New Tormek Online Class MB-100 on Mai 12th, 2021

[tgbto]

Hey guys, I just came across this https://www.youtube.com/watch?v=3r_1mZ9XjIs

[Ken S]

TBG,
Thanks for posting this. I must have been asleep at the switch. I encourage our members to watch this online class, as I plan to.

Please post your impressions after the class.

Ken

[tgbto]

Ken, it's okay, it's only fair that we share watch duty !

[Ken S]

Thanks, TGB.

For years I have enjoyed the innovative ideas shared by forum members. In fairness, Tormek has also produced some innovations, also. This online class with the Multibase finally explains some of its  innovative potential. I believe it is limited only by the user's imagination. I used mine to reshape a straight skew to Lacer grind. It worked well. Other than that, it has sat on the shelf.
It is time to put it on active duty!
Please share your experiences.

Ken

[Ken S]

Perhaps you are thinking, I do not have the diamond wheels which can grind flat bevels with the MBS-100 Multibase. Why should I bother to watch this video?

Good question. Here is a good answer. As an example, one of the frequently asked questions is about the dreaded "hollow grind". Near the beginning of this video is one of the best explanations of the amount of hollow grind left by a Tormek wheel I have ever seen. Using a 250mm diameter grinding wheel set to a 20º bevel and a 2mm thick blade, the deepest part of the hollow is .03mm, or roughly .001". That is roughly one third of the thickness of a single sheet of copy paper. That is small enough that I do not worry about it for my chisels, plane blades and kitchen knives.

Most of the online classes have parts like this which apply to several areas. Don't sell yourself short by watching only those classes which you think only apply to you.

Ken

[jvh]

Hello,

I would like to thank Wolfgang, Sébastien and Victor for next part of the Live Sharpening Class, it was excellent again.

Perhaps you are thinking, I do not have the diamond wheels which can grind flat bevels with the MBS-100 Multibase. Why should I bother to watch this video?

Good question. Here is a good answer. As an example, one of the frequently asked questions is about the dreaded "hollow grind". Near the beginning of this video is one of the best explanations of the amount of hollow grind left by a Tormek wheel I have ever seen. Using a 250mm diameter grinding wheel set to a 20º bevel and a 2mm thick blade, the deepest part of the hollow is .03mm, or roughly .001". That is roughly one third of the thickness of a single sheet of copy paper. That is small enough that I do not worry about it for my chisels, plane blades and kitchen knives.

Most of the online classes have parts like this which apply to several areas. Don't sell yourself short by watching only those classes which you think only apply to you.

Ken

Hello Ken,

0.03 mm is really small, but it's only one part of a more complex problem. It is indicated in the video (ca. 4:45), but it is not explained exactly.

Wolfgang said: "Force, of cource, is a little bit aggresive, it will dig in little bit faster..."
This is because in the example shown, the apex angle is 20°, but the angle between the apex and the edge heel is 21.26°. Compared to flat grinding there is "unground" material on the edge heel (due to the rounding of the wheel), which does not allow the blade to be tilted below 21.26°, because it would not cut as the apex does not touch the material. This makes the cut more aggressive because the edge is directed more into the material, and this is IMHO the main thing that should be taken into account.
This also affects the subsequent re-sharpening on a flat stone, where the minimum angle 21.26° is also ground (if the apex and the edge heel are touching the stone).

This problem increases with blade thickness, sharper angle and smaller wheel diameter. It is usually negligible for knives, but may not be the case for tools...

jvh

P.S." The picture shows a thickness of 4 mm, but this is because the calculation is performed for symmetrical blades. The example shows a chisel grind, from which you get a "symmetrical" by multiplying the thickness by two.

[Ken S]

JVH,

Thank you for your reply.

I appreciate the technical expertise members like you bring to the forum. I see the value of this refined technique, especially since with no false modesty, I admit that I have not developed it myself.

Two things heavily influence my thoughts on hollow grinding:

First, I believe many associate hollow grinding with the small diameter grinding wheels common several decades ago. One of the few advantages of old age is remembering things like this. My 1972 vintage dry grinder, six inch (150mm) diameter, is typical of the time. Two point grinding using the distinct hollow with water stones was very popular.

