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The "Constant" measurements for using the MB-102 as a FVB...

Started by cbwx34, October 24, 2023, 11:17:14 PM

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cbwx34

If you set the USB height by measuring directly to the wheel, none of this matters.


If you want to measure to the top of the MB-102 to set the USB height, like this...

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... these are the "Constant" measurements I got...

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(Constants input into Calcapp)

...with the legs pressed against the vertical part of the main frame of the Tormek...

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...YMMV (depending on how you set it up).  ;)


Again, if you measure directly to the wheel, this isn't needed.
Knife Sharpening Angle Calculator:
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Crabnbass

I'm a directly to the wheel guy, but this is good info. Thanks for sharing.

Ken S

I have never understood the reason for measuring to the frame instead of the wheel.
I realize this method was advocated by Wootz; I just never understood understood why. Measuring directly to the frame sees so much more direct.

Ken

cbwx34

Quote from: Ken S on October 25, 2023, 01:22:48 AMI have never understood the reason for measuring to the frame instead of the wheel.
I realize this method was advocated by Wootz; I just never understood understood why. Measuring directly to the frame sees so much more direct.

Ken

There was some testing going on a while back that required using the "to the frame" measurement, and I realized that once you get past the original idea that the "Constant" measurements "had" to be made to hundreths of a mm, and not get caught up in trying to make tenth of a mm angle changes, etc.... but keep it for what it is, a better alternative to the Anglemaster for knives, (that mainly eliminates the error created by blade taper), I found that it can be a bit easier to use, in some situations anyway.  It's one reason I added it to the Calcapp app.

The "to the wheel" measurements is still more versatile, and the one I still use the most, but either method will get your knives sharp. ;)

The real "secret" probably is to just pick a method, and find a simple consistent way to set the USB that works for you.
Knife Sharpening Angle Calculator:
Calcapp Calculator-works on any platform. New url!
(or Click HERE to see other calculators available)

RickKrung

Quote from: Ken S on October 25, 2023, 01:22:48 AMI have never understood the reason for measuring to the frame instead of the wheel.
I realize this method was advocated by Wootz; I just never understood understood why. Measuring directly to the frame sees so much more direct.

Ken

Do you mean "directly to the wheel" seems so much more direct... ?

Sure does to me and it alleviates all need to know or care about those "constants". 

Rick
Quality is like buying oats.  If you want nice, clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

tgbto

Plus I find that using a vernier caliper to measure to the wheel instead of the frame, one can avoid using the tiny flexible depth bar that protrudes on the back end of the caliper as shown in cbwx's pic.

This is wobbly whereas measuring to the wheel using the leftmost ends of the moveable and fixed jaws feels much more stable. One can feel the end of the jaw lifting up from the wheel with just the tiniest turn of the microadjust nut.

cbwx34

Quote from: tgbto on October 26, 2023, 10:49:31 AMPlus I find that using a vernier caliper to measure to the wheel instead of the frame, one can avoid using the tiny flexible depth bar that protrudes on the back end of the caliper as shown in cbwx's pic.

This is wobbly whereas measuring to the wheel using the leftmost ends of the moveable and fixed jaws feels much more stable. One can feel the end of the jaw lifting up from the wheel with just the tiniest turn of the microadjust nut.

You can (and I) actually use the caliper the other way... I just took the photo that way.  (Thought it'd be easier to see...)  :o

You cannot view this attachment.

Quote from: RickKrung on October 26, 2023, 06:17:38 AM...
Sure does to me and it alleviates all need to know or care about those "constants". 

Rick

"Constants" also flush out curmudgeons.  ::)  :D
Knife Sharpening Angle Calculator:
Calcapp Calculator-works on any platform. New url!
(or Click HERE to see other calculators available)

RickKrung

Quote from: cbwx34 on October 26, 2023, 03:22:36 PM
Quote from: RickKrung on October 26, 2023, 06:17:38 AM...
Sure does to me and it alleviates all need to know or care about those "constants". 

