always asks what's new. :)
I am her math and physics tutor. Now we repeat the tangent and the chord to a circle and maybe later we will touch the definition of bevel angle also. She understands quite well the BESS scale, because she already distinguishes between mass and weight and also between force and pressure. :)
She is mostly interested in images, links and somewhat controversial topics, not the ones where there is a consensus.
Jan
Jan,
What a joy that you and your granddaughter share a love of learning. Memories of your tutoring will enrich her entire life and give added meaning to your studies.
Almost all of the interests I have enjoyed for many years, some since boyhood, began as shared activities with family members. The interests themselves have long ago fused with the emotional bonds with loved ones. I believe the real legacy we pass on to the next generations is memories and values.
I look forward to ongoing progress reports from both of you! Both of you will learn from this special shared experience.
Very best wishes,
Ken
Ken, thank you for your kind words, greatly appreciated. :)
Jan
Quote from: Jan on May 25, 2016, 09:04:45 AMShe understands quite well the BESS scale, because she already distinguishes between mass and weight and also between force and pressure.
Keep in mind, Jan, that the definition of weight as a force is something unique to the fields of physics and engineering. In the medical fields, and in particular in the definition used for legal trade, mass and weight are synonyms. Children need to understand this if they are to make sense of the conflicting usages that await them as they explore human knowledge.
Most introductory physics books fail to point this out. They will, for example, define the pound as a unit of force. It is in fact defined as a unit of mass, and has the exact value of 0.453 592 37 kg. At least that's the case with the pound used in America. I realize that there are other definitions for the various different types of pounds, but they too are all definitions that establish the pound as a unit of mass. There is no officially-sanctioned definition of the pound-force, despite the fact that it's used in many legal documents such as NASA contracts.
What I tell people is that the word weight means different things to different people, and that the important thing to understand is not the distinction between weight and mass, but the distinction between force and mass. I rarely use the word weight as a noun, but instead always refer to the weight force, using it as an adjective.
Interestingly enough, the Scandinavian countries, as I understand have two separate words, one translating as the weight force and the other as the mass.
The important thing to know is that if it's measured in newtons, it's a force; and if it's measured in kilograms it's a mass. (If it's measured in pounds, you have to figure out from the context if it's a mass or a force). The BIPM officially removed the use of the kilogram as a unit of force way back in 1960, I think it was, but its use still persists. People still measure force in grams, for example, despite that fact the kilogram-force definition of 9.806 65 N was abandoned when BIPM took that action.
Herman, thanks for your consideration of the concepts of mass and weight. :)
As a teacher, I'm in a pretty good situation because my granddaughter already knows Newton's 2nd law F = m.a. So it is straightforward to say that weight is a force caused by the Earth gravity field, which gives bodies an acceleration g and write Weight = m.g. Because she understands, that our weight on the Moon would be circa six times smaller than on the Earth, I am quite sure she distinguishes the different concepts of mass and weight.
It makes me happy because I spent many years as geophysicist interpreting very tiny anomalies of the Earth gravity field for oil and mineral exploration purposes.
Jan
Jan,
With my very limited science background, many years ago I watched a fictional video about Einstein working with a third grader. It was very well done. From it, I learned that C=the speed of light. It helped me understand that Energy=Matter moving at the speed of light squared.
Would you help me understand the two Newton Laws you quote by defining ma and mg. I would like to understand them.
Thanks,
Ken
m = mass
a = acceleration
g = gravity
Most people don't do dimensional analysis, but it is pretty important to keep your units straight.
Quote from: Ken S on May 25, 2016, 11:10:29 PM
Would you help me understand the two Newton Laws you quote by defining ma and mg. I would like to understand them.
Newton's Second Law tells us that the net force exerted on a particle equals the mass of the particle times the particle's acceleration:
F=ma.
It follows from that law that for a particle in free fall
F=mg where
g is the free fall acceleration. It has a value of about 9.8 m/s² or 32 ft/s².
Acceleration is the hardest part of this to understand. An acceleration of 9.8 m/s² means the velocity of the particle
changes by 9.8 m/s ever second.
So what Newton's Second Law tells us is that a constant force results in a changing velocity. A concept particularly resistant to understanding.
Herman,
thank you for answering Ken's questions while I was sleeping. :)
As a professor of physics you are certainly better qualified for it than I am. You know better what is the stumbling block for understanding the physical concepts for your people.
Ken,
I'm glad you did not hesitate to ask for an explanation. :)
I think Herman's answer may help also some other members to better understand this fundamental low of motion which laid the foundation for classical mechanics.