Second, and related, is the time when I held a straightedge against a freshly ground chisel bevel. I can easily see the hollow of a chisel ground with a six inch diameter wheel. I have to look very hard to see any hollow with a 250mm Tormek wheel.

I realize that these thoughts are not very scientific. They are, however, aligned with my present expectations. If I can make my woodworking tools and kitchen knives very sharp, I am content. I do not believe the old English language idiom that "you can't teach an old dog new tricks". I am learning new tricks. After decades of using film cameras and working in a darkroom, I have become comfortable using my digital camera. I am comfortable with basic digital image manipulation. My computer literacy has advanced beyond beginner status. I have a lot more to learn in all of these areas. There are many new tricks for this old dog to learn. Among these new tricks to learn is your computer assisted setting program.

I do appreciate your sharing.

Ken

[Arthur]

some more use cas MB-100

[Ken S]

Well done, Arthur. Good thinking!

Ken

[Rimu]

some more use cas MB-100

Arthur,

What's is the shell you have mounted in the photos, and where did you get it?

[Arthur]

some more use cas MB-100

Arthur,

What's is the shell you have mounted in the photos, and where did you get it?

The photos show a grinding wheel for the Makita 9820 Horizontal Wheel Wet Blade Sharpener. There are three grinding wheels in total. A-69048 1000 grit, A-69054 6000 grit, A-69032 60 grit.

[Herman Trivilino]

Oh, it drives me nuts! Not the way to teach or demonstrate! A 52-minute lesson on how to use the MB-100, but it's 12 minutes into the lesson before I catch the vaguest of notions on how to use it. Seventeen minutes before the use of the MB-100 becomes clear, and 32 minutes into the lesson before the machine is actually turned on the MB-100 is used to grind an edge.

Don't get me wrong, all the information they provide is useful, but if I'm interested in a lesson on how to use a tool, I want to see it being used at the very beginning of the lesson. That can then be followed with an in-depth discussion of all the subtleties associated with its use.

[Dutchman]

... snip
Don't get me wrong, all the information they provide is useful, but if I'm interested in a lesson on how to use a tool, I want to see it being used at the very beginning of the lesson. That can then be followed with an in-depth discussion of all the subtleties associated with its use.

YES!
All the Tormek videos I've seen are way too long-winded.

[Herman Trivilino]

I had a 34-year career as a full-time college-level instructor. This is NOT the way to teach. The late great Arnold B. Arons of physics teaching fame, who was not only a professor of physics at the University of Washington, but was also widely-known for conducting  workshops for secondary school teachers, had a maxim: "First the thing, then the name of the thing".

The general idea here is that you first demonstrate or teach whatever the point of the lesson is, and then you follow that up with a more formal discussion of the concept that includes the details. In the case of a tool or jig like the MB-100 this is not to be taken literally. Of course you can start out with the name of the tool, but the point is you first show how to use the tool for the purpose for which it is intended, and then you follow that up with a more in-depth discussion of perhaps its use and the benefits, purpose, and intentions of its use.

For an example of what I'm talking about just go to YouTube and do a search for my name. The first hit you will see there is me demonstrating the use of an early protype of my version of the knife sharpening jig first inspired by Ionut here in this forum. In fact, Ken has made the associated thread that discusses the early adventures with this jig a sticky in this very sub-forum.

This is a discussion of a general issue, like Dutchman points out, about virtually all of the Tormek lessons. But of course it applies to many other how-to videos, especially many of the YouTube videos that are either professionally produced or just made by a user.

The lesson starts out with a discussion of hollow grinding versus flat grinding and teaches the difference between concave, convex, and flat. And several other topics all tangentially related to use of the MB-100, but the relationship of the discussions to the use of the MB-100 are perhaps not apparent to the viewer, resulting in boredom. Use of the MB-100 is the point of the lesson, so get on with it already before the viewer is bored to the point of impatience. We learn best when we experience positive emotions like keenness to learn, not negative emotions like boredom and impatience and the anxiousness of waiting for the instructor to get to the point.
 
The viewer has to sit through a long discussion of general issues before the main point of the lesson is even made.