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Removing hollows in the blade profile of a knife

Started by franzleo, August 17, 2012, 03:50:36 PM

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franzleo

One thing I find hard to do is to remove hollows in blades ; kitchen knives are particularly prone to a hollow just forward of the handle particularly if they have been sharpened by a steel. I have not had the Tormek very long and as yet I find keeping a straight edge leading up to the curve for the point one of the hardest things to do .
To date the easiest way I have found to true the edge of a blade is on a conventional stone . Does anyone have a trick that works to achieve an edge that is true - just to clarify when the edge is offered up to a sheet of glass or something else similarly flat the blade is in contact with the glass until it turns up towards the point.
My attempts so far have made the hollows worse in spite of concentrating on the high spots .
Would I do better using the tool rest so that the proud spots would come into contact before the hollows? I realise that although the machine is essentially straight forward to use there are subtleties that are mastered with experience

franzleo

I think I have cracked it now ! I centred the knife holder over the dip then I made sure it ran parallel with the desired profile and let it softly go onto the stone making sure everything was square on the resting bar then I concentrated on the rises (I raised the sharpening angle dramatically somewhere around 50˚) and I checked the progress after each pass-eventully getting a good flat profile . The next step was to lower the angle back to 17˚ and get the edge back .
The one thing I just cannot do and I think this is a limitation of the bit is to put a secondary bevel on the blade to effectively thin the blade to the primary bevel .
So out comes the Edge Pro and I put a secondary bevel of something like 10˚ ( the calibrations stop at 13˚) then I went back to the Tormek and honed the blade on the leather wheel.
This secondary bevel means that the amount of blade on the cutting edge is cut down so resharpening is a lot quicker and the knife has a better entry for cutting deep.

I am very pleased with both the Tormek and the Edge Pro since both have their strong points and there is a common ground between the two. The Edge Pro will cope with very curved or small blades and small scissors  but is not very good for chisels or for big repairs on a blade the Tormek is much better for that and a host of other tools .

So apart from fine serrated blades I feel pretty well covered (although it is possible to put a very fine bevel on the back of a serrated blade again I think more a job for the Edge Pro)

As for serrations I think unless one wants to spend huge amounts for an occasional thing I will make do with what I have.

One happy Tormek owner!

Herman Trivilino

It takes a bit of practice, especially with knives.  I've gotten to the point now that can pretty much free hand a knife.
Origin: Big Bang

Mike Fairleigh

Knives are perhaps the simplest of all cutting tools, yet they give me the most trouble with sharpening.  Especially those that benefit from a convex edge profile.
Mike

"If I had 8 hours to chop down a tree, I'd spend 7 sharpening my axe."  --Abraham Lincoln