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Asymmetric knife jig

Started by Sharpco, January 16, 2018, 10:40:05 AM

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Sharpco

I have two SVM-45. The one is 1~2 month old, the another is new one.

But these are all asymmetric.

It depends on the orientation of the handle. If I set it like the first picture, the right side is set as low as 0.5 ~ 2 degrees. But in the case of the second picture, the angles on both sides become the same (check with anglemaster).

The jig that I used for a month was OK at first but over time caused this problem. I also have similar problems with the SVM-140.

Does your jig have this problem?

Jan

Sharpeco, it is quite common issue. The problem is probably not in properties of your jigs, but in the way how is the blade mounted into the jig.

Please read more about it in a thread "My way of mounting knife in SVM-45 jig" https://forum.tormek.com/index.php?topic=3249.0

Jan

cbwx34

#2
Quote from: sharpco on January 16, 2018, 10:40:05 AM
I have two SVM-45. The one is 1~2 month old, the another is new one.

But these are all asymmetric.

It depends on the orientation of the handle. If I set it like the first picture, the right side is set as low as 0.5 ~ 2 degrees. But in the case of the second picture, the angles on both sides become the same (check with anglemaster).

The jig that I used for a month was OK at first but over time caused this problem. I also have similar problems with the SVM-140.

Does your jig have this problem?

Haven't seen it myself... asymmetry changing based on which way the knife is mounted?  Are you seeing it on every knife?  If not, I would check the knife itself for asymmetry.

As Jan stated, there is some asymmetry in the clamp setup itself.  Try closely following the steps he posted for each way... and see if it improves.  Could be something as simple as you're changing how you set the clamp when you switch direction (especially if you're switching hands to set it).

(But if true, yet another reason for a jig redesign). ;)
Knife Sharpening Angle Calculator:
Calcapp Calculator-works on any platform.
(or Click HERE to see other calculators available)

Sharpco

#3
Quote from: Jan on January 16, 2018, 02:34:48 PM
Sharpeco, it is quite common issue. The problem is probably not in properties of your jigs, but in the way how is the blade mounted into the jig.

Please read more about it in a thread "My way of mounting knife in SVM-45 jig" https://forum.tormek.com/index.php?topic=3249.0

Jan

Thank you, Jan.

A few minute ago, I tried Sander's method. But...I couldn't solve it.

Sharpco

Quote from: cbwx34 on January 16, 2018, 03:10:11 PM
Haven't seen it myself... asymmetry changing based on which way the knife is mounted?  Are you seeing it on every knife?  If not, I would check the knife itself for asymmetry.

As Jan stated, there is some asymmetry in the clamp setup itself.  Try closely following the steps he posted for each way... and see if it improves.  Could be something as simple as you're changing how you set the clamp when you switch direction (especially if you're switching hands to set it).

(But if true, yet another reason for a jig redesign). ;)

My knife's edge is perfectly centered, so it is not a knife problem. I'm very confused.

wootz

#5
It is not the jig.
It is the wheel not parallel with the Universal Support.

You should lock the Universal Support for sharpening knives exactly in the same way you lock it for truing the wheel.
Locking down the truing tool on the Universal Support, press the Universal Support downwards over the left post with the adjusting wheel. Don't press left or right of that point. The Universal Support has a bit of play in the vertical sleeves, more pronounced in T-8 compared to T-7, and the only reference point or surface that you can rely on is the adjusting wheel and the base in which the left post is being inserted. The Universal Support play translates on its horizontal bar into up to probably 2-3 degrees in the effective sharpening area.
Lock the same way when sharpening.

This is stated in the Tormek Manual for truing, you have to do the same in sharpening.
Unlike shown in the manual, press with one finger only.

Sharpco

Quote from: wootz on January 17, 2018, 01:19:58 PM
It is not the jig.
It is the wheel not parallel with the Universal Support.

You should lock the Universal Support for sharpening knives exactly in the same way you lock it for truing the wheel.
Locking down the truing tool on the Universal Support, press the Universal Support downwards over the left post with the adjusting wheel. Don't press left or right of that point. The Universal Support has a bit of play in the vertical sleeves, more pronounced in T-8 compared to T-7, and the only reference point or surface that you can rely on is the adjusting wheel and the base in which the left post is being inserted. The Universal Support play translates on its horizontal bar into up to probably 2-3 degrees in the effective sharpening area.
Lock the same way when sharpening.

Until now, I locked the support when the jig is on it. Thank you for letting me know I was wrong.  ;)

But I think this is jig's problem. Because the angles are still measured differently even though the supports are properly locked.

cbwx34

Quote from: sharpco on January 17, 2018, 12:09:01 PM
My knife's edge is perfectly centered, so it is not a knife problem. I'm very confused.

It is interesting.  I've tried to duplicate it... but I'm not seeing it.  I know that a lot of knives that seem "symmetrical" I find are not, when mounted into a guided system.  (You'll find a lot of "issues" when a knife is mounted in a guide, and sharpened with a controlled angle, that need to be corrected).

The only other thing I can think of, is you're seeing the asymmetry that is in the jig itself.  If you sharpened a knife mounted one direction, then the next time sharpened it mounted the other direction, it would look like one way was correct, and the other asymmetric.

If you solve it, pass on the information.  :)
Knife Sharpening Angle Calculator:
Calcapp Calculator-works on any platform.
(or Click HERE to see other calculators available)