Jan
P.S.: This morning I have asked my British teacher of English if he distinguishes between the concepts of mass and weight, and his answer was no, but he admitted that he knows that they are not identical terms. ;)
Quote from: brettgrant99 on May 26, 2016, 03:30:07 AM
m = mass
a = acceleration
g = gravity
Most people don't do dimensional analysis, but it is pretty important to keep your units straight.
Yes, you are correct. :)
For insiders, it is a valuable test of consistency. I do it if I have some doubts, but I am not quite sure how easy it is for people who are already long time out of school.
Jan
Thanks all for explaning the terms.
Ken
Quote from: Jan on May 26, 2016, 11:50:49 AM
This morning I have asked my British teacher of English if he distinguishes between the concepts of mass and weight, and his answer was no, but he admitted that he knows that they are not identical terms. ;)
But by the laws of commerce, both national and international, they are identical terms. And in the medical field, too. The Bureau of Weights and Measures (BIPM) governs this, and they started out with just two units: the kilogram and the meter. The "weight" standard was and is the kilogram; the "measure" standard was and is the meter.
The distinction of importance is that between force and mass. The term weight means different things in different contexts.
A good example of this is the astronauts aboard the ISS. They are weightless but their physicians carefully monitor their weight because loss of muscle mass is always a danger for people in a microgravity environment.
Quote from: Herman Trivilino on May 26, 2016, 05:14:54 PM
Quote from: Jan on May 26, 2016, 11:50:49 AM
This morning I have asked my British teacher of English if he distinguishes between the concepts of mass and weight, and his answer was no, but he admitted that he knows that they are not identical terms. ;)
But by the laws of commerce, both national and international, they are identical terms. And in the medical field, too. The Bureau of Weights and Measures (BIPM) governs this, and they started out with just two units: the kilogram and the meter. The "weight" standard was and is the kilogram; the "measure" standard was and is the meter.
The distinction of importance is that between force and mass. The term weight means different things in different contexts.
A good example of this is the astronauts aboard the ISS. They are weightless but their physicians carefully monitor their weight because loss of muscle mass is always a danger for people in a microgravity environment.
Herman,
we are discussing here physical concepts of mass and weight. In physics there is only one system of units valid for the whole world – SI. In this system weight is defined as force in the following way:
"The weight of an object is defined as the force of gravity on the object and may be calculated as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton."
http://hyperphysics.phy-astr.gsu.edu/hbase/mass.html
"In everyday usage, the mass of an object is often referred to as its weight, though these are in fact different concepts and quantities."
https://en.wikipedia.org/wiki/Mass_versus_weight
Jan
Now that I've been using the locking collar on the knife jig regularly, a few things about it.
The shaft locking collar I use was manufactured with one facet more sloping, and put on the jig with this facet facing the Universal Support, it slides better.
You can probably see this in the photo.
The collar facets were rough, and after I polished the facet facing the Universal Support, it slides smoothly.
Locking the collar must be done on the side as in the photo below, to avoid nicking the riding surfaces of the jig.
(http://home.exetel.com.au/dropbox/collar.JPG)
I've switched to an aluminium clamp style collar 12mm, advantages over the previous one are:
- perfect fit;
- lightweight, don't change the downward pressure and feel of the jig;
- doesn't nick the jig when clamped.
(http://home.exetel.com.au/dropbox/shaft_collar2.JPG)
(http://home.exetel.com.au/dropbox/shaft_collar1.JPG)
Clever idea, Wootz....even better with your upgrade!
Ken
Quote from: Herman Trivilino on May 25, 2016, 07:00:40 PM
... Interestingly enough, the Scandinavian countries, as I understand have two separate words, one translating as the weight force and the other as the mass.
All Western European countries except UK, use the SI system of physical quantities.
In high school we learn to use the difference between weight and mass. Using SI units leads to simple calculations for energy, power etc.
It is sad that the Anglo-Saxon countries still use old-fashioned imperial units. They thereby cause major problems, not only for their school children but in all technical areas and jobs. :'(
NASA, as an example, has learned from a catastrophic failure of a Mars lander (Mars Climate Orbiter, 1999) due to bad usage of physical units and now uses SI units. ;)
Dutchman, sadly. I must agree. Of all the obsolete notions related to national pride, using the old Imperial measurement system seems one of the least logical. We I've in a global society. Our markets are global. Hopefully, our scientists work together globally.
We never seem to learn. Railroad track widths used to be different, supposedly for defense. In World War II we encountered difficulties because we were using sixty degree "National" threads and the British were using fifty five degree Whitworth threads. Tormek uses different motors because of different commercial power standards.
A generation ago, a movement began in the US to convert to metric. Unfortunately tradition seemed to triumph over logic.