Rick

"Constants" also flush out curmudgeons.  ::)  :D


Badge of Honor  8)
Quality is like buying oats.  If you want nice, clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

tgbto

Quote from: cbwx34 on October 26, 2023, 03:22:36 PMYou can (and I) actually use the caliper the other way... I just took the photo that way.  (Thought it'd be easier to see...)  :o

I think I remember I could not do that on the standard VUSB, as the jaws would interfere with the knobs/nooks/crannies. Maybe it is easier to do with the MB-102/FVB... or maybe I have a bad memory.

cbwx34

Quote from: tgbto on October 27, 2023, 09:42:42 AMI think I remember I could not do that on the standard VUSB, as the jaws would interfere with the knobs/nooks/crannies. Maybe it is easier to do with the MB-102/FVB... or maybe I have a bad memory.

Try between the left (sharpening wheel side) vertical support and the switch. ;)
Knife Sharpening Angle Calculator:
Calcapp Calculator-works on any platform. New url!
(or Click HERE to see other calculators available)

Ken S

Quote from: Ken S on October 25, 2023, 01:22:48 AMI have never understood the reason for measuring to the frame instead of the wheel.
I realize this method was advocated by Wootz; I just never understood understood why. Measuring directly to the frame sees so much more direct.

Ken

I misspoke! I meant to say MEASURING TO THE WHEEL SEEMS SO MUCH MORE DIRECT. If you look at my description of the kenjig, based on Dutchman's tables, you will note that I have always measured to the wheel. Please forgive my error.

Ken


RickKrung

Quote from: cbwx34 on October 26, 2023, 03:22:36 PM...snip...
You can (and I) actually use the caliper the other way... I just took the photo that way.  (Thought it'd be easier to see...)  :o
...snip...

Shared many times, amazing how often it comes up.  My solution is to use a woodworker's marking gauge, first setting the desired distance using the depth rod of any caliper. 

Rick
Quality is like buying oats.  If you want nice, clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.

Ken S

Rick,

Your solution works very well. However, with my simple needs (low sharpening volume, one grinding wheel and standardized 15° bevel angle), I never felt I needed to measure anything beyond the kenjig. Granted, my humble system may seem constraining to many users; however, it has worked for me.

Ken

Pargame

Hello, I bought the mb-102 to remove the burr on my knives with precision but I have a problem with it. even when tucking in the constants, I roll my edges in the places where I have the belly of the knife. I tried lowering the setting by two degrees. It's better but still not perfect. Do you have a solution/technique to do it correctly? the impression that this system is only useful on straight blades without curvature otherwise the angle changes by raising the knife to follow the curve.. Thanks for your help

RickKrung

Not entirely clear on your issue with the MB-102, but it sounds like you are getting a lower bevel angle around the curved part of blades as a result of lifting.  I have found this also when I tried to keep the location of contact between the blade and the grinding wheel in the same relative location, often referred to as the Line of Contact, or "LOC".  The solution I use is to move the location where the blade contacts the grinding wheel (LOC) closer to the USB as I lift the blade.  This steepens the angle as the blade is lifted.  It is a moving situation - that is, as the curve gets greater closer to the tip, the LOC gets closer to the USB.  When using the vertical USB, this would be moving the LOC "up" the grinding wheel and when using the horizontal USB, "down" the wheel. 

I'm not at all clear on how the MB-102 factors in to this, at least when using it as an FVB in the horizontal USB sleeves, as what is happening is a relationship between the blade and wheel.  If you are working on the side of the grinding wheel, I think it would be the same thing, shifting the LOC closer to the USB as the blade is lifted. 

I used to use a lazer line to indicate the LOC but it died and I get along just fine without it now.  I think that is a matter of having learned how to migrated the LOC relative to the amount of blade curvature. 

Hopefully I've interpreted your question reasonably well.  Early on in my knife sharpening with a T8, I was plagued by these wider/shallower bevels on the curves but that was because I wasn't lifting at all.  Once I started lifting, it helped a lot, but then I had to figure out about moving the LOC. 

Rick
Quality is like buying oats.  If you want nice, clean, fresh oats, you must pay a fair price. However, if you can be satisfied with oats that have already been through the horse, that comes at a lower price.