the missing knife test

[Ken S]

This topic needed to be revived. It is very useful for knife sharpeners, with some much needed, solid advice. I also had a good laugh reading koolingit's delightful comment.

Ken

[bisonbladesharpening]

I encounter this problem often.  Many times caused by pull-through type sharpeners that cannot
reach all the way to the back of a stamped blade, or by repeated sharpening of a forged blade without reducing the bolster.
For stamped blades, I use 80 grit Zirconia on a Viel and lightly run the blade up the belt (blade standing up directly on the belt) as it is running away from me until the blade is true.
Use a flashlight behind the blade and look for any light or test by chopping chives or parsley.  For forged blades, reduce the bolster first, and the do the above if necessary.
You may lose some or all of the bevel depending on how bad the damage.  Use the same process for chipped knives.
Then put a new bevel on using the tormek.  The 80 grit zirconia doesn't generate much heat as long as you are careful.
Best Wishes
Tim

[Ken S]

Good post, Tim

I have now recurved knives with several methods. First, I used a handfile, which works very well. While my Tormek is my go to sharpening tool most of the time, my collection of handfiles sees frequent use.

Second, like Tim, I restored the blade curve and lowered the bolster with a Viel belt grinder. In my opinion, the Viel is a very useful complement to the Tormek. As this is the Tormek forum, I do not wish to discuss the Viel extensively.

Most recently, I needed to grind the bolster on my slicing knife. I was trying out the T2. I worked on the bolster handheld with the T2 snd DWF-200. The T2 did the job with flying colors. I arrived at this proficiency by a roundabout path. The Tormek videos were no help. I knew I could do the job with the Viel. I was able to rethink the operation to the Tormek. Using the Viel is perhaps a small bit faster. Doing the entire job with the Tormek is definitely more cost effective, assuming one already owns a Tormek and not a Viel.

I believe a skilled sharpener should be flexible enough to be proficient with multiple techniques.

Ken

[bisonbladesharpening]

Tried it this way with a stamped knife using only the Tormek.  Hold knife perpendicular to a flat surface.
Run a fine point sharpie up between the 2 surfaces.  Set my angle at 30 deg. and only
ground where I saw sharpie mark. Repeat as necessary and reduce your angle as you
come closer to a true edge.  Done in under 5 minutes.   Would still recommend reducing bolster
first on a belt grinder for a forged knife.
Best wishes
Tim

[Ken S]

Tim,

Regarding which tool to use to reduce the bolster, having done it with both the Viel and the Tormek (T2 hand held), I would prefer whichever was handier........

To restore the blade curve, I would definitely use the Tormek if I did not own a Viel. 

Ken

[bisonbladesharpening]

Wondering how the T2 wheels hold up to heavy
work like reducing a bolster.  Do they maintain their
effectiveness. 

[Ken S]

That's a good question. I have no supporting data from Tormek. To the best of my knowledge, Tormek only promotes them for use with the T2 and with the T2 built in jig. However, I would be very surprised if the 200mm diamond wheels were of a lesser quality build than the 250mm wheels.  Tormek promotes the larger wheels as suitable for carbide. This differs from the "suitable for touchups with carbide" claim with the SB-250 blackstone. Between those claims and the limited use I have given the DWC-200 with my T2 and T4, I would guess these wheels would work well with extended heavy work provided they were used properly. By properly I mean with light grinding pressure.

I believe more diamond wheels will be damaged by heavy hands than by heavy work. With light pressure and being used with Tormek's anti corrosion compound (diluted 1:25 with water), I would expect a long life. In fact, I believe diamond or CBN wheels may be the answer to efficient grinding of planer blades. (I have not tested this idea.)

Worst case scenario, the DWF-200 and DWC-200 each cost about twice the price of an SG-200. If they only last three times as long, you are money ahead. You are also time ahead, as they require no dressing and, in my opinion, cut faster. I predict the diamond wheels will last considerably longer than this scenario.

Ken

[cbwx34]

...
Most recently, I needed to grind the bolster on my slicing knife. I was trying out the T2. I worked on the bolster handheld with the T2 snd DWF-200. The T2 did the job with flying colors. I arrived at this proficiency by a roundabout path. The Tormek videos were no help. I knew I could do the job with the Viel. I was able to rethink the operation to the Tormek. Using the Viel is perhaps a small bit faster. Doing the entire job with the Tormek is definitely more cost effective, assuming one already owns a Tormek and not a Viel.

I believe a skilled sharpener should be flexible enough to be proficient with multiple techniques.

Ken

You should make a video! 

Or at least a bit more info...  How much bolster did you need to remove?  Do you grind them flat, or do you shape the sides a bit?

Wondering how the T2 wheels hold up to heavy
work like reducing a bolster.  Do they maintain their
effectiveness. 

My .02...  I see it in part, like maybe reshaping some of the woodworking tools?

[cbwx34]

Tried it this way with a stamped knife using only the Tormek.  Hold knife perpendicular to a flat surface.
Run a fine point sharpie up between the 2 surfaces.  Set my angle at 30 deg. and only
ground where I saw sharpie mark. Repeat as necessary and reduce your angle as you
come closer to a true edge.  Done in under 5 minutes.   Would still recommend reducing bolster
first on a belt grinder for a forged knife.
Best wishes
Tim

That's a good idea.

Personally, I have better luck making repairs on the Tormek grinding at very high angles (which often means freehand), for things like tip repairs, and in this case removing recurves... the higher angle (or even perpendicular), keeps the stone from 'falling' into the recurve, plus I can see what I'm doing better.  You're spot on doing the initial work setting a higher angle IMO.

[Ken S]

Good post, CB. (Your last post came in while I was preparing mne. Must dash for now. I shall return.)

You are quite right; I should make a video. I have taught myself how to make them with my digital camera and ipad. I still have some learning to do with editing and posting them. I keep hoping that Tormek will make them. Tormek has decades of sharpening experience. They also have a studio. I do not understand their reluctance to make training videos. The getting started videos they made for the T7, T4, and T8 are very done, as are the DBS-22 video Alan Holtham did for them. The woodturning videos Jeff Farris did for them are, in my opinion, their gold standard.

If Tormek made these training videos, they would have content control. There are some very good videos online showing using the Tormek with other sharpening systems. A video by Tormek should show the Tormek doing all the operations. Video production appears to be low on the corporate priority totem pole.

With no false midesty, I can easily count the colsters I have reduced to the fingers on one hand, hardly a match for the factory. Incidentally, I also ground the sides of the bolsters a bit. The bolsters I ground were on the knives I use every day in the kitchen. The first one needed more work than subsequent knives. The first knife both focused my attention and gave me the confidence to do the job. Bolster work should be just a routine part of sharpening, as should minor curve correction. (I would add a surcharge for major curve repair.)

I agree, there will probably be more heavy grinding with woodworking tools. (How many bolsters does a farmers market sharpener grind on a typical Saturday morning? How many of those knives even have bolsters?

I have no expectations that a Tormek with a diamond wheel will match the grinding speed of a high speed dry grinder with a CBN wheel. However, I have been able to reshape a turning gouge on a Tormek with a CBN or Norton 3X wheel in only a couple minutes. That is plenty fast enough for me, and the Tormek cool, dust free environment makes the job pleasant.

Ken