Many products mix the two standards. The Tormek work station, made in Germany for a Swedish company, uses 5/8" x11 tpi threads for the feet. I would be curious to learn why.
Ken
Quote from: wootz on June 17, 2016, 01:55:57 AM
I've switched to an aluminium clamp style collar 12mm, advantages over the previous one are:
- perfect fit;
- lightweight, don't change the downward pressure and feel of the jig;
- doesn't nick the jig when clamped.
Wootz, thanks for letting us know you have switched to an aluminium clamp style collar. :)
What concerns the listed advantages, I was surprised by the lightweight of the collar. I think that the collar weight effect is very small and even more the major part of the collar's weight is supported by the universal support. ;)
Jan
Hi Jan,
I was using the locking collar to ensure straight grinding in studying the middle overgrinding problem in straight edges.
The former brass collar adds 20% to the jig weight, and I was concerned that might be worsening the middle overgrinding.
The aluminium one is free of that.
Don't laugh, but when puzzled with this problem, I even played with magnet weights added to segments of the blade and saw them affecting the straight line at as little as 30 grams, while the brass collar is 60. So i thought it would be safer to eliminate this factor.
Wootz,
the weight of the collar is producing torque (outside US moment of force) which is given by the product of its weight and its lever arm. The torque is small because the lever arm (distance between the USB and the collar) is short. ;)
The other reason for a small torque is that the collar weight does not act perpendicularly to the lever arm.
So far the Archimedes concept of torque. I hope there are no strings attached, but as Faust said: "All theory is grey, my friend. But forever green is the tree of life." . ;)
The torque caused by magnets attached directly to the blade is much larger because the lever arm is much longer also. In this case I have no reservations at all. The ring is yours. :)
Jan
Quote from: wootz on June 17, 2016, 01:55:57 AM
I've switched to an aluminium clamp style collar 12mm, advantages over the previous one are:
- perfect fit;
- lightweight, don't change the downward pressure and feel of the jig;
- doesn't nick the jig when clamped.
(http://home.exetel.com.au/dropbox/shaft_collar2.JPG)
(http://home.exetel.com.au/dropbox/shaft_collar1.JPG)
OK, but to extract it you have to remove the upper part in "plastic" of the SVM, not to mention that it can hinder the measurement of the SVM / knife blade distance. Perhaps it would be more convenient to use the same collar model but divided into two pieces.
Why would we need to extract the collar? I can see needing to move the collar for kniveswith a lot of curve in the blade. I would think just loosening, sliding it out of the way, and retightening it would solve the problem. I sharpen standard kitchen knives. Using Dutchman's tables and a kenjig, plus three knife jigs, I can leave the Projection set at 139 mm and rarely have to adjust the jig.
Ken
My thought comes from the fact that I use the same procedure as Vadim. And in measuring the distance from the jig to the edge of the blade this type of collar is a hindrance.
I loved the idea of the jig and bought an aluminum one and works well, but then I found a plastic version that I like even more since it is more self lubricating or slick since it is the plastic and works well. I bought mine from Amazon here in the U.S. Maybe these can be found elsewhere also?
https://www.amazon.com/gp/product/B0063KKTR0/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1#feature-bullets-btf
Quote from: Dastagg on June 01, 2019, 03:46:49 AM
I loved the idea of the jig and bought an aluminum one and works well, but then I found a plastic version that I like even more since it is more self lubricating or slick since it is the plastic and works well. I bought mine from Amazon here in the U.S. Maybe these can be found elsewhere also?
https://www.amazon.com/gp/product/B0063KKTR0/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1#feature-bullets-btf
Those look good Dastagg. I think I'll have to try them. And thanks to Wootz for coming up with the initial idea, I been watching his YouTube channel and noticed he was using those collars. I also just finished reading his book, Knife Deburring: Science Behind The Lasting Razor Edge. If anyone hasn't read it you really need too. Oh and by the way thanks for the physics refresher Jan and Herman! :)
Clever idea, Dastagg. I ordered one. It seems like something which may have several uses.
One of the joys of this forum is seeing ideas bounce around with our members with many differing skills. The combined total is indeed greater than the sum of the individual parts.
Ken
Quote from: Dastagg on June 01, 2019, 03:46:49 AM
I loved the idea of the jig and bought an aluminum one and works well, but then I found a plastic version that I like even more since it is more self lubricating or slick since it is the plastic and works well. I bought mine from Amazon here in the U.S. Maybe these can be found elsewhere also?
https://www.amazon.com/gp/product/B0063KKTR0/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1#feature-bullets-btf
Instead of making a modification to the support bar as Wootz shows early on in this thread would it work to alter this plastic collar instead? If you really messed it up it is a lot less of an investment.